On 24 May KVERT reported that the effusive eruption at Bezymianny continued, characterized by strong fumarolic emissions, lava-dome incandescence, and hot avalanches. Notable hot avalanches descended the E flank. Gas-and-steam plumes with some ash content drifted 30 km NW on 24 May and 25 km NE on 25 May, at altitudes of 3-4.5 km (9,800-14,800 ft) a.s.l. The Aviation Color Code was raised to Orange (the second highest 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)

AVO reported that during 17-24 May almost daily elevated surface temperatures over Cleveland were identified in satellite images. Daily sulfur dioxide emissions were visible, and steam plumes rose from the crater during 22-24 May. A series of small, local earthquakes were detected on 18 May. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

The Darwin VAAC reported that on 18 May a diffuse ash plume from Anak Krakatau rose to 2.4 km (8,000 ft) a.s.l. and drifted WNW based on satellite images and weather models. On 19 May a dense steam plume with diffuse ash rose to 2.4 km and drifted N.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

IMO reported an ongoing seismic swarm and uplift on the Reykjanes Peninsula, indicative of a magma intrusion. Satellite data analysis indicated that 4-4.5 cm of uplift occurred during 27 April-21 May centered just NW of Mt. Thorbjorn. Magma was accumulating at depths of 4-5 km, and the intrusion was possibly 7-8 km long. During 22-23 May about 400 earthquakes were recorded; a M 3 earthquake was recorded at 1113 on 22 May and a M 3.5 earthquake was recorded at 0715 on 23 May, both were located about 3 km E of Mt. Thorbjorn. The Aviation Color Code for Reykjanes remained at Yellow.

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

JMA reported that a very small eruptive event was recorded at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) during 16-23 May. Crater incandescence was visible at night. At 0900 on 17 May an eruptive event produced a plume that rose 1.5 km above the crater rim. That same day the sulfur dioxide rate was slightly high at 1,700 tons per day. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

Based on satellite and wind model data, the Darwin VAAC reported that during 17-20 May ash plumes from Dukono rose to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted W and NW. The plumes on 17 May drifted 185 km W. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC), Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

INGV reported that at around 1900 on 12 May a new vent opened along the N flank of Etna’s Southeast Crater (SEC) at an elevation of 3,250 m, and produced ash emissions that rose to 3.5 km (11,500 ft) a.s.l. and drifted SW. Small pyroclastic flows descended the flank. Lava effused from the vent and traveled N and NE into the snowy Valle del Leone, where lava blocks that rolled onto the snow caused steam plumes. The lava flow slowly advanced during 13-22 May, reaching 2,300-2,400 m elevation by 17 May. Discontinuous Strombolian activity of variable intensities occurred at SEC; ash emissions were visible during more intense phases, though the plumes dissipated rapidly.

A new lava flow emerged from the vent on the N flank at around 2300 on 17 May and traveled N and NE alongside the previous lava flow. During fieldwork conducted on 18 May, scientists observed that lava had reached an elevation of 2,700 m in the Valle del Leone. A new vent opened on the N flank of SEC by 1730 on 20 May, at 3,250 m elevation, just NW of the previous vent. The vent produced a small lava flow that curved N and NE, joining the previous flow. By 21 May lava flows were not advancing below the summit area, at elevations of 2,700-2,800. Strombolian activity of varying intensity continued at SEC; periodic ash emissions generated ashfall in areas as far as Catania. At 2305 on 21 May a pyroclastic flow from the 20 May vent traveled 700 m NNE. Ash emissions intensified during 0300-0400 on 22 May. By that evening, lava flows from the 12 May vent had ceased and the 20 May vent produced short lava flows.

Source: Sezione di Catania - Osservatorio Etneo (INGV)

INSIVUMEH reported that on 23 May lahars descended Fuego in the Las Lajas drainage (SE), the Ceniza drainage (SSW), and the Honda drainage (E); all three lahars carried fine material along with tree trunks, branches, and blocks as large as 1.5 m in diameter.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

AVO reported that the eruption at Great Sitkin continued during 17-24 May. Almost daily elevated surface temperatures were identified in satellite data, consistent with lava effusion. Steam emissions were visible during 23-24 May. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

PVMBG reported that the eruption at Ibu continued during 17-24 May. Daily gray-and-white ash plumes of variable densities generally rose 200-1,500 m above the summit and drifted in multiple directions. The Alert Level remained at a 2 (on a scale of 1-4), and the public was warned to stay at least 2 km away from the active crater and 3.5 km away on the N side.

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

KVERT reported that during 13-20 May daily explosions at Karymsky generated ash plumes that rose 3-9.5 km (9,800-31,200 ft) a.s.l. and drifted more than 450 km in various directions. A thermal anomaly over the volcano was visible in satellite images during 13-14 and 17-19 May. The Aviation Color Code remained at Orange (the second highest 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)

AVO reported that on 20 May strong winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes blew unconsolidated ash WNW at an altitude up to 1.8 km (6,000 ft) a.s.l. The ash was originally deposited during the Novarupta eruption in 1912. The Volcano Alert Level remained at Normal and the Aviation Color Code remained at Green.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

HVO reported that lava continued to effuse from a vent in the lower W wall of Kīlauea's Halemaʻumaʻu Crater during 17-24 May, entering the active lava lake and flowing onto the crater floor. The surface of the lava lake was active all week, though the height of the lake was high and relatively stable. Breakouts of lava occurred along the E, N, NW, and W margins of the lake. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

PVMBG reported that the eruption at Lewotolok continued during 17-24 May. Daily white steam plumes were visible rising 50-800 m above the summit and drifted multiple directions. White-and-gray emissions were visible on 19 and 21 May rose as high as 500 m above the summit and drifted SE, W, and NW. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater and 4 km away from the crater on the SE flank.

