At Piton de La Fournaise, after a sharp drop in its intensity during the night of 17 to 18 July, the intensity of the volcanic tremor (an indicator of surface eruptive intensity) is relatively constant on July 18th, intensity equivalent to that observed on the second day of the eruption.
This fall of the volcanic tremor is to be related to a morphological change at the level of the eruptive cone that is being formed. Compared to the observations of the previous day, a collapse of its upstream part has breached the cone to the east, leaving an easier opening and flowing of lava on the surface. Currently the activity focuses on 6 vents inside the cone. (See video)
Piton de La Fournaise: the eruptive site on July 18, 2017, 10 am (local time). - photo (© OVPF-IPGP)
Piton de La Fournaise: Evolution of the RSAM (volcanic tremor and eruption intensity indicator) between 00:00 (20h UTC) on July 14th and 15h00 (11h00 UTC) on July 18th on the seismic station of RVL, located on The southern flank of the volcano. (© OVPF / IPGP)
Video Pascal Vroug / You Tube
A slight deflation is observed at the top of the terminal cone. Since July 16, SO2 fluxes at the eruptive vent are decreasing and CO2 concentrations in the soil measured at the Volcano gîte at low level.
Deflation of the summit zone as well as low CO2 concentrations in the soil mean that there is currently little or no deep feeding.
HOTVOLC (OPGC - Clermont Ferrand) and MIROVA (University of Turin) estimations carried out by satellite methods indicate flow rates between 1 and 4 m3 / s.