News from Nevados de Chillan, La Fournaise, an unnamed volcano in Tonga and Popocatépetl.

Nevados of Chillan - explosion the 16.08.2019 / 06h23 - webcam Sernageomin

Several explosions were reported at Nevados de Chillan on August 16, including one around 6.30am and another at 12pm local. The latter has been associated with an LP earthquake in relation to the dynamics of internal fluids.

The technical alert level is orange and a map of potential risks has been updated by the Onemi.

Sources: Sernageomin & Onemi.

Nevados de Chillan - map of potential risks, review su 16.08.2019 - Doc. Onemi Chile

At the Piton de la Fournaise, since the eruption stopped on 15/08/2019 at approximately 22h local time, 9 volcano-tectonic earthquakes have been recorded. These earthquakes are located under the summit zone.

Piton de La Fournaise - Evolution of the RSAM (indicator of the volcanic tremor and the intensity of the eruption) between 04:00 (00:00 UTC) on August 11 and 14:30 (10:30 UTC) on August 16, 2019 on the GPS seismic station, station the closest to the eruptive site (© OVPF-IPGP).

The deformations recorded by the OVPF measuring devices on the ground do not show any noticeable signals since the end of the eruption.

It should be noted that the deformation field associated with the eruption of 11-15 August 2019 did not extend outside the Enclos Fouqué (dated 15/08/2019 17h47, date of the satellite acquisition according to the Sentinel-1 / ESA satellite InSAR interferogram, which shows that the dike ("feed duct") feeding the eruption did not propagate beyond this structure.

Piton de La Fournaise - Interferogram representing the deformations at Piton de la Fournaise associated with the eruption of August 11-15, 2019 (© OVPF-IPGP). In addition to ground measurements, the OVPF also uses a satellite technique called InSAR to monitor building inflation / deflation cycles associated with deep magma movement. For this, the satellite "illuminates" an area of the ground with an electromagnetic wave and collects the signal reflected from the ground. The comparison of two measurements of this type of the same surface taken at different times makes it possible to image the deformations of the surface. The above interferogram shows the deformation of the surface associated with the eruption of August 11-15, 2019. Each color cycle (from red to blue) complete of the interferogram corresponds to 27.8 mm of displacement of the surface to (positive) or opposite (negative) Sentinel-1 satellite (whose direction is represented by the arrow "LOS" at the top right of the figure).

Source : OVPF

Find all the information related to the Piton de la Fournaise activity on the different media of the OVPF-IPGP:
- the website (http://www.ipgp.fr/fr/ovpf/actualites-ovpf),
- the Twitter account (https://twitter.com/obsfournaise?lang=en),
- and the facebook account (https://www.facebook.com/ObsVolcanoPitonFournaise/)

Pieces of pumices encountered by the catamaran ROAM on 15.08.2019 / 19h local - photo ROAM Facebook

Pumice blocks of various sizes, but up to that of a basketball, were spotted by the ROAM Catamaran, en route from Bora Bora to the Fiji Islands (at coordinates 18 55 'S / 175 21'W August 15th at 19h local.

These rafts were also spotted on Terra Modis images on August 8 and Sentinel-2 on August 11, 2019.

Based on images of pumice rafts, the Global volcanism Program attributes these pumices to an eruption of an underwater volcano, listed under Vnum 243091, known but unnamed, located along the Tofua volcanic arc, presumably around from 5-6 August. Its last eruption was on September 27-28, 2001 (http://volcano.si.edu/showreport.cfm?doi=10.5479/si.GVP.BGVN200705-243091)

Sources: Global Volcanism Program, ROAM facebook & twitter, Simon Carn

Pumice rafts in the Pacific - images Sentinel-2 / Copernicus from 11.08.2019 / via Simon Carn

Popocatépetl shows intense activity in recent days: during the last 24 hours, 188 exhalations, accompanied by water vapor, gas and low quantities of ash, five minor explosions (4 on the 15th between 10h and 12h, and one the 16.08 to 8.40) and two moderate explosions (16.08 to 9.08 and 9:51) were counted. At the seismicity level, 790 minutes of tremor and a volcano-tectonic earthquake were recorded.

The volcanic alert remains in Amarillo fase 2, with a 12 km safety zone, recently violated by a group that descended into the crater.

Source: Cenapred

Popocatépetl 16.08.2019 / 7h16 - despite the danger, the volcano can present poetic images at sunrise, with the Moon and ashes exhaled a few moments before - webcamsdeMexico