Browsing by Author "Costa, M."
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- Improving the knowledge on seismogenic sources in Lower Tagus Valley for seismic hazard purposesPublication . Carvalho, João; Pinto, Carlos C.; Costa, M.; Duarte, H.; Terrinha, Pedro; Rabeh, Taha; Borges, José Fernando; Dias, Ruben Pereira; Caldeira, Bento
- Improving the seismic hazard evaluation of the Lisbon and Lower Tagus Valley areaPublication . Carvalho, João P. F.; Pinto, Carlos C.; Costa, M.; Heleno, S.; Silva, M.; Rabeh, Taha; Cooksley, G.; Carrilho, F.The Lisbon and surrounding area of the Lower Tagus Valley has experienced in the past the effects of several moderate sized earthquakes that caused significant damage and destruction. They have been attributed to local sources, though in some cases the source remains to be located. The lack of outcrops in the flat lying Quaternary terrains, the low slip-rates of the area in connection with sedimentation and erosion rates that erase surface ruptures are among the causes of a poor association between faults and seismicty, which has opened way to geophysical studies. Seismic, potential-field and seismicity data have been recently used to improve the seismic hazard evaluation of the area. In this work we complement these studies with DTM and PSInSAR data with the purpose of obtaining an accurate evaluation of the seismic hazard of the study area. The correlation of improved epicentre locations with major fault zones located from the above mentioned data shows that we have progressed in the understanding of the earthquake sources in the region. Some structures show no apparent relationship with present-day seismicity but some are known to be active into the Quaternary. Further geophysical and geological studies are required to understand the causes.
- Looking for earthquake sources in the Lisbon areaPublication . Carvalho, João P. F.; Pinto, Carlos C.; Costa, M.; Rabeh, TahaThe Lisbon and surrounding areas have suffered the effect of historical earthquakes that caused important damages and loss of lives. Some of these earthquake sources are local but they are still poorly known. The knowledge of these sources is important for seismic hazard studies. The use of geophysical methods in the area is required due to the difficulty in finding geological outcrops, together with low-slip rates and erosion/sedimentation processes that erase surface ruptures. Furthermore, most of earthquake occurs at great depth, emphasizing the need for the application of the latter methods. In this paper we present a revised structural interpretation of the area using newly reprocessed and reinterpreted seismic reflection and potential-field data, relocated epicentres, geological outcrop and well data. This interpretation differs in some aspects from previous ones. Well known active faults zones like the Azambuja fault and the Pinhal Novo-Setúbal fault have new interpretations, while other previously unknown structures, like the Ota-V. F. de Xira-Lisbon-Sesimbra fault zone, for example, have been interpreted. These studies, together with shallow geophysical data, which has been and will be acquired over selected targets from this work, will constitute na improvement to the seismic hazard evaluation of the area.
- Seismogenic sources in the Lower Tagus Area using geophysical dataPublication . Pinto, Carlos C.; Carvalho, João P. F.; Costa, M.; Catrapona, Afonso; Rabeh, Taha; Terrinha, Pedro; Duarte, Henrique; Borges, José Fernando; Caldeira, Bento; Cabral, João