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

The Darwin VAAC reported that during 17-19 May ash plumes from Manam rose to 2.4 km (8,000 ft) a.s.l. and drifted NW and W based on satellite images and weather models.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

BPPTKG reported that the eruption at Merapi continued during 13-19 May. The heights and morphologies of the SW lava dome and the central lava dome were unchanged from the previous week, and seismicity remained at high levels. As many as 82 lava avalanches traveled a maximum of 2 km, mostly down the Bebeng drainage on the SW flank. One pyroclastic flow traveled 2.5 km down the Bebeng drainage. Seismicity remained high. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit based on location.

Source: Balai Penyelidikan dan Pengembangan Teknologi Kebencanaan Geologi (BPPTKG)

SERNAGEOMIN reported low levels of activity at Nevados de Chillán during 1-15 May. The area of the lava dome on the floor of Nicanor Crater was 1,626 square meters, similar to measurements from March (1,665 square meters); deformation measurements indicated that extrusion had ceased. Crater incandescence was sometimes visible; thermal anomalies were identified in satellite images on 3, 5, 8, 10, 13, and 15 May. There were 217 explosions in the active crater recorded by the seismic network. The explosions mainly produced steam, though the plumes occasionally contained tephra. Material from explosive activity accumulated in the NE part of the crater. An energetic explosion on 16 May produced an ash plume that rose 900 m and pyroclastic flows that descended the SE, NE, and W flanks as far as 400 m. Seismicity remained at moderate levels. Sulfur dioxide emissions averaged 466 ± 54 tons per day, peaking at 802 tons per day on 7 May. An explosion was recorded on 21 May. The Alert Level remained at Yellow, the second lowest level on a four-color scale. ONEMI stated that Alert Level Yellow (the middle level on a three-color scale) remained in place for the communities of Pinto and Coihueco, noting that the public should stay at least 2 km away from the crater.

Sources: Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI), Servicio Nacional de Geología y Minería (SERNAGEOMIN)

AVO reported that the eruption at a vent on Pavlof’s upper E flank was ongoing during 17-24 May, and seismic tremor persisted. Daily elevated surface temperatures were identified in satellite images consistent with the effusion of short lava flows on the upper flank. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

OVSICORI-UNA reported that a few small phreatic explosions at Rincón de la Vieja were recorded during the previous week. A phreatic explosion at 1343 on 18 May produced a steam-and-gas plume that rose 200 m above the crater rim. At 1710 on 19 May an eruptive event produced a gas-and-steam plume that rose 100 m above the summit. More small eruptive events at 0251 and 0443 on 21 May were recorded by seismic and infrasound instruments.

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

On 24 May GeoNet reported that elevated unrest at Ruapehu continued, though at reduced levels. During the previous week the levels of volcanic tremor further declined, were variable, but remained above normal. The lake water temperature decreased from a peak of 41 degrees Celsius on 8 May to 30 degrees Celsius, showing a cooling trend. A gas measurement flight on 13 May confirmed continuing high levels of gas emissions, though at values lower than measured two weeks prior; sulfur dioxide and carbon dioxide flux rates were at 179 and 1,658 tonnes per day, respectively; data from new instruments confirmed that these levels remained elevated. The Volcanic Alert Level remained at 2 (on a scale from 0-5) and the Aviation Color Code remained at Yellow.

Source: GeoNet

PVMBG reported that the eruption at Semeru continued during 17-24 May. White plumes were occasionally visible rising 100-700 m above the summit. Several eruptive events (recorded at 0525 on 19 May, at 0552 on 20 May, at 0525 on 21 May, at 0632 on 22 May, and at 0624 on 23 May) produced ash plumes that rose 200-500 m above the summit and drifted S and SW. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 5 km away from the summit, and 500 m away from Kobokan drainages within 17 km of the summit, and along with other drainages originating on Semeru, including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

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

AVO reported that low-level eruptive activity at Semisopochnoi's North Cerberus cone continued during 17-24 May. Seismicity continued to be elevated with intermittent tremor and several daily explosions recorded by infrasound and seismic instruments. Low-level ash emissions were visible in clear satellite images and webcam views; clouds sometimes obscured views towards the end of the week. A sulfur dioxide plume drifted 240 km N during 17-18 May, and sulfur dioxide emissions were detected during 23-24 May. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 13-20 May, and lava-dome extrusion continued. The Aviation Color Code remained at Orange (the second highest 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)

JMA reported that eruptive activity continued to be recorded at Suwanosejima's Ontake Crater during 16-23 May. Eruption plumes rose as high as 1.9 km above the crater rim and material was ejected 400 m above the vent. Ash fell in Toshima village (3.5 km SSW) and in other areas within 5 km. Three explosions were recorded during 20-23 May and crater incandescence from the crater was visible at night. The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)