Nevados de Chillan (Chile) – Report for 7 July-13 July 2021

SERNAGEOMIN reported continuing explosive and effusive activity at Nevados de Chill�n?s Nicanor Crater during 16-30 June, alomg with increased sulfur dioxide emissions and thermal anomalies. Explosions generated ash plumes that rose as high as 1.4 km above the crater rim and crater incandescence at night; incandescent material was ejected as far as 500 m onto the N, E, and S flanks. The L5 and L6 lava flows continued to be active, with increased effusion rates during 17-19 and 27-28 June. During the periods of increased effusion rates the flow temperatures were higher, nighttime incandescence was more intense, emissions rose higher, and more pyroclastic flows were recorded. The pyroclastic flows traveled less than 500 m down the NE flank and were sourced from collapses at the sides of L6 and the front of L5. The average temperature was 131 degrees Celsius with a maximum of 174 degrees for L5 and an average of 163 degrees Celsius with a maximum of 181 degrees for L6. Temperatures at the vents at Nicanor Crater were as high as 360 degrees Celsius during explosive phases. Satellite images indicated that the L5 lava flow was 1,033 m long and L6 was 894 m long, and that the distal end of L6 had thickened. The average sulfur dioxide emission rate was 694 (� 43) tons/day, reaching a high value of 903 on 19 June. There was a total of 35 thermal anomalies. The Alert Level remained at Yellow, the second lowest level on a four-color scale. ONEMI stated that Alert Level Yellow (the middle level on a three-color scale) remained in place for the communities of Pinto and Coihueco, noting that the public should stay at least 2 km away from the crater.

Sources: Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI) ,Servicio Nacional de Geolog�a y Miner�a (SERNAGEOMIN)

Syndicated from Smithsonian / USGS Weekly Volcanic Activity Report

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