Geophysical methods applied to fault characterization and earthquake potential assessment in the Lower Tagus Valley, Portugal

Carvalho, João P. G.; Cabral, João; Gonçalves, R.; Torres, Luis Miguel Martínez; Mendes-Victor, L.

doi:10.1016/j.tecto.2006.02.010

Cited by 49 publications

(96 citation statements)

References 23 publications

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“…50 km (Figure 2). It was generated in the Mesozoic as a normal fault zone of the LB (e.g., Rasmussen et al 1998, Kullberg 2000, Carvalho et al2005, and was later tectonically inverted, moving with oblique reverse-left lateral slip since the Neogene (Ribeiro et al 1990, Cabral et al 2003, Carvalho et al 20062008;. It outcrops north of Lisbon as a steep east-verging reverse fault placing Jurassic rocks of the LB, at the west, over Miocene deposits of Tortonian age, at the east.…”

Section: Seismotectonic Settingmentioning

confidence: 99%

Los terremotos del Bajo Valle del Tajo (Portugal): Lisboa 26 de Enero de 1531 y Benavente 23 de Abril de 1909

2017

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Abstract. The Lower Tagus Valley (LTV) has been the source of several local earthquakes that affected the region of Lisbon, in the central part of Portugal. In spite of absence of strong earthquakes during the last 100 years, past events have produced large damage in this area. We present the state of the art concerning the last two major earthquakes, which occurred in 1531 and 1909. The effects of both events are described, based on coeval reports already interpreted by several authors. The source parameters determined by different authors are also presented. The characterization of the seismogenic potential of the LTV is very important to better estimate the seismic hazard and risk of the region of Lisbon and Tagus Valley.

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Section: Seismotectonic Settingmentioning

confidence: 99%

Los terremotos del Bajo Valle del Tajo (Portugal): Lisboa 26 de Enero de 1531 y Benavente 23 de Abril de 1909

2017

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“…This region is characterized by a moderate seismicity with a diffuse pattern, having been affected by historical earthquakes that caused many victims, severe damages and economic losses (Carvalho et al, 2006). These impacts are the outcome of seismic activity occurring in the collision of the Iberian and African plates, resulting in a historical seismicity which includes events originating both in the interplate region (distant source) and in the nearby faults of the intraplate region, including the Lower Tagus Valley.…”

Section: Study Areamentioning

confidence: 99%

Integrating population dynamics into mapping human exposure to seismic hazard

Freire

Aubrecht

2012

Nat. Hazards Earth Syst. Sci.

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Abstract. Disaster risk is not fully characterized without taking into account vulnerability and population exposure. Assessment of earthquake risk in urban areas would benefit from considering the variation of population distribution at more detailed spatial and temporal scales, and from a more explicit integration of this improved demographic data with existing seismic hazard maps. In the present work, "intelligent" dasymetric mapping is used to model population dynamics at high spatial resolution in order to benefit the analysis of spatio-temporal exposure to earthquake hazard in a metropolitan area. These night-and daytime-specific population densities are then classified and combined with seismic intensity levels to derive new spatially-explicit four-classcomposite maps of human exposure. The presented approach enables a more thorough assessment of population exposure to earthquake hazard. Results show that there are significantly more people potentially at risk in the daytime period, demonstrating the shifting nature of population exposure in the daily cycle and the need to move beyond conventional residence-based demographic data sources to improve risk analyses. The proposed fine-scale maps of human exposure to seismic intensity are mainly aimed at benefiting visualization and communication of earthquake risk, but can be valuable in all phases of the disaster management process where knowledge of population densities is relevant for decisionmaking.

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“…Instrumental seismicity and known geological faults also match poorly. Though some active faults are known in the area, like the Azambuja and Pinhal Novo faults (Cabral et al, 2003), several very probably active faults have recently been known due to the use of geophysical data, like the Ota-V. F. Xira-Lisbon-Sesimbra fault (OVFXLS; Carvalho et al, 2006b) and the Porto Alto fault (Carvalho et al, 2006a). 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 this poor association between faults and seismicty.…”

Section: Introductionmentioning

confidence: 99%

“…For the above reasons, available geophysical data and geological data have been used to locate possible earthquake sources. This information has been (Carvalho et al, 2006a;b) and will continue to be complemented with near surface data to confirm if faults are active and to estimate source parameters. Considering that most of the earthquakes are generated at crustal depths, the study of those structures at depth is of great importance.…”

Section: Introductionmentioning

confidence: 99%

“…Data from seismic reflection, potential-field, well, geological outcrop and seismicity are used in this paper to improve our knowledge on several recently known geological structures based on seismic reflection data. These are the Porto Alto fault (Carvalho et al, 2006a), the Pinhal Novo fault (Rasmussen et al, 1998;Cabral et al, 2003;Kullberg, 2000) and Azambuja fault (Rasmussen et al, 1998;Cabral et al, 2004). Except for the papers from Carvalho et al (2006a;b), the previous work was based on paper stacked sections.…”

Section: Introductionmentioning

confidence: 99%

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