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Sokolov V.,Karlsruhe Institute of Technology | Sokolov V.,National Center for Earthquakes and Volcanoes | Ismail-Zadeh A.,Karlsruhe Institute of Technology | Ismail-Zadeh A.,CNRS Paris Institute of Global Physics
Tectonophysics | Year: 2015

We present a new approach to assessment of regional seismic hazard, which accounts for observed (instrumentally recorded and historic) earthquakes, as well as for seismic events simulated for a significantly longer period of time than that of observations. We apply this approach to probabilistic seismic hazard analysis (PSHA) for the Tibet-Himalayan region. The large magnitude synthetic events, which are consistent with the geophysical and geodetic data, together with the observed earthquakes are employed for the Monte-Carlo PSHA. Earthquake scenarios for hazard assessment are generated stochastically to sample the magnitude and spatial distribution of seismicity, as well as the distribution of ground motion for each seismic event. The peak ground acceleration values, which are estimated for the return period of 475 yr, show that the hazard level associated with large events in the Tibet-Himalayan region significantly increases if the long record of simulated seismicity is considered in the PSHA. The magnitude and the source location of the 2008 Wenchuan M= 7.9 earthquake are among the range of those described by the seismic source model accepted in our analysis. We analyze the relationship between the ground motion data obtained in the earthquake's epicentral area and the obtained PSHA estimations using a deaggregation technique. The proposed approach provides a better understanding of ground shaking due to possible large-magnitude events and could be useful for risk assessment, earthquake engineering purposes, and emergency planning. © 2015 Elsevier B.V.


Al-Lazki A.I.,Sultan Qaboos University | Al-Lazki A.I.,Petroleum Development Oman | Al-Damegh K.S.,Astronomy and Geophysics Research Institute | El-Hadidy S.Y.,National Center for Earthquakes and Volcanoes | And 2 more authors.
Geological Society Special Publication | Year: 2014

We use Pn-tomography to map lithospheric mantle velocity and anisotropy at the Arabia-Eurasia plate boundary, namely Makran and Zagros. We use catalogue events recorded by Oman, UAE, Saudi Arabia and Iran networks, the International Seismological Centre and the National Earthquake Information Center. Events of 1.8-16 degree distances were used for this Pn-tomography. In this study we show that the northeastern Arabia plate is characterized by cold and stable lithospheric mantle. Contrastingly, Eurasia is underlain by hot unstable lithospheric mantle. The Arabia-Eurasia lithospheric suture follows the Zagros collision surface suture within c. 70 km lateral proximity. At the southernmost Zagros collision, the Arabia lithosphere is inferred to extend further NE beneath Lut Block. This may be indicative of extended subduction of Arabia beneath Eurasia in southernmost Zagros. We find that eastern Makran shows typical subduction characteristics, with inferred oceanic lithosphere underlying the eastern Oman Sea and hot unstable lithospheric mantle below overriding Helmand Block. Contrastingly, the western Makran subduction zone including Arabia and Eurasia continental sides is underlain by a low-Pn-velocity anomaly, indicative of hot unstable lithospheric mantle. Surface evidence show that western, southern and eastern boundaries of western Makran low-Pn-velocity anomaly may represent a Late Neogene reactivated Precambrian terrane boundary in north Oman. © The Geological Society of London 2014.


Sokolov V.,Karlsruhe Institute of Technology | Sokolov V.,National Center for Earthquakes and Volcanoes | Wenzel F.,Karlsruhe Institute of Technology
Bulletin of Earthquake Engineering | Year: 2015

