First eruption in seven years; lava effusion on the SE flank during January-April 2022

The first known observed eruption in the Galapagos occurred at Volcán Wolf on Isabela Island in August of 1797. Basaltic lava flows have occurred within the summit crater and on the flanks a few times each century since then. The most recent eruptions in 1982 (SEAN 07:08) and 2015 (BGVN 41:10) produced lava fountains and flows within the crater and on the flanks. A new eruption beginning on 7 January 2022 produced a large SO₂ plume, a small amount of ash, and lava flows on the SE flank that lasted through April 2022. Details of the 2022 eruption are provided with information primarily from the Geophysical Institute of the National Polytechnic School (IG-EPN) in Quito, Ecuador. IG maintains a broadband seismic network and a DOAS (Differential Optical Absorption Spectrometer) SO₂ monitoring station on the islands that transmits data to the mainland. The Washington Volcanic Ash Advisory Center (VAAC) is responsible for aviation warnings, and satellite data provide valuable remote thermal and SO₂ information.

Summary of January-April 2022 eruption. The 6 January through 14 April 2022 eruption lasted longer than the eruptions in 1982 and 2015. The eruption began with a very large SO₂ plume, a moderate-size ash plume, and multiple vents that produced lava flows. IG-EPN officials noted that the lava flows originated from an 8-km-long SE-flank radial fissure with at least five vents. The flows reached a maximum distance of about 18.5 km; they stopped 150-200 m from the coastline, covering an area of more than 30 km².

Description of January-April 2022 eruption. After seven years of no activity, a new eruption at Wolf was first reported shortly late on 6 January 2022, Galápagos time. Within the hour, a plume of gas and ash had reached 3.8 km altitude and drifted NE while a second plume drifted W at 1.9 km altitude. Lava flows were observed descending the SE flank. Seismicity had been detected at the FER1 station on Fernandina Island a few hours earlier that likely signaled the start of the eruption. Twenty-nine MODVOLC thermal alerts appeared on 7 January on the SE flank, confirming a significant thermal event from the lava flow. Rangers from Parque Nacional Galápagos reported that a fissure on the S flank was the source of the flow. They witnessed the flow descending the SE flank and burning vegetation (figures 12 and 13).

Figure 12. A new lava flow at Wolf descends the SE slope on 7 January 2022 burning adjacent vegetation and creating white smoke. Courtesy of Parque Nacional Galápagos.

Figure 13. Lava flows descended the SE flank of Wolf on 7 January 2022, burning shrubs and grasses in their path. Courtesy of Parque Nacional Galápagos.

The Washington VAAC issued its first report of ash emissions on 7 January 2022; plumes initially rose to two altitudes: 3.7 km drifting W, and 5.6 km altitude drifting NE. Later the plumes dropped to 2.4 km drifting W and 4.6 km drifting NE. The plume drifting to the W extended over 80 km. The VAAC noted reports of a large SO₂ plume later in the day reaching approximately 185 km W of the summit before dissipating. By the next day, they reported that emissions were primarily gas, drifting W at 1.3 km altitude. During 8-9 January gas emissions drifted SW at 700 m altitude. By 9 January, only an SO₂ plume was reported moving SW from the summit, and no further ash advisories were issued. Sulfur dioxide degassing decreased substantially from 60 million tons measured on 7 January to 8 million tons measured on 12 January (figure 14).

Figure 14. A large SO2 plume with a mass over 60 kilotons emerged from Wolf on 7 January 2022 at the beginning of the eruption as recorded by the TROPOMI instrument on the Sentinel-5P satellite. The mass decreased each subsequent day but remained very large for several days and measurable each day until early February 2022. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

During a flyover on 11 January 2022, the Park Minister noted continuing volcanic activity, and that the flow had traveled about 15 km from its source on the SE flank. IG-EPN reported that the lava flow was emerging from at least three fissures. The initial fissure from 7 January was at 1,290 m elevation and the subsequent fissures were located at 1,090 m elevation. By 11 January the flow was about 3 km from the coast (figure 15). IG-EPN produced the first map of the 7.4 km² flow on 12 January 2022 based on satellite data from 7 and 11 January (figure 16). The maximum length of the flow was estimated at 16.5 km from the initial vent, and 15 km from the two subsequent active fissures. The numbers of daily thermal alerts decreased steadily between 7 and 13 January, interpreted by IG-EPN as a decrease in the lava flow rate.

Figure 15. A Sentinel satellite image annotated by IG-EPN from 11 January 2022 showing gas emissions and the active lava flow at Wolf. Courtesy of IG-EPN, Informe Volcánico Especial – GALÁPAGOS – 2022 No. 02, Actualización de la actividad del volcán Wolf – Isla Isabela, Archipiélago de Galápagos, Quito, 13 de enero de 2022.

Figure 16. A preliminary map of the lava flow at Volcán Wolf on Isabela Island in the Galápagos as of 11 January 2022. The map was created from Sentinel-2 and PlanetScope satellite images. The flow covered an area of approximately 7.4 km2 and reached a maximum length of about 16.5 km. Courtesy of IG-EPN, Informe Volcánico Especial – GALÁPAGOS – 2022 – No. 02, Actualización de la actividad del volcán Wolf – Isla Isabela, Archipiélago de Galápagos, Quito, 13 de enero de 2022.

By 17 January the lava flow had advanced to slightly more than 2 km from the ocean. By early February the active vent was downslope from the original vents, and IG-EPN was able to map multiple flow fronts on the S and SE flanks (figure 17). Multiple near-daily MODVOLC thermal alerts continued throughout February, with pulses of lava flow activity producing tens of alerts on some days. The lava flows remained active on the SE flank, slowly advancing towards the coast; satellite imagery helped IG-EPN scientists to map the track of the lava flow (figure 18).

