Volcanos

Roundup of Global Volcanic Activity

Pacaya (Guatemala): The volcano’s activity has been comparably calm recently, characterized by strong degassing from the intra-crater cone that formed during the latest period (2015-16) of strombolian activity and has become impressively large, filling a good part of the crater now. On a recent video, no ejections of lava fragments are visible, but rather near-continuous, pulsating emissions of steam and ash. These probably reflect an activity weaker than, but essentially similar to what we observed in Dec last year: spattering-type degassing (“bubbling”) from the magma column inside the cone, generating near-continuous small strombolian explosions. The only real difference would be that this time the effusion rate is too low and activity too deep to eject incandescent lava spatter.

Turrialba (Costa Rica): The volcano continues to be restless with intermittent mild eruptive phases. After 5 days of no visible activity, it restarted to emit low-energy plumes of gas, steam and ash yesterday. According to OVSICORI-UNA, the new phase of eruptive activity began at 7 am local time and was accompanied by a weak tremor signal, which increased from 11:30 am to fluctuating medium to high levels. The observed ash emissions have been weak and produced a plume that did not exceed 500 m. Easterly winds have been carrying the ashes into nearby areas west and northwest of the volcano

Cayambe (Ecuador): The volcano has become restless. Scientists from Ecuador’s Institute of Geophysics (IGEPN) recorded an increased number of earthquakes under the volcano a new report shows. The increased seismicity could be (but not must be) a precursor of renewed activity in the medium-term future (weeks, months?). An increase of earthquakes began on 5 June this year when a seismic swarm of earthquakes started which totalled more than 2300 events by the end of the month. The quakes occurred concentrated in an area NE of the volcano and were volcano-tectonic in origin, likely caused by a magma intrusion at depth causing pressurization and fracturing of rocks. After the June swarm, the volcano returned to calm again first. New earthquakes started to appear in increased numbers from September and have been continuing. Different from in June, the quakes have been concentrated under the summit area of the volcano and been showing an upward trend in depth. In addition, there have been increased reports of strong sulfur smell from climbers who visited the volcano, suggesting that there has been an increase in SO2 emission.

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