Violent explosive activity at Ubinas volcano, ash to 12.1 km (40 000 feet) a.s.l., Peru

Violent explosive activity at Ubinas volcano, ash to 12.1 km (40 000 feet) a.s.l., Peru

Violent explosive volcanic activity started at Peru's Ubinas volcano around 07:35 UTC (02:35 local time) on July 19, 2019. The Geophysical Institute of Peru (IGP) recommended raising the alert level from Yellow to Orange.

New information provided by webcam and satellite imagery obtained at 11:00 UTC showed that eruptive cloud is reaching a height of 12.1 km (40 000 feet) above sea level.

Ashfall was reported in the villages across Ubinas Valley and the Arequipa region -  in the towns of Ubinas, Escacha, Anascapa, Matalaque, San Miguel, Huarina and Tonohaya for which an ash dispersion alert has also been issued so that the authorities and the population take measures to avoid damage to health.

Ash rising above Ubinas volcano at 12:50 UTC on July 19, 2019. Credit: NOAA/GOES-East, TW

Volcanic ash rising above Ubinas volcano on July 19, 2019. Image credit: IGP

The intense explosive activity recorded today has been repeatedly warned by the IGP during its latest technical reports, which detailed the record of earthquakes linked to the rise of magmatic material and the possible occurrence of explosions of greater intensity.

Volcano-tectonic events averaged 279 while long-period events (indicating fluid movement) averaged 116 events per day since July 1, accompanied by minor bluish emissions from the crater

The National Vulcanological Center (CENVUL), the country's service managed by the IGP for the monitoring and emission of volcanic alerts, has been carrying out the permanent analysis of the activity from the city of Arequipa, using the monitoring network installed on the volcano composed of 6 seismic stations, 2 scientific cameras, as well as GPS stations and inclinometers to determine possible deformations.

Geological summary

A small, 1.4-km-wide (0.8 miles) caldera cuts the top of Ubinas, Peru's most active volcano, giving it a truncated appearance. It is the northernmost of three young volcanoes located along a regional structural lineament about 50 km (31 miles) behind the main volcanic front of Perú.

The growth and destruction of Ubinas I was followed by the 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 degrees. The steep-walled, 150-m-deep (492 feet) summit caldera contains an ash cone with a 500-m-wide (1 640 feet) funnel-shaped vent that is 200 m (656 feet) deep.

Debris-avalanche deposits from the collapse of the SE flank about 3 700 years ago extend 10 km (6.2 miles) from the volcano. Widespread plinian pumice-fall deposits include one of Holocene age about 1 000 years ago. Holocene lava flows are visible on the flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor-to-moderate explosive eruptions. (GVP)

Featured image: Eruption at Ubinas volcano on July 19, 2019. Credit: IGP

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