case study for volcanic eruption

Volcanoes and volcanic eruptions - Eduqas Case study - volcanic eruption - La Palma, 2021

Composite and shield volcanoes are found along plate boundaries. They have distinctive characteristics and can have both positive and negative effects on people and the landscape.

Part of Geography Hazardous landscapes

Case study - volcanic eruption - La Palma, 2021

La Palma is one of the Canary Islands, which lie in the Atlantic Ocean. The Canary Islands are an autonomous region of Spain. The Cumbre Vieja volcano on La Palma erupted from the 19th September to the 13th December 2021.

• The Canary Islands have over 30 volcanoes, 10 of which lie on the island of La Palma.
• The volcanoes are unusual in that they are intraplate. This means that they are located above a ‘hot spot’ rather than along a plate boundary.
• Hot spots occur where columns of superheated magma, or mantle plumes, cause the Earth's crust to melt and become thinner.
• The Canary Island hotspot is located on the African plate, which is estimated to be moving between 2cm to 3cm per year.
• A build-up of magma swelled beneath the ground a week before the first eruption. Warnings were sent out and nearly 7,000 people evacuated the affected areas.

Increased vulnerability – physical factors

• An ‘earthquake swarm’ took place in the days and weeks before the eruption. This consisted of more than 20,000 earthquakes, some of which were sizeable.
• It was feared that the volcano could create a tsunami, which could reach Portugal and western African countries.
• Vigorous lava flows and explosive activity took place over a three-month period in total.
• Social - More than 7,000 people had to leave their homes. Over 1,300 homes were destroyed by the lava flow. Many other buildings, such as churches and schools, were damaged or destroyed.
• Economic - Hundreds of acres of farmland, including banana plantations, were destroyed. Flights were cancelled and tourist resorts closed, which affected the local economy.
• Environmental – Vast swathes of forest were destroyed by the lava. However, the molten rock increased the size of the island as it flowed into the ocean.

More guides on this topic

• Plate boundaries - Eduqas
• Earthquakes and tsunamis - Eduqas

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Report on La Palma (Spain) — October 2021

Bulletin of the Global Volcanism Network, vol. 46, no. 10 (October 2021) Managing Editor: Edward Venzke. Edited by A. Elizabeth Crafford. La Palma (Spain) First eruption since 1971 starts on 19 September; lava fountains, ash plumes, and lava flows

Please cite this report as: Global Volcanism Program, 2021. Report on La Palma (Spain) (Crafford, A.E., and Venzke, E., eds.). Bulletin of the Global Volcanism Network , 46:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN202110-383010

28.57°N, 17.83°W; summit elev. 2426 m

All times are local (unless otherwise noted).

Multiple eruptions have occurred during the last 7,000 years at the Cumbre Vieja volcanic center on La Palma, the NW-most of the Canary Islands. The eruptions have created cinder cones and craters, and produced fissure-fed lava flows that reached the sea a number of times. Eruptions recorded since the 15th century have produced mild explosive activity and lava flows that damaged populated areas, most recently at the southern tip of the island in 1971. During the three-week eruption in October-November 1971, eruptive activity created a new cone, Teneguia, that had as many as six active vents (CSLP 90-71), and blocky lava flows that reached the sea on the SW flank.

A new eruption began at La Palma on 19 September 2021 in an area on the SW flank of the island about 20 km NW of the 1971 eruption, after a multi-year period of elevated seismicity. Two fissures opened and multiple vents produced lava fountains, ash plumes, and flows that traveled over 5 km W to the sea, destroying hundreds of properties in their path (figure 2). Activity through the end of September is covered in this report with information provided by Spain’s Instituto Geographico Nacional (IGN), the Instituto Volcanologico de Canarias (INVOLCAN), the Steering Committee of the Special Plan for Civil Protection and Attention to Emergencies due to Volcanic Risk (PEVOLCA), maps from Copernicus EMS, satellite data, and news and social media reports.

Precursor seismicity. In early July 2017 IGN enhanced their Volcanic Surveillance Network at La Palma to include four GPS antennas, five seismic stations, and four hydrochemical groundwater control points. A seismic swarm of 68 events located on the southern third of the island was recorded during 7-9 October 2017. It was the first of a series of seismic swarms recorded during 2017-2021 (table 1) located in the same general area. This first swarm was followed by a similar set of events a few days later during 13-14 October. The magnitudes of the events during October 2017 (given as MbLg, or the magnitude from the amplitude of the Lg phase, similar to the local Richter magnitude) ranged from less than 1.5 to 2.7, and they occurred over a depth range of 12-35 km. The next seismic swarm of similar characteristics occurred during February 2018, followed by a smaller swarm of seven microseismic events recorded in the same area one year later, on 12 February 2019.

Table 1. Precursor seismicity episodes at La Palma between October 2017 and late June 2021 were all located in the southern third of the island. Magnitude is reported by IGN as MbLg, or the magnitude from the amplitude of the Lg phase, similar to the local Richter magnitude. Data courtesy of IGN Noticias.

By the time the next seismic swarm began in July 2020, IGN had a network of 13 seismic stations installed around the island. There were 160 located events that occurred during 24 July-2 August 2020 with magnitudes of 1.2-2.5 and depths of 16-39 km. Reprocessing of the previous data indicated a distribution of seismicity for the three series (October 2017, February 2018, and July 2020) in a wide strip in an east-west direction, although the October 2017 series occurred at a shallower depth and with the epicenters more concentrated. IGN noted similarities between the February 2018 and July-August 2020 events in terms of location and magnitude (figure 3). Another very similar swarm of 602 detected events was recorded during 23-26 December 2020, with most events located on the western slope of Cumbre Vieja. Two swarms on 21 January and 25 June 2021 had fewer events but similar depths and magnitudes to the earlier events.

Renewed seismicity began on 11 September 2021. The number, frequency, and magnitude of the events all increased over the next several days, while the depth of the events grew shallower. On 13 September a multi-agency scientific committee raised the Alert Level to Yellow (the second lowest level on a four-color scale) for the municipalities of El Paso, Los Llanos de Aridane, Mazo, and Fuencaliente de la Palma. IGN noted a migration of the seismicity toward the W side of the island on 14 September (figure 4). The accumulated surface deformation between 12 and 14 September measured 1.5 cm from the island GNSS network. Seismic activity on 15 September continued to migrate slightly NW at depths of around 7-9 km; in addition, 20 shallow earthquakes of 1-3 km depth were recorded. The accumulated deformation had reached 6 cm by 15 September. As of 0930 on 16 September 50 shallow earthquakes between 1-5 km depth had been located and the maximum vertical deformation was around 10 cm in the area of the seismicity. During 16-18 September seismic activity decreased, but a 3.2 magnitude earthquake located at 100 m depth was felt by the local population. Intense surface seismicity (between 0-6 km) increased in the early hours of 19 September and numerous earthquakes were felt by the local population (figure 4). The maximum accumulated deformation increased to 15 cm in the area close to the seismicity by 1100 on 19 September, and the eruption began about five hours later.

