JMA reported that there were 16 events at Minamidake crater (at Aira Caldera’s Sakurajima volcano) during 26 March-2 April, 12 of which were explosive. Tephra was ejected as far as 900 m from the crater. At 1541 on 26 March an explosion generated an ash plume that rose 3.4 km above the crater rim. An explosion recorded at 0740 on 1 April produced an ash plume that rose 3 km. Crater incandescence was visible the morning of 27 March and at night during 30 March-1 April.

During 30 March-2 April there were three events at Showa crater. An event at 1611 on 1 April ejected tephra 300-500 m from the crater, and produced a very small pyroclastic flow (the first since 3 June 2016) that traveled 800 m E. A plume rose 1.7 km above the crater rim, up into weather clouds. The previous eruption at Showa crater occurred on 8 January. The Alert Level remained at 3 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)

Based on satellite data, webcam and VGO observations, and wind model data, the Wellington VAAC reported that during 28 March-3 April ash plumes from the vent at Ambae’s Lake Voui rose to altitudes of 2.3-6.1 km (8,000-20,000 ft) a.s.l. and drifted in multiple directions. News articles noted that ashfall continued to damage crops and buildings, and contaminate water.

Sources: Wellington Volcanic Ash Advisory Center (VAAC), Radio New Zealand

PVMBG reported that a phreatic eruption at the Sileri Crater lake (Dieng Volcanic Complex) occurred at 1342 on 1 April, ejecting mud and material 150 m high, and up to 200 m in multiple directions. The event was preceded by black emissions that rose 90 m, and then diffuse white emissions that rose 150 m. The report noted that there were not many tourists in the area due to rainy weather; tourists are not permitted within 200 m of the crater rim.

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

JMA reported that the number of volcanic earthquakes at Satsuma Iwo-jima, a subaerial part of Kikai’s NW caldera rim, was low during 27 March-2 April after an increase recorded during 22-23 March. White plumes rose as high as 1.8 km above the Iwo-dake lava dome. Incandescence from the crater was visible at night during 27-28 March. The Alert Level remained at 2 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)

Based on observations during overflights on 28 March and 2 April, JMA reported that the crack on the W flank of Shinmoedake (Shinmoe peak), a stratovolcano of the Kirishimayama volcano group, continued to widen. White emissions rose as high as 500 m above the crater rim. Several high-temperature regions around the margins of the lava in the crater, and from the flow on the NW flank, were detected on 28 March. The lava flow on the NW flank advanced 85 m from 9-29 March. Sulfur dioxide emissions were 300 tons/day on 30 March. The number of volcanic earthquakes began to decline after 26 March; though from 0014 to 1430 on 3 April the number increased to 239. Many low-frequency earthquakes with shallow hypocenters continued to be recorded. The Alert Level remained at 3 (on a scale of 1-5).

Source: Japan Meteorological Agency (JMA)

OVPF reported that intermittent inflation at Piton de la Fournaise had been detected since the end of the last eruption on 28 August 2017. Seismicity began increasing the last two weeks in February. Seismicity fluctuated during March; peaks were recorded on 28 and 31 March, with volcano-tectonic earthquakes occurring less than 2 km below the summit area. An enrichment of carbon dioxide and sulfur dioxide in summit fumaroles was noted on 23 March.

A seismic crisis began at 0300 on 3 April, and along with deformation, indicted magma migration towards the surface. An eruption began at 1040 on the N flank, just below the rampart at the Nez Coupé de Sainte Rose area. During an overflight, scientist observed a 1-km-long fissure, divided in seven segments, with two active vents producing lava fountains. At 1600 many landslides were recorded by the seismic network in the active area. The eruption ended At 0400 on 4 April, though a few landslides were recorded through 1530.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)

Based on analyses of satellite imagery and wind model data, the Darwin VAAC reported that during 28 and 30 March and 1-3 April ash plumes from Dukono rose to altitudes of 1.5-2.1 km (5,000-7,000 ft) a.s.l. and drifted ENE, E, and ESE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Based on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 23-25 and 28-29 March generated ash plumes that rose as high as 2.3 km (7,500 ft) a.s.l. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 23-26 March. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

During 28 March-3 April HVO reported that the lava lake continued to rise, fall, and spatter in Kīlauea's Overlook crater. Surface lava flows were active above Pūlama pali. Webcams recorded spattering from a small lava pond in a pit on the W side of Puʻu ʻŌʻō Crater. The lava flow from a vent on the SE part of the crater floor continued to expand.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

On 29 March PHIVOLCS lowered the Alert Level for Mayon to 2 (on a 0-5 scale) noting a deflationary trend since 20 February, decreased seismicity, a lower sulfur dioxide flux, and decreased surficial activity. During the previous two weeks the number of rockfalls from collapse of unstable lava-flow deposits fell from a peak of 82 to less than 10 per day. Sulfur dioxide flux ranged from 500 to 2,000 tonnes/day during the previous two weeks, lower than 700-4,500 tonnes/day during 13 January-8 March. Lava last effused from the crater on 18 March, and crater incandescence from hot gas emissions had become faint. Fewer rockfalls and pyroclastic flows were noted as the lava flows stabilized; at 0934 on 27 March one pyroclastic flow traveled down the Bonga-Buyuan drainage and produced a dirty-white ash cloud that drifted SW. During 30 March-3 April a few rockfalls were recorded, there was faint crater incandescence, and steam plumes drifted SW, WNW, and NW. PHIVOLCS reminded residents to stay away from the 6-km-radius Permanent Danger Zone.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya was similar compared to the previous week; explosions averaged 18 per day during 26 March-1 April. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose as high as 4.7 km above the crater rim and drifted 50 km SW and NW. The sulfur dioxide flux was high, at 2,855 tons per day on 30 March. The MIROVA system detected six thermal anomalies. On 28 March a lahar which began at 1113 descended the SE flank towards the Sallalli river. The report noted that the public should not to approach the crater within a 12-km radius.

Sources: Instituto Geológico Minero y Metalúrgico (INGEMMET), Instituto Geofísico del Perú (IGP)

KVERT reported that a weak thermal anomaly over Sheveluch was identified in satellite images during 23-30 March. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Based on JMA notices and satellite data, the Tokyo VAAC reported that during 28-30 March and 2 April explosions at Suwanosejima produced plumes that rose 1.2-2.7 km (4,000-9,000 ft) a.s.l. and drifted NE, NW, W, SW, and S.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)

OVSICORI-UNA reported that events at Turrialba at 1802 on 31 March and 0838 on 1 April generated plumes that rose 400 and 500 m above the crater rim, and drifted SW and NW, respectively. An event at 0700 on 3 April produced an ash plume that rose 500 m and went NW; passive ash emissions followed.

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