Volcano World

PVMBG reported that an eruption at Dempo occurred at 0406 on 27 May. A video posted with the report showed a Surtseyan eruption at the crater lake with dark material being ejected 300 m from the center of the lake. Dense white-and-gray ash plumes rose around 500 m and drifted W. According to a news report, the crater lake water had been changing colors during the previous few weeks. The color changed from turquois-green to gray and white on 9 May, and a diffuse gas-and-steam plume was visible. A seismic signal indicating an emission was recorded at 1911 on 12 May. The water turned turquois-green again on 15 May and then to gray on 17 May. The Alert Level remained at 2 (on a scale of 1-4), and the public were reminded to stay 1 km away from the crater and as far as 2 km on the N flank.

Sources: Antara News,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

PVMBG reported that the eruption at Ibu continued during 22-28 May. White steam-and-gas plumes rose 200-600 m above the crater rim and drifted in multiple directions during 22-25 and 28 May. White-and-gray ash plumes rose 200-500 m and drifted SW, W, and N on 26 May. At 0303 on 27 May an eruptive event produced a white, gray, and black ash plume that rose 6 km above the crater rim and drifted SW and W. According to a news article ash fell in residential areas and at the Ibu observation post (9 km W). Incandescent material was ejected as far as 1 km from the vent onto the NW, W, SW, and S flanks. The Alert Level remained at 4 (the highest level on a four-level scale) and the public was advised to stay 4 km away from the active crater and 7 km away from the N crater wall opening.

Sources: Antara News,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

PVMBG reported that on 17 May the color of the crater lake water in Kelimutu?s Crater I (Tiwu Ata Polo) changed from green to dark green, water bubbles on the surface of the NE part of the lake were observed, and there was a weak sulfur odor. On 22 May the water color changed to a blackish-brown. The lake temperature dropped from 23 to 21 degrees Celsius during 17-22 May. At Crater II (Tiwu Koofai Nuwamuri) the water color was light blue on 17 May and had not changed color since the last visual observation. Golden-yellow sulfur deposits were scattered around the lake including in the central part and in areas to the NW, N, NE, E, and SE. Visual observations on 23 May revealed that the lake?s color had not changed, though sulfur deposits had shifted positions and had become more numerous. There was a swirling area of sulfur deposits on the water?s surface at the S part of the lake and a weak sulfur odor was noted. The lake temperature increased from 22 to 24 degrees Celsius during 17-23 May, indicating increased activity of the magmatic-hydrothermal system beneath it. The color of the lake water in Crater III (Tiwu Ata Bupu) was unchanged during 17-23 May. The changes in lake water color at Crater I, along with the changes in the floating sulfur deposits and increased water temperatures at Crater II, prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4) at 1300 on 24 May, and the public was warned to stay 250 m from the crater rims. According to a news article the Taman Nasional Kelimutu (Kelimutu National Park) restricted visitors from approaching the craters in accordance with the PVMBG guidelines. The last eruption was phreatic, and it occurred at Crater II during June 1968.

Sources: Antara News,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

IMO reported that seismicity increased on 28 May in an area near the Sundhnkaggar crater row and, along with continuing inflation, possibly indicated rising magma within the Reykanes volcanic system. According to news articles seismicity intensified during the morning of 29 May, prompting the evacuation of workers at the Svartsengi power plant, 35-38 residents of Grindavk (three remained), and visitors and residents at the Blue Lagoon spa area. At 1109 on 29 May IMO reported that the seismic swarm was likely related to a new dike intrusion. The Aviation Color Code was raised to Red (the highest level on a four-color scale) and then decreased back to Orange at 1115 because no additional geophysical data indicated significant changes. An effusive eruption began at 1246 near Sundhnk, NE of Slingarfell, with the propagation of a 1-km-long fissure that produced lava fountains at least 30-50 m high and dense, gas-rich plumes rose along the fissure. Radar data indicated that particulates were present in the plume up to 2 km and gases rose as high as 3 km. By 1415 lava had advanced about 1 km W and to the S, towards Grindavk road. A second fissure opened just W of the main fissure and eruption plumes rose as high as 3.4 km. The extrusion rate was estimated to be 1,500-2,000 cubic meters per second. The fissure continued to propagate and by 1450 it was 3.4 km long. Lava surrounded Hagafell to the E and advanced S towards Melhlsnma based on an overflight conducted by the Coast Guard. The southernmost part of the fissure was less than 1 km from the lava barriers N of Grindavk, and lava flowed over Grindavk road.

