Volcanos

Roundup of Global Volcanic Activity

Shiveluch (Kamchatka): KVERT reported that during 21-29 April lava-dome extrusion onto Sheveluch's N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed an intense daily thermal anomaly over the dome. The Aviation Color Code remained at Orange.

Mount St. Helens (Washington): Since the beginning of 2016, a swarm of small earthquakes has been occurring at under the volcano, suggesting that another phase of magma recharge is currently taking place. The recorded quakes have been at shallow depths between 2-7 km under the summit and ranged in magnitudes from 0 (or less) to 3 on the Richter scale, i.e. they are all tiny. Only rarely, they exceeded magnitude 2 and only a very few might have been felt by persons being very close. USGS volcanologists and seismologists interpret the vertical area where these quakes occurred as the area where a small amount of fresh magma has been rising into the volcano's plumbing system (a magma chamber). Magma rises, pressurizes surrounding rock to make space and causes fracturing = tiny quakes. The current swarm is only one of a series of similar swarms that have taken place since 1988, including some much more energetic ones (such as during 1998-99). Most such earthquake swarms, not only at Mt. St. Helens, but at almost any volcano, are NOT followed by eruption, or at least not immediately. In the case of Mt. St. Helens, the large earthquake swarm during 1998-99 preceded the small effusive activity during 2004-2008 by 5 years.

Nevados de Chillán (Central Chile): (9 May) Two new phases of ash explosions occurred at the volcano this morning. The first and strongest occurred at 13:03 local time, generating a dense ash plume that rose 1700 m above the crater, followed by a weaker series of ash emissions at 14:40. The eruption plumes caused moderate ash falls in areas up to a few km downwind (north) of the crater as well as small mud flows on its upper slopes. The latter were the result of rapid interaction of hot tephra (the erupted fragmented material) with snow.The new activity, sign of the volcano's ongoing phase of unrest, had been preceded by increasingly frequent gas and steam puffs since around yesterday evening; some of them possibly contained light ash ash well. According to SERNAGEOMIN, the seismic activity of the volcano has been at fluctuating, but generally low energy levels during the recent weeks. Out of 614 seismic events detected during 16-30 April, more than 90% were related to internal fluid movements, in turn indicative of interaction of the volcano's (deeper) magmatic with the shallow hydrothermal system.