فهرست مطالب

Seismology and Earthquake Engineering - Volume:20 Issue:4, 2019
  • Volume:20 Issue:4, 2019
  • تاریخ انتشار: 1398/06/03
  • تعداد عناوین: 7
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  • Mohammad Davoodi*, Fariborz Sanjari Pages 1-12
    One of the most important challenges in analysis of non-ordinary structures is the critical angle of incidence of earthquake ground motions. To accommodate these directional effects, several procedures and combination rules have been proposed. The major limitations of these methods are that they are restricted to elastic analyses, rarely considered near-fault earthquakes and are almost related to the building structures or bridges. The main objective of this work is to assess the influence of incident angle of ground motions on several engineering demand parameters (EDPs) of an embankment dam under Sarpol-e Zahab earthquake. To achieve this goal, after selecting proper ground motions, the as-recorded horizontal components (two orthogonal) were rotated to: fault-normal/parallel direction, principal direction, direction related to GMrotIpp (NGA relationships) and maximum direction of response history analysis of two degree of freedom system (MSD). In the next step, a typical embankment dam in the earthquakeaffected areas was modeled using the shear beam method. The model was excited by as-recorded motions with various directions in the range of 0-360 degrees with a step of 10 degrees and all four above-mentioned reference axes directions. Numerous equivalent linear analyses were carried out to obtain the critical angles of excitation that leads to maximum responses. The analyses results showed that the critical orientations of ground motions depend on: input motions, structure characteristics and EDPs.
    Keywords: Sarpol-e Zahab Earthquake, Reference axes, Embankment, Critical orientation, Incident angle
  • Abdollah Sohrabi*, Farhad Imanshoar, Shahram Maghami, Malek, Mirza Darvishi Pages 13-24
    Following the November 12, 2017 Sarpol-e Zahab earthquake with a magnitude of 7.3 in Richter scale, emergency inspection of dams has been performed for dams located at the epicentral distance of 125 km, according to the ICOLD recommendations. In the mentioned zone, there are 16 impounded operational storage dams. Inspected dams had no apparent significant damages and only some thin cracks had been observed in Tange-Hamam Dam that is a non-homogenous embankment dam and the closest operational dam to the epicenter of the earthquake, with a distance of 25 km from the epicenter. There were some defects such as longitudinal cracks and some tiny transversal cracks on the crest of the dam as well as some vertical cracks in the spillway's left approach wall. Regarding the observed evidence, more precise investigations of the dambehavior were performed through the instrumentation data. Settlement measuring on magnetic plates shows the settlement of 13 cmnear the embankment surface at the middle of the damcrest, which is about 0.22 of the dam height. This rate of strain has been compared with some published international experiences, which generally shows the acceptable performance of the dam. To ensure the safety of the dam, monitoring of all instruments should be continued, as well as the precise geodetic measuring in the dam body, which is in progress now.
    Keywords: Sarpol-e Zahab earthquake, Tange-HamamDam, Instrumentation data, Dam settlement
  • Mojtaba Moosavi*, Iman Ashayeri, Ebrahim Haghshenas, Mahnoosh Biglari, Mohsen Kamalian, Javad Jalili Pages 25-32
    The destructive earthquake of Sarpol-e Zahab (Mw=7.3, Depth=18 Km) lead to sever damages to manyof structures of the affected region. The first reconnaissance of the area showed that the structures damage distribution could be interpreted by the effect of local site conditions. Therefore, some microtremor measurements and geophysical surveys were performed to investigate this concern. The survey included totally 41 locations of microtremor measurements and 40 locations of geophysical refraction profiles, the distribution of which covered all over the city. The recorded motions were analyzed using horizontal to vertical spectral ratio (HVSR) method to determine the natural frequencies of the alluvium; primary and secondary waves velocitywere also measured as a complementarydata. The survey results concluded to the preliminary seismic site classification map for the city, which would be useful for future safe design of structures.
    Keywords: Seismic site classification, Geophysical surveys, Microtremor measurements
  • Investigation of Site Response Analyses of the Ezgeleh - Sarpol-e Zahab Earthquake, Iran, inWest of Sarpol-e Zahab Town
    Mojtaba Moosavi, Hamed Taleshi, Omid Hosseinian Pages 33-43
    In this paper, the site conditions of the western parts of Sarpol-e Zahab were studied for their impact on the seismic waves of the Ezgeleh - Sarpol-e Zahab earthquake, which occurred on November 12, 2017. The aforementioned earthquake resulted in widespread damage in the town, particularly in its south-west parts. Although the first assumptions focused on construction issues or design weaknesses related to the buildings, the site effects should not be underestimated. Site effects are widely recognized as an important factor of seismic risk. Subsurface geotechnical and geophysical data in four different sites in the town fromthe north to the south of the western parts have been obtained, and used to estimate the local site condition on earthquake ground motion in the area. The ground response analyses have been conducted considering the nonlinear behavior of the soil deposits using equivalent linear approach. Fromthe results of this study, it was determined that the reason for the increase of destruction from North to the South parts of the region was the amplification of seismic waves.
