Activity of Villarica, Copahue, Etna; and an update on the seismic swarm in the Reykjanes peninsula.

An LP earthquake was recorded on October 23 at 10:41 am local time in Villarica, associated with a moderate explosion at the active crater, accompanied by a plume of ash 180 meters high in incline towards me .; the displacement reduced (DR) to 4.1 cm².

The technical alert remains at amarilla.

The POVI has established the schedule of pyroclast emissions over the last 2 months: in September 2020: 3 - in October 2020: 6.

A drone flight over the Villarica crater by drone was carried out last week, revealing that recent explosions have deposited large lava splashes and boulders, some up to several meters. These projectiles are ejected, sometimes at supersonic speeds and reach parabolic trajectories. Its temperature is around 1000 ° C. Although the ascent is not forbidden, all those who undertake it must take into account these types of dangers, and the unpredictability of explosions, which lack instrumental precursors.

In addition, these explosions were caused by the conjunction between the level variations of the lava lake, which is a few hundred meters away in the conduit, and the falls of pyroclast crusts in the cylindrical conduit. 

Source: Sernageomin

In Copahue, on the Chilio-Argentina border, on October 23, we observe a plume of gas, lightly loaded with ash, blown by the winds above the village and Lake Caviahue.

According to Sernageomin, the seismic activity of the Copahue remains at a low level, but there are transient increases in the amplitude of the tremor, in relation to the emissions of particulate materials, suggesting the interaction between the magma and the superficial hydrothermal system. .

On the satellite images, we can observe a large area of ​​ash deposits estimated between 6-7 km. In diameter, mainly in the proximal area of ​​the crater.

Sources: Sernageomin and photo by Valentina Sepulveda / Twitter.

At Etna, an INGV press release dated 23.10.2020 / 8:32 UTC announces that the increase in explosive activity at the New Southeast Crater (NSEC), reported in the previous press release (Etna Communiqué 'Update n. 87 at 06:41 UTC), is no longer observable, as is the associated ash cloud.

However, strombolian activity of varying intensity remains at the NSEC, which fuels sporadic and light ash emissions that are rapidly dispersed in the summit area. Sporadic and light ash emissions can also be observed from the Bocca Nuova (BN) crater.

The temporal trend of the mean amplitude of the volcanic tremor and the location of its source, like infrasound activity, did not show significant changes. Signals from soil deformation monitoring stations do not show significant changes.

Source: INGV OE

IMO provided an update on October 23 on the seismic swarm of the Reykjanes Peninsula : On October 20 at 13:43, an earthquake of M5.6 occurred west of Kleifarvatn, at a depth of 10 km.

Almost 3,000 aftershocks were detected in the current swarm, the majority of them within two days of the M5.6 earthquake. About 30 aftershocks measured larger than M3.0. As of October 23, around 80 earthquakes were detected in the region, the largest of M2.6 near Kleifarvatn.

It is complicated to assess whether the swarm is decreasing or whether the activity has temporarily decreased. It is therefore not excluded that the seismic activity of the Reykjanes peninsula will increase again.

The meteorological office said on Wednesday there were indications that cracks in Krýsuvíkurbjarg had crept in and new ones were forming.

Ármann Höskuldsson, a geologist at the University of Iceland, says it is highly undesirable for people to travel on steep slopes or cliffs like in Krýsuvík during this earthquake cycle.

The InSAR Sentinel-1 image of the co-seismic deformation shows the expected north-south right lateral setback failure (processed by Y. Cao, CDI Group, KAUST). - via Sigurjón (Sjonni) Jónsson - Professor of Geophysics, KAUST

A full explanation of the seismic and intrusive phenomena that the Reykjanes Peninsula has experienced since early 2020 is given by Páll Einarsson, of the Institute of Earth Sciences, University of Iceland.

Sources: IMO, KAUST, Univ. Of Iceland