The seismic activity continues in the south of La Palma. In the last 24 hours, more than 116 earthquakes have been recorded by IGN. The current swarm has started 4 days ago, when another 115 rattled the same area within 24 hours.
Seismic activity 4-5 October
75 earthquakes have been located in the southern part of the island of La Palma between October 4 and 5.
Seventeen of them have been felt by the population. A maximum intensity of III-IV (EMS) has been reached in the epicentral zone of two M3.7 earthquakes that occurred at 14:30 UTC and 18:58 UTC.
An increase is observed both in the number of earthquakes and in their magnitudes with respect to previous days. 7 of the recorded earthquakes had a magnitude greater than or equal to 3.5 (mbLg).
As in previous days, most of the seismicity is located 10-15 km deep, in the area where the swarm began on September 11, although 7 of them are located deeper, between 25 and 40 km.
The mean amplitude of the volcanic tremor shows a slight progressive increase since yesterday morning. No large pulses were recorded in the last 24h.
The column height measured at 7:30 UTC is 4,000 m, showing a slight descent of the eruptive cloud.
Seismic activity 5-6 October
41 earthquakes have been located in the area affected by the volcanic reactivation of Cumbre Vieja, a lower number than the two previous days.
Six of the earthquakes have been felt by the population. A maximum intensity III (EMS) in the epicentral zone was reached by a M3.5 earthquake at 12:14 UTC.
Five of the earthquakes were greater than M3.5. Most of the epicenters are located 10-15 km deep, except four that hit 35km depth.
The mean amplitude of volcanic tremor remains stable in a medium range of values with respect to the observations measured during this eruption. No intensification pulses have been recorded in the last 24h.
The column height measured at 6:30 UTC is 3,000 m, showing a slight descent of the eruptive cloud.
Meanwhile, a cloud of sulphur dioxyde from the eruption has already crossed the Atlantic and is about to engulf Venezuela!
Subsidence and deflation
The island’s network of permanent GNSS stations shows slight deflation in the vertical component of the stations near the eruptive centers. These results are consistent with those obtained by InSAR, in which a possible subsidence is observed.
Surface Subsidence and Tsunamis
Scientists believe that the height of the tsunami caused by the Sulawesi earthquake in 2018 was higher than that estimated from the magnitude of the earthquake.
In a report, they investigated the traces of subsidence and the characteristics of the tsunami incidents in the bay far from the epicenter.
Subsidence was observed at a minimum of seven points along the coast. And in accord with the reports of eyewitnesses, this suggests that subsidence might have generated tsunamis.
And this may play as well for La Palma!