Devastating quake follows day in which Portugal registered four tremors on mainland
Last night’s devastating earthquake in Morocco – measuring upwards of 6.8 on the Richter Scale – was felt in various parts of Portugal which itself registered four earthquakes on the mainland in the space of a day earlier in the week.
IPMA meteorologists have confirmed that the quake was felt in an area stretching from Algarve to Lisbon – but they played down the significance of the four quakes felt last Tuesday in Albufeira, Olhão, Évora and Arouca. These were simply ‘coincidences’, that happen more frequently than people are in fact aware, said a source.
Meantime, the effects of Morocco’s quake which levelled buildings, killing hundreds over a wide area, including the popular tourist destination of Marrakech, were felt not only in Portugal, but in Mali, Algeria and Spain.
“Up till now we have not heard of any damages” caused to locations on Portugal’s mainland, said the IPMA source, confirming the intensity of the shock registered as a III/ IV on the modified Mercalli Scale (translating into weak/ light).
The tremor was felt in Castro Marim, Faro, Loulé, Portimão, Vila Real de Santo António (Faro), Cascais, Lisboa, Torres Vedras, Vila Franca de Xira (Lisboa), Almada, Setúbal and Sines (Setúbal).
“It was felt with a lesser intensity in the boroughs of Coimbra, Albufeira, Olhão, Silves, Alenquer, Loures, Mafra, Oeiras, Sintra, Amadora, Odivelas, Santo Tirso, Vila Nova de Gaia, Santiago de Cacém, Seixal and Sesimbra”, said the source, “admitting the possibility of further announcements on the subject”, writes Expresso.
The earthquake had an epicentre located around 65 kms south-west of Marrakech; it hit at 11.11pm. Witnesses describe just 15 seconds of intense shaking – enough to cause untold damages. Early reports talk of 800 people dead, with hundreds injured. All through the night rescue efforts were desperately trying to find survivors in the rubble.
International media sources have given a higher Richter Scale reading for the quake (as much as 7.2)
According to Moroccan media, a second 4.9 tremor was recorded north-east of Taroudant (200 kilometres south of Marrakech) at around 11.30pm.
The United States Geological Survey (USGS), which records seismic activity around the world, indicates that the epicentre was in the town of Ighil, in the Atlas mountains. The earthquake occurred at a depth of 8 kilometres, meaning it was ‘close to the surface’, hence the high level of damages.
According to witnesses quoted by Spanish news agency Efe, the tremor was felt in northern cities such as Larache, 550 kilometres from the epicentre, as well as in Casablanca and Rabat, 300 and 370 kilometres away respectively.
Four earthquakes in a day? ‘No great shakes’
Last Tuesday, it was the Algarve that felt the first tremor at 01.49: a quake with a magnitude of 3.9 on the Richter scale and an epicentre 98 kilometres south-southwest of Faro. According to IPMA, it “was felt with a maximum intensity of III (modified Mercalli scale) in the Albufeira region”.
The second earthquake was recorded at 11:17. The epicentre was located around 50 kms south of Olhão, in the district of Faro, with a maximum intensity of III/IV (modified Mercalli scale) in the municipalities of Faro, Loulé and Olhão.
Évora then felt a quake with a magnitude of 2.6 on the Richter scale at 15:47, and Arouca recorded a tremor with a magnitude of 2.5 on the Richter scale at 19:21.
These were not connected events, not even the two that were recorded in the Algarve region, says Fernando Carrilho, the head of IPMA’s geophysics division. “From the outset, I don’t see any connection between them (…) They occur in tectonically distinct zones, even those in the south of the Algarve. They are closer, it’s true, in a confluence zone, but I don’t attribute any special importance to them”, he told Expresso.
In fact, the “slightly higher” magnitudes (such as 3.7 and 3.9 in the Algarve) that were described don’t add any distinct quality to the event either.
“According to Fernando Carrilho, earthquakes with those magnitudes are events that happen with some regularity in Portugal. “
Earthquakes with these magnitudes also happen regularly, but further away from the coast, namely in the area to the south-east of Cape St Vincent, where earthquakes with a magnitude of 4 are often not felt. They often go unnoticed,” he said.
The paper concludes nonetheless: “Although the succession of earthquakes isn’t exactly extraordinary, this “doesn’t mean” that we shouldn’t pay attention, admits the expert – but without being alarmist.
“We should be attentive to what happens, to the seismic event, and we shouldn’t be more or less attentive because of these occurrences. Our level of attention and concern should remain the same”, he said.
Portugal has suffered a number of earthquake ‘in living memory’ that caused damages to homes, etc., but the ‘Great Earthquake of 1755’ is the one everyone ‘always talks about’, with experts adding to the ‘tension’ by generally admitting that it is not a matter of ‘if’ such a phenomenon will take place again, but when.
Source material: Expresso
