Volcanos

Global Volcanic Activity - Ongoing Activity for the week of 18 September - 24 September 2019

Aira | Kyushu (Japan) : JMA reported that incandescence from Minamidake crater (at Aira Caldera’s Sakurajima volcano) was occasionally visible at night during 17-24 September. There were 30 eruptive events, 11 of which were explosive. Plumes rose as high as 2.6 km above the crater rim, and material was ejected as far as 1.7 km from the crater. On 20 September one of the explosions produced an ash plume that rose 3.4 km above the crater rim before merging into weather clouds. Large blocks were ejected 500-700 m. The Alert Level remained at 3 (on a 5-level scale).

Ambae | Vanuatu : The Vanuatu Meteorology and Geo-Hazards Department (VMGD) lowered the Alert level for Ambae to 1 (on a scale of 0-5) on 23 September, noting that field observations on 12 August and ongoing monitoring data suggested that activity had declined and was stable. The public was warned to stay outside of the Danger Zone defined as a 2-km radius around the 2017-2018 active vents in Lake Voui.

Asosan | Kyushu (Japan) : JMA reported that ash emissions continued to be observed at Asosan, rising to 1.6, 1.1, and 0.9 km above the crater rim during 14-17, 18-20, and 21-24 September, respectively. Sulfur dioxide emissions were high at 3,600 tons per day on 17 September and 2,700 tons per day on 19 September. Ashfall was reported in downwind areas to the SW, including at the Kumamoto Regional Meteorological Observatory. The Alert Level remained at 2 (on a scale of 1-5).

Dukono | Halmahera (Indonesia) : Based on satellite and wind model data, and information from PVMBG, the Darwin VAAC reported that during 18-24 September ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 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.

Ebeko | Paramushir Island (Russia) : Volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, observed explosions during 13-15 and 18 September that sent ash plumes up to 2.5 km (8,200 ft) a.s.l. and drifted E. A thermal anomaly was identified in satellite images on 15 September. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Etna | Sicily (Italy) : INGV reported that Strombolian activity from vents at the bottom of Etna’s Voragine Crater (VOR) continued during 16-22 September. On 18 September guides observed intensified explosive activity at VOR characterized by the ejection of scoria and ash from several vents to heights of tens of meters. A lava flow from the cone had descended the W flank of the cone to its base, and then flowed several hundred meters S and branched into the Bocca Nuova Crater. Similar activity was observed on 19 September, though by 22 September the lava flows were cooling and Strombolian activity from VOR vents had become less frequent. Gas emissions rose from Northeast Crater (NEC); an ash emission was noted on 22 September.

Karangetang | Siau Island (Indonesia) : PVMBG reported that during 16-22 September lava continued to effuse from Karangetang’s Main Crater (S) and Dua Crater (N), 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 to 500 m above the summit. The Alert Level remained at 2 (on a scale of 1-4).

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Karymsky was visible in satellite images on 14 September. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Klyuchevskoy | Central Kamchatka (Russia) : KVERT reported that a weak thermal anomaly over Klyuchevskoy was sometimes visible in satellite images, though the temperature of the anomaly had steadily decreased over time. Gas-and-steam emissions persisted; ash was last emitted on 2 July. The Aviation colour Code was lowered to Green (the lowest on a four-colour scale) on 24 September.

Krakatau | Indonesia : PVMBG reported that Anak Krakatau’s seismic network recorded nine eruptive events during 16-22 September. A webcam at the summit recorded dense gray-to-white eruption plumes and diffuse white plumes rising 200 m from the bottom of the crater. An eruptive event at 0843 on 24 September produced a dense white-to-gray ash plume that rose around 360 m a.s.l. and drifted N. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km-radius hazard zone from the crater.

Merapi | Central Java (Indonesia) : PVMBG reported that the lava dome at Merapi slowly grew during 16-22 September and was an estimated 468,000 cubic meters, based on 19 September measurements from drone photos. Extruded lava fell into the upper parts of the SE flank, generating block-and-ash flows that traveled as far as 1.3 km down the Gendol drainage during 17 and 20-21 September. Diffuse white plumes rose as high as 100 m above the summit. At 1136 on 22 September the seismic network began recording signals indicating pyroclastic-flow generation, that lasted two minutes and five seconds; pyroclastic flows traveled 1.2 km down the Gendol drainage. An ash plume rose around 800 m above the summit and caused minor ashfall in areas as far as 15 km SW. Temperature increases at several points on the lava dome were recorded about one hour before the event. 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.

Pacaya | Guatemala : A special report from INSIVUMEH noted that seismic activity at Pacaya continued to increase, with RSAM values reaching 8,000 units by 18 September, coincident with an intensification of explosive activity at Mackenney Crater. Explosions from a growing cone in the crater ejected material as high as 100 m above the cone. Lava effusion increased; several lava flows (300-500 m long) advanced on the N and NW flank towards Cerro Chino and produced avalanches of blocks up to 1 m in diameter from the flow fronts. Strombolian explosions during 19-24 September ejected material 5-25 m above the cone, though on 21 September material was ejected as high has 100 m. Two lava flows traveled SW on 21 September.

Poas | Costa Rica : OVSICORI-UNA reported that at 2059 on 22 September an eruptive event at Poás generated a plume that rose 3 km above the crater rim and drifted NE. During 22-23 September eruption plumes rose 1 km.

Semisopochnoi | United States : AVO lowered the Volcano Alert Level for Semisopochnoi to Advisory and the Aviation colour Code to Yellow on 18 September noting a decrease in seismic activity over the past few weeks and an absence of tremor since 15 September. Low-levels sulfur dioxide emissions persisted, and the crater lake continued to fill with water.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch’s lava dome was identified daily in satellite images during 13-20 September. Ash plumes drifted 200 km SW, SE, and NE during 12-15, 17, and 19 September. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Shishaldin | Fox Islands (USA) : AVO reported that during 18-24 September low-level tremor at Shishaldin continued to be recorded, along with elevated surface temperatures at the summit crater visible in satellite images when views were not obscured by clouds. The data suggested ongoing, slight growth of the scoria cone and lava flows within the summit crater. The Aviation colour Code remained at Orange and the Volcano Alert Level remained at Watch.

Suwanosejima | Ryukyu Islands (Japan) : JMA reported that at 0704 on 16 September a very small eruptive event at Suwanosejima’s Ontake Crater generated a plume that rose 400 m above the crater rim. The Alert Level remained at 2 (on a 5-level scale).

Tangkubanparahu | Western Java (Indonesia) : PVMBG reported that the seismic network at Tangkubanparahu recorded continuous tremor during 16-22 September. A phreatic event at Ratu Crater on 17 September was accompanied by roaring. An ash plume rose as high as 40 m above the vent and steam plumes rose as high as 200 m. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

Ubinas | Peru : During 16-22 September the number of seismic events totaled 4,356, with volcano-tectonic (VT) signals being the most numerous, averaging 567 events per day, and all having magnitudes under M 2.5. Hybrid events averaged 119 events per day. Continuous emissions of blueish gas and water vapor were recorded by the webcam rising to heights less than 1 km above the summit. Four thermal anomalies were recorded by the MIROVA system. The Alert Level remained at Orange (the second highest level on a four-colour scale) and the public were warned to stay outside of a 10-km radius.