Roundup of Global Volcanic Activity – Ongoing Activity for the week of 15 February-21 February 2017 – cont.
Nevado del Ruiz | Colombia : Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico y Sismológico de Manizales reported that during 14-20 February seismicity at Nevado del Ruiz continued to indicate unrest. Earthquakes were located at depths of 1.1-1.7 km, in areas N, NE, SE, and SW of the volcano, but mainly beneath Arenas Crater. The largest event was a local M 1.4. Signals indicating fracturing rock increased in both size and number as compared to the previous week. Significant amounts of water vapour and gas continued to be emitted. Gas, steam, and ash plumes rose 1.2 km above the crater rim on 18 February and drifted NE, SE, and SW. Thermal anomalies were identified by the MIROVA system during 14, 16-17, and 19-20 February. The Alert Level remained at III (Yellow; the second lowest level on a four-colour scale).
Reventador | Ecuador : During 15-21 February IG reported a high level of seismic activity including explosions, long-period earthquakes, harmonic tremor, and signals indicating emissions at Reventador. Although cloud cover often prevented visual observations, activity was noted almost daily. Minor ashfall was reported on 15 February, and the next morning crater incandescence was visible. During 17-19 and 21 February steam, gas, and ash plumes rose 1-2 km above the crater rim and mainly drifted S and W. “Gunshot” sounds were heard on 18 February.
Sabancaya | Peru : Based on webcam views, satellite images, and seismic data the Buenos Aires VAAC reported that during 14-21 February sporadic gas-and-ash puffs rose from Sabancaya, and during 16-17 and 20 February rose to altitudes of 7.3-8.2 km (24,000-27,000 ft) a.s.l. Weather clouds often hindered observations of the volcano.
Santa Maria | Guatemala : INSIVUMEH reported that during 16-17, 19, and 20-21 February a few explosions at Santa María’s Santiaguito lava-dome complex generated ash plumes that rose 700 m above the complex and drifted SW. Minor ashfall was reported in La Florida (5 km S) on 19 February and in Monte Claro (S) during 20-21 February.
Sheveluch | Central Kamchatka (Russia) : KVERT reported that during 10-17 February lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a daily thermal anomaly over the dome. The Aviation Colour Code remained at Orange.
Sinabung | Indonesia : Based on PVMBG observations, satellite and webcam images, and wind data, the Darwin VAAC reported that during 16-18 and 20-21 February ash plumes from Sinabung rose to altitudes of 3-4.3 km (10,000-14,000 ft) a.s.l. and drifted W, SW, and S.
Turrialba | Costa Rica : OVSICORI-UNA reported that during 15-16 February high-amplitude tremor at Turrialba remained constant, and sporadic gas emissions with minor amounts of ash drifted S and E. Occasional ballistics were ejected from the crater. During 16-17 February sporadic gas emissions with low ash content rose no higher than 300 m and drifted NW and SW. Tremor amplitude had decreased to moderate levels. Similar emissions were observed during 20-21 February, although they drifted NW and NE.