Brava volcano (Cape Verde) - Smithsonian / USGS Weekly Volcanic Activity Report for 22 November-28 November 2023 (New Activity / Unrest)

According to the Cape Verde National Institute of Meteorology and Geophysics (INMG), seismicity at Brava increased on 30 October and remained elevated. A M 3.6 earthquake was recorded at 1819 on 30 October and was followed by eight more events of similar magnitudes that were felt by residents. A M 4.8 was recorded at 2100 and was followed by a 48-hour-long seismic swarm mostly consisting of low-magnitude events that were unable to be located.
The Alert Level was raised to 2 (the second level on a five-level scale) on 30 October.



The rate of seismicity was variable, with two events every 1-10 minutes during 30 October-1 November. Most of the events were located at depths of 3-4 km; the hypocenters were initially located in the Praia de Águada area but then they migrated towards the center of the island. Continuous harmonic tremor emerged on 9 November and was interpreted as indicating the movement of magmatic gases.
On 15 November seismicity increased and was characterized by more intense periods of volcanic tremor, long-period events, and “burst” events defined as identical events separated by a few seconds. In addition, residents began to feel earthquakes more often. The Alert Level was raised to 3.
Three earthquakes all with magnitudes greater than three occurred during 18-19 November, and harmonic tremor again intensified on 19 November.

Sources: Instituto Nacional de Meteorologia e Geofísica (INMG), Governo de Cabo Verde
---
From: Global Volcanism Program, 2023. Report on Brava. In: Mayberry, G (ed.), Weekly Volcanic Activity Report 22 November-28 November 2023. Smithsonian Institution and US Geological Survey.