Tungurahua volcano (Ecuador): surface activity calm, but increasing earthquakes and deformation suggest possibility of explosion
Wed, 14 Aug 2013, 07:4307:43 AM | BY: T
Since 2 August, surface activity has decreased significantly, but seismic and deformation monitoring suggest the arrival of a new batch of magma from depth in the near future.
Current seismic signal from Tungurahua (RETU station, IGPEN)
Visually, no more explosions have been observed since 31 July and no ash emissions since 3 August. Gas emissions have been declining as well.
Similarly, the number of earthquakes reflecting fluid movements (LP events) has decreased to about 30-80 events / day. However, volcanic-tectonic earthquakes (VT) related to rock fracturing (caused by changing pressures or intrusion of magma) have increased in both number and magnitude. This suggests that a new volume of magma from deeper areas is accumulating and inducing pressure onto the volcanic edifice. In agreement with this is the continued observation of inflation of the upper flanks of the cone.
The absence of surface activity in combination with the measured seismicity and deformation suggest that a blockage has established itself in the upper conduit, preventing magma and gasses to arrive there and allowing them to accumulate inside. This behavior is different to the activity observed between 14 July and early August when the volcano's conduit was relatively open and allowed magma to produce numerous explosions, steam and ash emissions.
A likely scenario is that continued increasing pressure will lead to a powerful vent-clearing explosion to break and eject the plug in the conduit. Such a vulcanian explosion could be of considerable size and cause dangerous pyroclastic flows.
IGPEN is monitoring the volcano closely.
Links / Sources:
Links / Sources:
Wed, 7 Aug 2013, 06:00
Tungurahua volcano (Ecuador) - Smithsonian / USGS Weekly Volcanic Activity Report for 7 August-13 August 2013 (New Activity / Unrest)
IG reported that seismic activity at Tungurahua was moderate to high during 7-13 August; the seismic network detected long-period earthquakes indicating fluid movement and some emissions. Although cloud cover mostly prevented visual observations of the crater, plumes were occasionally observed. On 8 August an ash plume rose 2 km and drifted W, and ash fell in Choglontus (SW). ... Read all
Sat, 3 Aug 2013, 09:31
The trend of increasing activity has continued over the past days. The volcano has been producing nearly constant steam and ash emissions to a maximum height of 2 km height, as well as discrete strombolian to vulcanian-type explosions accompanied by atmospheric shock waves and ground vibration. ... Read all