SERNAGEOMIN reported that, although the number and magnitude of earthquakes had decreased during 20-30 June, seismicity at the Laguna del Maule Volcanic Complex continued to remain anomalously elevated at east through 7 July. The location of the activity remained within an area about 5 km in diameter, near the intersection of two faults near Las Nieblas, and corresponded to elevated levels of carbon dioxide emissions. The Alert Level remained at Yellow, the second lowest color on a four-color scale; ONEMI recommended restricted access within a radius of 2 km from the emission center.

Geological Summary. The Laguna del Maule volcanic complex includes a 15 x 25 km caldera with a cluster of small stratovolcanoes, lava domes, and pyroclastic cones of Pleistocene-to-Holocene age. The caldera lies mostly on the Chilean side of the border, but partially extends into Argentina. Fourteen Pleistocene basaltic lava flows were erupted down the upper part of the Maule river valley. A cluster of Pleistocene cinder cones was constructed on the NW side of Maule lake in the northern part of the caldera. The latest activity produced an explosion crater on the E side of the lake and a series of Holocene rhyolitic lava domes and blocky lava flows that surround it.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)