The pattern of seismic activity at La Soufriere has changed
by Daria Blackwell 17 Apr 2021 13:25 UTC
Satellite new crater Soufriere © Capella Space
The Seismic Research Centre has released their 6pm 15th April Scientific Update. NEMO's Soufriere Bulletin 64, containing similar information, has also just been made available.
Key points to note from both the Update and the Bulletin are:
- The pattern of seismic activity at La Soufriere has changed
- The last of a series of bands of tremor ended about 5:40am and, unlike all previous bands, these had no strong venting or explosive activity associated.
- The seismic network has now recorded near constant swarms of long-period (LP) earthquakes, with three brief episodes of low level tremor each lasting less than 30 minutes.
- The continuous GPS Network shows a signal consistent with de-pressurisation of the magma reservoir following the initiation of explosive activity on 9th April.
- The volcano continues to erupt, although explosive activity appears to have ended at this time.
- Its current pattern of seismic activity may indicate the growth of a lava dome but this has not yet been confirmed.
- Explosions and accompanying ashfall, of similar or greater magnitude, could restart in the future.
- Alert Level remains at RED
Eighty-eight shelters are now activated, with 4,161 occupants. About 3718 persons are being housed in private shelter.
SRC published an image from the Capella Space satellite showing the changes to La Soufriere volcano - see photo. Photo credit: Capella Space; Analysis: Dr. Adam Stinton
In the centre of the image is a large depression which is the summit crater that once contained the 1979 and 2020/21 domes. The explosions that began on 9th April have destroyed both these domes, creating a smaller crater about 800 metres in diameter. Note: The base of the crater is very distorted in this image due to a) the presence of ash in the air b) the ongoing eruption and c) the way in which radar images are acquired.
Member John Chadwick sent two photos: One after climbing Soufriere in 2006 and the second taken from the same spot as the activity began in January 2021. We show this for comparison with the satellite image.
Nemo Report Bulletin 64 April 15 2021 9.00 PM
This article has been provided by the courtesy of Ocean Cruising Club.