Single-Station MHVSR as a Rapid Tool to Detect Faults: Case Study of a Reverse Fault at Aharbal, Shopian, Kashmir Valley

Abstract

This study is an attempt to experimentally validate the presence of a high angle reverse fault at Aharbal Falls of Kashmir Valley. The compressional forces across the south-southwest bounding orogeny has resulted in reverse faulting of Panjal Traps (Early Permian) over the Fluvio-glacial Deposits (Pleistocene). Single-station microtremor horizontal-to-vertical spectral ratio (MHVSR) method and multichannel simulation with one-receiver (MSOR) surface wave tests have been conducted along a profile across the suspected fault zone. HVSR curves exhibit an anomalously high H/V amplitude (~8) at ~4.5 Hz within the fault zone. As the distance from fault zone increases the amplitude decreases gradually to ~2-3 in stable zones. Sub-surface shear wave velocity also reveals a drop from 1,250-1,350 m/s in surrounding host rock to ~860 m/s in the fault zone. The study concludes that MHVSR can be used as an effective tool for rapid detection and validation of reverse faults. © ASCE