Figure 17. A map of the lava flow at Volcán Wolf as of 8 February 2022 shows the active flow fronts as of various dates (yellow dots, red arrows). The original, inactive vents are shown with a green triangle and the active vent as of that date is shown in orange. Courtesy of IG-EPN, INFORME DIARIO DEL VOLCAN WOLF No. 2022-034, Quito, miércoles 09 de febrero de 2022.

Figure 18. Sentinel-2 satellite imagery of Volcán Wolf from 11 and 16 January (top), and 15 and 25 February (bottom), show the active area of the lava flow changing over the first seven weeks of the eruption. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Lava flows remained active on the SE flank throughout March 2022; IG-EPN scientists used the location of the FIRMS thermal anomalies to map the active areas of the flow over time (figure 19). By the end of March, the number of daily thermal alerts had diminished significantly, suggesting a further decrease in the flow rate. Parque Nacional Galápagos personnel reported at the end of March that lava flow activity continued on the SE flank but had not reached the ocean. Multiple hot spots in satellite images suggested that lava was flowing through tubes that were visible to the park rangers patrolling the coast.

Figure 19. Maps of the advance of the lava flows at Volcán Wolf from 9 and 15 March 2022 show the progress of the different branches over time. Data is based on thermal anomalies reported by FIRMS. Courtesy of IG-EPN, INFORME DIARIO DEL VOLCAN WOLF No. 2022-062 and 2022-068, Quito, miércoles 09 y 15 de marzo de 2022.

MODVOLC thermal alerts were issued on 13 days during April 2022, with the number of daily alerts significantly fewer than previous months since January. Thermal anomalies continued to be present in satellite imagery through 21 April, and then briefly on 29 and 30 April (figure 20). IG-EPN scientists plotted the advance of the flow as the location of thermal alerts on a satellite image base several times during April; no advance was detectible after 14 April (figure 21). No surface activity was observed after 21 April. An updated map of the lava flow was published on 20 April 2022 (figure 22). Single MODVOLC thermal alerts were issued on 3 and 7 May, and two alerts on 16 May were the last recorded for the eruption.

Figure 20. Thermal anomalies in Sentinel-2 satellite imagery of Volcán Wolf on 17 March, 27 March, 6 April and 16 April 2022 show the slow advance and decrease in thermal energy from the flow. Images use Atmospheric penetration rendering (12, 11, 8a). The summit crater in the upper left is about 4 km across. Courtesy of Sentinel Hub Playground.

Figure 21. Maps from Volcán Wolf plot the advance of the thermal alerts through 8 April (left) and 14 April 2022 (right) on a satellite image base, indicating the decrease in flow. No further advances were mapped after 14 April. Courtesy of IG-EPN, INFORME DIARIO DEL VOLCAN WOLF No. 2022-092 and 2022-098, Quito, viernes 08 y 14 de abril de 2022.

Figure 22. The preliminary map from 20 April 2022 of the lava flows emitted during the eruption of Volcán Wolf that began in January. The map was made based on satellite images from PlanetScope. The lava flows covered more than 30 km2, and the maximum length covered was approximately 18.5 km from the highest vent; the flow did not reach the coast. Courtesy of IG-EPN and F.J. Vasconez, INFORME ESPECIAL VOLCÁN WOLF No. 2022-003 APARENTE FINAL DEL PERIODO ERUPTIVO Quito, 05 de mayo de 2022.

Eruption review using satellite data. Sulfur dioxide emissions that were initially as high as 60 kilotons, gradually tapered off during January and none were recorded in satellite data after early February (figure 23); they decreased steadily throughout the period and ended in early April (figure 24). Hundreds of thermal alerts from satellite data created rough maps of the 2015 and 2022 flow areas showing the difference in their relative locations. The 2015 flow started on the crater rim and flowed both into the crater and down the E flank and into the ocean, while the 2022 flow started about 1.5 km down the SE flank from the caldera rim and stopped a few hundred meters from the coastline (figure 25).

Figure 23. Sulfur dioxide emissions at Volcán Wolf decreased significantly after 15 January 2022, the last day where the mass of the SO2 plume exceeded 10 kilotons. Only very faint emissions were recorded by satellite instruments after early February. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Figure 24. Sulfur dioxide emissions in tons per day for Volcán Wolf from 6 January through 2 April 2022. Data from Mounts and NASA (F.J. Vasconez). Courtesy of IG-EPN, INFORME ESPECIAL VOLCÁN WOLF No. 2022-003 APARENTE FINAL DEL PERIODO ERUPTIVO Quito, 05 de mayo de 2022.

Figure 25. The MODVOLC thermal alerts plotted on a Google Earth base from eruptions at Wolf during 2015 (left) and 2022 (right) show how the thermal alerts roughly outline the area affected by lava flows. Lava during the 2015 eruption effused from the crater rim and flowed into crater and down the E flank into the ocean. The 2022 flow started about 1.5 km down the SE flank from the caldera rim and traveled about 18.5 km before stopping a few hundred meters from the coastline. Courtesy of MODVOLC.

The MIROVA Log Radiative Power graph of MODIS data shows the onset of the eruption in early January 2022 with high levels of heat initially, followed by a period with more fluctuations, and then a period of gradual decrease through mid-April 2022 before dropping off quickly to low levels (figure 26). The MIROVA distance graph based on the central caldera location shows how the lava flow initially quickly extended 10 km beyond SE-flank vent location, was then restricted to higher on the flank, and then gradually moved farther away over time.

