Roundup of Global Volcanic Activity
Pagan (Mariana Islands): USGS reports that “low-level unrest continued at Pagan Volcano throughout the past week. Seismic activity remains above background. A vapor plume was visible in web camera and satellite images. Volcanic gas from Pagan may be noticed downwind of the volcano as a distinctive sulfurous odor.” The Aviation Color Code remains at YELLOW.
Santa María / Santiaguito (Guatemala): Ongoing rainfall has been causing a number of mud flows (lahars) in the rivers draining from Santiaguito, including Samala, San Isidro and Tambor. A first large hot lahar descended the Nima I river bed yesterday. The sulfur-smelling mud flow was about 25 m wide and 3 m deep, carrying blocks of up to 50 cm in diameter and pieces of tree trunks and branches of up to 2 m. On its passage near the observatory, it made the ground vibrate. The lahar drained into the Samala river.
Fuego (Guatemala): Activity has decreased a bit. Strombolian explosions produced incandescent ejections to up to about 100 m and ash plumes rose to approx. 500 m.
San Miguel (El Salvador): The amplitude of internal vibration (tremor) at Chaparrastique volcano has suddenly dropped during the past 24 hours indicating that the volcanic system remains unstable, MARN informs in its latest special bulletin. Gas emissions remain elevated. The possibility of an eruption from a summit or flank vent remains high and monitoring continues at highest level.
Galeras (Colombia): Activity at the volcano is currently low. Seismic activity and gas emissions are at low to moderate levels. No recent ash emissions have occurred.
Cumbal (Colombia): Seismic unrest continues at the volcano, still on alert status Yellow, with little variation over the past months. The Pasto volcano observatory reported a 50% increase in earthquakes during the past week. Most earthquakes were associated with internal fluid movements. The other quakes, all very small, were due to rock fracturing at shallow depths. No other signs of unrest were observed at the volcano recently.
Sotará (Colombia): Seismic activity associated with rock fracturing processes under the volcano showed a slight increase during the past week. The earthquakes occurred mainly under the Paletará valley, approximately 12 km northeast of the volcano at depths between 6 and 10 km, and had local magnitudes between 0.3 and 2.2 on the Richter scale. Slight deformation has been detected at the volcano, but no changes or signs of activity are visible at the surface. The volcano remains at Yellow alert.
Cerro Negro de Mayasquer (Colombia): Unrest at the volcano continues in the form of earthquakes under the Chiles-Cerro Negro volcanic massif. During the past week, the monitoring network recorded around 6500 quakes, mostly located less than 4 km SW from the summit at depths ranging between 1 and 8 km and with magnitudes of up to 4.0 on the Richter scale. Most of the earthquakes are volcanic-tectonic, i.e. associated with the fracturing of rock due to fluid pressure underground. On May 21, 3 earthquakes at 02:53, 15:44 and 18:46 local time were felt felt by local inhabitants.