Volcano World

OVSICORI-UNA reported continuing gas-and-steam emissions from vents Boca A and Boca C on the crater floor of Pos during 24-30 April. Although emissions from Boca C often contained low ash content, no ash was present for a period of time during 25-27 April. Plumes intensified on 28 April and rose several hundred meters high. A sulfur odor was reported in Sarch and Grecia (both about 17 km SW) on 25 April. Incandescence from Boca A was visible at night during 27-28 April and from both Boca A and Boca C at night during 29-30 April.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

SERNAGEOMIN reported that inflation had been detected at the Puyehue-Cordn Caulle volcanic complex since 2011 based on GNSS satellite and radar data. The inflation is centered about 6 km WNW of the 2011 eruption vents. The rate of inflation had increased during the first few months of 2024, reaching a maximum average of 2.4 cm per month, which was the highest rate detected since GNSS equipment was installed in 2017. Seismicity began to slightly increase in mid-2020 and was characterized by volcano-tectonic and hybrid events from a shallow source near the 2011 vents. Gas emissions rose from the 2011 vents and were nearly 90 degrees Celsius. The Alert Level was raised to Yellow (the second lowest color on a four-color scale) on 26 April based on the high deformation rates.

Source: Servicio Nacional de Geologa y Minera (SERNAGEOMIN)

OVSICORI-UNA reported that the amplitude of seismic tremor at Rincn de la Vieja intensified on 17 April and then increased again on 25 April. The tremor signals were accompanied by long-period events occurring at a rate of sometimes hundreds per day. The intensities of the earthquakes were the highest recorded within the last five years. A total of 19 small eruptive events were recorded during 17-25 April and produced steam-and-gas plumes that rose as high as 2 km. Sulfur dioxide emissions began to increase on 21 April and increased more notably during 24-25 April, rising from around 77 tonnes per day (t/d) to around 493 t/d. Tremor amplitude fluctuated at high levels during 26-29 April, reaching a new peak at around 0200 on 28 April. Gas-and-steam emissions were continuous. The Alert Level remained at Level 3, Orange, the third highest level on a four-level scale.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

PVMBG reported that seismicity significantly increased at Ruang on 29 April and the signals indicated magma moving towards the surface. Earthquakes began to be felt at 0015 on 30 April. At 0115 the earthquakes intensified; residents in neighboring Tagulandang Island reportedly felt continuous shaking, heard loud roaring, and saw an ash plume rising about 2 km above the summit. Activity continued to escalate and at 0130 the Alert Level was raised to 4 (the highest level on a scale of 1-4). The public was warned to stay 7 km away from the active crater and residents on Tagulandang within 6 km were instructed to evacuate. A webcam photo from 0232 on 30 April showed lava being ejected above the summit; an eruptive event was recorded in seismic data at 0235. According to the Darwin VAAC ash plumes had risen to 15.2 km (50,000 ft) a.s.l. by 0300 and to 19.2 km (63,000 ft) a.s.l. by 0320, and by 0620 were expanding radially; the plumes may have risen to 23 km (75,400 ft) a.s.l. or more based on other expert analysis. PVMBG noted that at 0835 dense gray-to-black ash plumes rose at least 5 km and drifted E and S. A webcam photo from 0827 showed multiple pyroclastic density currents descending the flanks. According to a characterization by BNPB the eruption ejected incandescent lava high above the summit and lightning was frequently seen in the plumes. Tephra fell over a more extensive area compared the 16-18 April eruption phase; gravel-sized tephra fell in Apengsala, about 8 km NNE from Ruang?s central vent, and outside of the exclusion zone. According to a news report residents felt shock waves from the explosions. At least three eruptive events were recorded during 1200-1800 that produced gray-and-black ash plumes at least as high as 1.5 km. The VAAC noted that by 1510 the high-level plume had detached from the summit and was drifting W and SW, and ash between 13.7-19.2 km (45,000-63,000 ft) a.s.l. continued to be identified drifting WNW at least through 0940 on 1 May. Ash plumes continued to be identified in satellite images, rising to 3 km (10,000 ft) a.s.l. and drifting N and SE at least through 1240 on 1 May. According to a news report the eruption and the presence of ash and ashfall caused the closure of seven airports, scheduled to reopen on 1 May: the Sam Ratulangi International Airport (98 km SW in Manado, North Sulawesi), the Gorontalo Airport (371 km SW), the Siau/Sitaro Airport (40 km N), the Bolaang Mongondow Airport (215 km SW), the Tahuna/Naha Airport (150 km N), the Pohuwato Airport (445 SW), and the Pogogul Airport (460 km WSW). On 1 May about 123 residents were evacuated to Bitung City by boat. Ashfall was notable at the Sam Ratulangi International Airport with delays affecting about 7,000 passengers.

