Cotopaxi volcano news & activity updates:
Cotopaxi volcano update: Speculation about the eruption's near future development
Tuesday Oct 20, 2015 17:07 PM | BY: T
Seismic energy of Cotopaxi during the past weeks
Number of volcano-tectonic quakes during the past weeks
The volcano's activity has been similar as during the past weeks. It continues toerupt a weak to moderate steam plume with more or less ash content, rising up to 1.5 km above the summit crater. Occasional weak ash falls have occurred in areas to the west and southwest of the volcano.
SO2 emissions from Cotopaxi
The following is drawn from the latest, very detailed report of the Istituto Geofisico (link below):
Seismic activity, dominated by shallow (less than 12 km deep) rock-fracturing volcanic earthquakes has decreased in numbers, but increased in total energy since the end of September. SO2 emissions remain elevated, ranging between 1,000 and 7,600 tons / day.
Most likely scenario for the near future:
According to scientists from IGEPN, the most likely scenario is that the volcano will continue to produce small emissions that might become gradually stronger, as a new batch of magma is slowly rising within the volcano, until the supply is depleted after some weeks of activity. Explosions of small size are likely to occur as well, but ejecta from such are expected to be limited to the summit area.
Associated phenomena are likely mud flows (lahars) caused by melting of ice from the volcano's summit region.
During the last week, the activity of Cotopaxi volcano was characterized by the sporadic presence of seismic signals associated with emissions, called tremors emission, and the generation of volcano-tectonic earthquakes (VT) at an average of ~ 50 events / day. The magnitudes of the VTs were generally less than 1, but some magnitude 2.7 events were recorded n October 14. Emission tremor was characterized by low to moderate amplitudes and duration of between 1 and 12 hours. The energy associated with the seismic activity slightly decreased from the second to third week of October.
Most VT events were located less than 9 km beneath the crater.
No clear trends were observed during the past weeks.
Besides the mentioned scenario believed most likely (nr 1 in the report), assuming a gradual, continuous, relatively mild release of energy, IGEPN mentions other possibilies:
2) moderate vulcanian explosion scenario:
The conduit becomes plugged, leading to an increase in pressure. Eventually, the magma pressure overcomes the resistance of the cap, producing one (or more) moderate to large explosions with significant ballistic ejecta reaching up to 5 km distance, and possibly small to moderate pyroclastic flows (such as Tungurahua did in July 2013).
Ash falls could be moderate to strong in the prevailing wind directions with an accumulation of a few millimeters to a few centimeters of ash.
Additionally, significant lahars could form and threaten areas of the Cotopaxi National Park, but also populated areas near the main drainages around the volcano (rivers Pita, and / or Cutuchi and / or Aláquez and / or Jatunyacu).
3) Large vulcanian explosion scenario:
The ascending magma is much larger in volume and rises faster than anticipated. This could lead to a major explosive eruption that generates large pyroclastic flows on all sides of the volcano, heavy ash fall, and large mud flows, such as the eruption of Cotopaxi in June 1877.
4) Activity fades, magma does not reach crater scenario:
It is also possible that the eruption slowly fades, and that magma doesn't reach the crater. At the moment, this seems to be the least likely of the 4 scenarios.
Source: Actualización de la Actividad Eruptiva--Volcán Cotopaxi N° 20 - 2015 (IGEPN report 19 Oct 2015)
Sunday, Oct 11, 2015
During the past days, intermittent explosive activity has resumed at the volcano's summit crater. Intense activity on 8 and 9 Oct generated ash plumes that rose up to 1-1.5 km height above the crater and drifted to the west. [more]
Saturday, Oct 03, 2015
Visible activity of the volcano has been relatively low during the past week. Only a strong steam plume mixed with low ash contents has been emitted, but there has been a significant change: incandescence has now become visible from the crater. According to scientists from IGEPN, the glow originates from high-temperature gasses. However, this suggests that magma continues to approach the vent, and that the eruption might now be about to become magmatic. ... [more]
Monday, Sep 21, 2015
The volcano remains active at low to moderate levels (seismicity and emissions). It continues to produce mild ash emissions that usually drift westwards and rise approx. 1 km from the crater. ... [more]
Wednesday, Sep 09, 2015
The activity at volcano continues, but has been less intense during the past days. Weak to moderate intermittent explosions produce ash plumes that vary in height from a few hundred to 1000 meters. ... [more]
Friday, Sep 04, 2015
IGPEN estimates that the total volume of ash erupted so far is about 630,000 m3 weighing about 700,000 tons. This would make the eruption rank so far as VEI 1 only. ... [more]