An earthquake was recorded at 21:15 local time (22:15 in Lisbon) with its epicenter approximately four kilometers east of Serreta, in the municipality of Angra do Heroísmo, according to the CIVISA.
“Based on the information available at the moment, the earthquake was felt with a maximum intensity of IV/V (Modified Mercalli Scale) in Serreta and Raminho (municipality of Angra do Heroísmo),” it was reported.
The event was also felt with an intensity of IV in Altares, Doze Ribeiras, and Santa Bárbara (municipality of Angra do Heroísmo), Biscoitos, and Agualva (municipality of Praia da Vitória), and with a maximum intensity of III in São Bartolomeu dos Regatos, Terra Chã, and Nossa Senhora da Conceição (municipality of Angra do Heroísmo).
CIVISA indicated that the quake “is part of the ongoing seismo-volcanic crisis on Terceira Island since June 2022.”
On the Richter scale, earthquakes are classified by magnitude as micro (less than 2.0), very minor (2.0-2.9), minor (3.0-3.9), light (4.0-4.9), moderate (5.0-5.9), strong (6.0-6.9), major (7.0-7.9), great (8.0-8.9), exceptional (9.0-9.9), and extreme (above 10).
The Modified Mercalli Scale measures “degrees of intensity and their respective descriptions.”
With an intensity of V, considered strong, the quake is “felt outside, the direction of movement can be evaluated, people are awakened, liquids oscillate and some spill over, small unstable objects move or fall,” describes the Instituto Português do Mar e da Atmosfera (IPMA) on its website.
With an intensity of IV, considered moderate, “hanging objects swing, the vibration is similar to that caused by passing heavy vehicles or the sensation of a heavy ball hitting walls, parked cars rock, windows, doors, and dishes rattle, glass and dishes clink, and at the upper end of this grade, walls and wooden structures creak.”
With an intensity of III, the quake is considered weak, it is felt indoors and pendulum objects swing, with a “vibration similar to that caused by passing heavy vehicles,” according to the IPMA.
