An earthquake was recorded at 03:33 (04:33 in Lisbon) by the Azores Archipelago Seismic Network stations, with an epicenter approximately 6 km south-southwest of Altares (Terceira).
The available information indicates that this earthquake did not cause personal or material damage and was felt with a maximum intensity of III/IV (modified Mercalli scale) in the parish of São Bartolomeu de Regatos.
It was also felt, but with less intensity, in the parish of Ribeirinha.
The Azorean Seismo-Volcanic Information and Surveillance Center (CIVISA) stated that the quake “is part of the seismo-volcanic crisis ongoing on Terceira island since June 2022”.
According to the Richter scale, earthquakes are classified by magnitude as micro (less than 2.0), very small (2.0-2.9), small (3.0-3.9), light (4.0-4.9), moderate (5.0-5.9), strong (6.0-6.9), large (7.0-7.9), major (8.0-8.9), exceptional (9.0-9.9), and extreme (above 10).
The Modified Mercalli scale measures “degrees of intensity and their description”.
With an intensity of IV, considered moderate, “suspended objects sway, the vibration is similar to the passage of heavy vehicles or the sensation of a heavy ball hitting the walls, parked cars rock, windows, doors, and dishes rattle, glassware and dishes clatter or tinkle, and at the upper end of this degree, walls and wooden structures creak,” describes the IPMA on their website.
At an intensity of III, the tremor is considered weak, felt indoors, and hanging objects sway, with a “vibration similar to the passage of heavy vehicles”.
