Roundup of Global Volcanic Activity – New Activity for the week of 6 June – 12 June 2018

Fuego | Guatemala : During 6-12 June INSIVUMEH and CONRED reported that strong lahars at Fuego were often hot, steaming, and had a sulfur odor, and were generated from heavy rains and the recent accumulation of pyroclastic-flow deposits from the 3 June events. On 6 June lahars descended the Santa Teresa, Mineral, and Taniluyá drainages (tributaries of the Pantaleón river) and possibly the Honda drainage, halting search-and-rescue efforts. The lahars were 30-40 m wide, 2-5 m deep, and carried blocks (2-3 m in diameter) and tree parts. CONRED noted on 9 June that deposits on roads were being cleaned at a rate of 150 m per day, and that exposed deposits were as hot as 150 degrees Celsius. Significant hot lahars, 40 m wide and 5 m deep, traveled down the Seca, Mineral, Niágara, and Taniluyá drainages, carrying rocks and tree branches. On 10 June a strong lahar traveled down the Seca, Mineral, Niagara, Taniluyá, and Ceniza drainages. It was 35 m wide, 3 m deep, and carried blocks up to 1 m in diameter, tree trunks, and branches. Lahars that traveled down the Seca and Mineral drainages on 11 June were 40 m wide and 3 m deep. Lahars on 12 June were 20-45 m wide and 2-5 m deep, and flowed down the Ceniza and Mineral rivers. During 6-11 June as many as nine weak explosions per hour produced ash plumes that rose as high as 1.1 km above the crater and drifted 8-15 km W, SW, and S. Avalanches of material descended the Las Lajas and Santa Teresa ravines. Some explosions vibrated local structures. At 0820 on 8 June a pyroclastic flow descended the Las Lajas and El Jute drainages, producing an ash plume that rose as high as 6 km and drifted W and SW. Explosive activity increased during 11-12 June, with dense ash plumes rising 1.3 km and drifting as far as 25 km N and NE. Pyroclastic flows traveled down the Seca drainage. According to CONRED, as of 12 June, the number of people that had died due to the 3 June pyroclastic flows was 110, and 197 more were missing. In addition, 12,578 people had been evacuated.

Great Sitkin | Andreanof Islands (USA) : Seismicity at Great Sitkin was elevated during the previous five days, though at 1139 on 10 June a seismic signal indicating a possible short-lived steam explosion prompted AVO to raise the Aviation colour Code to Yellow and the Volcano Alert Level to Advisory. No infrasound signal associated with the event was detected, and no volcanic clouds rose about the meteorological cloud deck at 2.4 km (8,000 ft) a.s.l.

Ibu | Halmahera (Indonesia) : PVMBG reported that at 1206 on 6 June an eruption at Ibu generated an ash plume that rose at least 500 m above the crater rim and drifted N. An event at 1750 on 12 June produced an ash plume that rose 600 m 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.

Kerinci | Indonesia : Based on satellite data, the Darwin VAAC reported that on 10 June an ash plume from Kerinci rose to an altitude of 4 km (13,000 ft) a.s.l. and drifted W.

Manam | Papua New Guinea : Based on a pilot observation, the Darwin VAAC reported that on 10 June an ash plume from Manam rose to an altitude of 1.8 km (6,000 ft) a.s.l. The ash plume was not identifiable in satellite images.

Ruapehu | North Island (New Zealand) : On 5 June GeoNet reported that a new heating cycle at Ruapehu’s summit Crater Lake began, as indicated by a recent rise in the water temperature. The increasing lake temperature began 29 May, at a rate of about 1°C per day. Volcanic tremor also increased, representing a greater flow of hydrothermal fluids into the lake. Many heating and cooling cycles have occurred in the past; the current cycle does not indicate an unusual sign of unrest. The Volcanic Alert Level remained at 1 (minor volcanic unrest) and the Aviation colour Code remained at Green.

Sierra Negra | Isla Isabela (Ecuador) : On 8 June IG reported a continuing high level of seismicity at Sierra Negra, characterized by a larger number and magnitude of earthquakes, indicating magma movement. The number of events per day had been significantly increasing since mid-2016. In the previous 10 days there was an average of 42 local events/day; on 25 May there were 104 events, the largest number of earthquakes per day recorded since 2015. In addition, in a 24-hour period during 7-8 June there were a total of 48 volcano-tectonic events, two long-period events, and three hybrid earthquakes; a M 4.8 long-period earthquake was recorded at 0715 on 8 June. The earthquake epicenters were mainly located on the edges of the crater, in two NE-SW trending lineaments; the first covered the N and W edges of the crater and the second went from the NE part around to the S edge. Data showed very large deformation at the caldera’s center, compared with lower levels of deformation outside of the caldera.

Ulawun | New Britain (Papua New Guinea) : According to the Darwin VACC, a NOTAM (Notice to Airmen) stated that on 8 June an ash plume from Ulawun rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted W.

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