IGP reported that the eruption of Ubinas was continuing during 12 June-10 July. During 12-30 June six explosions generated plumes 1,400-3,600 m above the crater. Volcanic tremor was associated with ash emissions during 12-21, 25, and 26 June. During 28-29 June more than 1,000 hybrid earthquakes were recorded, but volcano-tectonic earthquakes were scarce. A moderate explosion on 30 June generated an incandescent plume. After more than 50 hours of tremor, a moderate explosion occurred at 0858 on 30 June; the plume reached 1,800 m above the crater and ejected tephra 1,500 m down the NW flank.

During 30 June-10 July IGP detected five, small-sized explosions that generated plumes 400-1,500 m above the crater. Seismicity was also reduced during this period; the greatest number of hybrid earthquakes was registered on 6 July when a swarm of 115 earthquakes occurred.

Geological Summary. The truncated appearance of Ubinas, Perú's most active volcano, is a result of a 1.4-km-wide crater at the summit. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front. The growth and destruction of Ubinas I was followed by construction of Ubinas II beginning in the mid-Pleistocene. The upper slopes of the andesitic-to-rhyolitic Ubinas II stratovolcano are composed primarily of andesitic and trachyandesitic lava flows and steepen to nearly 45°. The steep-walled, 150-m-deep summit crater contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank about 3,700 years ago extend 10 km from the volcano. Widespread Plinian pumice-fall deposits include one from about 1,000 years ago. Holocene lava flows are visible on the flanks, but activity documented since the 16th century has consisted of intermittent minor-to-moderate explosive eruptions.

Source: Instituto Geofísico del Perú (IGP)