According to the statement from the Portuguese Institute of the Sea and Atmosphere (IPMA), the event was felt at 05:10 AM (06:10 AM Lisbon time) with its epicenter about three kilometers east of Serreta.
Based on the information available so far, the earthquake was felt with a maximum intensity of IV on the Modified Mercalli Scale in Serreta, Raminho, Altares, Doze Ribeiras, Santa Bárbara, Cinco Ribeiras, and S. Bartolomeu, in the municipality of Angra do Heroísmo.
The event was also felt with an intensity of III/IV in Biscoitos, in the municipality of Praia da Vitória.
This event is part of the ongoing seismovolcanic crisis on Terceira Island since June 2022.
According to the Richter scale, earthquakes are classified by their magnitude as micro (less than 2.0), very small (2.0-2.9), small (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 (when greater than 10).
The Modified Mercalli Scale measures the “degrees of intensity and respective description.”
With an intensity of IV, considered moderate, “suspended objects swing, the vibration is similar to that caused by the passage of heavy vehicles or the sensation of a heavy ball hitting the walls, parked cars sway, windows, doors and dishes shake, glasses and dishes collide or tinkle, and at the upper end of this degree, walls and wooden structures creak,” reveals the IPMA.
With an intensity of III, considered weak, the tremor is felt indoors and hanging objects swing, with a “vibration similar to that caused by the passage of heavy vehicles.”