    Keywords: Earthquake, Site Effects, Sarpol-e Zahab
  • Babak Mansouri*, Shakiba Mousavi, Kambod Amini Hosseini Pages 45-55
    A strong earthquake with Mw 7.3 occurred on Nov. 12, 2017, at the Iran-Iraq border where the city of Sarpol-e Zahab (24 km from the epicenter) and many other towns and villages were affected severely. Rapid damage mapping essentially helps to understand the location, the extent and the severity of high hit areas, and it is regarded as an important source of information in assisting proper crisis management. Rapid damage mapping can be completed according to three general methods namely; manual, semi-automated, and automated. This research explores a proposed semi-automated method that once calibrated and operational it can be utilized as an automated process. After preprocessing the satellite data, individual buildings or building parcels are identified using either some building extraction tools or with the use of some ancillary data sets. The proposed damage detection algorithm is based on deriving a set of textural indices associated to individual building or property footprints. These parameters have been input into an Artificial Neural Network (ANN) for damage classification. The trained ANN created urban damage maps. For detecting significant observable physical changes/damages to the buildings, two schemes were developed: 1) by comparing the post-event with the pre-event VHR satellite images, and 2) using a post-event image only. In scheme-1, before and after images were acquired from different satellites (TripleSat_2 with 89 cm and SV1 with 50 cm spatial resolution) as input and the Overall Accuracy (OA) of the proposed damage classification was reported as 72%. The damage classification accuracy in scheme-2 produced an OA of 75%.
    Keywords: Object-oriented image processing, Damage detection, Textural analysis, Artificial Neural Network
  • Kambod Amini *, Yasamin O. Izadkhah, Babak Mansouri, Mohammadreza Ghayamghamian Pages 57-68
    On November 12, 2017, at 9:48 p.m. (local time), a destructive earthquake (Ml=7.3) occurred in the border region between Iraq and Iran, followed by many weak to strong aftershocks. The earthquake claimed more than 620 lives with a further 10000 injured. At least eight cities including Qasr-e Shirin, Ezgeleh, Salas-e Babajani, Gilan-e Gharb, Sarpol-e Zahab, Dalahou, Eslamabad-e Gharb and Javanrud as well as around 2000 villages were damaged or affected severely by this earthquake and its aftershocks. Additionally, the earthquake was felt in many adjacent provinces and caused extreme fear and horror. Considering the time of earthquake and lack of appropriate damage assessment tools, it took fewhours to evaluate the location of the most stricken areas and to estimate the number of casualties. Moreover, due to the wide extent of damaged areas, the local needs were much higher than the existing resources and capacities. These issues caused delay in providing emergency response services and dispatching the rescue and relief teams to the affected areas. In this paper, the most important challenges in preparedness and emergency response aspects regarding this earthquake will be addressed and discussed. Lessons learnt and recommendations are provided based on the authors' field observation undertaken few days after the earthquake.
    Keywords: Emergency Response, Preparedness, Challenges, Sarpol-e Zahab Earthquake
  • Parisa Shahbazi, Babak Mansouri* Pages 69-80
    The November 12, 2017 Sarpol-e Zahab earthquake (Mw 7.3) occurred at 18:18 GMT (21:48 local time) and affected vastly the western part of Iran especially the Kermanshah province. The death toll was at least 620, the total number of injured people just the day after the earthquake was 5346 and around 70000 people were left homeless. This study aims to estimate the distribution of physical damages to the building stock using our domestic model and to calculate and validate the associated casualties under Sarpol-e Zahab earthquake event using a global model with some modifications. This region has been chosen because it has suffered major losses due to the recorded high PGA value of 684 gal and also due to the fact that some adequate field surveys and documentations were completed for this event. Since accurate building distribution maps are not available or accessible, to develop a spatial building database, a dasymetric mapping technique has been employed by merging a grid world population distribution map and the national census data. OpenQuake platform is utilized to simulate the ground motion field and to assess the physical damages and human loss. The results were compared with the actual observed data and showed relatively a proper match.
    Keywords: Sarpol-e Zahab earthquake, Seismic hazard, Lossmodeling, Physical damage, Human loss, OpenQuake