Eruption begins 19 September 2021. A fissure eruption began at 1510 local time (1410 UTC) on 19 September after the intense seismic and deformation activity that began on 11 September. Observers near the eruption site in the area of Cabeza de Vaca, in the municipality of El Paso, witnessed a large explosion with ejecta that produced a gas-and-ash plume. Strombolian activity was accompanied by phreatomagmatic pulses along two 100-m-long N-S fissures about 200 m apart. INVOLCAN scientists observed seven vents along the fissures during the initial stage of the eruption (figure 5). Multiple tall lava fountains fed flows downslope to the W, igniting fires. The PEVOLCA steering committee briefly raised the Alert Level to Orange, and then to Red by 1700 for high-risk municipalities directly affected by the eruption. About 5,500 people evacuated with no injuries reported, and authorities recommended that residents stay at least 2 km from the vents. INVOLCAN scientists determined an average flow rate of 700 m/hour and lava temperatures of around 1,075°C at the start of the eruption (figure 6).

The Toulouse VAAC issued the first ash advisory for the La Palma eruption about 90 minutes after it began. They reported ongoing lava fountains and an ash plume to about 1 km altitude. The plume drifted SW at less than 1.5 km altitude, while SO 2 emissions were reported drifting ESE at 3 km altitude. Later that day, they noted continuing intense lava fountains and ashfall in the vicinity of the volcano. The next day ash emissions drifted S at 2.4 km altitude. Sulfur dioxide emissions were measured by satellite instruments beginning on 19 September; they increased dramatically and drifted hundreds of kilometers E and SE toward the NE coast of Africa over the next few days (figure 7). Ongoing ash emissions rose to 4.6 km altitude later on 20 September. The first Sentinel-2 satellite images of the eruption appeared on 20 September showing a strong point source thermal anomaly partly covered by meteoric clouds (figure 8).

The first map of the new flow on 20 September produced by IGN in partnership with Copernicus Emergency Management Service (EMS) showed that the main channel of the lava flow had traveled more than 3 km W. The flows had covered about 1 km 2 and destroyed an estimated 166 buildings (figure 9). A report of the PEVOLCA Scientific Committee indicated that activity on 20 and 21 September was concentrated at four main vents that produced parallel flows with an average flow rate of 200 m/hour; the maximum flow thickness was 10-12 m (figure 10). Strong lava fountaining continued both days and ash fell in the vicinity of the vents. By 0814 on 21 September an updated Copernicus EMS map showed that 350 homes had been covered by lava and the flow field had expanded to 1.54 km 2 . A few hundred more residents evacuated as lava advanced towards Tacande; bringing the number of evacuees to about 5,700. One lava flow branch was advancing slowly S at a rate of 2 m/hour. An ash cloud was observed later that day on the W flank of the volcano slowly drifting SW at 2.4 km altitude. Sulfur dioxide emissions were present over the SE part of the island and were visible at Gomera Island, 80 km SE. Late in the day, ash was observed in satellite imagery about 50 km W of the volcano, while intense lava fountaining continued at the source vent (figure 11).

Activity during 22-25 September 2021. Ash emissions during 22 and 23 September drifted SW and S from 0-3 km altitude, and NE and E from 3-5 km altitude (figure 12); ashfall up to 3 cm thick was reported downwind. An SO 2 plume was also noted drifting NE in satellite imagery. PEVOLCA reported on 23 September that two relatively slow-moving lava flows continued to advance downslope from the vent (figure 13). The northernmost flow was moving at 1 m/hour and was 12 m high and 500 m wide in some places. The southern flow, which surrounded Montaña Rajada, was moving at 4-5 m/hour and about 10 m high. The overall flow was 3.8 km long and 2.1 km from the coast (figure 14). By late on 23 September reports indicated 420 structures had been destroyed and the flow covered just under 2 km 2 .

Lava fountains rose hundreds of meters above the summit crater of the new cone early on 24 September 2021 (figure 15). IGN reported an increase in explosive activity on 24 September that was accompanied by a sharp increase in tremor amplitude. This was followed a short while later by the opening of two new vents on the NW flank of the cone; the fast-moving flows merged into one and produced a new flow over top of the earlier flows. Part of the upper section of the S flank of the cone collapsed on 24 September and briefly caused flow speeds to increase to 250-300 m/hour overnight before slowing to an average speed of 40 m/hour. Due to the fast-moving flow, an evacuation order was issued in the early afternoon for Tajuya, Tacande de Abajo, and part of Tacande de Arriba, affecting 300-400 people. Three airlines also suspended flights to La Palma. The Toulouse VAAC reported ash plumes throughout the day. Ash plumes drifted SW below 3 km altitude and E and SE at 3-5.2 km altitude and resulted in significant ashfall in numerous locations by the next morning (figure 16). Pilots also reported ash near Tenerife and over La Gomera.

By 25 September there were three active vents in the crater and one on the flank of the cone (figure 17), and two active lava flows. On 25 and 26 September dense ash emissions (figure 18) closed the airport and produced ashfall not only in the municipalities near the eruption, but also on the eastern slope of the island; it was reported in Villa de Mazo, Breña Alta and Breña Baja, and Santa Cruz de La Palma or Puntallana. Plumes were drifting SW at altitudes below 1.5 km and NE between 1.5 and 3.9 km altitude over a large area. Mapping by Copernicus EMS indicated that the ashfall covered an area of 13 km 2 (figure 19).

Activity during 26-28 September 2021. During the evening of 26 September jets of lava up to 1 km high were visible from La Laguna and some explosions were strong enough to be felt within 5 km of the vent (figure 20). The main, more northerly lava flow overtook the center of Todoque, in the municipality of Los llanos de Aridane, which had been evacuated several days earlier. It crossed the highway (LP-213) in the center of town and continued 150 m W. It was initially moving at about 100 m/hour, was 4-6 m high, and the front was about 600 m wide, but it slowed significantly after crossing through Todoque, and the height grew to 15 m; it was located about 1,600 m from the coast. The more southerly flow continued moving at about 30 m/hour and was about 2.5 km long.

The PEVOLCA Scientific Committee determined that the volume of erupted material from the beginning of the eruption on 19 September until 27 September was about 46.3 m 3 . By early on 27 September the front of the flow was close to the W side of Todoque Mountain (figure 21), and reports indicated that 589 buildings and 21 km of roads had been destroyed by the 2.5 km 2 of lava. A seismic swarm on the morning of 27 September was located at about 10 km depth in the same area of the previous seismicity below the vent. In addition, pulses of tremor coincided with pulses of ash emissions. A new flow appeared on the N flank of the cone during the afternoon and partly covered previous flows through the center of Todoque, reaching about 2 km from the coast (figure 22). Ash emissions were more intermittent on 27 and 28 September, drifting SW to 1.5 km altitude and NE to 4.3 km altitude in sporadic pulses associated with lava fountains.

The new flow moved through the upper outskirts of Todoque and had reached the road to El Pampillo on the border of the municipalities of Los Llanos and Tazacorte, about 1 km from the coast, early on 28 September (figure 23). A plume with moderate to high ash concentration rose to 5.2 km altitude and extended up to 25 km W. The altitude of the plume increased to 6.1 km drifting E later in the day. A significant SO 2 cloud was clearly identifiable in satellite imagery in a 75 km radius around the island. In addition, satellite instruments measured very large plumes of SO 2 drifting hundreds of kilometers E, S, and N over the next several days (figure 24).

Activity during 28-30 September 2021. Effusive activity continued with a sharp decrease in tremor during the day on 28 September. By evening, sustained fountaining was continuing at the N flank vent, while pulsating jets from three vents within the main crater produced strong effusion into both lava flows. The volume of the cone that had formed at the vent was estimated by PEVOLCA to be 10 million m 3 . Around 2300 local time on 28 September the main lava flow passed on the S side of Todoque Mountain and entered the sea in the area of Playa de Los Guirres in Tazacorte. A continuous cascading flow of lava fell over the cliff (figure 25) and began to form a lava delta. By dawn on 29 September the delta was growing out from the cliff, producing dense steam explosions where the lava entered the sea (figure 26).