Figure 26. The MIROVA data shows both the intensity of the Radiative Power (left) and the distance from the summit of the volcano (right). The graph of Log Radiative Power from December 2021 through May 2022 shows the onset of the eruption in early January 2022 followed by an overall decrease in heat emissions. The Distance graph of the eruption shows the onset of activity more than 10 km from the caldera center, then activity higher up the flank and gradually moving farther away as the eruption continued. Courtesy of MIROVA.

IG-EPN scientists plotted the hundreds of daily thermal alerts recorded by different satellite sensors such as MODIS (Moderate Resolution Imaging Spectroradiometer) and VIIRS (Visible Infrared Imaging Radiometer Suite), which are processed by different platforms (e.g., MIROVA , FIRMS, WORLDVIEW). The plot indicated a decreasing trend in thermal alerts, in both quantity and intensity from the beginning of the eruption in early January 2022 through the end of April (figure 27). This decrease reflected the decline in the rate of lava emission, as well as the progressive cooling of the lava flows.

Figure 27. A time series plot of thermal alerts from several different instruments for Volcán Wolf from January through April 2022 has a moving average of 7 days plotted as a black line over the primary data. After an initial peak at the start of the eruption, the activity gradually decreases through the end of April (F.J. Vasconez). Courtesy of IG-EPN, INFORME ESPECIAL VOLCÁN WOLF No. 2022-003, APARENTE FINAL DEL PERIODO ERUPTIVO Quito, 05 de mayo de 2022.

Information Contacts: Instituto Geofísico, Escuela Politécnica Nacional (IG-EPN), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Parque Nacional Galápagos (URL: https://galapagos.gob.ec/noticias/, https://www.facebook.com/parquegalapagos/posts/290645263104217); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard MD 20771, USA (URL: https://so2.gsfc.nasa.gov/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html).

Information is preliminary and subject to change. All times are local (unless otherwise noted)

July 1971 (CSLP 42-71)

Aerial reconnaissance shows caldera unchanged

Card 1249 (07 July 1971) Aerial reconnaissance shows caldera unchanged

Information Contacts: Educational Expeditions International Research Team, Galapagos Islands, Ecuador; T. Simkin, SI.

March 1973 (CSLP 31-73)

Earthquake swarm near Isla Isabella

Card 1588 (21 March 1973) Earthquake swarm near Isla Isabella

A small earthquake swarm took place in the Galapagos Islands in late January 1973. The Charles Darwin Research Station reported 57 events on its seismograph (GIE) from 23 through 28 January and estimated an epicentral distance of 110-160 km. The NOS/NOAA National Earthquake Information Center has located hypocenters for three events (Mb 4.4 and 4.5). These fit the Research Station's estimates, and are 15 km E, 26 km E, and 5 km SW of the center of Wolf, Isla Isabella. Dr. John Filson reports additional events (Mb 4.0-4.3) detected by LASA on 16 January and 18 February; the latter events are confirmed by NOS/NOAA but reliable hypocenters have not yet been located. The Charles Darwin Research Station reports no visible activity associated with this earthquake swarm.

Information Contacts: R. Sievers, Charles Darwin Research Station, Galapagos Islands, Ecuador; W. Person, U.S. National Earthquake Information Center; J. Filson, Massachusetts Institute of Technology; T. Simkin, SI.

November 1973 (CSLP 147-73)

Park wardens hear strong and constant rumbling from the caldera

Card 1749 (30 November 1973) Park wardens hear strong and constant rumbling from the caldera

"Galapagos National Park Wardens on W flank of Wolf two weeks ago heard strong and constant rumbling from caldera. The roar could be heard at the coast 6 km from the caldera rim and continued through the night. No reports of eruptive cloud, but clouds frequently obscure summit and volcano cannot be seen from inhabited parts of the archipelago. Darwin Station seismograph reports no unusual activity, but earthquake swarm early this year (see Event Card 1588) appeared centered on the SE flank of Wolf, the site of the last, largest (Mb 4.9), and best-located event on 19 March 1973. Darwin Station party is en route to investigate and SKYLAB will photograph.

"The last recorded eruptions of this, the northernmost shield volcano on the largest Galapagos Island, were on the SE flank in 1948 and 1963. The equator crosses the S end of the caldera at 91.3°W and the rim is 6 km in diameter, 1,710 m above the sea, and 670 m above the caldera floor. Reports of Galapagos volcanism in early August of this year appear to have been influenced by NASA press release on successful SKYLAB photography of 'Galapagos Eruptive Centers.' No Galapagos eruption was sighted by SKYLAB II but shortly after the press release emerged from Ecuadorian newspapers clouds and lights were reported from the volcano at Cape Berkeley, NW Isabella. These reports have been investigated on the volcano by Darwin Station personnel and no evidence of an August eruption has been found. The only other Galapagos volcanism known since the 1968 Fernandina caldera collapse is the 1972 Fernandina eruption reported in June of this year (Event Card 1659). . . ."

Information Contacts: Peter Kramer, Charles Darwin Research Station, Galapagos Islands, Ecuador; Tom Simkin, SI.

December 1973 (CSLP 150-73)

Thermal anomalies, but no confirmed activity

Card 1752 (13 December 1973) Space-based observations of activity

Observations from space... support previous indication of eruption on Wolf (Event Card 1749), and suggest strong thermal activity on Darwin. . . . NOAA-2 [satellite imagery] shows additional hot spots on E flank of Wolf . . . .

