Volcano activity of July 6, 2012 - Colombia, Mexico, California, Hawaii, Sicilia, Indonesia, DR Congo and Canary Islands

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 6, 2012 volcano activity

A sedate day in volcano land.

The on-going volcano-seismic crisis at El Hierro (Canary Islands) while not over, appears to be on the wane.  Bursts of spasmodic tremor have become less frequent and are of lower amplitude than when the crisis began last month.

Tremor has dropped to even lower levels at Nevado Del Ruiz volcano (Colombia) and the once robust plume of SO2 emitted by the volcano has dwindled.

A strong plume of SO2 over the Virunga volcanoes (DR Congo) which became visible (through satellite imagery) during the past few days is not evident on the most recent satellite pass. The plume was the only evidence of increased activity there. There have been no reports of an eruption in the region so far and no earthquakes associated with the plume (unlike that which accompanied plume activity there last month).

Another Colombian volcano, Galeras volcano continues to be rattled by numerous small earthquakes and occasional pulses of tremor (station ANGV).

Volcano-tectonic earthquakes and pulses of spasmodic tremor also affect Popocatepetl volcano (Mexico) today.

Small (M1-M2) earthquakes continue along the southern margin of the resurgent dome in Long Valley Caldera (CA).  A cluster of events occurred there today.  The resurgent dome has been inflating since last year.

Kilauea volcano, Hawaii activity summary of July 6 : At the summit, back-to-back DI events continued with the lava lake dropping and rising in response to most of them. 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: there was no seaward progress of the flows closest to the coast overnight and no ocean entry. Seismic tremor levels were generally low; gas emissions were elevated.

Stromboli volcano (Eolian Islands, Italy): short lava fountain and lava flow on 5 July. An episode of increased activity was observed at Stromboli on 5 July evening. Tremor was visible on the seismic recording and Dr. Boris Behncke (INGV Catania) reported a lava fountain from the western vent in the crater accompanied by a small lava flow on the Sciara del Fuoco. Last year, there have also been similar episodes of this kind. (Source : Volcanodicovery)

During a recent VolcanoDiscovery expedition to Krakatau volcano (Indonesia), the lava dome active during Feb-May this year could no longer be seen. Probably, the magma column had dropped in mid to late May and the dome collapsed. At its place, there were only 2 collapse pits, very hot ground and intense degassing from numerous fumaroles inside and outside of the now large summit crater.
Seismic activity when visiting the local volcano observatory was at very low levels, suggesting that Anak Krakatau is at the moment in a phase of repose. Interestingly, a number (at least 4) areas with apparent submarine hydrothermal iron-bearing vents were observed that had not been there last year. In these areas, bubbling could be seen in the water, and where accessible, iron-rich greenish warm mud was found at the sea floor, which oxidized to orange when brought to the surface. The sea water around these areas had an intense yellow stain. Very similar submarine activity is known from around Nea Kameni island, Santorini. (Source : Volcanodicovery)

In the news

Relatively small volcanic eruptions can affect global temperatures when material is carried into the atmosphere by weather systems, Canadian researchers said.
Until now it was thought that only a massively energetic volcanic eruption could inject aerosols past the troposphere, the turbulent atmospheric layer closest to the Earth, into the stable layers of the stratosphere higher up, researchers at the University of Saskatchewan said. Read more

The SO2 satellite image from the Dr Congo, Virunga volcanoes - strong bursts

The SO2 satellite image from the Dr Congo, Virunga volcanoes at 12:49 - no more activity

Long Valley Caldera California map with earthquake epicenters

Earthquake hypocenter depths at Long Valley, California USA

Galeras volcano, Colomboa - seismogram

An image of the Kilauea volcano, Hawaii SO2 emission

El Hierro volcano, Canary Islands, Spain - epicenters in relation to depths

SO2 emissions satellite picture above Colombia and Ecuador - SO2 plume from Nevado del Ruiz

Popocatepetl seismogram, Mexico