Volcano activity of July 20, 2012 – Mt. Tongariro (New Zealand), Soufrière Hills (Montserrat), Bagana, Nyiragongo, Popocatepetl, Fuego and Galeras

Last update: July 20, 2012 at 4:14 pm by By

This (almost) daily post intends to follow up the activity changes of volcanoes all over the world.
This post is written by geologist Richard Wilson who specializes in Volcano seismicity and Armand Vervaeck. Please feel free to tell us about new or changed activity if we haven’t written about it. -

July 20, 2012 volcano activity

Richard Wilson daily overview :

Beside the frequently mentioned Central American volcanoes Popocatepetl (Mexico) and Galeras (Colombia) and Nyiragongo (DRC), there is some new volcanic unrest in New Zealand.

GNR reports elevated seismicity at the Tongariro Volcanic Complex since earlier this week.  At this point, scientists can only watch for increasing numbers and (perhaps) magnitudes of events, changes in gas output and/or chemistry, along with inflation (via GPS instrumentation) as indicators of possible eruptive activity. (see also our earlier overview article below)

The Montserrat Volcano Observatory reported today that small pyroclastic flows occurred at the Soufriere Hills volcano on 10 July and that muffled roars were heard through the week from points near the volcano.

Volcano-tectonic earthquakes and tremor are observable on seismic records from Popocatepetl today.  The volcano exhaled gas and ash an average of 2 to 3 times per hour overnight.

Tremor is again on the increase at Fuego volcano (Guatemala). (station FG3)

Galeras volcano continues to tremble with small pulses of volcanic tremor and small earthquakes as it has for the past several months. (station ANGV)

Satellite-based SO2 monitors show plumes at Nyiragongo, Bagana and Popocatpetl today.


This was an early July 20 report without our usual items which will be added later today (we write partly in Europe and the USA, which means that some are sleeping while others are working :) ). Whenever we get interesting news, we will bring it to you when it reaches us.

New Zealand Herald writes that scientists have raised the Mt. Tongariro (New Zealand) volcanic alert for the first time (from 0 to 1).  The article states that more than 20 “small” volcanic earthquakes had been recorded at Tongariro since July 13 (too small to be picked up by our own Tongariro earthquake monitoring system) – more than the average of two per year according to historic seismic data. The quakes had a depth of 2 to 7 km with epicenters in the cluster zone between Emerald Crater and Te Maari craters.
There have been five reported eruptions from the Te Māri craters between 1855 and 1897 and these have since been dormant.
It was the first time the alert level had been lifted at Mt. Tongariro since the alert system was introduced. The description of Alert Level 1 is as follows : signs of volcano unrest – Departure from typical background surface activity. The alert levels are ranging from 0 to 5. The next step or alert level 2 = minor eruptive activity – Onset of eruptive activity, accompanied by changes in monitored indicators.
White Island and Mount Ruapehu are also in Alert Level 1 status since longer time.
Business people in the direct vicinity of the volcano are telling tourists not to worry too much about all this at the moment.
An in-depth article will be started when the current swarm would extend or if other parameters would get to unusual values.
Images (below) courtesy and copyright GNS Science and tramper.com.nz

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