Report for Piton de la Fournaise
OVPF reported that a seismic crisis at Piton de la Fournaise was recorded during 0815-0851 on 2 April and was accompanied by rapid deformation (10-20 microradians). After a lull in activity for about three hours, volcanic tremor beginning at 1220 indicated the likely arrival of magma at the surface, though weather conditions prevented visual confirmation. During an overflight that day around 1500 observers confirmed a fissure eruption around 1,900 m elevation on the E flank about 1.7 km from the center of Dolomieu Crater, and just below the 10-16 February eruption site. Lava fountains rose no more than 30 m. By 0625 on 3 April lava flows had traveled as far as the top of Grandes Pentes, at 1,000 m elevation and 3.8 km from RN2 (the national road). By 1500 no significant deformation had been recorded and five volcano-tectonic earthquakes were located less than 2 km deep. The report noted that the weak seismicity and minor deformation indicated that the magma followed an existing pathway while propagating towards the surface.
The average lava-flow rate during 3-4 April was between 2 and 45 cubic meters per second with an average around 7-10 cubic meters per second. Lava flows continued to advance, reaching 800 m elevation. During 0400-0900 on 5 April the seismic network recorded 10 volcano-tectonic earthquakes (less than 2 km deep) prompting a request for an overflight and an inspection of the flow field. The distal end of the lava flow was located at 550 m elevation, about 2.7 km from RN2. The lava-flow rate had increased to between 3 and 63 cubic meters per second with an average around 24.2 cubic meters per second on 5 April and increased again to an estimate average of 30 cubic meters per second on 6 April. The longest flow had stopped advancing with activity focused on a new, more southern lava flow. By 1000 on 6 April the southern lava flow had descended to 360 m elevation, or about 2 km from RN2, as mapped during an overflight. Large quantities of Pele's hair were located in areas to the N, especially in La Plaine des Cafres. A sharp decrease in tremor intensity was recorded around 1330 on 6 April, signaling the end of the eruption.
Report for Yasur
Based on webcam images and information from the Vanuatu Meteorology and Geo-Hazards Department (VMGD), the Wellington VAAC reported that during 2-3 April low-level ash plumes from Yasur rose to an altitude of 1.5 km (5,000 ft) a.s.l. and drifted N and SE. Ashfall was confirmed on the SSW parts of the island.
Report for Kerinci
PVMBG reported that at 0854 on 6 April a brown ash emission rose 500 m above Kerinci’s summit and drifted NNW. Another brown emission was visible the next day at 0717, rising at least 400 m and drifting ENE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 3-km exclusion zone.
Report for Merapi
PVMBG and BPPTKG reported that incandescence from Merapi’s summit crater was visible at night and in the morning during 30 March-5 April. White plumes with variable densities rose as high as 600 m above the summit. An eruption at 1510 on 2 April generated an ash plume that rose 3 km above the summit. The morphology of the lava dome in the summit crater changed slightly based on a comparison of photos (taken from the DELES 3 station, SW) from 15 March to 2 April. The Alert Level remained at 2 (on a scale of 1-4), and residents were warned to stay outside of the 3-km exclusion zone.
Report for Semeru
PVMBG reported that during 30 March-5 April white plumes rose 100 m above Semeru’s summit. Incandescent material was ejected 10-50 m above the Jonggring-Seloko Crater. Incandescent material from the ends of lava flows descended 700 m, reaching a maximum distance of 950 m from the crater. The Alert Level remained at 2 (on a scale of 1-4), and the public was reminded to stay outside of the general 1-km radius from the summit and 4 km on the SSE flank.
Report for Soputan
The Darwin VAAC reported that on 2 April an ash plume from Soputan was seen by a pilot drifting W at an altitude of 4.3 km (14,000 ft) a.s.l.
Report for Karangetang
PVMBG reported that during 30 March-5 April lava continued to effuse from Karangetang’s Main Crater (S), traveling as far as 1.8 km down the Nanitu, Pangi, and Sense drainages on the SW and W flanks. Sometimes dense white plumes rose up to 300 m above the summit; foggy weather occasionally prevented observations. Incandescence from both summit craters was visible at night. The Alert Level remained at 2 (on a scale of 1-4).
Report for Dukono
Based on satellite and wind model data, the Darwin VAAC reported that during 1-7 April ash plumes from Dukono rose to 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted in multiple directions. 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.
