The Centro de Informação e Vigilância Sismovulcânica dos Açores (CIVISA) raised the alert level at Furnas volcano on São Miguel island to V1, which corresponds to a volcanic system in a metastable equilibrium phase with weak activity. The upgrade in the monitoring scale was decided following an increase in seismic activity recorded in the municipality of Povoação.
The increase in seismicity began on Tuesday morning, with low-magnitude events. The largest tremor occurred at 4:41 PM (local time), with magnitude 2.9 on the Richter scale and an epicenter located approximately four kilometers west-southwest of Furnas. Despite the low magnitude, the main tremor was felt with maximum intensity V on the Modified Mercalli scale in the parish of Furnas, classified as a strong vibration that can cause doors, picture frames and blinds to rattle, as well as liquid to spill from containers.
The V1 alert level will be in effect for an initial period of eight days, should the evolution of the seismovolcanic system not require a new update. The surveillance scale used in the Azores consists of eight levels, ranging from V0 (resting phase or normal activity) to V7 (eruption in progress with mega-colossal explosivity).
The reactivation of Furnas volcano occurs in an international context of intense volcanic activity recorded in the first days of September. In Southeast Asia, the Anak Krakatau volcano in Indonesia experienced a strong explosive eruption that released an ash column and forced the temporary closure of several airports. Also Mount Semeru in Java and Mount Sinabung in Sumatra showed violent reactivations that prompted preventive evacuations of hundreds of residents.
