Volcanos

Roundup of Global Volcanic Activity – New Activity for the week of 4 July – 10 July 2018

Agung | Bali (Indonesia) : PVMBG reported that the eruption at Agung continued during 4-10 July. Sulfur dioxide flux was 1,400-2,400 tons/day on 3 July and 400-1,500 tons/day on 4 July. Satellite data acquired on 4 July indicated continuing lava effusion in the crater, with 4-5 million cubic meters effused in the past week. At 1220 an ash plume rose 2.5 km above the crater rim and drifted W. An event was detected at 2216, though an ash plume was not visible possibly due to poor viewing conditions. At 0047 on 5 July an ash plume rose at least 1 km and drifted W, and an event at 1633 produced an ash plume that rose 2.8 km and drifted E and W. A small event was detected on 6 July. According to BNPB a third Strombolian event occurred at 0522 on 8 July, generating an ash plume that rose 2 km. They noted that 4,415 evacuees were housed in 54 evacuation centers. An ash plume rose from the crater at 1120 on 9 July and drifted W. The Alert Level remained at 3 (on a scale of 1-4) and the exclusion zone was stable at a 4-km radius.

Ambae | Vanuatu : The Vanuatu Meteorology and Geo-hazards Department reported that the recent eruption at Ambae’s Lake Voui was characterized by three phases of activity: Phase 1, September to late November 2017; Phase 2, late December 2017 to early February 2018; and Phase 3, February to April 2018. A fourth phase, which began on 20 June, consists of gas-and-steam emissions sometimes with ash; an ash plume on 1 July caused ashfall on the NW and W parts of the island and also on the NE part of Santo Island. The Alert Level remained at 2 (on a scale of 0-5), and the report reminded residents to stay at least 2 km away from the active crater.

Ibu | Halmahera (Indonesia) : Based on satellite images and PVMBG (a ground observer) notices, the Darwin VAAC reported that on 6 July an ash plume from Ibu rose to 2.1 km (7,000 ft) a.s.l. and drifted N. 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.

Karangetang | Siau Island (Indonesia) : Based on analyses of satellite imagery and model data, the Darwin VAAC reported that on 4 July a diffuse ash plume from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted ENE. The Alert Level remained at 2 (on a scale of 1-4).

Krakatau | Indonesia : PVMBG reported that during 4-5 July there were four ash-producing events at Anak Krakatau, each lasting between 30 and 41 seconds. Inclement weather conditions prevented an estimation of the ash-plume height from the event at 0522 on 4 July; ash plumes from events at 1409, 1425, and 1651 on 5 July rose 300-500 m above the crater rim and drifted N and NW. The Alert Level remained at 2 (on a scale of 1-4); residents and visitors were warned not to approach the volcano within 1 km of the crater.

Saunders | South Sandwich Islands (UK) : Satellite data acquired during 1 January-9 July periodically (a few times a month) showed volcanic plumes originating from Michael on Saunders Island. A thermal anomaly was last detected on 3 April 2018.

Sierra Negra | Isla Isabela (Ecuador) : IG reported that a new magmatic intrusion at Sierra Negra was heralded by a M 5.2 earthquake recorded at 1830 on 4 July, and followed by 68 events between M 1.1 and 3.9. Seismic tremor began to be recorded at 1700 on 7 July by a station on the NE edge of the caldera. At the same time satellite data showed an increase in the intensity of the thermal anomaly on NW flank (it had decreased the previous day). Parque Nacional Galápagos staff confirmed strong incandescence in an area near the beach. A weak plume of water vapor and ash rose as high as 3.3 km (10,800 ft) a.s.l. and drifted SW and W. Tremor continued to be registered on 8 July, though the amplitude gradually decreased. Vapor-and-ash plumes reported by the Washington VAAC rose about 2 km (6,600 ft) a.s.l. and drifted SW, and the thermal anomaly remained intense. Gas clouds drifted 115 km W. The current eruption at Sierra Negra began on 26 June and, according to news articles, prompted tourist restrictions and the evacuation of 50 residents.