An earthquake with a magnitude of 8.5 occurs off Cape São Vicente, in Sagres, and eight minutes later Civil Protection is alerted. This was the scenario simulated at the Tsunami Warning Center in Portugal, this Friday, October 31st, the day before 270 years have passed since the Lisbon earthquake and tsunami of 1755.
Fernando Carrilho, head of IPMA’s Geophysics division, simulated the occurrence of an earthquake of more or less the same magnitude as that of 1755, explaining the monitoring process and the steps that would be taken today.
Before alerting Civil Protection – in charge of disseminating the warning to authorities at national level, so that they can alert people, for example through messages and sirens – and after immediately identifying the location of the earthquake, the center’s technicians have already tried to calculate its magnitude and capacity to generate a tsunami, as well as identify the coastal areas at greatest risk and the expected time of arrival of the first wave.
In the case of the simulacrum, the first wave of the tsunami took 50 minutes to reach the coast, having reached Sagres, on the mainland coast of Portugal, and Porto Santo, in Madeira. Arriving at the coast requires a second alert.
After the system has observed the tsunami and measured the waves, the information is shared and in the 24 hours following its decline, attention continues to be high.
The Portuguese Tsunami Warning Center – operating at the Portuguese Institute of the Sea and Atmosphere (IPMA) – has existed since 2017, having been recognized by the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 2019.
The Portuguese system in the Northeast Atlantic, Mediterranean and Connected Seas (NEAM) region should also issue tsunami messages close to the country’s coast and alert countries such as Spain, Morocco, France, United Kingdom, Germany, Greece, Italy, Turkey.
Usually staffed by two people per shift, the tsunami early warning center operates 24 hours a day throughout the year, because earthquakes cannot be predicted, they can only be warned about their occurrence as quickly as possible, says Telmo de Carvalho, member of the IPMA Board of Directors.
It has a network to monitor seismic activity and the behavior of the sea, with seismic stations on land and tide gauges along the coast, and is connected through the IOC to the international warning network.
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