Card 1757 (17 December 1973) Infrared hot-spot probably not eruption related

Close inspection of NOAA-2 imagery shows hot spots reported on Event Card 1752 coincide with caldera floors, not outer flanks, and can probably be explained by normal daytime temperature differences. . . . Darwin Station party "saw nothing on Wolf" but gave no further details on that eruption (Event Card 1749).

Information Contacts:
Card 1752 (13 December 1973) F. Parmenter, NOAA; M. McEwen, NASA; J. Filson, MIT; T. Simkin, SI.
Card 1757 (17 December 1973) A. Krueger and F. Parmenter, NOAA; J. Filson, MIT; P. Kramer, Darwin Research Station; T. Simkin, SI.

August 1982 (SEAN 07:08) Cite this Report

Lava fountaining and flows in caldera and on SE flank

Eruption clouds began to emerge from the volcano during the afternoon of 28 August. Plume emission was first detected on visible band satellite images between 1300 and 1400, and feeding continued until nightfall. The plume, which drifted W, could not be seen on infrared imagery, indicating that it remained at low altitudes. Observers on a tour ship first saw clouds issuing from the summit about 1430-1500 and reported strong summit glow that night. Activity on the SE flank was first observed at 0830 the next morning, but heavy weather clouds had obscured this area the previous afternoon, and flank vents may have been active then as well.

Tui DeRoy Moore and others arrived at the SE flank late 31 August. Lava fountained from a radial fissure that extended 1 km or more downslope from 875 m altitude. Fresh lava covered the area near the fissure. Lava flowed SE then turned toward the E, reaching about 280 m altitude. This flow had stopped advancing by 1 September and fountaining had ended by that evening, although some SE flank glow remained visible. As the flank activity declined, summit activity increased. Summit glow had been visible since 28 August, but strengthened during the night of 1-2 September and a large convecting cloud was present over the caldera. Moore reached the caldera rim on 3 September and found several vents active in the caldera, the strongest on its floor at the base of the steep SW wall. Lava fountaining from this vent was continuous and the fountains occasionally rose as high as the caldera rim, approximately 700 m above the floor. Intermittent, relatively weak fountaining (less than 50 m estimated height) occurred from four small vents along a 100-200-m-long fissure on the S caldera floor. Thick-looking pahoehoe lava covered slightly more than half of the caldera floor, or approximately 6 km², and was mainly on the N and NW side. Gases emerging from the base of the convecting eruption cloud formed a haze that drifted W, away from the observers. By early 4 September, when Moore left the volcano, a cone had begun to form around the main vent. Activity appeared to be dominated by scoria ejection, with little lava being added to the caldera floor flows. No earthquakes were felt by the observers, and Moore reported that there seemed to be little effect on the flora and fauna. Glow was still visible in the eruption cloud late 5 September and airplane passengers saw a strong plume 6 September.

Wolf has been one of the more active Galápagos volcanoes. Flank eruptions from the same SE vent area took place in 1948 and 1963, but summit caldera activity had not been documented since 1800. A probable SE flank eruption was heard but not seen in 1973. The present eruption is a two-hemisphere event, with the caldera lying mostly N of the equator and the SE vent, less than 10 km distant, in the Southern Hemisphere.

Further Reference. Schatz, H., and Schatz, I., 1983, Der ausbruch des Vulkanes Wolf (Inseln Isabela, Galápagos-Inseln Ecuador) im Jahre 1982—Ein Augenzeugenbericht; Ber. Nat. Med. Verein Innsbruck; v. 70, p. 17-28.

Information Contacts: T. Moore, Isla Santa Cruz, Galápagos.

October 2016 (BGVN 41:10) Cite this Report

Explosion on 25 May 2015; lava flows down the E and SE flanks, and into the caldera

The first documented historical eruption in the Galapagos was at Wolf in 1797, and basaltic lava flows have spilled down its flanks a number of times since then. The most recent previous eruption began with an ash plume on 28 August 1982, and continued with lava fountains and flows from a fissure on the SE flank and inside the summit caldera into the first weeks of September 1982 (SEAN 07:08).

Volcan Wolf erupted with a 15-km-high plume of mostly water vapor and SO₂ on 25 May 2015. This was followed by the emission of lava flows from a fissure on the SE edge of the caldera down the NE, E, and SE flanks to the ocean for several weeks. Beginning on 13 June, the first lava flows were observed within the crater, and flows down the outer flanks decreased. Lava flows were also observed within the crater via satellite in late June, and strong daily thermal anomalies from the crater continued through 4 July before tapering off.

The volcanoes on the Galapagos Islands are monitored by the Geophysical Institute of the National Polytechnic School (IG-EPN) in Quito, Ecuador, and the Washington Volcanic Ash Advisory Center (VAAC) is responsible for aviation warnings. IG maintains a broadband seismic network and a DOAS (Differential Optical Absorption Spectrometer) SO₂ monitoring station on the islands that transmits data to the mainland.

Ecuador's Instituto Geofisico (IG) reported that its seismic station FER1, located on Fernandina Island approximately 38 km SW of Wolf, began recording seismic events in the vicinity of Wolf at 2350 (local Galapagos time) on 24 May 2015. The most significant signal occurred at 0058 on 25 May, corresponding to an explosion and the start of an eruption. This was followed by other smaller seismic events in the following hours. At 0215 local time the Washington VAAC detected a plume that rose to an altitude of 10.7 km and drifted 65 km SW. Ongoing emissions at 0345 were drifting in two directions, S at 13.7 km altitude and ENE as high as 15.2 km. By 0600 the plumes were observed 250 km from the volcano. Later in the day at 1245 a remnant of the original plume was observed 186 km SSE of the summit, while a new emission at 10.7 km was detected 150 km SW. There was no report of ashfall in the Galapagos Islands, leading IG scientists to infer a low ash content for the plume, although a large SO₂ plume was identified by satellite instruments.