By nightfall on 29 September vigorous Strombolian activity was continuing at the pyroclastic cone, and the main lava flow was active all the way to the sea, with a growing delta into the ocean. Ash emissions continued on 29 and 30 September, rising in pulses to 5.2 km altitude and drifting SE, changing to S, SW, and finally NW. Sentinel-2 satellite imagery comparing 25 and 30 September showed the growth of the lava flow during that interval (figure 27). Strombolian and flow activity continued at the fissure vent on 30 September with new surges of activity sending fresh pulses of lava over existing flows (figure 28). The ocean delta continued to grow and reached a thickness of 24 m by the end of 30 September. Mapping of the flow indicated that 870 buildings had been destroyed and the flow covered 3.5 km 2 by midday on 30 September (figure 29).

Late on 30 September 2021 two new vents emerged about 600 m NW of the base of the main cone. They created a new flow about 450 m away from, and parallel to, the main flow that crossed a local highway by the next morning and continued moving W (figure 30). Multiple vents also remained active within and on the flank of the main cone. As of 1 October, the front of the delta was 475 m out from the coastline and 30 m deep. IGN concluded that the volume of material erupted through the end of September was approximately 80 million m 3 .

Geological Summary. The 47-km-long wedge-shaped island of La Palma, the NW-most of the Canary Islands, is composed of two large volcanic centers. The older northern one is cut by the steep-walled Caldera Taburiente, one of several massive collapse scarps produced by edifice failure to the SW. On the south, the younger Cumbre Vieja volcano is one of the most active in the Canaries. The elongated volcano dates back to about 125,000 years ago and is oriented N-S. Eruptions during the past 7,000 years have formed abundant cinder cones and craters along the axis, producing fissure-fed lava flows that descend steeply to the sea. Eruptions recorded since the 15th century have produced mild explosive activity and lava flows that damaged populated areas. The southern tip of the island is mantled by a broad lava field emplaced during the 1677-1678 eruption. Lava flows also reached the sea in 1585, 1646, 1712, 1949, 1971, and 2021.

Information Contacts: Instituto Geographico Nacional (IGN) , C/ General Ibáñez de Íbero 3, 28003 Madrid – España, (URL: https://www.ign.es/web/ign/portal, https://www.ign.es/web/resources/volcanologia/html/CA_noticias.html); Instituto Volcanologico de Canarias (INVOLCAN) (URL: https://www.involcan.org/, https://www.facebook.com/INVOLCAN, Twitter: INVOLCAN, @involcan); Steering Committee of the Special Plan for Civil Protection and Attention to Emergencies due to Volcanic Risk (PEVOLCA) , (URL: https://www3.gobiernodecanarias.org/noticias/los-planes-de-evacuacion-del-pevolca-evitan-danos-personales-en-la-erupcion-volcanica-de-la-palma/); NASA Global Sulfur Dioxide Monitoring Page , Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); Copernicus EMS (URL: https://emergency.copernicus.eu/, https://twitter.com/CopernicusEMS ); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); Cabildo La Palma (URL: https://www.cabildodelapalma.es/es/algunas-de-las-imagenes-de-la-erupcion-volcanica-en-la-palma); El Periodico de Cataluny, S.L.U. (URL: https://www.elperiodico.com/es/fotos/sociedad/erupcion-palma-imagenes-12093812/12103264). Corporación de Radio y Televisión Española (RTVE) (URL: https://rtve.es, https://img2.rtve.es/imagenes/casas-todoque-alcanzadas-lava-este-miercoles-22-septiembre/1632308929494.jpg); Tom Pfeiffer , Volcano Discovery (URL: http://www.volcanodiscovery.com/); Volcanes de Canarias (URL:https://twitter.com/VolcansCanarias/status/1441711738983002114); Agence France-Presse (AFP) (URL: http://www.afp.com/ ); Bristol Flight Lab , University of Bristol, England (URL: www.https://flight-lab.bristol.ac.uk, https://twitter.com/UOBFlightLab).

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When Kilauea Erupted, a New Volcanic Playbook Was Written

Scientists learned lessons from the 2018 outburst on the island of Hawaii that are changing how responders prepare for eruptions in other places.

By Robin George Andrews

Back in the summer of 2018, Wendy Stovall stood and stared into the heart of an inferno.

Hawaii’s Kilauea volcano had been continuously erupting in one form or another since 1983. But from May to August, the volcano produced its magnum opus , unleashing 320,000 Olympic-size swimming pools’ worth of molten rock from its eastern flank.

Dr. Stovall, the deputy scientist-in-charge at the U.S. Geological Survey’s Yellowstone Volcano Observatory , recalls moments of being awe-struck by the eruption’s incandescence: lava fountains roaring like jet engines, painting the inky blue sky in crimson hues. But these briefly exhilarating moments were overwhelmed by sadness. The people of Hawaii would suffer hundreds of millions of dollars in economic damage. The lava bulldozed around 700 homes. Thousands of lives were upended. Even the headquarters of the Hawaiian Volcano Observatory itself, sitting atop the volcano , was torn apart by earthquakes early in the crisis.

Like many volcanologists who were there during the eruption, Dr. Stovall is still processing the trauma she witnessed. Sadness is not quite the right word to describe what she feels, she said: “Maybe it’s an emotion that I don’t even have a word for.”

But not only trauma has resulted from the crisis: It has also produced something of a sea change in the way scientists and their emergency services partners are able to respond to volcanic emergencies.

During Kilauea’s devastating outburst, responders found novel ways to deploy drones and used social media to help those in the lava’s path. They also achieved more ineffable insights into how to keep cool in the face of hot lava. And this pandemonium of pedagogical experiences will prove valuable in times to come. The United States is home to 161 active or potentially active volcanoes — approximately 10 percent of the world’s total. When — not if — a Kilauean-esque outburst or something more explosive takes place near an American city, scientists and emergency responders will be better prepared than ever to confront and counter that volcanic conflagration.

A Patchwork of Fire

In volcano preparedness, knowing where the next socially disruptive eruption may take place is half the battle.

Not all of America’s active volcanoes are equally hazardous. Many in Alaska are situated on extremely remote islands . The Yellowstone supervolcano may sound frightening, but this cauldron does not deserve to be a boogeyman. “The odds of a supereruption happening are infinitesimally small,” said Emilie Hooft , a geophysicist at the University of Oregon.

California is home to at least seven potentially active volcanoes. Although they are “mostly where the people aren’t, a lot of California’s infrastructure crosses these volcanic zones,” said Andy Calvert , the scientist-in-charge at the Geological Survey’s California Volcano Observatory. An eruption at any of them could destroy power lines, highways, waterways and natural gas pipelines.

The volcanoes of the Pacific Northwest are not dissimilar to bombs lingering in the background of populous American ports, towns and cities. Some, like Mount St. Helens , are infamous for giant explosions and superheated, superfast exhalations of noxious gas and volcanic debris.

