Volcanos

Global volcanic activity:

Another strong explosion occurred this morning at Lokon volcano in North Sulawesi (Indonesia). The eruption produced an ash plume about 3 km high and has been followed by several smaller explosions. This marks one of the most intense phases of activity during the year.

Popocatépetl volcano in Mexico continues to produce frequent (about 3 per hour) but small emissions, only some of which contain ash.

In Guatemala, Fuego volcano continues to erupt a lava flow towards the Ceniza canyon. On 10 Dec morning, the flow had increased to 700 m length and produced glowing avalanches that reached the vegetation line. Few weak strombolian explosions, sometimes accompanied by rumbling sounds, were occurring as well.

Activity of Santiaguito remains being dominantly effusive. The new block lava flow that had recently formed on the southern flank of the Caliente dome produces glowing avalanches. The other flows on the SE side remain active as well. A constant steam plume rises from the dome to an altitude of approx. 3000 m and incandescence is seen at the dome at night.

Compared to November, the activity of Reventador volcano in Ecuador has decreased, but weak explosions with small ash emissions continue, accompanied by moderate seismic activity.

Nevado del Ruiz volcano in Colombia remains at low activity, with occasional tremor pulses and volcanic quakes, sometimes accompanied by small ash eruptions.

On December 7, 2012 at 05:47 (local time) a magnitude 3.1 volcano-tectonic earthquake occurred at 14.6 km depth southeast of main dome of Cerro Machin volcano. The quake was felt by residents near the volcano, and in the towns of Cajamarca and Ibague.

The seismic swarm in the Tjörnes Fracture Zone north off Iceland still continues at reduced intensity and there seems no end in sight. Most quakes are very small, but there are still occasional quakes at around magnitude 3, and the area remains at risk for a larger quake.

The recent earthquake swarm at Coso Volcanic Field in California seems to be over. The swarm which began in late November included hundreds of events ranging from less than magnitude 0.0 to M3.7, at depths of >10 km at the beginning to shallow 2 km near the end of the swarm. A small magmatic intrusion could have been the cause.