An earthquake was detected by CIVISA at 5:18 PM local time (6:18 PM in Lisbon), with the epicenter approximately five kilometers northeast of Santa Bárbara.
The earthquake was reported to be felt with a maximum intensity of IV on the Modified Mercalli Intensity Scale in Santa Bárbara, Cinco Ribeiras, Doze Ribeiras, Serreta (Angra do Heroísmo municipality), and Biscoitos (Praia da Vitória municipality).
The tremor also reached an intensity of III in Terra Chã and São Bartolomeu, within the Angra do Heroísmo municipality.
CIVISA stated that the tremor is part of the ongoing seismic-volcanic crisis on Terceira Island since June 2022.
The Portuguese Institute for Sea and Atmosphere (IPMA) also issued a statement regarding the quake, recording a magnitude of 2.1 on the Richter scale, with its epicenter located about four kilometers northeast of Santa Bárbara.
According to the IPMA, the quake did not cause personal or material damages. It was felt with a maximum intensity of II/III (Modified Mercalli scale) in the parishes of Cinco Ribeiras and Santa Bárbara, and with lesser intensity in Quatro Ribeiras.
The Richter scale classifies earthquakes based on magnitude as micro (less than 2.0), very minor (2.0-2.9), minor (3.0-3.9), light (4.0-4.9), moderate (5.0-5.9), strong (6.0-6.9), major (7.0-7.9), great (8.0-8.9), significant (9.0-9.9), and extreme (above 10).
The Modified Mercalli Intensity Scale measures “degrees of intensity and their description.”
At intensity IV, considered moderate, “hanging objects sway, and the shaking feels like heavy vehicles passing or the impact of a heavy ball on walls. Parked cars rock, windows, doors, and dishes rattle, glass and china clink, and at the upper part of this level, walls and wooden structures creak,” as described by the IPMA on its website.
At intensity III, the tremor is deemed weak, felt indoors, with pendulum-like objects swaying, resembling vibrations caused by passing heavy vehicles.
At intensity II, considered very weak, the quake is “felt by people at rest on upper floors of buildings or in favorable conditions.”