Others, like Washington State’s Mount Rainier, are more insidious. The volcano is known for making concrete-like slurries called lahars , in which freshly erupted ash mixes with snow or rainwater and gushes downslope, consuming everything in its path. These lahars “are a huge and real hazard,” Dr. Hooft said. Populous settlements within or at the terminus of the volcano’s many valleys, including parts of the Seattle-Tacoma metropolis, are built on ancient lahar deposits — and as the geologist’s refrain goes, the past is the key to the present.

Another major concern is America’s poorly understood volcanic fields: sprawling collections of cones, craters and fissures nestled between countless towns stretching from California to Washington State. Except for Mount St. Helens, said Dr. Stovall, “it is statistically more likely that an eruption will occur from any one of these volcanic fields than from one of the charismatic stratocones of the Cascades.”

While constantly watching Kilauea , the eyes of the Hawaiian Volcano Observatory also remain fixed on Mauna Loa, Kilauea’s colossal neighbor.

It has not erupted since 1984 — a disquietingly long pause. But in recent years, Mauna Loa has been grumbling. Several of this titan’s lava flows have come agonizingly close to obliterating the city of Hilo in the past century, and although they have serendipitously stopped short , they may one day succeed.

When Ken Hon , the scientist-in-charge at the Hawaiian Volcano Observatory, was asked if a future Mauna Loa eruption concerned him, he replied with a question of his own.

“Are you wary of a tiger when it’s sleeping?” he said. “It’s a sleeping tiger in your yard, and there’s no cage, and you’re just kind of watching it.”

A Kilauean Education

Fortunately, the lessons learned from the 2018 eruption have strengthened the armor of America’s volcanic vanguard.

Kilauea took not just the Hawaiian Volcano Observatory but the entire U.S. Geological Survey to school. During the 2018 crisis, staff from the Alaska, California, Cascades and Yellowstone observatories headed to Hawaii to assist, like white blood cells from throughout the body rushing to the site of a pathogen’s incursion. Despite some parts of America not seeing an eruption for over a century, this across-the-spectrum response allowed scientists from the Geological Survey to “keep the tools sharp,” Dr. Calvert said.

Hawaii’s lava factories are now better understood. They may sometimes be the deliverers of destructive horrors, but “volcanic eruptions are this amazing opportunity for scientists to do basic research,” said Ken Rubin , a volcanologist at the University of Hawaii at Manoa. The eruption in 2018, revealed that “there’s a lot of ways this volcano can operate,” he said.

Some key observations made during the 2018 crisis are likely to apply to countless other volcanoes, including those enigmatic volcanic fields on the West Coast. For instance, Kilauea stopped erupting despite retaining most of its magma . A change in the rhythm of its seismic soundtrack also revealed changes in the magma’s gloopiness , a key factor in an eruption’s explosive capacity. Monitoring such changes may help forecast how future eruptions will evolve, and how long they will continue once they start.

Kilauea’s outburst also changed the way scientists communicate with the public.

“It was the first big eruption we’ve had in the social media age,” said Tina Neal , director of the Geological Survey’s Volcano Science Center. During the eruption, her colleagues provided a constant stream of updates on Facebook and Twitter, debunking misconceptions and rumors. This proved to be one of the most effective ways of providing lifesaving advice to those fleeing the eruption.

“I’ll admit that I was skeptical of spending too much time delivering information via social media,” said Ms. Neal, who was the Hawaiian Volcano Observatory’s scientist-in-charge during the 2018 eruption. She was concerned that in doing so she would mainly be catering to curious but unaffected parties further afield.

But she said she was happy to be proved wrong — and added that she thinks the Geological Survey’s volcanologists now have an effective social media operation that can spring into action whenever a volcano starts twitching.

Drones and Tweets

The 2018 crisis also kick-started a nationwide technological revolution. It had long seemed strange to Angie Diefenbach , a geologist at the Cascades Volcano Observatory, that management did not appear to see the value of using drones to study erupting volcanoes in the United States, particularly as academics both inside and outside the country had been doing just that for several years.

Kilauea’s dramatic eruption was a paradigm-shifting moment. Ms. Diefenbach, who was already equipped with a pilot’s license, was sent to the effervescing volcano with a handful of keen colleagues and a small fleet of flying robots.

The pilots had a steep learning curve. The drones frequently flitted over the incandescent fury emerging from fissure eight, one of the two dozen cracks in the volcano’s flank, to film the seemingly endless flow of lava and sniff the chasm’s noxious gases.

“That fissure eight plume was intense, and the river of lava was extremely hot,” Ms. Diefenbach said. Every now and then, an upswell of heat would knock the levitating robots skyward by a couple hundred feet, threatening a loss of control that might plunge them into molten rock. Fortunately, they all survived to fly another day.

Immediately, she said, the powers that be recognized that drones “really add a fundamental piece to the story” for volcano monitoring. Bird’s-eye views of lava flows allowed scientists to study the evolution of the eruption in real time. And communities in the path of the lava could be given advance warning; at one point, a man trapped in his home at night and surrounded by lava was led by a drone through the maze of molten rock to safety.

Ms. Diefenbach, who works with uncrewed aircraft systems like drones for the Volcano Science Center, is now training more drone pilots across all five volcano observatories. While awaiting the next socially disruptive eruption, some of her drones are being used to study volcanoes that could one day reawaken, including inaccessible snowcapped peaks in Alaska.

Meandering Paths Forward

This is not to say that the scientists of the U.S. Geological Survey have been “twiddling their thumbs waiting” for a ruinous eruption like Kilauea, Ms. Neal said.

The agency’s staff are working constantly with their academic partners to improve their understanding of America’s fiery mountains. They are also continually learning from the way other countries respond to their own volcanic crises . The scientists regularly team up with emergency managers to conduct drills, including the annual evacuation exercises near Mount Rainier.

But the path to volcanic enlightenment is not a straight line. Although all of America’s active volcanoes are monitored, some considered to be high risk are not adorned with sufficient sensors. This can be a result of budgetary constraints, the difficulty of instrumenting treacherous volcanoes and, in some cases, red tape preventing the placement of sensors in wilderness areas.

“There are some volcanoes where we’re more at the starting line,” said Seth Moran , a seismologist at the Cascades Volcano Observatory, citing Washington’s Glacier Peak and Mount Baker .

Climate change and California’s increasingly intense wildfires are also aggravating the situation. A newly installed ground deformation sensor on Mount Shasta, for example, was taken out by this summer’s furious Lava fire , Dr. Calvert said.

Despite these setbacks, the Geological Survey continues to strengthen its monitoring efforts, with its network of instruments on several particularly hazardous volcanoes being upgraded and expanded . It also participates in tabletop exercises to test everyone’s mettle. One that took place over several days last November pitted scientists against a hypothetical eruption of Oregon’s Mount Hood.

Like the Kilauean eruption, this virtual volcanic gauntlet served up an underappreciated reminder: The people responding to volcanic crises may have extraordinary skill sets, but they are not superhuman.

“The general feeling afterwards was just of overwhelming exhaustion,” said Diana Roman , a geophysicist at the Carnegie Institution for Science and one of those who ran the exercise. “And that was part of the point.”

When it comes to America’s readiness for the next eruption, preparing scientists psychologically for the reality of a prolonged volcanic crisis is a necessity.

In 2004, when Mount St. Helens began to cough and splutter in a concerning manner, Dr. Moran became wrapped up in a surfeit of tasks. “It was about week three when my wife brought our kids to say good night to me,” he said. “That was my indication that I was probably doing too much. I should at least be able to get home and say good night to my kids.”

