A week at the OVT

Day 1

I’m living in the middle of nowhere! I have just started a week’s work at the OVT (Observatorio del Volcan Tungurahua). This is an observatory belonging to IGEPN exclusively dedicated to monitoring the behaviour of Tungurahua, an active stratovolcano whose name means Throat of Fire in the local Kichwa language. Tungurahua towers over the local landscape; from the window of OVT, 8km south of the village of Patate, I can see it clearly through vertiginous valleys decked with fields and crops.

Location of OVT (blue dot), Volcan Tungurahua and Banos. 

This morning dawned bright, clear, and warm, so I took the opportunity to go for a walk to the end of the road. Tungurahua looked wonderfully peaceful and calm in the still morning air; and when I returned to the main observatory room, the monitoring instruments detected minimal activity.

The monitoring room of IGEPN’s Observatorio del Volcan Tungurahua (OVT).
Summit of Tungurahua seen at 7:30am, behind tomates del arbol crops and
trumpet flowers in a local field.

In the early morning, we spent half an hour creating new drums for our seismograph. We have here a seismograph that incorporates sooted drumrolls for monitoring seismic signals; apparently, this method is very rarely used, and the OVT is one of very few still active. Creating a new sooted drum involves wiping the drum clearof charcoal, and then reblackening it over a diesel fire in a little hut.

Creating a new charcoal drum.

In the late morning, the skies became clouded, and we continued to observe minimal activity at the summit of the volcano. The skies cleared in the mid-afternoon, and I saw something incredible – my first active eruption! From OVT we observed minor ash emissions, which manifested as a small column of grey vapour that grew towards the northwest (presumably in the prevailing wind direction). The small emission was monitored by infrasound, seismic and visual instruments (all observable on the large-screen TV monitor) and the sooted drum seismograph. The latter showed a long period of emission tremors that slowly decreased in amplitude; smaller LP events were seen earlier in the day. The eruption occurred at 15:35 local time (20:35 UTC).

Small ash emission, seen at 15:35 local time (20:35 UTC).

Set-up of the OVT monitoring data.
Appearance of a long-period (LP) seismic event on the seismograph.

Throughout the late afternoon, the amplitude of the emission tremor seismic event decreased steadily. In the later evening Tungurahua showed a return to greater activity. A new emission, smaller than that seen at 15:35 local time, occurred at 18:09 local time (23:09 UTC), manifested by a small plume of grey vapour that rose from the volcano and drifted towards the northwest. Wind direction appears not to have changed.

Ash emission at 18:09 local time (23:09 UTC)
Occurrence of emission tremors on seismograph. Seismograph moves from
left to right, with needle drawing grey bands in soot. Compare amplitude
of emission at 15:35 (wide grey band) with amplitude of emission at 18:09
(thinner grey band on right-hand side).

After Cotopaxi, this is the second volcanic plume that I have seen! Very exciting. I hope to see some incandescence tonight; if a small explosion occurs on the summit, and the sky is clear of clouds, we may see a reddish glow emanating from the summit.

White patches of snow appear on the eastern side of Tungurahua’s summit.
The convex shape of the summit shows the morphology of the most
recent lava flows from the volcano.

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