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 group of the Azores, according to the Portuguese Sea and Atmosphere Institute (IPMA).
IPMA, the earthquake was recorded at the stations of the Seismic Network of the Azores Archipelago on Sunday at 23:56 local time (00:56 in Lisbon), with the epicenter located about six kilometers southwest of Agualva.
This was at least the third earthquake felt on Terceira island on Sunday. The first had a magnitude of 2.4 on the Richter scale and was felt at dawn and the other had a magnitude of 3.6 and was felt in the early afternoon.
The most recent earthquake, at 11.56pm (local time), caused no personal or material damage and was felt with a maximum intensity of IV/V (modified Mercalli scale) in the parishes of Santa Luzia, Ribeirinha, Agualva, Fontinhas, Lajes, Quatro Ribeiras, São Brás and Vila Nova.
It was also felt with less intensity in the parishes of Nossa Senhora da Conceição, São Pedro, Sé, Cinco Ribeiras, Feteira, Porto Judeu, Santa Bárbara, São Bartolomeu de Regatos, São Bento, Terra Chã, Vila de São Sebastião, Fonte do Bastardo and Praia da Vitória (Santa Cruz).
According to the Azores Seismic Information and Surveillance Center (CIVISA), this event is part of “the seismic crisis that has been ongoing 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”.
When there is an intensity of IV, considered moderate, parked cars shake, windows, doors and crockery shake and “glass and crockery rattle or clink”, and walls or wooden structures may creak.
With intensity V, the shaking is felt outside the house and the direction of movement can be assessed, people are woken up; liquids sway and some leak, small objects in unstable balance move or are knocked over, doors swing, close or open and blinds and pictures move.