These experiences have taught Dr. Moran and his colleagues an invaluable lesson: “You can’t have people getting burned out right off the bat,” he said. Giving individuals clear roles ahead of time, and making their teams small and manageable, will hopefully prevent this sort of exhaustion in the future.

Though it’s not only scientists who can get drained during lengthy volcanic eruptions. As the weariness over the pandemic is grimly demonstrating , “it’s hard to keep people’s attention on something for a long time,” said Brian Terbush , the program coordinator for earthquakes and volcanoes at Washington State’s Emergency Management Division. “They get really tired of it. I’m tired of it.”

And protecting the public is considerably more difficult if people are not paying attention.

Fires of the Future

The location, timing and effects of America’s next volcanic disaster remain unknown. Even after a significant eruption begins, forecasting its evolution will be difficult.

“Even on the world’s best instrumented volcano,” said Dr. Hon, referring to Kilauea, “we still don’t really understand it that well.”

And yet, despite having so many dangers and complications to contend with, no one died and thousands of lives were saved during the 2018 crisis.

Those who were involved in the Kilauea response hope that the public will remember the role geoscientists played during the next volcanic emergency and see them as trustworthy protectors.

Not everyone will. “We often get told that we’re lying, and we’re hiding things, because we’re the government,” said Dr. Stovall — an uncomfortable echo of the similarly unfounded charges of conspiracy that many have directed toward public health professionals during the pandemic.

But the volcanologists and their peers say they will remain unwavering in their mission to decipher the country’s beguiling but occasionally menacing volcanoes.

“We are doing our best,” Dr. Stovall said. “And we’re in it for the greater good.”

An ash cloud rises over the lake as Taal Volcano erupts in the Philippines on January 12. The ongoing eruption is blanketing the region with debris and has already spurred evacuations, school closings, and flight cancellations.

What the Philippines volcano ‘worst-case scenario’ could look like

With millions of people at risk, experts are looking to past big eruptions to better understand the unique hazards this peak can produce.

Normally, the view from the webcam sitting inside Lake Taal in the Philippines shows clouds drifting over the lake’s placid waters, as verdant slopes rise in the distance. But on the afternoon of January 12, this peaceful scene was suddenly interrupted by a torrent of hot ash and gas, before the camera was smothered by darkness.

The outpouring marked the beginning of an unnerving eruption sequence at Taal Volcano, which sits on the island of Luzon. On the first day, steam-driven blasts flung ash nine miles into the sky . Startling displays of volcanic lightning ricocheted around this dark maelstrom , and a myriad of intense volcanic earthquakes rocked the region. On January 13, the eruption became somewhat more magmatic, as lava fountains started shooting up from the main crater.

Ash continues to blanket the Philippines as of press time, including in the capital city of Manila , about 62 miles north of the volcano. Flights have been cancelled, schools and other public institutions have closed, and tens of thousands of people have been evacuated from both the volcanic isle within Lake Taal and from the vast shorelines around it.

So far, no casualties have been reported, and there is a chance this eruption could fizzle out. Still, many people likely remain in high-risk zones, and “the biggest bang is not always at the beginning of an eruption,” says Jenni Barclay , a volcanologist at the University of East Anglia. “On a timescale much longer than the threat of a hurricane, something else could happen that’s even bigger.”

Past eruptions at Taal demonstrate that this volcano has a profoundly lethal capability, claiming thousands of lives throughout recorded history. If the latest event does become more explosive—a possibility that has scientists deeply concerned—it could yield a surfeit of volcanic hazards, from rocky debris bouncing across the lake to overwhelming tsunamis.

“This is definitely a volcano to be taken seriously,” says Beth Bartel , an outreach specialist at UNAVCO , a geoscientific consortium of universities and scientific institutions.

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Telling taal tales.

With a plentiful supply of magma, Taal is one of the Philippines’ most active volcanoes , having erupted dozens of times in the past few centuries. Some of those past eruptions rank among the most powerful in the country’s history. But Taal Volcano is visually deceptive.

Many of these historical eruptions took place on the volcanic island in the middle of the more expansive Lake Taal. However, the entire volcano is far larger than this rocky outpost; it is a giant cauldron-shaped edifice known as a caldera. Much of the caldera is hidden by Lake Taal, and only a small portion of the volcano sits above the waves.

This is a problem not only for those who live on the central volcanic isle, but also for the 25 million people living within 60 miles of the volcano, including a huge number on Lake Taal’s shorelines.

Due to the continuing intense volcanic earthquakes and eruptive activity, the Philippine Institute of Volcanology and Seismology, or PHIVOLCS , has set the alert level to four , meaning that a hazardous explosive eruption is possible within hours to days.

A link to the past

To understand what that might mean, experts can look to the past for hints. The most recent past eruption at Taal was a minor steam-driven event in 1977, notes Ed Venzke , the database manager at the Smithsonian Institution’s Global Volcanism Program.

While there may not have been an eruption for four decades, the volcano has “clearly been restless for a very long time,” says Amy Donovan , an expert in volcanic risk at the University of Cambridge. Although often moderate when compared to other volcanic eruptions, many of Taal’s paroxysms have been violently explosive and, due to the huge number of people living on or close to it, frequently fatal.

Greater ash production that often accompanies bigger booms will exacerbate matters. Ash can pollute water supplies, damage electronic infrastructure, smother agriculture, and kill off farm animals and pets . It can also kill people if they inhale enough of it; breathing in glassy ash is always bad, but people with pre-existing respiratory ailments are most at risk, as are the very young and the elderly.

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Either through explosive mixing of magma and water, or through magmatic activity alone, Taal has also previously produced thundering, high-velocity clouds of hot ash, debris, and gas named pyroclastic flows that have killed thousands of people in mere moments. Boris Behncke , a volcanologist at Italy’s National Institute of Geophysics and Volcanology, shared some examples on Twitter , including flows from a 1911 eruption that killed 1,335 people on the central island.

A reasonable worst-case scenario would not just feature pyroclastic flows, but also low-altitude surges of ash and scorching gas that, due to their low density, can literally bounce over the water , says Donovan. These base surges—a term borrowed from nuclear explosion science—“can sandblast everything in their path, including the lake shore on the other side,” Bartel says.

What’s more, if explosions dislodge parts of the volcanic island that then fall into Lake Taal, that could generate tsunamis that will swamp the lake’s shorelines. As an eruption at Indonesia’s Anak Krakatau showed in December 2018 , it only takes a small volcanic collapse to generate a lethal tsunami.

Even if there is no tsunami, falling debris and volcanic earthquakes can cause peculiar and potentially destructive waves known as seiches ; if that debris has enough energy, it can miss the lake entirely and instead land directly on shore.

Back to Taal's future

Of course, forecasting eruptions is fraught with difficulty . Donovan points out that we don’t know how the properties of the magma under Taal have changed since the 1977 eruption. And while looking to old eruptions for clues is helpful, the past can only tell you so much.

“Every eruption is different,” Venzke says. “There’s nothing guaranteed.”

It’s possible that this grim future may not transpire, and that we’ve seen the worst of what Taal has to offer this time, Donovan says: “It might just generate a bit of ash, have a few fire fountains, then go back to sleep again.”

Every eruption is different. There's nothing guaranteed. Ed Venzke , Smithsonian Institution Global Volcanism Program

Alternatively, what we are seeing here could perhaps be the opening salvo of a far longer eruption sequence, says James Hickey , a geophysical volcanologist at the University of Exeter. And even if the eruption becomes more explosive, some, all, or none of these hazards may occur.

