Roundup of Global Volcanic Activity – New Activity for the week of 26 July – 1 August 2017

Katla | Iceland : On 29 July the Iceland Met Office (IMO) reported that a glacial outburst flood (jökulhlaup) in the Múlakvísl river, SE of Katla, had begun, and a M 3 earthquake along with a few smaller earthquakes were located in the N part of the caldera. Nearby seismic stations detected tremor possibly linked to the flood, though a subglacial volcanic component was not ruled out. The Aviation colour Code was raised to Yellow, the second highest level on a four-colour scale. The public was advised to stay away from the river; it was dark coloured and had a sulfur odor. By 31 July the jökulhlaup had subsided with conductivity measurements and tremor slowly reaching normal levels. The Aviation colour Code was lowered to Green.

Moyorodake [Medvezhia] | Iturup (Etorofu) Island (Japan/Russia) : The Institute of Volcanology and Geodynamics (Russian Academy of Natural Science) reported that during the morning of 31 July volcanologists working on Kudryavy, a stratovolcano of the Medvezhia volcanic complex, noted a sharp increase in the volume of vapor-and-gas emissions, with a plume rising more than 1 km. The emissions rose from a new crater, Malysh, that was formed after the 1999 phreatic eruption. A significant increase in temperature (an average of 100 degrees Celsius) was measured at fumarolic sites, and new high-temperature areas were noted. Crusts of native sulfur at the boundaries of high-temperature areas were melting and burning. Two people at the top of the volcano and workers at the main base camp (3.5 km S) self-evacuated. The report noted that a M 5.7 earthquake had occurred at 0800 that same morning, 200 km NE, within the same system of tectonic faults that the volcano resides on. The volcano has a permeable system of fissures, through which there has been constant degassing for more than 130 years.

Piton de la Fournaise | Reunion Island (France) : OVPF reported that the eruption at Piton de la Fournaise that began on 14 July continued through 1 August, though weather conditions often prevented visual observations. Tremor levels fluctuated. A few estimates based on satellite data indicated a minimum flow rate of 1-2 cubic meters per second. During the early evening on 25 July two vents in the main cone were active, and lava frequently overflowed parts of the channel. Visual observations on 30 July revealed that the lava-flow terminus remained 2.8 km from the vents.

Sangay | Ecuador : Based on information from the Guayaquil MWO, the Washington VAAC reported that on 1 August an emission from Sangay rose to an altitude of 5.3 km (17,500 ft) a.s.l. and drifted W.

Sangeang Api | Indonesia : Based on analyses of satellite imagery, pilot observations, and wind data, the Darwin VAAC reported that during 29-30 July ash plumes from Sangeang Api rose to altitudes of 2.4-2.7 km (8,000-9,000 ft) a.s.l. and drifted NW and W.


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