At first light, personnel from the Galapagos National Park (PNG) were able to photograph the plume and a lava flow erupting from a fissure on the SSE flank (figure 1). A strong thermal anomaly on the SE flank was also detected in MODIS data analyzed by the Hawai'i Institute of Geophysics and Planetology (HIGP) MODVOLC system early on 25 May, and grew stronger in subsequent days. A very strong SO₂ plume, eventually releasing around 200 kt of sulfur dioxide, was also captured by the Aura/OMI satellite SO₂ instrument on 25 and 26 May (figure 2).

Figure 1. The first images of the eruption taken in the early morning on 25 May 2015 show lava flowing down the SSE flank of Wolf. Courtesy of Dr. Galo Quezada, Galapagos National Park (PNG) (IG-EPN, Informe Volcanico Especial Galapagos No. 2, 25 May 2015).

Figure 2. Sulfur dioxide emissions from Wolf captured by the OMI instrument on the Aura satellite on 25 and 26 May 2015. The total release for the event was around 200 kilotons of SO2. Courtesy of NASA Goddard Space Flight Center (GSFC).

In the days following the explosion, lava flows descended the NE, E, and SE flanks from a fissure located near the edge of the caldera. IG scientists were able to observe the flowing lava during an overflight on 29 May (figures 3 and 4). They noted a steam plume rising 2-3 km above the volcano with no visible ash, and a strong sulfur odor.

Figure 3. Incandescent lava flows down the NE flank of Wolf on 29 May 2015. Courtesy of B. Bernard, IG-EPN (Informe Volcanico Especial Galapagos No. 3, 2 June 2015).

Figure 4. Oblique satellite image from the NE of the lava field on the E flank of Wolf. The two incandescent flows are outlined in orange with the probable fissure vent shown in red. The blue line is the flight path taken on 29 May 2015. Image was taken by the ALI (Advanced Land Imager) camera on board the EOS-1 satellite on 28 May 2015, and superimposed on Google Earth imagery by IG-EPN scientists. Courtesy of B. Bernard, IG-EPN (Informe Volcanico Especial Galapagos No. 3, 2 June 2015).

By 28 May the E lava field was approximately 7 km long and flows had reached the ocean. Thermal imaging during the overflight revealed two areas with apparent maximum temperatures (TMA) greater than 500°C, one at the site of the fissure near the caldera rim, and one in the lava field on the E flank. SO₂ emissions measured during the overflight were 40.6 kt/day. Satellite images gathered on 5 and 11 June confirmed the source of the lava flows as an arcuate fissure around the SE and E edges of the caldera in a similar location to the 1982 fissure.

Another overflight by IG-EPN scientists on 12 June confirmed the continuing emission of lava flows down the SE and E flanks. The helicopter landed on the north rim of the crater with a view to the south of the lava flow from the 1982 eruption and gases emitting from the active fissure zone (figure 5). IG scientists heard at least five explosions during their visit to the crater rim. Thermal images gathered during the 12 June flight revealed that temperatures of the flows on the SE flank had dropped to less than 100°C, but temperatures at the fissure vent were still greater than 500°C, and steaming lava was observed near the emission zone (figure 6).

Figure 5. Panorama of the interior of the Wolf caldera on 12 June 2015 showing the lava flow from the 1982 eruption covering the floor, and gas clouds from the active fissure on the SE side of the caldera rim. Courtesy of P. Ramon, IG-EPN (Informe Volcanico Especial Galapagos No. 4, 26 June 2015).

Figure 6. Lava flows near the source vent at Wolf on 12 June 2015 seen in a thermal image (top) and regular photograph (bottom). Courtesy of P. Ramon, IG-EPN (Informe Volcanico Especial Galapagos No. 4, 26 June 2015).

On 13 June 2015 satellite imagery showed new thermal anomalies inside the crater, suggesting active lava flowing into the crater in addition to the flows on the E and SE flanks. This was confirmed with visible low-resolution imagery from the WorldView 3 satellite on 16 June which showed an area of likely incandescence near the S rim. An image from the WorldView 1 satellite on 18 June showed a new lava flow on the floor of the caldera (figure 7). IG-EPN scientists combined the thermal data from their overflights with satellite imagery to define the areas of new lava flow through late June (figure 8).

Figure 7. Satellite images of Wolf showing an incandescent zone and possible new vent on 16 June 2015 (circle at left; image from WV3 satellite), and a new lava flow inside the caldera on 18 June (right, image from WV1 satellite). Courtesy of IG-EPN (Informe Volcanico Especial Galapagos No. 4, 26 June 2015).

Figure 8. Preliminary estimate of areas covered by lava flows from the eruption at Wolf beginning 25 May 2015 through 25 June. Base from Google Earth. Courtesy of IG-EPN (Informe Volcanico Especial Galapagos No. 4, 26 June 2015).

The thermal alert pixels from the MODVOLC system show an evolution of the heat anomalies from the MODIS infrared satellite data that corresponds well with the satellite imagery and ground observations. The first anomalies were recorded on 25 May 2015. Strong multi-pixel anomalies (in some cases, more than 50 per day) were mapped daily until 4 July. After this, they become intermittent, and the daily number dropped below 11, tapering to one or two pixels every few days between 17 July, with the last two observed on 1 August. Two lobes of lava flows to the E and SE can be distinguished on the MODVOLC maps between 25 May and 12 June; anomalies within the crater appear on 13 June, increase to a maximum in the third week of June, and then taper off during July (figure 9).

