A 5.3 magnitude earthquake on the Richter scale shook the Madeira archipelago this Saturday night, according to data from the Portuguese Institute of the Sea and Atmosphere (IPMA). The earthquake was recorded at 8:58 pm at 40 kilometers southwest of Deserta Grande (the largest in the Desertas Islands sub-archipelago) and originated at 4.7 kilometers deep.
Half an hour after the first shock, at 9:22 pm, a replica of magnitude 2.4 was recorded on the Richter scale. The epicenter of the second earthquake is about 35 kilometers south of Câmara de Lobos, in a region close to the origin of the first earthquake. According to the IPMA, the earthquake occurred at a depth of 24 kilometers.
In a telephone interview with the Observer, Miguel Gouveia, Mayor of Funchal, confirmed that “there is no record of any material damage, nor any information from people injured” by the earthquake.
The mayor, who is currently at the Sapadores Firefighters in Funchal, where the Madeira Civil Protection works, indicated, however, that the authorities received some calls from people in panic, although they were not in danger: “We had to reassure them”, he explained .
For now, there is no indication of the danger of landslides or landslides on the island – although the municipality puts the possibility of making assessments to confirm the stability of the terrain, says the mayor. An IPMA statement indicates that experts determined that this shock had a maximum intensity IV to V on the Mercalli scale.
This scale assesses the damage caused by an earthquake. An earthquake of intensity IV to V is considered “moderate to strong”: “The suspended objects swing. The vibration is similar to that caused by the passage of heavy vehicles or the sensation of a heavy ball being hit on the walls. The parked cars sway. The windows, doors and dishes are shaking. Glasses and crockery crash or tinkle. And the walls and wooden structures creak ”.
This description coincides with the report made to the Observer by Miguel Gouveia. The mayor told the Observer that he was in the Funchal City Hall building when he felt the shock: “The Chamber is in an old palace and everything started to shake, the windows too”. It was “a little disconcerting”, added Miguel Gouveia: “I didn't even realize it could be an earthquake. We are not very used to these phenomena ”.
When the earthquake started, Miguel Gouveia and the building's security guard went to the street: “The cars stopped and people left the buildings to the street. Everyone followed the procedures that are recommended in situations like this ”, he guaranteed. “Six or seven seconds had passed,” recalled the Madeiran mayor.
This is the strongest earthquake recorded in the Madeira archipelago since 1975, when the earthquake with the greatest magnitude of which there was memory was felt. That year, a 7.9 shock on the Richter scale broke out in Madeira, but it was felt across the country, but it only caused minor material damage.
Earthquakes normally occur when the materials that make up lithosphere – the most superficial layer on Earth – release the energy they have accumulated over time because of tectonic movements, that is, from the plates into which the earth's surface is divided.
Contrary to what happens in the Azores archipelago, Madeira is not in a region where tectonic plates meet, a region of high seismicity. Even so, the island of Madeira is based on some flaws, that is, tears within the tectonic plates that appear when the rocks yield to the pressure that tectonic movements cause.