Volcanos

Roundup of Global Volcanic Activity – Ongoing Activity for the week of 6 December - 12 December 2017

Aira | Kyushu (Japan) : JMA reported that an explosion at Showa Crater (at Aira Caldera’s Sakurajima volcano) occurred at 1845 on 4 December and generated an ash plume that rose 1.4 km above the crater rim. Very small events occurred at Minamidake Crater during 7 and 9-10 December, and at Showa Crater on 10 December. The Alert Level remained at 3 (on a 5-level scale).

Ambrym | Vanuatu : On 7 December Vanuatu Geohazards Observatory (VGO) lowered the Alert Level for Ambrym to 2 (on a scale of 0-5), noting that activity had stabilized by the end of November and was characterized by gas-and-steam emissions. Seismicity had also declined. The report reminded the public to stay outside of the Permanent Danger Zone defined as a 1-km radius from Benbow Crater and a 2.7-km radius from Marum Crater.

Aoba | Vanuatu : Vanuatu Geohazards Observatory (VGO) reported that observations of Aoba’s Lake Voui on 22 and 29 November confirmed that activity had declined, characterized by less frequent explosions, steam emissions, and decreased seismicity. On 7 December the Alert level was reduced to 2 (on a scale of 0-5) and residents and tourists were reminded to stay outside of the Danger Zone defined as a 2-km radius around the active vent in Lake Voui.

Bogoslof | Fox Islands (USA) : On 6 December AVO decreased the Aviation colour Code and Volcano Alert Level for Bogoslof to Unassigned, noting that no significant activity had been observed in seismic, infrasound, satellite, or lightning data during the past three months. The last detected explosive activity occurred on 30 August 2017.

Cleveland | Chuginadak Island (USA) : AVO reported that during 6-12 December no thermal anomalies were visible in mostly clear satellite images, and no activity was detected by seismic or infrasound sensors. AVO noted that lava effusion may have paused or stopped; a satellite image acquired on 26 November showed that the lava dome had the appearance of rubble in the bottom of the shallow crater. On 12 December AVO lowered the Aviation colour Code to Yellow and the Volcano Alert Level to Advisory, though an explosion the next day prompted a return to Orange and Watch, respectively. That explosion on 13 December was detected at 0420, and produced an eruption cloud identified in satellite data rising to an altitude of 6.1 km (20,000 ft) a.s.l. and drifting E.

Dukono | Halmahera (Indonesia) : Based on analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 6-10 and 12 December ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE, E, and SE.

Ebeko | Paramushir Island (Russia) : Based on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 2-5 and 7 December generated ash plumes that rose as high as 2 km (6,600 ft) a.s.l. Ashfall was reported in Severo-Kurilsk during 1-4 and 7 December. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).

Fuego | Guatemala : INSIVUMEH reported that the 12th effusive/explosive eruption at Fuego in 2017 began on 10 December and, based on seismicity, lasted for about 36 hours. Ash plumes from moderate-to-strong explosions rose as high as 1.2 km above the crater rim and drifted 20 km S and SW. Lava flowed as far as 1.5 km W down the Seca (Santa Teresa), SW down the Taniluyá, and SSW down the Ceniza ravines. Ash fell in the communities of La Rochela, San Andrés Osuna, Morelia (9 km SW), and Panimaché I and II (8 km SW). On 12 December there was an average of 10 explosions per hour, generating avalanches in the Ceniza and Taniluyá drainages and ashfall in nearby areas.

Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite data during 3 and 5-6 December. An ash cloud rose to an altitude of km (9,000 ft) a.s.l. and drifted 200 km E on 4 December. The Aviation colour Code was raised to Orange (the second highest level on a four-colour scale).

Kilauea | Hawaiian Islands (USA) : During 6-12 December HVO reported that the lava lake continued to rise, fall, and spatter in Kilauea’s Overlook crater. Webcams recorded incandescence from long-active sources within Pu'u 'O'o Crater and from a small lava pond in a pit on the W side of the crater. Surface lava flows were active above and on the pali, and on the coastal plain.

Lopevi | Vanuatu : On 7 December Vanuatu Geohazards Observatory noted that unrest continued at Lopevi, and the Alert Level remained at 2 (on a scale of 0-4). Photos and satellite images acquired at the end of November confirmed ongoing activity from the vents in the summit crater characterized by gas-and-steam emissions.

Nevados de Chillan | Chile : POVI reported that observations of Nevados de Chillán's Volcán Arrau dome complex during 7-11 December indicated phreatic explosions, ash emissions, and a new sulfur deposit on the flank. On 11 December Servicio Nacional de Geología and Minería (SERNAGEOMIN) reported that explosive activity generated an ash plume to 3 km above the complex. The Alert Level remained at Yellow, the middle level on a three-colour scale, and the public was reminded not to approach the craters within a 3-km radius.

Sabancaya | Peru : Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya decreased compared to the previous week; there was an average of 63 explosions recorded per day during 4-10 December. Seismicity was dominated by long-period events, with signals indicating emissions. Gas-and-ash plumes rose 3 km above the crater rim and drifted 50 km NE and SW. The MIROVA system detected four thermal anomalies. The sulfur dioxide flux was high, at 1,392 tons per day on 4 December. The report noted that the public should not to approach the crater within a 12-km radius.

Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 2 and 4-6 December. A strong explosive event on 5 December generated ash plumes that rose as high as 10.5 km (34,500 ft) a.s.l. and drifted NE. Ash plumes at 5 km (16,400 ft) a.s.l. drifted E. The Aviation colour Code remained at Orange.

Sinabung | Indonesia : Based on observations by PVMBG, satellite and webcam images, and model data, the Darwin VAAC reported that during 6-9 and 11-12 December ash plumes from Sinabung rose 4.3-4.9 km (14,000-16,000 ft) a.s.l. and drifted ENE, E, SE, and SW.

Yasur | Vanuatu : On 7 December the Vanuatu Geohazards Observatory stated that the Alert Level for Yasur remained at 2 (on a scale of 0-4) and that, based on seismic data and visual observations, explosions continued to be intense. VGO reminded residents and tourists that hazardous areas were near and around the volcanic crater, within a 395-m-radius permanent exclusion zone, and that volcanic ash and gas could reach areas impacted by trade winds.