hide
Free keywords:
-
Abstract:
The Alborz mountain range is part of the Alpine–Himalayan seismic belt that passes through northern Iran and considers as an active region within the Arabia–Eurasia collision zone. The southern part of central Alborz is the most populous regions in Iran, home to over 15 million people. The central Alborz basin is located between longitudes 50.5°E and 51.5°E, and includes the cities of Tehran and Karaj, as well as approximately 50 smaller developing towns. While the empirical site amplification from temporary seismological network deployed in the region revealed significant ground motion amplification over a broad frequency range from 0.3 Hz to 4 Hz in Tehran, amplification in Karaj is moderate. Recently, Soltani et al. (2023) derived a 3D velocity model of the Tehran’s basin using active and passive surface waves methods. This velocity model exhibit a very thick sedimentary cover on the southern part of the Tehran basin with a seismic bedrock depth around 900 m, consistently with a fundamental resonance frequency of about 0.4 Hz. In this study the same peak observed in the southern part of Karaj shows the possibility of deep alluvium structure in this area and suburb towns. We extend the existing model to the west and south in order to develop the first site specific hazard map in central Alborz. With total amount of data include 19 temporary seismic, 800 single station measurements, 38 passive and over 50 active array measurements we also develop the first 3D shear wave velocity for central Alborz basin.
