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Velocity and structural model of the Lower Tagus Basin according to the study o...
Torres, Ricardo; Furtado, Augusto; Silva, Hugo; Borges, JF; Caldeira, Bento; Bezzeghoud, Mourad; Carvalho, JoãoAlong his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them produced in large ruptures of offshore structures located southwest of the Portuguese coastline. Among these is the Lisbon earthquake of 1 November 1755 (M∼8.5-8.7), and other moderates earthquakes that were produced by local sources such as the 1344 (M6.0), 1531 (M7.1) and 1909 (M6.0) earthquakes. Previous sim...
Source rupture process, directovity and Coulomb stress change of the ...
Borges, JF; Caldeira, B; Bezzeghoud, M; Santos, RubenIn order to obtain the spatiotemporal slip distribution of a finite rupture model we have used teleseismic body wave and the Kikuchi and Kanamori's method [1]. Rupture velocity was constrained by using the directivity effect determined from waveforms recorded at regional and teleseismic distances [2]. The spatiotemporal slip estimated points to a unilateral rupture that propagates from WNW to ESE with a rupture...
Source rupture process, directivity and and Coulomb stress change of the 12 Ja...
Borges, JF; Caldeira, B; Bezzeghoud, MThe Haiti earthquake occurred on Tuesday, January 12, 2010 at 21:53:10 UTC. Its epi- center was at 18.46 degrees North, 72.53 degrees West, about 25 km WSW of Haiti’s capital, Port-au-Prince, along the tectonic boundary between Caribbean and North America plate dominated by left-lateral stri- ke slip motion and compression with 2 cm/yr of slip velocity eastward with respect to the North America plate. The earth...
Searching for Earthquake Sources in the Lower Tagus Valley (Portugal): First Re...
Ferry, M; Carvalhoo, J; Borges, JF; Fitzenz, DelphineThe area of Lisbon has been struck by destructive earthquakes in the past and with very intense consequences. As of today, two main areas host active faults with concern for the region: offshore with the still unclear source of the famous and catastrophic 1755 earthquake and inland with the Lower Tagus Valley where unknown fault(s) have produced the 1909 and 1531 events with estimated magnitudes ranging from 6 ...
Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate...
Silva, HG; Bezzeghoud, M; Biagi, P; Rosa, RN; Silva, MS; Caldeira, B; Reis, AH; Borges, JF; Tlemçani, M; Manso, MThis paper presents a future research plan that aims to monitor Seismo-electromagnetic (SEM) phenomena in the western part of the Eurasia-Nubia plate boundary (WENP). This region has a significant tectonic activity [1] combined with relatively low electromagnetic noise levels and for that reason presents the possibility to perform high quality SEM measurements. Further, it is known that low-frequency [ultra (UL...
Validation of Velocity the Lower Tagus Valley (Portugal) velocity model using H...
Furtado, A; Borges, JF; Bezzeghoud, M; Caldeira, BAlong his history the Lower Tagus Valley LTV area was shaken by several earthquakes. The largest reported had their origin in the southwestern part of Iberia. These earth- quakes were destructive, and some of them were produced in large ruptures of offshore structures located southwest of the Portu- guese coastline; other moderates earthqua- kes were produced by local sources such as the 1344, 1531 and the 1909...
Imaging 3D seismic velocity along the seismogenic zone of Algarve region (south...
Rocha, J; Bezzeghoud, M; Caldeira, B; Dias, N; Borges, JF; Dorbath, L; Carrilho, FThe present seismic tomographic study is focused around Algarve region, in South of Portugal. To locate the seismic events and find the local velocity structure of epicentral area, the P and S arrival times at 38 stations are used. The data used in this study were obtained during the Algarve campaign which worked from January/2006 to July/2007. The preliminary estimate of origin times and hypocentral coordinate...
Influence of model parameters on synthesized high-frequency strong-motion wavef...
Zadonina, E; Caldeira, B; Bezzeghoud, Mourad; Borges, JFWaveform modeling is an important and helpful instrument of modern seismology that may provide valuable information. However, synthesizing seismograms requires to define many parameters, which differently affect the final result. Such parameters may be: the design of the grid, the structure model, the source time functions, the source mechanism, the rupture velocity. Variations in parameters may produce signifi...
Slip distribution, coseismic deformation and Coulomb stress change for the 12 M...
Zadonina, E; Caldeira, B; Bezzeghoud, Mourad; Borges, JFThe May 12, 2008 Wenchuan earthquake (Mw7.9) took place at the transition between the mountainous chain of Shan and the basin of Sichuan along the Longmen Shan Fault zone (31.1oN, 103.3oE; USGS). With a magnitude of 7.9 and a depth of ∼19 km the earthquake produced a 300-km-long fault rupture. It was the largest earthquake recorded in the region during the last centuries. It claimed more than 69,000 lives, indu...
Seismicity along the Azores-Gibraltar region controlled by global plates’kinema...
Adam, C; Bezzghoud, M; Buforn, E; borges, JF; Caldeira, BThe seismicity along the western part of the Eurasia-Nubian plate boundary has been widely studied and is charac- terized by a very complex pattern. The movement is transtensional in the Azores, dextral along the Gloria transform and convergent between the SW Atlantic margin and the Ibero-Maghrebian zone. In order to understand geograph- ical evolution of the seismicity pattern along this plate frontier, we com...
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