Sources: Andrew Tupper, Natural Hazards Consulting ,Antara News,Antara News,Antara News,Antara News,Antara News,Badan Nacional Penanggulangan Bencana (BNPB) ,Darwin Volcanic Ash Advisory Centre (VAAC),Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

PHIVOLCS reported ongoing unrest at Taal during 23-30 April. Upwelling gasses and hot fluids in the lake were visible during daily observations. Daily emissions of gas-and-steam rose from Main Crater Lake as high as 1.8 km, were sometimes voluminous, and drifted generally NW and SW. There were 0-14 daily earthquakes recorded by the seismic network including a few periods of volcanic tremor lasting 2-4 minutes. One phreatic event lasting two minutes long was recorded during 28-29 April. 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)

Tonga Geological Services reported that activity at Tofua increased on 26 April and was characterized as having an unusual pattern of activity. A total of 45 eruptive events were identified in data from 0956 on 26 April to 0246 on 28 April. An intensifying thermal anomaly was also identified in satellite images. At 2200 on 28 April an ash plume was identified in a satellite image rising 4-6 km above the summit and drifting NW; it was no longer visible 4 hours later. A SW-drifting plume of sulfur dioxide was also identified in a few satellite images. The number of thermal anomalies over the volcano decreased during 28-30 April, and though sulfur dioxide emissions continued to be detected, the flux had decreased. Mariners were advised to stay 2 km away from the island.

Source: Tonga Geological Services, Government of Tonga

JMA reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 22-29 April with nighttime crater incandescence. Sulfur dioxide emissions averaged 1,800 tons per day on 22 April. Very small eruptive events were occasionally recorded during 22-26 April. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 2 km away from both craters.

Source: Japan Meteorological Agency (JMA)

On 25 April the Vanuatu Meteorology and Geo-Hazards Department (VMGD) reported that small fumarolic steam emissions were ongoing in both of Ambrym?s Benbow and Marum craters. A satellite image from 20 April showed minor amounts of gas emissions. Incandescence at Marum was visible at night during 20-21 April and a low- to moderate-intensity thermal anomaly was identified in a satellite image on 23 April. Seismic data also confirmed ongoing unrest. The Alert Level remained at 2 (on a scale of 0-5). VMGD warned the public to stay outside of Permanent Danger Zone A, defined as a 1-km radius around Benbow Crater and a 2-km radius around Marum Crater, and to stay 500 m away from the ground cracks created by the December 2018 eruption.

Source: Vanuatu Meteorology and Geohazards Department (VMGD)

PVMBG reported that the eruption at Dukono was ongoing during 24-30 April. Gray-and-white ash plumes rose 100-1,500 m above the summit and drifted NW, W, and SW almost daily; emissions were not observed on 26 April. The Alert Level remained at Level 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.

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

KVERT reported that moderate explosive activity was ongoing at Ebeko during 18-25 April. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E), explosions during 22-25 April generated ash plumes that rose as high as 3 km (11,500 ft) a.s.l. and drifted S, SE, and NE. A thermal anomaly was identified in satellite images during 22-24 April; on other days either no activity was observed or weather conditions prevented views. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are UTC; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)