Still, it is sensible for people in the region to assume the worst-case scenario is unfolding and to take reasonable, responsible action, Donovan says. If you are still around Taal and haven’t yet heeded instructions to evacuate , it's best to immediately get away from low-lying areas near the volcano. Always listen to local authorities for updates.

In the meantime, volcanologists will wait with bated breath, since lessons from the past show just how dangerous this particular peak can be.

“When I saw yesterday that Taal was in eruption,” Bartel says,” I was somewhat horrified.”

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Case Studies Highlighting Impacts of Volcanic Ashfall, Gas & Vog

Case studies of past impacts and mitigation strategies for specific eruptions are given here. Sector specific information from these case studies also appear under their relevant topic headings (topics on the left).

Each case study begins with a brief overview discussing the size and volume of ash dispersed where known or approximated. Specific impact & mitigation information is organized into the following categories (where it is reported):

• Agriculture – Plants & Animals – includes livestock, pastoral land, horticulture and forestry.
• Health – direct and indirect from exposure.
• Infrastructure – may be summarised or some or all of the following are detailed depending on complexity
• Equipment & Communications
• Power supply
• Transportation
• Water & Wastewater
• Cleanup & Disposal
• Remobilization and coping with long-term ash – includes water and wind remobilised ash.
• Eyewitness &ndash Accounts from eruptions where available.
• Emergency management – monitoring, response during the eruption and recovery post eruption.

Please contact the Ash Web Team if you would like to contribute additional case study information. We are always looking for additional information.

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• 2.1 Earthquakes and volcanoes
• 2.4 Weather
• 2.5 Climate and natural vegetation
• Distribution
• Plate Tectonics
• Plate Boundaries | Plate Margins

Volcano case study - Mount Etna (2002-2003), Italy

• Volcano case study - Mount Nyiragongo, Democratic Republic of Congo
• Volcanic hazard management - Mount Rainier, USA
• Earthquakes
• Earthquake case study - 2005 Kashmir
• Earthquake case study - Chuetsu Offshore Earthquake - 2007
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• Earthquakes - Managing the hazard

Can you describe the location of Mount Etna? Could you draw a sketch map to locate Mount Etna?

Case study task

Use the resources and links that can be found on this page to produce a detailed case study of the 2002-2003 eruption of Mount Etna. You should use the 'Five W's" subheadings to give your case study structure.

What happened?

The Guardian - Sicilian city blanketed in ash [28 October 2002]

When did it happen?

Immediately before midnight on 26 October 2002 (local time=GMT+1), a new flank eruption began on Mount Etna. The eruption ended after three months and two days, on 28 January 2003.

Where did it happen?

The eruption occurred from fissures on two sides of the volcano: at about 2750 m on the southern flank and at elevations between 2500 and 1850 m on the northeastern flank.

Why did it happen?

Mount Etna is a volcano. The reasons why Mount Etna is located where it is are complex. Here are some of the theories:

• One theory envisages a hot spot or mantle-plume origin for this volcano, like those that produce the volcanoes in Hawaii.
• Another theory involves the subduction of the African plate under the Eurasian plate.
• Another group of scientists believes that rifting along the eastern coast of Sicily allows the uprise of magma.

Who was affected by it happening?

• The Italian Government declared a state of emergency in parts of Sicily, after a series of earthquakes accompanying the eruption of forced about 1,000 people flee their homes.
• A ship equipped with a medical clinic aboard was positioned off Catania - to the south of the volcano - to be ready in case of emergency.
• Emergency workers dug channels in the earth in an attempt to divert the northern flow away from the town of Linguaglossa.
• Schools in the town have been shut down, although the church has remained open for people to pray.
• Villagers also continued their tradition of parading their patron saint through the streets to the railway station, to try to ward off the lava flow.
• Civil protection officials in Catania, Sicily's second-biggest city, which sits in the shadow of Etna, surveyed the mountain by helicopter and were ready to send water-carrying planes into the skies to fight the fires.
• The tourist complex and skiing areas of Piano Provenzana were nearly completely devastated by the lava flows that issued from the NE Rift vents on the first day of the eruption.
• Heavy tephra falls caused by the activity on the southern flank occurred mostly in areas to the south of the volcano and nearly paralyzed public life in Catania and nearby towns.
• For more than two weeks the International Airport of Catania, Fontanarossa, had to be closed due to ash on the runways.
• Strong seismicity and ground deformation accompanied the eruption; a particularly strong shock (magnitude 4.4) on 29 October destroyed and damaged numerous buildings on the lower southeastern flank, in the area of Santa Venerina.
• Lava flows from the southern flank vents seriously threatened the tourist facilities around the Rifugio Sapienza between 23 and 25 November, and a few days later destroyed a section of forest on the southwestern flank.
• The eruption brought a heightened awareness of volcanic and seismic hazards to the Sicilian public, especially because it occurred only one year and three months after the previous eruption that was strongly featured in the information media.

Look at this video clip from an eruption on Mount Etna in November 2007.  What sort of eruption is it?

There is no commentary on the video - could you add your own explaining what is happening and why?

You should be able to use the knowledge and understanding you have gained about 2002-2003 eruption of Mount Etna to answer the following exam-style question:

In many parts of the world, the natural environment presents hazards to people. Choose an example of one of the following: a volcanic eruption, an earthquake, or a drought. For a named area, describe the causes of the example which you have chosen and its impacts on the people living there. [7 marks]

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White Island Volcano Case Study

New Zealand’s Whakaari/White Island volcano erupted on Monday 9th December 2019. The strato or composite volcano, located on New Zealand’s east coast, erupted at 14:11 NZDT on 9 December 2019.

Whakaari lies at the northern end of the North Island’s ‘line of fire’ – a large volcanic plateau which stretches from the Bay of Plenty on the coast, to Mt Ruapehu inland. The line of fire forms part of the wider ‘Ring of Fire’ around the Pacific ocean.

It also has a water-filled crater lake. When water reacts with hot rock or magma, it can create explosions, and therefore, can make eruptions even more difficult to forecast.

The uninhabited island covers an area of approximately 325 ha (800 acres),  which is only the peak of a much larger submarine volcano. 

White Island is privately owned. It was declared a private scenic reserve in 1953. Visitors cannot land without permission, however, it is accessible by authorised tourist operators by boat and helicopter.

Why did White Island volcano erupt?

There are several volcanoes in New Zealand, like White Island, that have the ability to produce sudden explosive eruptions at any moment. In the case of White Island, the magma is very shallow, and the heat and gases produced by it affect ground and surface water to create vigorous hydrothermal systems.

Water is trapped in a super-heated state in pores of the rocks. An external influence, such as gas input from below, an earthquake or a change in water level can release the pressure on the hot water trapped below.

Experts identified the event as a phreatic eruption. A phreatic eruption involves the release of steam and volcanic gases which caused an explosion, launching rock and ash 3km into the air. The speed of the expansion of water into steam is supersonic, and the liquid can expand to 1,700 times its original volume. The expansion energy is enough to shatter solid rock, create craters and throw volcanic material several kilometres away.

What were the impacts of the eruption of White Island?

It was reported that there were 47 people on the island when the eruption occurred. Eighteen people were killed and a further 26 were seriously injured, many critically. Many of the surviving tourists on the island experienced burned lungs from inhaling sulphur dioxide and volcanic ash, and “very significant” deep-tissue burns, some to more than half of their body. Twenty-seven of the 31 people injured in the eruption of the Whakaari/White Island volcano had burns to more than 30% of their body.

