Earthquake measuring 2.7 on the Richter scale on Terceira Island

Angra do Heroísmo, Azores, 09 September 2025 (Lusa) – An earthquake measuring 2.7 on the Richter scale was felt today south-southwest of Altares, on Terceira Island, in the Azores, according to the Portuguese Institute of the Sea and Atmosphere (IPMA).

The earthquake was recorded at 03:33 (04:33 in Lisbon) at the stations of the Azores Archipelago Seismic Network with its epicenter approximately 06 km south-southwest of Altares (Terceira).

According to information available to date, this earthquake did not cause any 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.

According to the Azores Seismovolcanic Information and Surveillance Center (CIVISA), the earthquake “is part of the ongoing seismovolcanic crisis on Terceira Island since June 2022”.

According to the Richter scale, earthquakes are classified according to their magnitude as micro (less than 2.0), very small (2.0-2.9), small (3.0-3.9), slight (4.0-4.9), moderate (5.0-5.9), strong (6.0-6.9), large (7.0-7.9), important (8.0-8.9), exceptional (9.0-9.9) and extreme (when greater than 10).

The Modified Mercalli scale measures “degrees of intensity and their description”.

With an intensity IV, considered moderate, “suspended objects sway, the vibration is similar to that caused by the passage of heavy vehicles or the sensation of a heavy ball hitting walls, parked cars shake, windows, doors and crockery shake, glass and crockery clash or tinkle and at the highest part of this degree, walls and wooden structures creak”, describes the IPMA on its website.

With an intensity of III, the tremor is considered weak, it is felt inside the house and hanging objects sway, feeling a “vibration similar to that caused by the passage of heavy vehicles”.

DD // SB

Lusa/End