A seismic event was recorded by CIVISA at 10:07 PM local time (11:07 PM in Lisbon) with its epicenter approximately 51 kilometers southeast of Água Retorta.
“Based on the information available so far, the earthquake was felt with a maximum intensity of IV (Modified Mercalli scale) in the municipality of Povoação,” stated CIVISA.
The tremor was also felt with intensity III in the other municipalities of São Miguel Island, they noted.
The Portuguese Institute for Sea and Atmosphere (IPMA) also released a statement about the earthquake, assigning it a magnitude of 4.6 and an epicenter approximately 18 kilometers north of the islet of Formigas.
According to the Richter scale, earthquakes are categorized by their 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), significant (8.0-8.9), exceptional (9.0-9.9), and extreme (greater than 10).
The Modified Mercalli scale measures “degrees of intensity and their respective description.”
With an intensity of III, the tremor is considered weak, felt indoors, and causes hanging objects to sway, described as a “vibration similar to that caused by the passage of heavy vehicles,” the IPMA notes on its website.
At an intensity of IV, considered moderate, “suspended objects sway, the vibration is similar to that caused by the passage of heavy vehicles or the feeling of a heavy ball hitting walls, parked cars rock, windows, doors, and crockery rattle, glassware clinks or jangles, and at the upper end of this grade, walls and wooden structures creak.”