Figure 9. Four MODVOLC thermal anomaly maps of Wolf showing the evolution from lava flows down the E and SE flanks (29 May and 12 June 2015) to the active flows inside the crater (13 and 16 June). Green grid lines represent decimal degrees of longitude and latitude. Data courtesy of MODVOLC.

MODIS data processed by MIROVA recorded a large thermal energy signature between 25 and 30 May, which then decreased for several days before increasing again in the second week of June (figure 10). The MIROVA radiative power data showed that the anomalies continued to decrease, suggestive of cooling lava flows, through November 2015, however, they picked up again early in 2016 (figure 11), indicating some continuing source of heat from the volcano.

Figure 10. Radiant energy of thermal anomalies at Wolf detected by MIROVA from 25 May through 25 June 2015. Note the spike on 25 May followed by the decrease in values until after 15 June when they again increased (upper graph). Courtesy of MIROVA, taken from IG-EPN (Informe Volcanico Especial Galapagos No. 4, 26 June 2015).

Figure 11. MIROVA analysis of MODIS infrared satellite data from Wolf between 6 September 2015 and 6 September 2016 showing Log Radiative Power (top), Radiative Power (middle), and Distance from summit (bottom). Virtually all of the anomalies are located within 5 km of the summit (lower graph). A gradual decrease in the anomalies between September and 1 December 2015 is consistent with cooling lava flows. Waxing and waning anomalies between March and September 2016 indicate some continued source of heat from Wolf. Courtesy of MIROVA.

No further special reports were issued by the Instituto Geofisico after June 2015 and available evidence suggests active lava flows ceased by late July 2015.

Information Contacts: Instituto Geofísico, Escuela Politécnica Nacional (IG-EPN), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: http://www.ospo.noaa.gov/Products/atmosphere/vaac/) [Archive at: http://www.ssd.noaa.gov/VAAC/archive.html]; Hawai'i Institute of Geophysics and Planetology (HIGP), MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/, http://modis.higp.hawaii.edu/cgi-bin/modisnew.cgi); NASA Goddard Space Flight Center (NASA/GSFC), Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, Goddard, Maryland, USA (URL: https://so2.gsfc.nasa.gov/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/).

May 2022 (BGVN 47:05) Cite this Report

First eruption in seven years; lava effusion on the SE flank during January-April 2022

The first known observed eruption in the Galapagos occurred at Volcán Wolf on Isabela Island in August of 1797. Basaltic lava flows have occurred within the summit crater and on the flanks a few times each century since then. The most recent eruptions in 1982 (SEAN 07:08) and 2015 (BGVN 41:10) produced lava fountains and flows within the crater and on the flanks. A new eruption beginning on 7 January 2022 produced a large SO₂ plume, a small amount of ash, and lava flows on the SE flank that lasted through April 2022. Details of the 2022 eruption are provided with information primarily from the Geophysical Institute of the National Polytechnic School (IG-EPN) in Quito, Ecuador. IG maintains a broadband seismic network and a DOAS (Differential Optical Absorption Spectrometer) SO₂ monitoring station on the islands that transmits data to the mainland. The Washington Volcanic Ash Advisory Center (VAAC) is responsible for aviation warnings, and satellite data provide valuable remote thermal and SO₂ information.

Summary of January-April 2022 eruption. The 6 January through 14 April 2022 eruption lasted longer than the eruptions in 1982 and 2015. The eruption began with a very large SO₂ plume, a moderate-size ash plume, and multiple vents that produced lava flows. IG-EPN officials noted that the lava flows originated from an 8-km-long SE-flank radial fissure with at least five vents. The flows reached a maximum distance of about 18.5 km; they stopped 150-200 m from the coastline, covering an area of more than 30 km².

Description of January-April 2022 eruption. After seven years of no activity, a new eruption at Wolf was first reported shortly late on 6 January 2022, Galápagos time. Within the hour, a plume of gas and ash had reached 3.8 km altitude and drifted NE while a second plume drifted W at 1.9 km altitude. Lava flows were observed descending the SE flank. Seismicity had been detected at the FER1 station on Fernandina Island a few hours earlier that likely signaled the start of the eruption. Twenty-nine MODVOLC thermal alerts appeared on 7 January on the SE flank, confirming a significant thermal event from the lava flow. Rangers from Parque Nacional Galápagos reported that a fissure on the S flank was the source of the flow. They witnessed the flow descending the SE flank and burning vegetation (figures 12 and 13).

Figure 12. A new lava flow at Wolf descends the SE slope on 7 January 2022 burning adjacent vegetation and creating white smoke. Courtesy of Parque Nacional Galápagos.

Figure 13. Lava flows descended the SE flank of Wolf on 7 January 2022, burning shrubs and grasses in their path. Courtesy of Parque Nacional Galápagos.

The Washington VAAC issued its first report of ash emissions on 7 January 2022; plumes initially rose to two altitudes: 3.7 km drifting W, and 5.6 km altitude drifting NE. Later the plumes dropped to 2.4 km drifting W and 4.6 km drifting NE. The plume drifting to the W extended over 80 km. The VAAC noted reports of a large SO₂ plume later in the day reaching approximately 185 km W of the summit before dissipating. By the next day, they reported that emissions were primarily gas, drifting W at 1.3 km altitude. During 8-9 January gas emissions drifted SW at 700 m altitude. By 9 January, only an SO₂ plume was reported moving SW from the summit, and no further ash advisories were issued. Sulfur dioxide degassing decreased substantially from 60 million tons measured on 7 January to 8 million tons measured on 12 January (figure 14).

