Seismic hazard analysis and local site effect of the 2017 M w 7.3 Sarpol-e Zahab, Iran, earthquake
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Seismic hazard analysis and local site effect of the 2017 Mw 7.3 Sarpol‑e Zahab, Iran, earthquake Hamid Zafarani1 · Yaser Jafarian1 · Alireza Eskandarinejad2 · Ali Lashgari3 · Mohammad Reza Soghrat1 · Hassan Sharafi4 · Masoud Afraz‑e Haji‑Saraei5 Received: 18 March 2019 / Accepted: 8 May 2020 © Springer Nature B.V. 2020
Abstract A strong earthquake occurred on November 12, 2017, in Sarpol-e Zahab city, western Iran, with the moment magnitude ( Mw ) of 7.3 and a focal depth of 18 km. The maximum horizontal peak ground acceleration of 0.69 g was recorded at the Sarpol-e Zahab station. Significant damages were observed in frame and masonry buildings, while the damage distribution was non-uniform throughout this small city. The preliminary site reconnaissance revealed that numerous engineering structures collapsed or considerably damaged in some regions, contrary with those non-structural masonry buildings in other regions which remained intact during earthquake. This paper represents a preliminary reconnaissance report prepared through the site visit done by the authors, a few days following the earthquake occurrence. Then, the data recorded by the strong ground motion stations in the affected city and the surrounding regions together with the geotechnical data gathered from the available boreholes in Sarpol-e Zahab are incorporated for probabilistic seismic hazard and local site effect analyses. The observed response spectra at two stations and distance-dependency of ground acceleration are compared with those predicted by some attenuation models. The results of probabilistic seismic hazard analysis in the return periods of 475 and 2475 years are compared with the observed ground response and the design spectra recommended by the Iranian seismic code (for site classes Types I and II). Several geotechnical boreholes from the previous works in the affected area were analyzed through the equivalent-linear site response approach in order to obtain the seismic response at the soil surface. The results are then compared with the code design spectra for the site classes of Types III and IV. It is demonstrated that the calculated response spectra are generally larger than those recommended by the Iranian seismic code, especially for the 4–7 stories buildings. Keywords Sarpol-e Zahab earthquake · Seismic hazard · Site effect · Uniform hazard spectra · ground motion prediction equations
* Yaser Jafarian [email protected] Extended author information available on the last page of the article
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Natural Hazards
1 Introduction On Sunday, November 12, 2017, at 21:48:16 local time, a strong earthquake occurred in the border region between Iran and Iraq in Kermanshah province in the vicinity of Sarpole Zahab city. The epicenter coordinates of the earthquake with moment magnitude ( Mw ) of 7.3 and a focal depth of 18.1 km were reported at 34.77 N and 45.76 E by the Iranian Seismological Center (IRSC, available at https://irsc.ut.ac.ir/). The locations of earthquake epicenter and the recording statio
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