Volcano activity of July 7-8, 2012 - California, Hawaii, Italy, Spain, Colombia and Mexico

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. -

July 8, 2012 volcano activity

Apparently a new round of seismicity at El Hierro (Spain) during the past 24-48 hours.  This is typical of intrusive activity, but not eruptive activity.  Typically eruptive seismicity is sustained and builds to a crescendo (and occurs at much shallower depth) before material is erupted at the surface.  Also, the up-down-up pattern in GPS data also suggests lateral spreading and intrusion rather than an eruptive pattern, which would also build and build and build.  Now, that being said, this is my interpretation, with very limited resources as far as instrumental data  and does not preclude a sudden shallowing and intensification of seismicity and deformation (and,...finally eruption!).  All instrumental signs of intrusive activity beneath a volcano must be watched vigilantly while they are in-progress in order to "catch" any of these "signs" of a forthcoming eruption.  This has been what is so intriguing/challenging for me to watch since I was in my 20s (I'm 52 years old now!). (Richard)

While tremor has fallen to very low levels at Nevado Del Ruiz (Colombia) during the past week (following a "surprise" eruption there last week!), the volcano is producing an impressive plume of SO2 today.

Meanwhile, at nearby Galeras volcano (Colombia), small earthquakes and pulses of tremor continue (station ANGV).

Small earthquakes and pulses of tremor also continue at Popocatepetl volcano (Mexico) in-concert with low-level ash emissions. This has become the "normal" daily behavior of the volcano for the past several months.

Another spat of small earthquakes continues along the southern margin of the resurgent dome at Long Valley Caldera (CA) as it continues with an (again,..."normal") episode of expansion that began last summer.

At the Kilauea volcano (Hawaii) summit, a stronger DI deflation started last night and the lava lake dropped with tilt. At Pu`u `O`o, there were no visible changes in the crater. Lava flows from Pu`u `O`o were active to the southeast on the pali and on the coastal plain with some discernible seaward progress of the flows closest to the coast overnight but no ocean entry. Seismic tremor levels were generally low; gas emissions were elevated.


A amateur video of a walk to the summit viewing area of Stromboli volcano, Eolian Islands (Italy). The walk is mostly done in the afternoon to get the effects of incandescence at night. The walk downhill is made with flashlights. One of the few "easy to reach" places in the world to come close to an active ash spewing volcano! (Armand)

NOAA SO2 satellite image with a lot of activity from Nevado del Ruiz, Colombia


Ingeominas webcam image on July 8 from Nevado del Ruiz, Colombia

Seismogram at Galeras volcano, Colombia

Seismicity at Popocatepetl volcano, Mexico

El Hierro, Canary Islands, Spain epicenter and hypocenter map - courtesy IGN

El Hierro deformation data

El Hierro seismogram shows the strong action in the evening hours of July 7