Wednesday, October 29, 2014

Cerro Negro de Mayasquer Has Large Quake Swarm

On the Columbia-Argentina border, a volcano that has not had an eruption for over quite some time. There is a report of activity in 1936, however this is now assumed to have been from nearby Reventador volcano. The volcano itself does not appear to have been active during the Holocene, so it would be another in a line of eruptions of volcanoes with no historical eruptions.

Fumeroles, and hot springs are found on the volcano.

The Smithsonian GVP reports the following:

"Cerro Negro de Mayasquer | Colombia-Ecuador | 0.828°N, 77.964°W | Elevation 4445 m

On 20 October Servicio Geológico Colombiano (SGC) reported that a M 5.8 earthquake, the largest to date, occurred in the vicinity of the Cerro Negro de Mayasquer and Chiles volcanoes at a depth of less than 10 km. The event was felt to the N in Pasto (Colombia) and to the S in Quito (Ecuador). On 21 October SGC raised the Alert Level for the volcanic complex to Orange (level 3 of 4) noting that a seismic swarm characterized by 4,300 earthquakes was detected in an 18-hour period. Hypocenters were located 1-4 km SW of Chiles volcano at depths of 3-5 km and local magnitudes between M 0.2 and 4.5. Inhabitants felt 11 of the events. On 22 October a report noted that the total number of earthquakes recorded on 21 October reached 7,717, which was the largest number of earthquakes recorded on one day since the installation of a local seismic network in November 2013. Several swarms have occurred in the area since February 2013."

Since this report, around 12,000 people have been evacuated as the number and magnitude of quakes have sharply increased since October 24th. It is looking likely this volcano will erupt.

The South American West Coast has had several eruptions from long-dormant volcanoes recently. Chile's Chaiten volcano erupted after more than 8,000 years of dormancy in a large rhyolitic explosion. There has been seismic activity recorded at Machin volcano in Columbia, which has been dormant for 8,000 years. Other long-dormant or presumed extinct volcanoes have also erupted in Africa and the Red Sea, such as Nabro volcano in Eritrea (which was presumed to be a dead Pliestocene volcano), and Jebel Zubair/Jebel Al-Tair volcanoes.

This only means that no volcano should ever truly be deemed 'dead', especially if it is in line with, and surrounded by other active volcanoes.