In October 2021, the OVPF recorded in the Piton de la Fournaise massif in total:
- 763 superficial volcano-tectonic earthquakes (0 to 2.5 km above sea level) under the summit craters;
- 49 deep earthquakes (below sea level);
- 261 long period type earthquakes;
- 382 collapses (in the Crater Dolomieu, the ramparts of the Enclos Fouqué and Piton de Crac, and the Rivière de l'Est)
Piton de la Fournaise - Illustration of the deformation over 1 year (02.11.2020 - 02.11.2021). The baselines (variation of distance between two GPS receivers) crossing the Piton de la Fournaise building, at the top (top), the base of the terminal cone (in the middle) and in the far field (bottom) are shown here. ) (see location on the associated maps). An increase is synonymous with elongation and therefore swelling of the volcano; conversely, a decrease is synonymous with contraction and therefore deflation of the volcano. Any periods colored in light pink correspond to eruptions. - Doc. OVPF
Following the increase in surface seismicity (between 0 and 2 km above sea level) recorded between September 20 and 27, 2021, with an average of 4 events per day under the Dolomieu crater, this one continued in early October 2021 with a total of 97 superficial volcano tectonic earthquakes and 9 deep earthquakes recorded between October 1 and 17, 2021 (Figures 1 and 2). This resumption of seismicity preceded the seismic crisis of October 18, 2021, which began at 4:33 a.m. (local time; 12:33 a.m. UT) and which ended on the morning of October 19. During this seismic crisis, 660 shallow top volcano-tectonic earthquakes, 26 deep volcano-tectonic earthquakes, 255 long-period earthquakes and 24 shallow landslides / collapses were recorded by the OVPF. This seismicity was localized under the summit and under the northeast flank of the volcano in the Plaine des Osmondes sector, west northwest of Piton de Crac (between 0.7 km above sea level and 1.4 km below sea level).
Location map (epicenters) and north-south and east-west sections (showing the location in depth, hypocenters) of the earthquakes recorded and located manually by the OVPF-IPGP in October 2021 under the Piton de la Fournaise massif . Only localizable earthquakes have been shown on the map - Doc. © OVPF-IPGP.
Following this seismic crisis, linked to a deep magma intrusion towards the north northeast flank of the volcano, the seismicity gradually decreased until it reached an average of 1 earthquake / day at the end of October.
This pressurization of the most superficial storage system is at the origin of the seismic crisis and the intrusion of October 18, 2021. This seismic crisis was accompanied by rapid deformations of the ground, of around ten cm at the top of the volcano. about sixty cm on the north-northeast flank, reflecting the migration of a source of pressure to the northeast, causing a displacement of the upper part of the Grandes Pentes to the east. The displacement map from radar interferometric data (InSAR) shows on the northeast flank a maximum displacement of 45 cm to the east and 60 cm in uplift. Following the magmatic intrusion of October 18, inflation of the edifice is again observed.
The building's inflation and the CO2 levels in the soil, which have remained high in recent months (since the end of the eruption of April 9 - May 24, 2021) have witnessed magmatic transfers from areas deep towards the superficial magmatic reservoir, at the origin of the seismic crisis of October 18, 2021. This crisis was linked to an intrusion of magma under the north-northeast flank of the volcano which stopped at depth. Following the magmatic intrusion of October 18, an inflation of the edifice was again observed, testifying to the continuation of magmatic transfers from deep areas to the surface magmatic reservoir.
Source: OVPF - Monthly bulletin
Piton de La Fournaise - Radar Sentinel -1 interferometry (15.10.2021 - 27.10.2021) - via Mounts project
The Servicio Geologico Columbiano informs that during the last days, it has continued to record earthquakes associated with movements of internal fluids in Nevado del Ruiz.
This November 1, 2021, an earthquake at 6:22 local time was accompanied by an emission of ash and gas rising to 2,500 m. above the summit, scattered to the northeast. Ash falls are possible on Letras, Herveo, Casabianca, Villahermosea, Libano and Murillo. At around 7.15 am the seismic signal decreased, as did the height of the ash and gas plume.
The level of activity remains at Amarillo / 3 / change in behavior of volcanic activity
In October 2021, the University of Utah Seismographic Stations, responsible for operating and analyzing the Yellowstone Seismic Network, located 267 earthquakes in the Yellowstone National Park area. The biggest event of the past month was a minor magnitude 2.6 earthquake located about 4 miles east-northeast of the Norris Geyser Basin on October 4 at 5:30 p.m. MDT.
The October seismicity in Yellowstone was marked by 3 earthquake swarms, respectively at Old Faithful, Norris Geyser Basin, West Yellowstone.
The Steamboat Geyser continues to be active, with two eruptions in the past month: October 13 and 25. This brings the total number of eruptions for the year to 17. At the end of October, minor eruptive activity occurs at the geyser, suggesting that the current period of major eruptions, which began in 2018, will continue into November.
The subsidence of the Yellowstone caldera has been ongoing since 2015, but this deformation usually stops or turns into a slight uplift during the summer months due to seasonal groundwater recharge. The summer break in 2021 appears to have continued into October, with little overall caldera deformation since June.
A GPS station near Norris Geyser Basin is now showing signs of uplift - the station has risen by about 1.5 cm (less than 1 inch) in recent months. It is not yet known whether this is a seasonal signal or linked to magmatic or hydrothermal processes at depth.
Current volcano alert level: NORMAL
Current Aviation Color Code: GREEN