Cotopaxi, Equateur : sporadic presence of seismic signals .

Cotopaxi, Equateur :  sporadic presence of seismic signals .

Seismicity:
During the last week, the activity of the volcano Cotopaxi was characterized by the sporadic presence of seismic signals related to emissions, called tremor of emission, and the generation of volcano tectonic earthquakes (VT) who have had an average of 50 ~ events / day. The amplitudes of VT events are generally less than M 1 , but some events were recorded with an amplitude of M 2.7 , on 14 October. The emission tremor was characterized by low to moderate amplitude and duration between 1 and 12 hours. The energy associated with the activity experienced a slight increase in the second to third week of October. Most VT events are located under the crater, less than 12 km deep. In addition, there have been other types of events, such as hybrid and very low frequency events (VLPs). A typical day of seismic recording took place on October 17 in which were recorded 11 hours of tremor of emission followed by several VT type events.

SO2 emissions:
The values of the flow of SO2 obtained by the permanent network DOAS show variations. Between October 07-09, these values were about 1,400 tons / day. Then between 10 and 12 October an increase in the concentration of the gas rising between 4100 to 7600 tonnes / day. Since October 13, the flow is in the approximately 1500 tons / day.

Dispersion and ash fall:
From 08 October to present, there have been reports of fall of fine light ash in the West–Southwest (San Ramon, San Agustin de Callo) and Barrancas, on the evening of October 16. Ash falls were reported in Rumipamba and Vallecito in Canton Rumiñahui on October 17. On Sunday, October 18th ashes were spread in the west of the volcano.

Visual observations:
Because of cloudy weather during the last week, it was rarely possible to see the summit of the volcano and its emissions. A columns were lightly to moderately loaded view ash up to 1.5 km above the summit. However, on October 19 in the morning there was sufficient visibility to observe a column of at least 1.5 kilometers high, seen from a camera from the cable car.

October 23 , 2015. Cotopaxi, Equateur :

Source : IGEPN

Photo : José Luis Espinosa Naranjo.

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