Figure 14. A large SO2 plume with a mass over 60 kilotons emerged from Wolf on 7 January 2022 at the beginning of the eruption as recorded by the TROPOMI instrument on the Sentinel-5P satellite. The mass decreased each subsequent day but remained very large for several days and measurable each day until early February 2022. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

During a flyover on 11 January 2022, the Park Minister noted continuing volcanic activity, and that the flow had traveled about 15 km from its source on the SE flank. IG-EPN reported that the lava flow was emerging from at least three fissures. The initial fissure from 7 January was at 1,290 m elevation and the subsequent fissures were located at 1,090 m elevation. By 11 January the flow was about 3 km from the coast (figure 15). IG-EPN produced the first map of the 7.4 km² flow on 12 January 2022 based on satellite data from 7 and 11 January (figure 16). The maximum length of the flow was estimated at 16.5 km from the initial vent, and 15 km from the two subsequent active fissures. The numbers of daily thermal alerts decreased steadily between 7 and 13 January, interpreted by IG-EPN as a decrease in the lava flow rate.

Figure 15. A Sentinel satellite image annotated by IG-EPN from 11 January 2022 showing gas emissions and the active lava flow at Wolf. Courtesy of IG-EPN, Informe Volcánico Especial – GALÁPAGOS – 2022 No. 02, Actualización de la actividad del volcán Wolf – Isla Isabela, Archipiélago de Galápagos, Quito, 13 de enero de 2022.

Figure 16. A preliminary map of the lava flow at Volcán Wolf on Isabela Island in the Galápagos as of 11 January 2022. The map was created from Sentinel-2 and PlanetScope satellite images. The flow covered an area of approximately 7.4 km2 and reached a maximum length of about 16.5 km. Courtesy of IG-EPN, Informe Volcánico Especial – GALÁPAGOS – 2022 – No. 02, Actualización de la actividad del volcán Wolf – Isla Isabela, Archipiélago de Galápagos, Quito, 13 de enero de 2022.

By 17 January the lava flow had advanced to slightly more than 2 km from the ocean. By early February the active vent was downslope from the original vents, and IG-EPN was able to map multiple flow fronts on the S and SE flanks (figure 17). Multiple near-daily MODVOLC thermal alerts continued throughout February, with pulses of lava flow activity producing tens of alerts on some days. The lava flows remained active on the SE flank, slowly advancing towards the coast; satellite imagery helped IG-EPN scientists to map the track of the lava flow (figure 18).

Figure 17. A map of the lava flow at Volcán Wolf as of 8 February 2022 shows the active flow fronts as of various dates (yellow dots, red arrows). The original, inactive vents are shown with a green triangle and the active vent as of that date is shown in orange. Courtesy of IG-EPN, INFORME DIARIO DEL VOLCAN WOLF No. 2022-034, Quito, miércoles 09 de febrero de 2022.

Figure 18. Sentinel-2 satellite imagery of Volcán Wolf from 11 and 16 January (top), and 15 and 25 February (bottom), show the active area of the lava flow changing over the first seven weeks of the eruption. Images use Atmospheric penetration rendering (bands 12, 11, 8a). Courtesy of Sentinel Hub Playground.

Lava flows remained active on the SE flank throughout March 2022; IG-EPN scientists used the location of the FIRMS thermal anomalies to map the active areas of the flow over time (figure 19). By the end of March, the number of daily thermal alerts had diminished significantly, suggesting a further decrease in the flow rate. Parque Nacional Galápagos personnel reported at the end of March that lava flow activity continued on the SE flank but had not reached the ocean. Multiple hot spots in satellite images suggested that lava was flowing through tubes that were visible to the park rangers patrolling the coast.

Figure 19. Maps of the advance of the lava flows at Volcán Wolf from 9 and 15 March 2022 show the progress of the different branches over time. Data is based on thermal anomalies reported by FIRMS. Courtesy of IG-EPN, INFORME DIARIO DEL VOLCAN WOLF No. 2022-062 and 2022-068, Quito, miércoles 09 y 15 de marzo de 2022.

MODVOLC thermal alerts were issued on 13 days during April 2022, with the number of daily alerts significantly fewer than previous months since January. Thermal anomalies continued to be present in satellite imagery through 21 April, and then briefly on 29 and 30 April (figure 20). IG-EPN scientists plotted the advance of the flow as the location of thermal alerts on a satellite image base several times during April; no advance was detectible after 14 April (figure 21). No surface activity was observed after 21 April. An updated map of the lava flow was published on 20 April 2022 (figure 22). Single MODVOLC thermal alerts were issued on 3 and 7 May, and two alerts on 16 May were the last recorded for the eruption.

Figure 20. Thermal anomalies in Sentinel-2 satellite imagery of Volcán Wolf on 17 March, 27 March, 6 April and 16 April 2022 show the slow advance and decrease in thermal energy from the flow. Images use Atmospheric penetration rendering (12, 11, 8a). The summit crater in the upper left is about 4 km across. Courtesy of Sentinel Hub Playground.

Figure 21. Maps from Volcán Wolf plot the advance of the thermal alerts through 8 April (left) and 14 April 2022 (right) on a satellite image base, indicating the decrease in flow. No further advances were mapped after 14 April. Courtesy of IG-EPN, INFORME DIARIO DEL VOLCAN WOLF No. 2022-092 and 2022-098, Quito, viernes 08 y 14 de abril de 2022.

