Volcano activity of October 8, 2012

This (almost) daily post intends to follow up the activity changes of volcanoes all over the world.
This post is written by geologist Richard 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. -

October 8, 2012 volcano activity

The North American volcanoes are staid this morning, but there is some interesting activity at Machin volcano in Colombia.  A magnitude 4.6 earthquake struck near the volcano overnight and lesser magnitude events continue there. (station CIMA)  Machin awakened from a long slumber in the 1990s with numerous earthquake swarms similar to today's, but there has yet to be an eruption.  The past several years have been relatively quiet ones at the volcano, but in the past few months, the volcano appears to have returned to form with frequent seismic unrest.  Another interesting feature of today's activity is that it was centered southwest of the volcano within a "nest" of seismicity that has recently (again, in the past several years) formed in the middle crust (12-15 km depth).  These deeper events may be indicative of magma movement in the deep plumbing of the volcano.  Machin has not erupted in historic times, but the geologic record near the volcano suggests the volcano produces very large (> 1 km3), explosive eruptions. Definitely a volcano to keep an eye on!
Also in Colombia, Galeras volcano shows some low-level volcanic earthquakes this morning. (station ANGV).
In Mexico, Popocatepetl volcano shows very little activity today with only 9 weak exhalations in the past 24 hours.
In Guatemala, seismicity remains somewhat elevated at Pacaya volcano (station PCG).  Nearby Fuego is rumbling with volcanic earthquakes and tremor (station FG3).
In El Salvador, volcanic earthquakes and tremor have strengthened during the past month at San Miguel volcano (station VSM), but are within "normal" levels.
In Nicaragua, San Cristobal volcano is also exhibits a "normal" level of internal activity with small earthquakes and volcanic tremor. (station CRIN)
Across the pond, in New Zealand, White Island continues to rumble with continuous volcanic tremor.
Recent satellite imagery shows continued strong SO2 output from Popocatepetl and a relatively weak SO2 plume eminating from Manam volcano in New Guinea.