Volcano World

JMA reported continuing unrest at Asosan. Sulfur dioxide gas emissions were somewhat high, averaging 1,600 tons per day (t/d), when measured during a field survey on 9 May. The amplitude of volcanic tremors began to increase at around 0600 on 15 May and increased again round 0900. At 0920 the Alert Level was raised to 2 (on a scale of 1-5) and the public was warned to stay at least 1 km away from the crater. During a field visit later that morning scientists observed a hot spring within the pool on the Nakadake Crater floor and measured sulfur dioxide emissions of 800 t/d. Volcanic tremor amplitude was variable and decreased to low levels by 0700 on 16 May. White steam-and-gas plumes rose 100-300 m above the crater rim during 16-17 May and crater incandescence was occasionally visible in webcam images at night. Sulfur dioxide emissions had decreased to 500 t/d on 17 May.

Source: Japan Meteorological Agency (JMA)

Instituto Nicaragense de Estudios Territoriales (INETER) reported that a small-to-moderate explosion at Concepcin occurred at 1420 on 16 May. An ash-and-gas plume rose at least 2 km above the crater rim and caused ashfall up to 1 mm deep in Los Ramos (SE), La Unin (SE), Los Angeles, La Flor (5 km NW), Urbaite, and Las Pilas. According to the Washington VAAC the ash plume was identified in satellite images at 1520 drifting NW at an altitude of about 5.5 km (18,000 ft) a.s.l., or at around 3.8 km above the summit.

Sources: Instituto Nicaragense de Estudios Territoriales (INETER),Washington Volcanic Ash Advisory Center (VAAC)

PVMBG reported that the eruption at Ibu continued to intensify during 11-21 May, with ash plumes rising higher and having denser ash content. Seismicity was also high and increasing. Beginning on 11 May the ash plumes began rising 4-5 km above the summit; the plumes were dense and gray and drifted N and NW, and incandescent ejecta was visible. Eruptive events were recorded on 12 and 14 May, though weather conditions prevented visual observations. During 13-16 May gray-to-black ash plumes rose as high as 5 km and drifted multiple directions. Roaring and banging noises were heard in areas as far away as the Ibu observation post (9 km W). At 1500 on 16 May the Alert Level was raised to 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. BNPB reported that 263 residents evacuated from three villages, Gam Ici, Goin, and Sangaji Nyeku. White-and-gray ash plumes with variable densities rose 4-5 km above the summit and drifted multiple directions during 17-18 and 20-21 May. Photos from just after 2000 on 18 May showed lightning in the dense ash plumes. Only white steam-and-gas plumes were visible on 19 May, rising 200-300 m above the summit and drifting N, NE, and E. According to a news report the total number of evacuees rose to more than 400 by 19 May; the residents were from seven villages in the West Halmahera District.

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

PVMBG reported that eruptive activity at Marapi (on Sumatra) was ongoing during 15-21 May. White gas-and-steam plumes rose 200-300 m above the summit and drifted in multiple directions on most days; no emissions were visible on 16 and 20 May. White-and-gray ash plumes rose 400-550 above the summit and drifted NW on 18 May. The 11 May lahars that caused several fatalities, evacuations, and widespread damage in the Agam Regency continued to impact the area. As of 1700 on 16 May BNBP reported that the death toll had reached 67 people, while 20 remained missing and 40-44 had been injured; overall 989 families were impacted by the lahars. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 4.5 km away from the active crater.

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

Observatorio Vulcanolgico y Sismolgico de Popayn, Servicio Geologico Colombiano (SGC) reported that the daily number of both volcanic tremor (VT) and long-period (LP) seismic events at Purac trended downward during 14-21 May, and by the end of the week had reached pre-29 April levels. The VT events had low magnitudes and were located at depths up to 2.4 km beneath the volcano and its E flank. The largest VT events, M 1.5, were recorded at 1821 on 14 May and at 0711 on 16 May. LP earthquakes were located at depths less than 3 km beneath the volcano and its N flank. Inclement weather often prevented visual observations of emissions, though during 15-16 May a gas plume rose as high as 650 m above the summit and drifted W. Both carbon dioxide and sulfur dioxide emissions remained above baseline levels. The Alert Level remained at Orange (the second highest level on a four-color scale).

Source: Servicio Geolgico Colombiano (SGC)

On 15 May BNPB reported that a total of 9,343 residents of Tagulandang and Ruang islands remained in evacuation centers because of eruptions from Ruang. According to PVMBG daily white steam-and-gas plumes that were sometimes dense rose as high as 700 m above the summit and drifted in multiple directions during 15-21 May. The Alert Level was lowered to 2 (the second lowest level on a scale of 1-4) at 0900 on 18 May and the public was warned to stay 2 km away from the active crater.

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

KVERT reported that the Karan-1 lava dome on Sheveluch?s SW flank continued to grow during 9-16 May. An intense and large thermal anomaly over the dome was identified in satellite images during 9-12 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 daily white emissions rose 50-500 m above Slamet?s summit and drifted W during 15-21 May. The Alert Level remained at 2 (on a scale of 1-4). On 16 May the exclusion zone was increased from 2 km to 3 km based on monitoring data.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

On 15 May AVO reported that elevated seismicity at Spurr was consistent with an intrusion of magma deep beneath the volcano. An extended outage of the seismic network occurred during February-April; elevated seismicity was already occurring when the network returned on 3 April. An average of four earthquakes per day were located after that time, with a maximum of 33 earthquakes detected on 26 April. They were typically smaller than M 1 and were located near the summit and as deep as 30 km below sea level. This activity represents an increase in earthquake rate and occurrence of deeper (>20 km) low-frequency earthquakes compared to recent years. Minor uplift of the ground surface at the volcano of about 1 cm was detected in local GPS data beginning in November 2023, which was a deviation from the long-term trend and may be related to the seismicity. Minor steaming from fumaroles in the summit crater area was sometimes visible; no notable changes to the ice-and-snow cover or gas-and-steam emissions were observed in association with these geophysical observations. A short observational flight was conducted on 14 May. The Volcano Alert Level remained at Normal (the lowest level on a four-level scale) and the Aviation Color Code remained at Green (the lowest color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

PHIVOLCS reported ongoing unrest at Taal during 13-21 May. Daily upwelling of gases and hot fluids in the lake generated steam-and-gas plumes that rose as high as 2.4 km above the crater rim and drifted WNW. Sulfur dioxide emissions increased to 5,094 tonnes per day (t/d) on 13 May. A phreatic event began at 1345 on 15 May, lasted about five minutes, and produced a steam plume that rose 500 m above Main Crater rim and drifted W and NW. On 16 May a series of short phreatic events were visible in webcam images and detected by the seismic network during 0854-0857, 1107-1110, 1348-1350, 1737-1738, and a fifth that ended at 2303. The events produced steam plumes that rose 50-300 m and drifted WNW. Sulfur dioxide emissions decreased to 3,823 t/d on 20 May. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ) and to take extra precautions around Main Crater, when boating on Taal Lake, and along the Daang Kastila fissure.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)