Sources: Icelandic Meteorological Office (IMO),Icelandic National Broadcasting Service (RUV)

KVERT reported that the Karan-1 lava dome on Sheveluch?s SW flank continued to grow during 16-23 May. Thermal anomalies over both the new and older lava domes were identified in satellite images during 17, 19-21, and 23 May; the dome was obscured by weather clouds on the other days. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

PVMBG reported that a phreatic eruption at Suoh?s Nirwana Crater occurred at 0830 on 24 May and produced a dense white steam plume; two more phreatic explosions occurred within the following half hour. According to BNPB the first event ejected sediment, the second event ejected sediment-laden water, and the third produced a dense black plume. Loud booming was heard within a radius of several kilometers. During a field visit, scientists noted that pebble-sized material had been ejected and temperatures around the vent were higher. The public was warned to stay 500 m away from Nirwana Crater and to avoid Suah?s craters and associated drainages due to potentially elevated levels of carbon dioxide. Very minor hydrothermal explosions took place in 1994; large phreatic explosions last occurred in 1933.

Sources: Badan Nacional Penanggulangan Bencana (BNPB) ,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

At 0900 on 23 May Tonga Geological Services reported that elevated activity at Tofua had ceased during the previous week. The characteristics of a thermal anomaly identified in a satellite image indicated a return to baseline levels. The Aviation Color Code was lowered to Green (the lowest color on a four-color scale), the Maritime Alert Level was lowered to Green (the lowest level on a four-color scale), and the Alert level for residents of Vava?u and Ha?apai remained at Green (the lowest color on a four-color scale).

Source: Tonga Geological Services, Government of Tonga

Instituto Geofsico del Per (IGP) reported that thermal anomalies from the main crater floor at Ubinas were identified daily during 21-28 May, except during 22-23 May. Daily gas-and-steam plumes rose as high as 900 m above the crater rim. The Alert Level remained at Yellow (the second level on a four-color scale) and the public was warned to stay 2 km away from the crater.

Source: Instituto Geofsico del Per (IGP)

GeoNet reported that a minor eruption at Whakaari/White Island occurred at around 0820 on 24 May and produced a vigorous steam-and-gas plume that rose 2-3 km high. There was no clear indication of ash in the plume at the time, based on webcam images. The Volcanic Alert Level was raised to 3 (on a scale of 0-5) and the Aviation Color Code was raised to Orange (the third level on a four-color scale). Steam emissions had returned to normal conditions by 1045. During an overflight of the island later that day scientists observed ash deposits downwind, on the N part of the island. Geysering at the crater lake that had been ongoing for months was stronger, ejecting material 20-30 m high for periods of several seconds. The vent area was obscured by gas-and-steam emissions. The level of the crater lake had subsided and exposed parts of the lake floor. The eruption was much smaller than the December 2019 eruption. At 1700 the Volcanic Alert Level was lowered back down to 2 and the Aviation Color Code was lowered back to Yellow. GeoNet noted that there were no instruments on the island and therefor a lack of real-time monitoring data; monitoring was conducted with a webcam located in Whakatane, satellite images, and observational and gas measurement overflights. A second minor eruption occurred at 0810 on 25 May, again prompting GeoNet to raise the Volcanic Alert Level to 3 and the Aviation Color Code to Orange. The eruption produced a vigorous steam-and-gas plume that rose above the island, similar to the day before. There were no clear indications of ash in the plume based on the webcam view. According to the Wellington VAAC ash was not identifiable in a satellite image from 1107 on 25 May. In a statement issued at 1445, GeoNet noted that intermittent ejections of gas and steam continued to be visible throughout the day. No further activity was observed over the next few days; the Volcanic Alert Level was lowered to 2 and the Aviation Color Code was lowered to Yellow at 1500 on 29 May. GeoNet noted that analysis of data collected during a 27 May overflight indicated elevated levels of magmatic gas compared to previous observations in April and early May.

Source: GeoNet

JMA reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 20-24 May with nighttime crater incandescence. A total of five eruptive events and two explosions were recorded. The first explosion, at 0121 on 20 May, produced an ash plume that rose 2.3 km above the crater rim and drifted W. Large blocks were ejected 800-1,100 m from the vent. The second explosion, at 1718 on 22 May, generated an ash plume that rose 3 km and drifted NW. Large blocks were again ejected 800-1,100 m from the vent. Eruptive events at 1442, 1520, 1615, and 1710 on 20 May and at 0823, 2110, and 2230 on 24 May generated ash plumes that rose 1-1.3 km and drifted SE, S, and SW. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 1 km away from both craters.

Source: Japan Meteorological Agency (JMA)