The bodies of two victims have not been recovered and may have been lost to the sea.

The ongoing seismic and volcanic activity in the area and subsequently heavy rainfall as well as low visibility and toxic gases all hampered recovery efforts.

What are the long-term impacts of the eruption?

It is too early to say what the long term impacts of the eruption will be, however, there is likely to be a negative economic impact on the companies providing island tours.

What were the immediate responses to the eruption of the White Island volcano?

23 people were rescued from the island. It was estimated that there were less than 50 people on the island at the time of the eruption.

Seven helicopters were dispatched to the island by St John Ambulance.

Tour operators rescued people roughly 15 minutes after the eruption.

A national warning was issued for the eruption

Aviation authorities implemented a 26 nautical mile no-fly zone around the island to help rescue crews. White Island is 22 nautical miles offshore.

The New Zealand Red Cross activated the Family Links website for those concerned that their loved ones may have been caught up in the incident.

The military deployed drones at first light the following day to assess the situation on the ground.

A team of six New Zealand soldiers wearing breathing apparatus and special fire-retardant suits battled heat stress as they recovered six of the victims of the Whakaari/White Island volcano eruption four days after the eruption.

Australia offered additional support to the New Zealand medical services after requests from the New Zealand government.

New Zealand health authorities reportedly ordered 1.2 million sq cm of skin from the US in order to treat those injured: 27 of whom had burns to more than 30% of their body, with some having burns to 90-95% of their body. For context, experts say the palm of a hand is about 1.5% of the area of the body.

Why were there no warnings?

In this age of technology and volcanic monitoring , it seems strange that there should be little or no warning for eruptions such as this. However, the eruption is not caused by magma, but by steam, and this is much harder to track in our current monitoring systems.

Monitoring and warning for phreatic eruptions are very challenging. It is difficult to predict when they will occur. Most systems are already primed for explosive eruptions, but their triggers are poorly understood.

The warning period for such eruptions is in seconds to minutes. The potential for monitoring and anticipating these events lies in tracking vapour and liquid pressure in the system. Unfortunately, there are no simple rules to follow as each hydrothermal system is different.

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• BOOK REVIEW
• 22 April 2024

How volcanoes shaped our planet — and why we need to be ready for the next big eruption

• Heather Handley 0

Heather Handley is an associate professor of volcanic hazards and geoscience communication in the Department of Applied Earth Sciences at the University of Twente in Enschede, the Netherlands.

You can also search for this author in PubMed   Google Scholar

Lava erupts from a volcano in Iceland, part of a series of eruptions that began last year. Credit: Anton Brink/Anadolu via Getty

You have full access to this article via your institution.

Adventures in Volcanoland: What Volcanoes Tell Us About the World and Ourselves Tamsin Mather Abacus (2024)

Unlike Alice in Alice in Wonderland , volcanologists cannot fall down a deep rabbit hole to discover what goes on in the bowels of the Earth. Instead, they scour the surface and examine the chemistry of emitted gases, lava and rocks ejected during eruptions. Only by combining many clues can researchers learn where and how molten rock (magma) forms, how it ascends from the mantle below Earth’s crust and what triggers volcanic eruptions.

In Adventures in Volcanoland , volcanologist Tamsin Mather takes readers on a journey to some of the world’s most notorious and active volcanoes — from Mount Vesuvius in Italy to Masaya in Nicaragua. Her eloquent and enchanting book, which is rich in analogies and anecdotes, weaves together geological, historical and personal stories to explain how volcanoes work, how they have shaped our planet and how they have been understood through history.

Santorini’s volcanic past: underwater clues reveal giant prehistoric eruption

Volcanoes’ captivating power clearly entrances Mather, as it does me. And volcanoes make volcanologists work hard to uncover their secrets. Mather explains how researchers, equipped with the geochemical equivalent of a stethoscope, listen to the beating pulses of volcanoes. Scientists can also capture volcanoes’ ‘breath’ — toxic gases that often enshroud Mather as she works and that eat away at her clothes. Mather describes navigating through thick jungle in Guatemala to collect samples of lava while volcanic blasts hurled plumes of ash into the sky. Repairs to broken equipment had to be improvised using duct tape and superglue. Mather once resorted to using an inverted children’s paddling pool to collect gases fizzing up inside the caldera of Santorini volcano in Greece . The effort is worth it, Mather explains, to help volcanologists to answer big questions, such as how eruptions alter the climate and our environment, and how they affect life on Earth.

Volcanologists must exploit a vast array of knowledge, from planetary-scale shifts in Earth’s carbon cycle to the analysis of trapped gases in microscopic beads of glass. They must put eruptions in geological context, on timescales from Earth’s formation more than four billion years ago to the rapid radioactive decay of gases emitted by magma (such as radon-222, with a half-life of just under four days).

Each rock tells a story

Mather describes human experiences of volcanic eruptions, including her own time spent staring into churning lakes of molten rock, a “roiling, red and restless” fiery sea. She first encountered volcanoes and their hazards as a child, when she visited Vesuvius and the former Roman towns of Pompeii and Herculaneum. In ad 79, several scorching (350–550 ºC), fast-moving clouds of ash, pumice and gases surged down the flanks of Vesuvius, with devastating consequences for the people below, including hundreds who had taken refuge at the waterfront in Herculaneum, waiting to flee by boat.

In pictures: lava flows into Icelandic town during volcanic eruption

Today, tourists standing at the excavated pre-eruption shoreline are presented with an intimidating wall of volcanic deposits. After the eruption, the land surface gained up to 20 metres of elevation, and the coastline moved seawards by one kilometre. And all this happened in a geological blink of an eye.

Looking down from the crater rim of Mount Vesuvius towards the urban sprawl of metropolitan Naples, now home to around three million people, it’s sobering to consider just how the city will respond to the next large eruption of the slumbering volcano. It’s hard to know when that will be, but managing a future evacuation will be a colossal task for the authorities.

To prepare and plan, it is essential to better understand the hazards of volcanic regions. By ‘reading the rocks’ deposited by volcanoes, layer upon layer over thousands or millions of years, volcanologists can unravel the frequency, style and magnitudes of past eruptions. For example, rock stripes exposed in the walls of the Santorini caldera reveal how the catastrophic 1600 bc Minoan eruption unfolded; underwater studies of rocks point to other events that were much larger than previously thought. The consequences of another large eruption in the Eastern Mediterranean would be grave.

The Hunga Tonga-Hunga Ha’apai volcano in the South Pacific. Credit: Maxar via Getty

Volcanic and sedimentary rocks, along with signals from deposited sulphate in ice cores, hold clues about how eruptions have altered conditions across our planet. The impacts can be temporary or permanent. Plumes of sulphur dioxide gas can trigger short periods of global cooling called volcanic winters, such as the one following the 1815 eruption of Tambora in Indonesia. Lengthy outpourings of lava can form large igneous provinces — huge accumulations of volcanic rocks, such as the Siberian Traps. In the past, such events might have led to significant changes in planetary conditions that affected the course of life on Earth. As Mather points out, four out of the five largest mass extinctions overlapped approximately in time with volcanic activity that formed large igneous provinces, which would have pumped out vast amounts of carbon dioxide over millions of years.

