An earthquake with a magnitude of 2.7 on the Richter scale was felt on Tuesday on the island of Terceira, in the Azores, after two tremors were recorded, one with a magnitude of 2.8 and another of 2.5 on the same day.
According to the Portuguese Institute of the Sea and Atmosphere (IPMA), the earthquake measuring 2.7 on the Richter scale was recorded at 22:57 (23:57 in Lisbon) at the stations of the Seismic Network of the Azores Archipelago, and had its epicenter about four kilometers south of Raminho (Terceira).
This earthquake caused no personal or material damage and was felt with a maximum intensity of II/III (modified Mercalli scale) in the parishes of São Bartolomeu de Regatos and Terra Chã in the municipality of Angra do Heroísmo.
Earlier, an earthquake measuring 2.8 on the Richter scale was recorded at 22:16 local time (23:16 in Lisbon) with its epicentre around three kilometers from Serreta, on Terceira island.
According to the Azores Seismic Information and Surveillance Center (CIVISA), this earthquake was felt with a maximum intensity of IV (Modified Mercalli Scale) in the parishes of Serreta, Raminho, Altares Doze Ribeiras and Santa Bárbara (municipality of Angra do Heroísmo, Terceira island).
The quake was also felt with intensity III/IV in the parish of Biscoitos (municipality of Praia da Vitória, Terceira island), and III in the parish of Terra Chã (municipality of Angra do Heroísmo, Terceira island)”.
According to CIVISA, the event “is part of the seismic crisis that has been ongoing on Terceira Island since June 2022”.
Also on Tuesday, an earthquake with a magnitude of 2.5 on the Richter scale was felt on the island of Terceira.
According to CIVISA, the quake was felt at 16:39 local time (17:39 in Lisbon) and had its epicentre about three kilometers north-northeast of Santa Bárbara, having been felt with a maximum intensity of III/IV (Modified Mercalli scale) in the parishes of Santa Bárbara and Doze Ribeiras (municipality of Angra do Heroísmo, Terceira island).
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 of III, considered to be weak, the tremor was felt inside the house and pending objects shook, with a “vibration similar to that caused by the passage of heavy vehicles”, reveals the Portuguese Institute for the Sea and Atmosphere (IPMA) on its website.
When there is an IV intensity, considered moderate, parked cars sway, windows, doors and crockery shake and “glass and crockery rattle or clink”, and walls or wooden structures may creak.