Identification of hidden faults using determining velocity structure profile by spatial autocorrelation method in the west of Mashhad plain(Northeast of Iran)  

作　　者：Seyedeh Fatemeh NEMATI Naser HAFEZI MOGHADAS Gholam Reza LASHKARIPOUR Hosein SADEGHI 

机构地区：[1]Department of Geology,Faculty of Science,Ferdowsi University of Mashhad,Mashhad 91775-1436,Iran

出　　处：《Journal of Mountain Science》2021年第12期3261-3274,共14页山地科学学报（英文）

摘　　要：Characterizing the subsurface structure is an important parameter for the improvement of seismic hazard assessment.Due to the tectonic complexity of the earth,some deep fractures do not reach the earth's surface and are not detectable with visual analysis.Therefore,the lack of knowledge of faults and fractures can result in disasters,especially in urban planning.Many geophysical methods can be used to estimate subsurface structure characterization.However,a more reliable method is required to assess seismic hazards and reduce potential damage in metropolitan areas without destroying buildings and structures.This paper aims to identify hidden faults and structures using shear wave velocity sections.To do this,surface wave dispersion curve was extracted from the vertical component of microtremor array recording using the spatial autocorrelation(SPAC)method in two profiles and 13 array stations(perpendicular to the altitudes)to obtain shear wave velocity structure(Vs)in the west of Mashhad,northeast of Iran.The results of shear wave velocity profiles(Vs)indicate sudden changes in the thickness of sediments.This can be related to the displacement of a normal fault in this area causing the bottom rock to fall and an increase in the alluvial thickness in the central part of the plain.The velocity in the floor rock is 2000 meters per second in this area.According to the surface outcrops and water wells data,its material is slate and Phyllite metamorphic rocks that are exposed in the adjacent heights.Besides,the seismic profile results were well consistent with electrical resistance data and well logs indicating that the tool array method is flexible,non-invasive,relatively fast,and effective for urban areas with satisfactory accuracy.

关 键 词：Subsurface Structure Hidden Fault Array Microtremor SPAC Method Vs Profile Mashhad Seismic hazard assessment 

分 类 号：P315.9[天文地球—地震学]