According to the Portuguese Institute of the Sea and Atmosphere (IPMA), an earthquake measuring 3.7 on the Richter scale was recorded on Sunday night with its epicenter southwest of Agualva, on the island of Terceira, in the central Azores group of islands.
According to IPMA, the earthquake was recorded at stations of the seismic network of the Azores archipelago on Sunday at 23:56 local time (00:56 Lisbon time), the epicenter of which was approximately six kilometers southwest of Agualva.
This was at least the third earthquake to hit the island of Terceira on Sunday. The first had a magnitude of 2.4 on the Richter scale and was felt in the early morning, while the other had a magnitude of 3.6 and was felt in the early morning.
The last earthquake, which occurred at 23:56 (local time), did not cause any personal or property damage and was felt with maximum intensity IV/V (modified Mercalli scale) in the parishes of Santa Luzia, Ribeirinha, Agualva, Fontinhas, Lajes, Cuatro- Ribeiras, Sao Bras and Vila Nova.
This was also felt with less intensity in the parishes of Nossa Senhora da Conceiço, São Pedro, Sé, Cinco Ribeiras, Feteira, Porto Judeu, Santa Barbara, São Bartolomeu de Regatos, São Bento, Terra Chan, Vila de San Sebastian, Fonte do. Bastardo and Vitoria Beach (Santa Cruz).
According to the Azores Center for Seismovolcanic Information and Observation (CIVISA), the event is part of the “ongoing seismovolcanic crisis on the island of Terceira since June 2022.”
On the Richter scale, earthquakes are classified by magnitude into micro (less than 2.0), very small (2.0-2.9), small (3.0-3.9), weak (4.0-4.9), moderate (5.0-5.9), medium (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 above 10).
The Modified Mercalli Scale measures “degrees of intensity and corresponding description.”
At intensity IV, considered moderate, parked cars shake, windows, doors, and utensils shake, “glasses and utensils rattle or clank,” and walls or woodwork may creak.
At intensity V, shaking is felt outside the house and the direction of movement can be assessed, people wake up; liquids fluctuate and some leak, small objects in unstable equilibrium move or topple, doors vibrate, close or open, and blinds and pictures move.