Intensity-distance attenuation laws for the Portugal mainland using intensity data points

Goff, Boris Le; Borges, José Fernando; Bezzeghoud, Mourad

doi:10.1093/gji/ggu317

Cited by 15 publications

(7 citation statements)

References 20 publications

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“…6a; Table 3) we concluded that this relationship is linear and decreasing. This behaviour reflects the effect of the geometric attenuation and constitutes an attenuation law (LE GOFF et al 2014). By separating points inside the basin from points outside the basin we arrive at dual behaviour of the attenuation.…”

Section: Discussionmentioning

confidence: 93%

Ground-Motion Simulation in the Lower Tagus Valley Basin

Borges

Bezzeghoud

Caldeira

et al. 2015

Pure Appl. Geophys.

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Abstract-Throughout history, the Lower Tagus Valley (LTV) region has been shaken by several earthquakes, including some with moderate to large magnitudes and with sources located inside the basin, for example the 1344 (M6.0) and 1909 (M6.0) earthquakes. Previous simulations (BEZZEGHOUD et al. Natural Hazard 69: 1229-1245, 2011 have revealed strong amplification of the amplitude waves in the region, because of the effect of the lowvelocity sediments that fill the basin. The model used in those simulations was updated in this work by including new highresolution geophysical and geotechnical data available for the area (seismic reflection, aeromagnetic, gravimetric, deep wells, standard penetration tests, and geological data). To contribute to improved assessment of seismic hazard in the LTV, we simulated propagation of seismic waves produced by moderate earthquakes in a 3D heterogeneous medium by using elastic finite-difference wave propagation code. The method, successfully used by GRANDIN et al. (Geophys J Int 171: 1144-1161, involves evaluation of the seismic potential of known faults in the area studied and threedimensional seismic ground motion modelling by use of finite difference methods. On the basis of this methodology, we calculated the ground motion for the April 23, 1909, Benavente (Portugal) earthquake (Mw = 6.0) in dense grid points, then computed the synthetic isoseismic map of the area by use of appropriate relationships between seismic intensity (MMI) and peak ground velocity (PGV). The synthetic results, in contrast with available macroseismic and instrumental data, enable validation of the source models proposed for the area, identification of the sources of historical earthquakes, and could also indicate which areas are more exposed to seismic ground motion.

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Section: Discussionmentioning

confidence: 93%

Ground-Motion Simulation in the Lower Tagus Valley Basin

Borges

Bezzeghoud

Caldeira

et al. 2015

Pure Appl. Geophys.

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“…To draw the MOI map, we used data from 160 earthquakes from historical catalogs in the period 1300-1985 (see Ⓔ Table S1, available in the electronic supplement to this article), which we designated the historical period, and data from 15 earthquakes in the more recent period 1986-2014 (Carrilho et al, 2004;Bezzeghoud et al, 2012;Le Goff et al, 2014; we designated the instrumental period. Ⓔ All of the data used in this study are listed in Table S1.…”

Section: Macroseismic Datasetmentioning

confidence: 99%

“…Strong earthquakes occurred along the coast of the Algarve, such as the 27 December 1722 Tavira earthquake (I o VIII; Baptista et al, 2007), which generated a tsunami. The northern and central regions of Portugal are characterized by a low seismicity rate and few events, with the exception of the LTV region, which is oriented in a northeast direction and extends into the southern part of Lisbon, covering an area of approximately 3200 km 2 (Teves-Costa and Batló, 2011; Le Goff et al, 2014).…”

Section: Macroseismic Datasetmentioning

confidence: 99%

“…Based on the historical data for the LTV region, four important earthquakes occurred with maximum intensities greater than VIII: the earthquakes of 1344, 1356, 1531 (Udias, 2015), and 1909 (Teves-Costa and Batlló, 2011; Le Goff et al, 2014). According to Bonito (1691) and Mendonça (1758) show earthquakes with moderate intensities.…”

Section: Macroseismic Datasetmentioning

confidence: 99%

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The Seismicity of Portugal and Its Adjacent Atlantic Region from 1300 to 2014: Maximum Observed Intensity (MOI) Map

Ferrão

Bezzeghoud

Caldeira

et al. 2016

Seismological Research Letters

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In this study, we considered earthquakes with a maximum observed intensity (MOI) I o ≥ V that occurred throughout the Portuguese mainland and its adjacent Atlantic region to produce the map of maximum intensities of Portugal. This map is based on a wide variety of historical and recent sources, including 175 earthquakes, over the period of 1300-2014. This MOI map allows the regions of high, medium, and low levels of seismic hazard to be highlighted. The entirety of Portugal has been affected by major seismic events, some of which have caused serious damage. In addition, offshore earthquakes have had significant impacts on the coastal cities located in the central and southern regions of the country. Because the southern region of mainland Portugal is more active than the northern region, the largest concentrations of events with I o ≥ VI are in the southern region, especially on the mainland near the city of Évora, in the Lisbon region, in the Lower Tagus Valley region, and along the Algarve coast, especially in the southwest region in Cape of São Vicente and the Gorringe Bank.

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“…In cluster d, Bindi et al (2011) was chosen because only LLH would rank Allen et al (2012) higher. From the single IPE clusters (c and d), we implement only Chandler and Lam (2002) because, although Le Goff et al (2014) fits well for smaller events, it is applicable only to M w ≤ 6:2 and, as Figure 4f shows, it strongly overestimates the intensity for large M w .…”

Section: Macroseismic Intensity Predictionmentioning

confidence: 99%

Data‐Driven Seismic‐Hazard Models Prepared for a Seismic Risk Assessment in the Dead Sea Region

Haas

Agnon

Bindi

et al. 2016

Bulletin of the Seismological Society of America

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We derive a probabilistic seismic-hazard model for the Dead Sea region to allow for seismic risk estimation, which will be part of a subsequent study. This hazard model relies as much as possible on data-driven approaches, utilizing a seismic catalog compiled for the region by integrating data from different sources. We derive seismicity models using two different smoothing approaches and estimate a hypocentral depth distribution from historical observations. We do not include paleoseismological evidence apart from the observed seismicity. Because ground-motion records are sparse in the region, we formulate the model in the European Macroseismic intensity scale from 1998. However, the collected macroseismic intensity data are still too few to derive a local intensity prediction equation (IPE). Thus, we choose among existing equations derived for different regions and combine them in a logic tree. Here, motivated by Scherbaum et al. (2010), we propose a two-step approach to select the IPEs for the logic tree. First, we cluster a set of 10 candidate IPEs to identify groups of models that can be considered similar with respect to the distribution of the predicted values for a selection of the explanatory variables (i.e., magnitude and distance), using a k-mean approach (Steinhaus, 1956). Then, we apply different ranking techniques (Scherbaum et al., 2009;Kale and Akkar, 2013) to identify within each cluster the most suitable model to be included in the logic tree. The resulting hazard models are consistent with existing probabilistic seismic-hazard models for the region. We estimate a moderate-to-high hazard of intensity grade VII-VIII with 10% probability of exceedance within 50 years in close vicinity to the Dead Sea transform fault, the dominant seismogenic structure in this region.

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Intensity-distance attenuation laws for the Portugal mainland using intensity data points

Cited by 15 publications

References 20 publications

Ground-Motion Simulation in the Lower Tagus Valley Basin

Ground-Motion Simulation in the Lower Tagus Valley Basin

The Seismicity of Portugal and Its Adjacent Atlantic Region from 1300 to 2014: Maximum Observed Intensity (MOI) Map

Data‐Driven Seismic‐Hazard Models Prepared for a Seismic Risk Assessment in the Dead Sea Region

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