The Regional Civil Protection and Fire Service of the Azores (SRPCBA) reported that an earthquake was recorded by the Azores Seismovolcanic Information and Surveillance Center (CIVISA) at 3:57 PM local time (4:57 PM in Lisbon) and had its epicenter approximately 13 kilometers south-southwest of Faial da Terra.
The statement noted, “According to the information available at the moment, the earthquake was felt with a maximum intensity of III (Modified Mercalli scale) in Povoação.”
The Portuguese Institute for Sea and Atmosphere (IPMA) also issued a statement, describing the earthquake as having a magnitude of 2.8 with its epicenter about 14 kilometers south-southeast of Ribeira Quente.
This earthquake followed an earlier, larger tremor, which measured 3.1 according to CIVISA and 3.0 according to IPMA, recorded at 7:15 AM local time (8:15 AM in Lisbon) with an epicenter approximately 15 kilometers south-southeast of Ribeira Quente.
The tremors are part of increased seismic activity occurring since Wednesday south of São Miguel Island, in the Povoação municipality, with 21 recorded quakes felt so far, reaching a maximum intensity of III/IV on the Modified Mercalli scale.
In a statement, CIVISA indicated that the seismic activity remains, “stationary slightly above reference levels.”
The seismicity has been characterized by “low magnitude events, located roughly between 10 and 20 kilometers south of the Povoação municipality.”
“The observed activity pattern suggests that the seismicity will continue in the coming hours, with the potential for new felt earthquakes,” it added.
CIVISA advises avoiding unstable areas near cliffs and coastal slopes, as well as staying in buildings with low seismic resistance.
According to 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 corresponding description.”
An earthquake with an intensity of III is considered weak, felt indoors, causing pendulum objects to sway and generating “vibrations similar to those caused by the passage of heavy vehicles,” as described on IPMA’s website.
An intensity of IV is considered moderate, where “suspended objects sway, the vibration is similar to that caused by heavy vehicles or the impact of a heavy ball against walls, parked cars sway, windows, doors, and crockery rattle, glasses and crockery clink or tinkle, and at the upper end of this degree, walls and wooden structures creak.”
