 | Paleoseismological and morphological evidence of slip rate variations along the North Tabriz fault (NW Iran)
Auteur(s) : Solaymani Azad, Shahryar Philip, Hervé DOMINGUEZ, Stéphane Hessami, Khaled Shahpasandzadeh, Majid Foroutan, Mohammad Tabassi, Hadi Lamothe, Michel
Auteurs secondaires : Geological Survey of Iran, Azadi sq., Meraj blvd., PO Box 13185-1494 Tehran, Iran (GEOLOGICAL SURVEY) ; Geological Survey of Iran, Azadi sq., Meraj blvd., PO Box 13185-1494 Tehran, Iran Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) International Institute of Earthquake Engineering and Seismology (IIEES) ; Teheran Kerman Graduate University of Technology Institut des Sciences de la Terre de Paris (iSTeP) ; Université Pierre et Marie Curie - Paris 6 (UPMC) - Centre National de la Recherche Scientifique (CNRS) Azad University ; Azad University University of Quebec at Montreal, Montreal, Quebec, Canada ; Université du Québec à Montréal (UQAM)
Éditeur(s) : HAL CCSD Elsevier Résumé : International audience Northwest Iran is characterized by a high level of historical and instrumental seismicity related to the ongoing convergence between the Arabian and Eurasian plates. In this region, the main right-lateral strike-slip fault known as the North Tabriz fault (NTF) forms the central portion of a large crustal fault system called the Tabriz fault system (TFS). The NTF is a major seismic source along which at least three strong and destructive earthquakes have occurred since 858 AD. The two most recent destructive seismic events occurred in 1721 AD and 1780 AD, rupturing the SE and NW fault segments, respectively. This paper reports paleoseismological and quantitative geomorphologic investigations on the SE segment of the NTF, between the cities of Bostanabad and Tabriz. These observations help to improve our understanding of the seismic hazard for Tabriz city and its surrounding areas. Our field investigations revealed evidence of successive faulting events since the Late Quaternary. Paleoseismic investigations indicate that since 33.5 kyr, the SE segment of the NTF has experienced at least three major (M>7.5) seismic events, including the 1721 AD earthquake (M=7.6–7.7). Along the NW segment of the fault, however, our results suggest that the amount of strong (M~7.5) seismic events during the same period is significantly greater than along the SE segment. One possible explanation of such a difference in seismic activity is that the Late Quaternary-Holocene coseismic slip rate is decreasing along the NTF from the northwest to the southeast. This explanation contradicts the former hypothesis of a constant slip rate along the whole length of the NTF. In addition, more distributed deformation along several parallel fault branches, in a wider fault zone of the SE segment of the NTF may be considered as additional evidence for the estimation of lower rate of deformation along the fault segment. Such a slip distribution pattern can explain the existence of smaller (~300 m) Pliocene-Quaternary cumulative dextral offsets along the SE fault segment than the measured cumulative offsets along the NW segment (~800 m) of the NTF. ISSN: 0040-1951 hal-01089420 http://hal.upmc.fr/hal-01089420 http://hal.upmc.fr/hal-01089420/document http://hal.upmc.fr/hal-01089420/file/Solaymani%20Azad%20et%20al.%2C%202014%20%28accepted%29.pdf DOI : 10.1016/j.tecto.2014.11.010 | Partager
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