Roundup of Global Volcanic Activity – New Activity for the week of 10 May – 16 May 2017

Aira | Kyushu (Japan) : According to JMA, fieldwork at Aira Caldera’s Sakurajima volcano revealed that the sulfur dioxide flux rose from 300 tons on 28 April to 1,700 tons on 8 May; the last time sulfur dioxide flux was above 1,000 tons was 23 June 2015. At 1312 on 12 May an explosion at Showa Crater generated a plume that rose 700 m above the crater rim, into a weather cloud. Four events were detected during 13-15 May; one of the events, an explosion at Showa Crater on 14 May, produced a plume that rose 2.3 km above the crater rim. The Alert Level remained at 3 (on a 5-level scale).

Fuego | Guatemala : INSIVUMEH reported that during 9-16 May explosions at Fuego generated ash plumes that rose as high as 950 m above the crater rim and drifted 7-12 km W, SW, S, and E. Ashfall was reported in San Pedro Yepocapa (8 km N), Morelia (9 km SW), Santa Sofía (12 km SW), and Panimache I and II (8 km SW) during 9-12 May. On 14 May a hot lahar descended the Río Ceniza (SSW) and Santa Teresa (W) drainages, carrying blocks 2 m in diameter, branches, and tree trunks. Sounds from colliding blocks were audible more than 1 km away, and steam plumes rose from the lahar. During 14-16 May avalanches descended the Ceniza and Las Lajas (SE) drainages, and gas emissions rose from pyroclastic-flow deposits in the ravines.

Manam | Papua New Guinea : RVO reported that during 11-14 May Manam’s Main Crater was quiet, emitting only dense white vapor. On 12 May Southern Crater emitted dark gray ash plumes, and on 13 May only whitish-blue vapor emissions were observed. During 0100-0400 on 14 May roaring and explosions were heard in Bogia Station; incandescent lava fragments were ejected from the crater. Seismicity was low (RSAM averaged 50 units) and dominated by low-frequency events during 11-12 May. RSAM increased on 13 May, peaking at 450 units at 2330, and then dropped to 110 units at 0500 on 14 May. RSAM increased to 250 by 0800 and remained at that level through 14 May. The Alert Level remained at Stage 2.

Masaya | Nicaragua : The Washington VAAC reported that on 13 May a west-drifting ash emission from Masaya was identified in satellite images and observed by a pilot.

Poas | Costa Rica : OVSICORI-UNA noted ash emissions at Poás on 10 May. Gas emissions were measured by an instrument mounted on a drone, revealing a gas plume rich in sulfur dioxide and low in carbon dioxide. During 10-11 May tremor amplitude was variable but low, and several volcano-tectonic events were detected. During 11-13 May tremor was constant, and volcano-tectonic and long-period events were detected; the seismicity possibly indicated small eruptions. Deformation was high, with vertical inflation of 3 cm since February.

Sheveluch | Central Kamchatka (Russia) : KVERT reported continuing lava-dome extrusion at Sheveluch’s N flank during 5-11 May. A daily thermal anomaly over the dome was identified in satellite images, and ash plumes drifted 90 km NNE and NW on 8 and 10 May. Strong explosions on 12 May generated ash plumes identified in satellite images that rose 9-10 km (29,500-32,800 ft) a.s.l., spread 70 km wide, and drifted 115 km NW. The Aviation Color Code was raised to Red. A few hours later satellite images showed a thermal anomaly and no ash emissions; the Aviation Color Code was lowered to Orange. Explosions on 16 May generated ash plumes that rose 8-9 km (26,200-29,500 ft) a.s.l., prompting KVERT to again raise the Aviation Color Code to Red. Pyroclastic flows descended the flanks and produced ash plumes that rose 3.5-4 km (11,500-13,100 ft) a.s.l. and drifted NE. Within a few hours satellite images showed a thermal anomaly and no ash emissions; the Aviation Color Code was lowered to Orange. An ash cloud with the dimensions of 51 x 43 km was still visible in satellite images, moving E.


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