This (almost) daily post intends to follow up the activity changes of volcanoes all over the world.
This post is written by geologist Rodger Wilson who specializes in Volcano seismicity and Armand Vervaeck. Please feel free to tell us about new or changed activity if we haven't written about it. -
April 20, 2013 volcano activity
Update Nevado del Ruiz
A magnitude M2.7 event (large "black" event at top of record) was felt by National Park personnel near Nevado Del Ruiz volcano (Colombia) in the past few hours. Also, volcanic tremor amplitude has increased during the day at the volcano. INGEOMINAS has issued prognostic ashfall charts.
A magnitude M3.6 earthquake struck Nevado Del Ruiz volcano (Colombia) late yesterday,...part of the ongoing volcano-tectonic earthquake swarm occurring there. As with the magnitude M4.0 event at the volcano the day before, seismicity (which had been ebbing) re-juvenated afterward with more frequent and larger magnitude earthquakes. This is an example of "strain-hardening" where the volcanic edifice is reaching its structural "limit" for accommodating intruding magma. As the intruding magma "binds-up" within the volcano, it must generate more hydraulic pressure to move the surrounding rock aside, hence the fall-off in earthquake activity followed by large magnitude events and a resumption of the earthquake swarm. INGEOMINAS reports an increase in exhalative plume (with some entrained ash) height over the volcano (when visible, owing to inclement weather there!) during the past day.
KVERT reports seismicity has returned (from previously weak level) to a moderate level overnight at Sheveluch volcano (Kamchatka Peninsula). Otherwise,...there have been no significant changes in seismic/eruptive activity at the three remaining active Kamchatkan volcnaoes: Tolbachik, Bezymianny, Kizimen, and Karymsky. Moderate seismicity affects Gorely volcano, in-concert with strong hydrothermal activity occurring within and around its summital crater lake.
Small earthquakes (and numerous glacier-quakes) continue at Mount Rainier (station RCS) and Mount Saint Helens (station VALT) volcanoes in the Cascade Range (WA). Small earthquakes also continue at the southern end of the Cascades at Lassen Peak volcano (CA) (station LEL).
Small earthquakes continue to be frequent along the southern boundary of Long Valley Caldera (CA) (station MCS).
Colima volcano (Mexico) continues to be very active with numerous hybrid earthquakes, rockfalls, and small pyroclastic flows. The frequency of gas (and occasional block and ash) exhalations has diminished at Popocatepetl after a very active week. Today's Popo seismogram shows a mix of local and regional tectonic earthquakes that punctuate low-level volcanic tremor occurring at the volcano.
Generally low-level strombolian activity affects both Pacaya (Guatemala) (station PCG) and Fuego (station FG3) volcanoes today, but degassing events have picked-up at Santiaguito Dome Complex (Santa Maria volcano) during the past 24 hours. Light ashfall from the increased activity was reported this morning across a broad region within about 15 km radius from the volcano.
The tempo of volcanic earthquakes picked-up again at both San Cristobal volcano (Nicaragua) (station CRIN) and Telica volcano (station TELN) overnight. Thus far, this internal unrest has not been reflected by changes in surface activity at either volcano.
Colombian volcano Machin (station CIMA), Cumbal (station MEVZ), Sotara (station SOSO) and Galeras (station CUVZ) all exhibit earthquake activity in the form of small (magnitude <M1.0) local events today. Small degassing (and ash emission?) events are also evident on the Galeras records.
Seismograms for the Ecuadoran volcanoes were not available at the time of this writing today.
Volcanic tremor remains unstable at White Island volcano (New Zealand).
OMI satellite data were not updated, and no volcanogenic "hotpots" were detected in recent MODIS satellite transits (due to thick cloud coverage?) today.