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.

Geological Summary. Volcán Wolf, the highest volcano of the Galápagos Islands, straddles the equator at the north end of the archipelago's largest island, Isabela. The edifice has steeper slopes than most other Isabela volcanoes, reaching angles up to 35°. The summit caldera is 6 x 7 km across and 700 m deep. A prominent bench on the west side of the caldera rises 450 m above the caldera floor, much of which is covered by a lava flow erupted in 1982. Radial fissures concentrated along diffuse rift zones extend down the N, NW, and SE flanks, and submarine vents lie beyond the N and NW fissures. Similar unvegetated flows originating from a circumferential chain of spatter and scoria cones on the eastern caldera rim drape the forested flanks to the sea. The proportion of aa lava flows exceeds that of other Galápagos volcanoes. An eruption in in 1797 was the first observed and documented in the Galápagos Islands.

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).