The results of classical probabilistic seismic hazard analysis (PSHA) contain no information about simultaneous ground motions at different sites during a particular earthquake. Seismic risk analysis for distributed critical structures requires estimates of the level of earthquake shaking that are likely to occur concurrently at multiple locations: whether the vulnerable elements of a lifeline system are likely to be simultaneously affected by shaking of sufficient strength to disable them and whether the shaking at any one of critical points may be sufficient to cause failure of the whole system. While the analysis of lifeline performance requires multiple-location estimations, the sparsely located elements of a network or critical facilities are designed on the basis of point-wise PSHA. In this paper we study specific features of multiple-location PSHA, as compared with the classical point-wise PSHA, using Monte Carlo simulations. We analyze the level of ground motion (PGA) that will be exceeded at any site inside a particular area or at several sites simultaneously with reference annual probability. The analysis has been performed for regions of Western and South-Western Germany, Northern and Eastern Taiwan, which represent different levels of seismicity (low, moderate and high, respectively). The relationship between the multiple-location and point-wise estimations are analyzed and quantified. Results of the study may be used to decide whether it may be possible to utilize the procedure of point-wise PSHA in particular cases of multiple-location PSHA, i.e. for assessment of maximum level of ground motion among several sites, or for estimation a reasonable lower safety level when considering simultaneous exceedances. © 2014, Springer Science+Business Media Dordrecht.


Sokolov V.,Karlsruhe Institute of Technology | Sokolov V.,National Center for Earthquakes and Volcanoes | Ismail-Zadeh A.,Karlsruhe Institute of Technology | Ismail-Zadeh A.,Russian Academy of Sciences | Ismail-Zadeh A.,CNRS Paris Institute of Global Physics
Tectonophysics | Year: 2015

We present a new approach to assessment of regional seismic hazard, which accounts for observed (instrumentally recorded and historic) earthquakes, as well as for seismic events simulated for a significantly longer period of time than that of observations. We apply this approach to probabilistic seismic hazard analysis (PSHA) for the Tibet-Himalayan region. The large magnitude synthetic events, which are consistent with the geophysical and geodetic data, together with the observed earthquakes are employed for the Monte-Carlo PSHA. Earthquake scenarios for hazard assessment are generated stochastically to sample the magnitude and spatial distribution of seismicity, as well as the distribution of ground motion for each seismic event. The peak ground acceleration values, which are estimated for the return period of 475. yr, show that the hazard level associated with large events in the Tibet-Himalayan region significantly increases if the long record of simulated seismicity is considered in the PSHA. The magnitude and the source location of the 2008 Wenchuan M = 7.9 earthquake are among the range of those described by the seismic source model accepted in our analysis. We analyze the relationship between the ground motion data obtained in the earthquake's epicentral area and the obtained PSHA estimations using a deaggregation technique. The proposed approach provides a better understanding of ground shaking due to possible large-magnitude events and could be useful for risk assessment, earthquake engineering purposes, and emergency planning. © 2015 Elsevier B.V.


Tang Z.,King Abdullah University of Science and Technology | Julia J.,Federal University of Rio Grande do Norte | Zahran H.,National Center for Earthquakes and Volcanoes | Mai P.M.,King Abdullah University of Science and Technology
Tectonophysics | Year: 2016

We investigate the lithospheric shear-wave velocity structure of Saudi Arabia by conducting H-κ stacking analysis and jointly inverting teleseismic P-receiver functions and fundamental-mode Rayleigh wave group velocities at 56 broadband stations deployed by the Saudi Geological Survey (SGS). The study region, the Arabian plate, is traditionally divided into the western Arabian shield and the eastern Arabian platform: The Arabian shield itself is a complicated mélange of crustal material, composed of several Proterozoic terrains separated by ophiolite-bearing suture zones and dotted by outcropping Cenozoic volcanic rocks (locally known as harrats). The Arabian platform is primarily covered by 8 to 10 km of Paleozoic, Mesozoic and Cenozoic sedimentary rocks. Our results reveal high Vp/Vs ratios in the region of Harrat Lunayyir, which are interpreted as solidified magma intrusions from old magmatic episodes in the shield. Our results also indicate slow velocities and large upper mantle lid temperatures below the southern and northern tips of the Arabian shield, when compared with the values obtained for the central shield. We argue that our inferred patterns of lid velocity and temperature are due to heating by thermal conduction from the Afar plume (and, possibly, the Jordan plume), and that volcanism in western Arabia may result from small-scale adiabatic ascent of magma diapirs. © 2016 The Authors.

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