. Piton de La Fournaise - the eruptive crack and the active cone - July 21, 2017 at 9:10 - photo OVPF
At Piton de La Fournaise, observations made on 21 July by the OVPF teams show that the eruptive cone downstream of the eruptive crack continues its edification and closes. Three main eruptive mouths are visible on the inside. This morning only the central eruptive mouth remained eastward towards the east.
The intensity of the volcanic tremor (indicator of surface eruptive intensity) has been increasing for 24 hours. This is to be related in particular to the closure of the cone which increases the pressure on its walls.
Numerous lava tunnels have been formed downstream of the cone. Fractures within these tunnels allow many lateral extension arms to escape.
Piton de La Fournaise - Evolution of the RSAM (volcanic and erosion intensity indicator) between 12:00 pm (8:00 pm UTC) on July 14th and 4:00 pm (12:00 pm UTC) on July 21st on the RVL seismic station, located on The southern flank of the volcano. (© OVPF / IPGP)
Piton de La Fournaise - the cone active July 21, 2017 at 11:30 - notice the partial closure of the cone and its three mouths, compared with the picture below taken earlier and the video of July 14 - photo OVPF
No earthquakes were recorded today. A slight deflation is always observed at the top of the terminal cone.
Estimates carried out by satellite methods via the HOTVOLC platform (OPGC - Clermont Ferrand) show flow rates between 1 and 3 m3 / s.
An interesting remark of Aline Peltier, Director of the OVPF, in Clicanoo: the eruptions of the Piton de La Fournaise concern for 20% the craters, for the rest it is the rift zones of the northern and southern flanks that are ... with a generally observed alternation: in 2017, in January-February, on the southern flank; In May, on the northern flank; and again on the southern flank in July. In this alternation, eruptions on the southern flank tend to last longer.
Source: OVPF - Clicanoo - video by Thierry Sluys
Piton de La Fournaise - video of our friend Thierry Sluys 14.07.2017
In Poas, the seismic activity generated on July 20th started at 5:52 pm local and during the night, started decreasing around 8 pm.
The first earthquake was magnitude 4.6. The earthquake of Mw 4.8, located in an area north of the active crater of the Poas, is located at 17h58, an earthquake of Mw 3.8; at 18h17, another of Mw 4.2, and at 19h32, an earthquake of Mw 4,8, all at a depth of between 2 and 4 km. During the morning of the 21st, the seismic activity showed a significant decrease, but is maintained. The Ovsicori counted 192 volcano-tectonic earthquakes on July 21 at 11:30 am, with a magnitude of less than 3.8.
The volcano maintains conditions known as normal, characterized by the emission of water vapor and gas from the main exit points of the active crater, as in the previous days, as well as nighttime incandescence.
Sources: Ovsicori and RSN
Poas - nocturnal activity of 21 July 2017 between midnight and 7 am - Doc. Ovsicori
In Sabancaya, an alert concerning the fall of ashes was issued by the Ingemmet on 21 July at 15:43 local time.
The explosive plume reaches 4,000 meters above the crater and spreads over 40 km., mainly in the southern direction, affecting the populations of Huanca and Lluta.