MITMOTION - Ground motion prediction in Mitidja Basin - Alger

Funder

Organizational Unit

Publications

The Arraiolos – Portugal – Moderate-Sized 2018 (M = 4.9) earthquake of January 15 and aftershocks: preliminary results

Publication . Borges, José; Caldeira, Bento; Fontiela, João; Custódio, Susana; Dias, Nuno; Waschilala, Piedade; Oliveira, Rui; Vales, Dina; Bezzeghoud, Mourad; Araújo, Alexandre; Carrilho, Fernando; Corela, Carlos; Rio, Inês; Vaz, José; Matias, Luís

On 15 January 2018 at 11:51 UTC, an earthquake of 4.9 ML occurred in the Northeast of Arraiolos region near Aldeia da Serra village. The hypocentral location, determined by Instituto Português do Mar e da Atmosfera (IPMA), has coordinates 38.79 N, 7.93 W at 11 km depth. The focal mechanisms determined by P-wave first motion polarities and waveforms inversion indicate a dominance of strike-slip events with nodal plans near NS (left lateral) and EW (right lateral) directions. Due to the lower magnitude, the earthquake didn’t cause damage but was widely felt in the Centre and South of Portugal mainland. In the vicinity of the epicentre, at the Aldeia da Serra village, it reached a maximum intensity VI, having been felt with intensity IV/V in the city of Évora, about 20 km from the epicentre. The event was also felt with intensity III in Lisbon at more than 100 km from the epicentre. This event caused alarm in the population that haven’t felt an earthquake for several decades. It also raised the media attention with many reports and interviews on TV and newspapers. The main ear thquake was immediatel y followed by a sequence of aftershocks of which the largest one, with ML=3.1, occurred the 1st February, fifteen days after the main shock and was largely felt by the population in the region of Arraiolos.

2018-09Conference object

Open access