Plan for big eruptions

All this raises the question of how prepared we are for the next large-scale volcanic eruption. Not very, I would argue. Humans have short memories — the COVID-19 pandemic showed us that, only 100 years after the severe influenza pandemic that began in 1918, we were still not ready.

Monitoring of volcanoes has advanced tremendously, with support from satellites in space , but they can still catch us off guard. For example, the powerful 2022 eruption of Hunga Tonga–Hunga Ha‘apai in Tonga was unexpected and had global ramifications. A shockwave and tsunamis reached the coasts of North and South America, resulting in an oil spill and two drownings in Peru. Tsunami warnings and evacuation orders were issued in Japan, and beaches were in Australia. Water vapour launched into the stratosphere by the blast could temporarily boost global temperatures.

Tonga volcano eruption triggered ‘mega-tsunami’

Population growth, technology dependency and the increased complexity of global systems have put the world at catastrophic risk from volcanic eruptions. Today, more than 800 million people in more than 85 countries live within 100 kilometres of an active volcano. An eruption near densely populated areas would have disastrous immediate impacts. Pyroclastic flows — fast-moving mixtures of hot gas, ash and rock fragments — could wipe out entire cities. Metres-thick ash falls would devastate crops and overwhelm power lines, water-treatment facilities, ventilation and heating systems, machinery and more. Farther away, flights might be grounded, power grids and undersea cables could be damaged and food security and supply chains could be affected, spreading economic losses.

With little regard for international borders, large eruptions’ far-reaching impacts would require a rapid and coordinated national and international response. Yet, global preparedness for the impacts of volcanic eruptions is lacking. There is no international United Nations treaty organization for ‘operational volcanology’ (systematic monitoring of volcanoes and assessment of risk). There’s no global coordination on issuing cross-border volcanic hazard warnings that address the full range of threats: pyroclastic flow, tephra fall (deposits of lofted rock fragments), lava flow, lahar (volcanic mudflow), volcanic gases, rafting pumice, drifting ash, tsunami and lightning.

Tambora-size eruptions occur somewhere in the world once or twice every millennium on average, and every 400 years in the Asia Pacific region. It’s not a matter of if, but when.

Adventures in Volcanoland reminds us that we should all keep careful watch on the world’s volcanoes. They are more than alluring natural landmarks. They are powerful drivers of processes on our planet that are crucial to understand. Volcano enthusiasts, those interested in the history of this adventurous science and those questioning our place in the world will find much to enjoy in this absorbing book.

Nature 628 , 713-715 (2024)

doi: https://doi.org/10.1038/d41586-024-01179-1

Competing Interests

The author declares no competing interests.

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'Has opened our eyes': Study proposes surprising trigger for Tonga volcanic eruption

New research proposes a vastly different trigger caused Tonga's volcanic eruption in 2022. 

The study by GNS Science and the Australian National University suggests the underwater eruption of the Hunga Volcano was a gas-driven explosion, instead of the result of magma and water reacting through the water column, known as a phreatomagmatic  explosion. 

The eruption, on 15 January 2022, caused a 58km high ash plume within minutes and a 2-3 km diameter steep-walled crater deeper than the Burj Khalifa Tower. It was so powerful it sent out atmospheric shock waves that promulgated the entire planet.  

The study's authors concluded a gas-driven trigger is likely based on the eruption magnitude, the time sequence, the mass amounts of volcanic gas release, the remaining volcano structure and the presence of minerals formed through magmatic gas interactions with the surrounding rock.  

"What we witnessed during this event was a Plinean eruption. These are the kind most people think of when imagining an erupting volcano - very intense, violent and sudden with extremely high ash columns," said lead author Richard Henley.  

"Our model describes a process that explains how the accumulation of volcanic gases over the months leading up to the eruption could generate this scale of explosive energy."  

The study suggests an eruption sequence as follows: a fluctuation of magma-derived reactive gases aggressively alters the rocks in the volcano core, creating a seal that blocks gas flow to the surface. This then increases the internal gas pressure and puts stress on the volcanic structure. Then the seal fractures, leading to an explosive release of compressed gas.   

"Not only does the paper suggest that the Hunga Plinean eruption was gas-driven but proposes that this mechanism may be characteristic of all Plinean eruptions regardless of whether the volcano is oceanic or subaerial. If correct, a pause in gas discharge may act as a precursor of a large eruption event," lead author Richard Henley said.  

"Understanding the cause of the eruption is important for volcano monitoring and risk preparedness, not just for the Tongan archipelago but for the numerous submarine volcanoes that sit within New Zealand's maritime estate," GNS co-author Cornel de Ronde added.  

"The eruption at Hunga has opened our eyes."  

GNS Science will lead an international marine voyage from 14 May to 12 June to Hunga Volcano to collect geological, geophysical and water column data inside the crater to further investigate the cause of the eruption.  

Iceland Volcanic Eruption: Activity Could Persist as Magma Could Be Accumulating Below Surface, IMO Warns

Scientists have issued warnings that volcanic activity in Sundhukur in Iceland could persist. This comes after reports that even more magma could breach through the surface.

Iceland Volcanic Eruption

The volcanic eruption started on March 16 and is currently the fourth one in a series that began with the accumulation of magma in Svartsengi at the Reykjanes Peninsula. The accumulation started in October 2023, while the first eruption was seen in December 2023.

The eruption unleashed a huge lava flow that triggered several evacuations and razed several homes in the nearby town of Grindavik.

The eruption in Sundnukur has been persisting for four weeks. This makes it the second-largest one in recent years across Iceland, only second to the 2021 Fagradalsfjall eruption, which lasted six months.

ALSO READ:  Iceland's Fourth Volcanic Outburst Sends Molten River Close to Grindavik, Raises Coastal Hazard Concerns

More Magma Could Be Accumulating

According to the Icelandic Meteorological Office (IMO), ground lift and increased pressure have been observed in the area. This could mean that magma is once more below the surface.

The persistent magma accumulation in Svartsengi boosts the chances of another  magma propagation . A magma propagation refers to a large and sudden flow of magma beyond the reservoir. Magma is molten rock that comes from melting the Earth's crust or mantle.

This may result in lava erupting from various fissures in the surface within the coming weeks or days. Moreover, the eruptive crater could also become larger because of the sudden increase in lava flow.

The IMO shares in a statement that at the start of Apri, ground uplift started to increase. A similar magma volume is not expelled at Sundhnukur as it accumulates in the reservoir. This leads to higher magma pressure.

Such developments are new. A persisting volcanic eruption with relatively stable lava flows at the crater row of Sundhnukur is uplifting the ground in Svartsengi.

If magma accumulation persists at a similar rate, the chances of magma propagation in the coming weeks or days will increase despite the ongoing eruption.

Magma propagation during an ongoing eruption from a reservoir has not been observed before in this region. Hence, there is more uncertainty regarding activity development in the coming weeks or days.

More eruptive fissures could end up opening between Hagafell and Stora-Skogfell. The uncertainty due to the growing pressure under the surface has prompted the Met Office to heighten the hazard rate in several areas, increasing it from "low" to "considerable."

Meteorologists estimate that over six million cubic meters of magma could have built up in the reservoir beneath Svartsengi since the fourth eruption. For previous eruptions, they took place when eight to 13 million cubic meters were added to the magma reservoir.

The eruption's gas emissions also pose persisting hazards to locals, who are encouraged to check air quality in the area.

RELATED ARTICLE: Iceland Volcanic Eruption: NASA Images Reveal Extent of Streaming Lava Flows, Charred Land

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