Himalayan Geology, Vol. 44 (1), 2023, pp. 71-80, Printed in India
The Effects of Quaternary Sediments on Earthquake Acceleration
RAMA HABIBI, MOHSEN POURKERMANI, MANUCHEHR GHORASHI, MOHMOUD ALMASIAN, HADI JARAHI*
Department of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran
*Email (Corresponding author) : hadijarahi@gmail.com
Abstract: Earthquakes are one of the most devastating natural hazards, resulting in untold casualties and destruction worldwide. The extent of destruction depends on various factors, of which the distribution of Quaternary sediments where a construction site lies stands out. These sediments control the amount of shear wave velocity and site amplifications. This study investigates the effect of alluvium on Peak Ground Acceleration (PGA) in Tehran and Karaj regions using the shear wave velocity map (VS30). The global VS30 map is modified using additional geotechnical and geological data. Next- generation attenuation properties are used for calculating PGA. The obtained PGA distribution map for the study area clearly shows the effect of VS30 on PGA changes. The inverse relationship between these two parameters is observed as a longitudinal strip stretched between Rey and Eslamshahr. On the edge of the triple escarpments at the Palaeo-, Mega- Lake of Rey, the PGA values vary with quaternary sediments. These sediments are responsible for the effect on the construction site, which resonates the seismic waves. Even with increasing distance from the fault, the PGA value is enhanced ue to the presence of these sediments.
Keywords : Earthquake, Quaternary Sediments, Shear Wave Velocity, Palaeo- Mega- Lake of Rey, Resonance