Report for Ibu
The Darwin VAAC reported that on 2 April an ash plume from Ibu rose to 2.1 km (7,000 ft) a.s.l. and drifted SW based on satellite images and weather models. On 7 April an ash plume rose to 1.8 km (6,000 ft) a.s.l. and drifted S. The Alert Level remained at 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.
Report for Suwanosejima
JMA reported that during 27 March-3 April incandescence from Suwanosejima’s Ontake Crater was visible nightly. An eruptive event on 2 April produced a grayish-white plume that rose 800 m above the crater rim; ringing sounds were noted in a village 4 km SSW. The Alert Level remained at 2 (on a 5-level scale).
Report for Kuchinoerabujima
JMA reported that during 30 March-3 April white plumes rose 500 m above the rim of Kuchinoerabujima’s Shindake Crater. Sulfur dioxide emissions were at high levels. Very small eruptive events during 5-6 April generated plumes that rose 900 m and merged into weather clouds. The Alert Level remained at 3 (the middle level on a scale of 1-5).
Report for Aira
JMA reported that during 30 March-6 April incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible nightly. The seismic network recorded 22 eruptive events and one explosion (at 1558 on 4 April). The highest plume during the period rose to 3.8 km above the crater rim, visible at 1621 on 4 April. Material was ejected 500-900 m away from the crater. The Alert Level remained at 3 (on a 5-level scale).
Report for Asosan
JMA reported that eruptive activity at Asosan was recorded during 9-16 March. Gray-to-white ash plumes rose as high as 1 km above the crater rim and caused ashfall in areas downwind. The sulfur dioxide emission rate was high; the rate on 2 April was 1,900 tons per day. The Alert Level remained at 2 (on a scale of 1-5).
Report for Ebeko
Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 29 and 31 March and 1-2 April that sent ash plumes up to 2.2 km (7,200 ft) a.s.l. Ash plumes drifted NE and E, causing ashfall in Severo-Kurilsk on 1 April. A thermal anomaly was identified in satellite images during 30-31 March. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Report for Klyuchevskoy
KVERT reported that Strombolian activity at Klyuchevskoy was visible during 27 March-3 April, and a bright thermal anomaly was identified in satellite images those same days except for 1 April. Vulcanian activity was visible during 29-20 March; ash plumes drifted as far as 455 km E and NE at altitudes of 5.5-6 km (18,000-19,700 ft) a.s.l. on those same days. The Aviation Color Code remained at Orange.
Report for Sheveluch
KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 27 March-3 April. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).
Report for Semisopochnoi
On 1 April AVO reported that seismic, infrasound, and satellite data collected during the previous two weeks indicated no signs of eruptive activity at Semisopochnoi; the Aviation Color Code was lowered to Yellow and the Volcano Alert Level was lowered to Advisory. A crater lake and robust steam plume were both identified in recent satellite images.
Report for Shishaldin
AVO reported elevated seismicity at Shishaldin during 1-7 April characterized by weak continuous tremor and occasional low-frequency earthquakes. The webcam recorded steam plumes rising from the summit crater on 1 April. Weakly elevated surface temperatures were visible in satellite images on a few days. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.
Report for Rincon de la Vieja
OVSICORI-UNA reported that occasional low-frequency and low-amplitude volcanic earthquakes were ongoing at Rincón de la Vieja. A steam explosion was recorded at 0240 on 1 April. An eruption at 0824 on 4 April generated a plume that rose 1 km above the crater rim. Continuous activity during part of 6-7 April produced emissions rising 50 m above the crater rim.
Report for Sangay
IG reported a high level of activity at Sangay during 1-7 April. Weather clouds often prevented visual observations of the volcano; according to Washington VAAC notices ash plumes rose 570 m above the summit and drifted NW, W, and SW during 2-4 April. Signals indicating lahars were recorded by the seismic network on 2 and 5 April. Incandescent blocks were seen descending the S flank during a break in cloud cover on 4 April.
Report for Nevados de Chillan
The Buenos Aires VAAC reported that during 1-2 and 4-6 April ash plumes from Nevados de Chillán rose to altitudes of 3.7-4.3 km (12,000-14,000 ft) a.s.l. and drifted N, NE, E, and SE, based on webcam and satellite images.