The Center for Seismic Volcanic Observation and Information of the Azores (CIVISA) recorded three earthquakes this Saturday felt by the population on the island of Terceira, with intensity III on the Mercali scale and magnitudes of 1.9, 2.1 and 2.3 on the Richter scale.
According to CIVISA, the first earthquake was recorded at 15:51 local time (16:51 in Lisbon) with a magnitude of 1.9 on the Richter scale.
At 4:02 pm local time, a new event was recorded with a magnitude of 2.3 on the Richter scale, followed by a third at 4:31 pm with a magnitude of 2.1 on the Richter scale.
The epicenter of the three earthquakes was located about three kilometers east of the parish of Serreta on the island of Terceira.
According to data collected by CIVISA, the first two earthquakes were felt with a maximum intensity of III on the modified Mercalli scale in the parishes of Doze Ribeiras, Serreta and Santa Barbara in the municipality of Angra do Heroismo, and the third was felt with the same intensity, but only in the arrival of Serret.
Since June 24, the seismic activity of Santa Barbara Volcano on Terceira Island is “above normal reference values” with scientific hazard level V2 (possible reactivation of the system – signs of moderate activity).
The CIVISA crisis office convened this week after an increase in the number of earthquakes recorded on the island, but decided to keep the scientific alert level at V2.
On the other hand, São Jorge Island has been on V3 alert since June 2022 (confirmation of system reactivation – signs of high activity), after which it was placed on alert V4 (threatened eruption) in March of the same year.
The President of the Regional Government of the Azores, José Manuel Boleiru, on Friday called for serenity, calm and confidence for the people of Sao Jorge and Terceira.
“We look at these recurring natural phenomena in the Azores, especially with regard to seismicity, with a certain amount of concern, it’s true. This is always inevitable, given the greatness and monstrosity of nature, coexisting with its beauty. But let there be one call for serenity, calmness and confidence. For science,” he said at the launch of the MRMI course “Medical Response to Serious Incidents” at the San Miguel Science and Technology Park in Lagoa.
On the Richter scale, earthquakes are classified by magnitude into micro (less than 2.0), very weak (2.0-2.9), small (3.0-3.9), weak (4.0-4.9), moderate (5.0-5.9), strong (6.0-6.9), major (7.0-7.9), important (8.0-8.9), exceptional (9.0- 9.9) and extreme (when more than 10).
The modified Mercalli scale measures “degrees of intensity and corresponding description”, and when there is an intensity III considered weak, the impact is “felt in the room” and “hanging objects sway”, feeling “a vibration similar to that caused by the passage of heavy vehicles” – according to the website of the Portuguese Institute of the Sea and Atmosphere (IPMA).
Author: Portuguese
Source: CM Jornal
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