The Furnas volcano, located on the island of São Miguel, in the Azores, was elevated to alert level V1 due to an increase in seismic activity in the region. The decision was announced by the Azores Seismic Volcanic Information and Surveillance Centre (CIVISA), which specified that the alert will be in effect for a period of eight days, and may be revised during that interval if new information emerges.
The V1 level corresponds to the first level above the resting state, indicating a volcanic system in a "metastable equilibrium phase" with weak activity. The scale used by CIVISA comprises eight levels, from V0 to V7, with V0 representing the normal activity of a volcano at rest and V7 identifying an ongoing magmatic or hydromagmatic eruption. The transition to V1 therefore does not correspond to the classification of an eruption in progress.
The increase in seismic activity began on Tuesday, September 8, at 11:47 local time. The most energetic earthquake occurred at 16:41 the previous day, with magnitude 2.9 on the Richter scale, classified as very small, but which was still felt by the population. The epicenter was located approximately four kilometers west-southwest of Furnas, in the municipality of Povoação, where the tremor was felt with maximum intensity V on the Modified Mercalli scale.
The parish of Furnas is known for its fumaroles and secondary volcanic manifestations, commonly referred to as calderas. However, the justification for raising the alert focused on the seismic activity, with CIVISA clarifying that all recorded events are of low magnitude.