Figure 22. The preliminary map from 20 April 2022 of the lava flows emitted during the eruption of Volcán Wolf that began in January. The map was made based on satellite images from PlanetScope. The lava flows covered more than 30 km2, and the maximum length covered was approximately 18.5 km from the highest vent; the flow did not reach the coast. Courtesy of IG-EPN and F.J. Vasconez, INFORME ESPECIAL VOLCÁN WOLF No. 2022-003 APARENTE FINAL DEL PERIODO ERUPTIVO Quito, 05 de mayo de 2022.

Eruption review using satellite data. Sulfur dioxide emissions that were initially as high as 60 kilotons, gradually tapered off during January and none were recorded in satellite data after early February (figure 23); they decreased steadily throughout the period and ended in early April (figure 24). Hundreds of thermal alerts from satellite data created rough maps of the 2015 and 2022 flow areas showing the difference in their relative locations. The 2015 flow started on the crater rim and flowed both into the crater and down the E flank and into the ocean, while the 2022 flow started about 1.5 km down the SE flank from the caldera rim and stopped a few hundred meters from the coastline (figure 25).

Figure 23. Sulfur dioxide emissions at Volcán Wolf decreased significantly after 15 January 2022, the last day where the mass of the SO2 plume exceeded 10 kilotons. Only very faint emissions were recorded by satellite instruments after early February. Courtesy of NASA Global Sulfur Dioxide Monitoring Page.

Figure 24. Sulfur dioxide emissions in tons per day for Volcán Wolf from 6 January through 2 April 2022. Data from Mounts and NASA (F.J. Vasconez). Courtesy of IG-EPN, INFORME ESPECIAL VOLCÁN WOLF No. 2022-003 APARENTE FINAL DEL PERIODO ERUPTIVO Quito, 05 de mayo de 2022.

Figure 25. The MODVOLC thermal alerts plotted on a Google Earth base from eruptions at Wolf during 2015 (left) and 2022 (right) show how the thermal alerts roughly outline the area affected by lava flows. Lava during the 2015 eruption effused from the crater rim and flowed into crater and down the E flank into the ocean. The 2022 flow started about 1.5 km down the SE flank from the caldera rim and traveled about 18.5 km before stopping a few hundred meters from the coastline. Courtesy of MODVOLC.

The MIROVA Log Radiative Power graph of MODIS data shows the onset of the eruption in early January 2022 with high levels of heat initially, followed by a period with more fluctuations, and then a period of gradual decrease through mid-April 2022 before dropping off quickly to low levels (figure 26). The MIROVA distance graph based on the central caldera location shows how the lava flow initially quickly extended 10 km beyond SE-flank vent location, was then restricted to higher on the flank, and then gradually moved farther away over time.

Figure 26. The MIROVA data shows both the intensity of the Radiative Power (left) and the distance from the summit of the volcano (right). The graph of Log Radiative Power from December 2021 through May 2022 shows the onset of the eruption in early January 2022 followed by an overall decrease in heat emissions. The Distance graph of the eruption shows the onset of activity more than 10 km from the caldera center, then activity higher up the flank and gradually moving farther away as the eruption continued. Courtesy of MIROVA.

IG-EPN scientists plotted the hundreds of daily thermal alerts recorded by different satellite sensors such as MODIS (Moderate Resolution Imaging Spectroradiometer) and VIIRS (Visible Infrared Imaging Radiometer Suite), which are processed by different platforms (e.g., MIROVA , FIRMS, WORLDVIEW). The plot indicated a decreasing trend in thermal alerts, in both quantity and intensity from the beginning of the eruption in early January 2022 through the end of April (figure 27). This decrease reflected the decline in the rate of lava emission, as well as the progressive cooling of the lava flows.

Figure 27. A time series plot of thermal alerts from several different instruments for Volcán Wolf from January through April 2022 has a moving average of 7 days plotted as a black line over the primary data. After an initial peak at the start of the eruption, the activity gradually decreases through the end of April (F.J. Vasconez). Courtesy of IG-EPN, INFORME ESPECIAL VOLCÁN WOLF No. 2022-003, APARENTE FINAL DEL PERIODO ERUPTIVO Quito, 05 de mayo de 2022.

Information Contacts: Instituto Geofísico, Escuela Politécnica Nacional (IG-EPN), Casilla 17-01-2759, Quito, Ecuador (URL: http://www.igepn.edu.ec/); Parque Nacional Galápagos (URL: https://galapagos.gob.ec/noticias/, https://www.facebook.com/parquegalapagos/posts/290645263104217); Hawai'i Institute of Geophysics and Planetology (HIGP) - MODVOLC Thermal Alerts System, School of Ocean and Earth Science and Technology (SOEST), Univ. of Hawai'i, 2525 Correa Road, Honolulu, HI 96822, USA (URL: http://modis.higp.hawaii.edu/); MIROVA (Middle InfraRed Observation of Volcanic Activity), a collaborative project between the Universities of Turin and Florence (Italy) supported by the Centre for Volcanic Risk of the Italian Civil Protection Department (URL: http://www.mirovaweb.it/); Sentinel Hub Playground (URL: https://www.sentinel-hub.com/explore/sentinel-playground); NASA Global Sulfur Dioxide Monitoring Page, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center (NASA/GSFC), 8800 Greenbelt Road, Goddard MD 20771, USA (URL: https://so2.gsfc.nasa.gov/); Washington Volcanic Ash Advisory Center (VAAC), Satellite Analysis Branch (SAB), NOAA/NESDIS OSPO, NOAA Science Center Room 401, 5200 Auth Rd, Camp Springs, MD 20746, USA (URL: www.ospo.noaa.gov/Products/atmosphere/vaac, archive at: http://www.ssd.noaa.gov/VAAC/archive.html).