Two earthquakes measuring 4.2 and 4.4 on the Richter scale were felt today on Terceira island in the Azores, the Azores Seismic Information and Surveillance Center (CIVISA) said.
According to CIVISA, the quakes were recorded at 12:07 local time (13:07 in Lisbon) and 12:10, with the epicentre of both events around 65 kilometers north-northwest (WNW) of Várzea, on the island of São Miguel.
“According to the information available so far, the earthquakes were felt with a maximum intensity of IV (Modified Mercalli Scale) in Santa Cruz, Vila das Lajes, Fontinhas, Cabo da Praia, Fonte do Bastardo, Porto Martins (Praia da Vitória), São Sebastião, Porto Judeu and Feteira (Angra do Heroísmo),” CIVISA said in a statement.
The events “were also felt with intensity III/IV in São Brás (Praia da Vitória), Conceição, São Bento, Santa Luzia, Sé, São Pedro (Angra do Heroísmo), and intensity III in Vila Nova, Agualva, Quatro Ribeiras (Praia da Vitória), and Posto Santo (Angra do Heroísmo),” he adds.
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 Sea and Atmosphere Institute (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.
