Volcano activity of July 28, 2012 - Bagana, Sakurajima, Masaya, Batu Tara, Ijen, Rincon de la Vieja, Fuego, Santa Maria, Nevado del Ruiz, Sotara and Popocatepetl

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 28, 2012 volcano activity

Surface activity has been subdued the past week at Popocatepetl (Mexico) with an average of only one exhalation per hour the past few days, versus 3-4 per hour during periods the past month. Tremor is barely visible on the Popo seismogram this morning. A software "glitch is producing the repeating pattern from 20 UTC onward.

In Guatemala, volcanic tremor is elevated this morning at Fuego volcano. Perhaps we will see another outburst similar to those affecting the volcano through most of this spring and summer in the near future. (station FG3)

At nearby Santa Maria volcano, seismic signals indicative of small explosions and/or pyroclastic flows are visible on station STG3 this morning.

Satellite imagery this morning shows weak plumes of SO2 eminating from Masaya volcano (Nicaragua) and a slightly stronger one over Rincon De La Vieja volcano (Costa Rica).
Weak volcanic tremor is apparent on the Masaya seismogram, but it is not any stronger than "normal" tremor levels at the volcano. (station MASN)
Rincon De La Vieja has been showing signs of life the past year, including small phreatic (steam-driven) eruptions from its crater lake. Perhaps the satellite caught such an outburst. OVSICORI used to post seismograms from the Costa Rican volcanoes on their website, but that has been discontinued.

Slightly elevated volcanic tremor and small earthquakes continue at Nevado Del Ruiz (Colombia) since last week. (station OLLE)

Also in Colombia, Sotara volcano continues to produce small volcanic earthquakes. The earthquakes have occasionally exhibited larger magnitudes than most day to day events, but that is the only noticeable change in activity at the volcano. Sotara has not had a historically documented eruption and experienced a swarm of over 900 earthquakes in late June of this year. (station SOSO)

Ijen volcano, Java, Indonesia shows continued seismicity. The temperature of the crater lake does not rise further. PVMBG, the Indonesian volcano agency has asked people not to enter a 1.5 km radius around the acidic crater lake.

Activity observed by satellites
Satellite data also show SO2 plumes of varying size over Bagana (Solomon Islands), Sakurajima (Japan) and Popocatepetl (Mexico).
VAAC Darwin continues to alert aviation for Batu Tara, Lesser Sunda Islands (Indonesia)