Work

Investigating reservoir-triggered seismicity in the Koyna–Warna region through nodal ambient noise tomography

Year: 2025

Type: article

Abstract: The Koyna-Warna region in southern India is a unique case of dual Reservoir-Triggered Seismicity (RTS), surrounding impoundments on Koyna and Warna rivers. In this study, we perform ambient noise surface wave tomography using data from a temporary dense deployment of three-component geophones in order to understand the origin of RTS. To achieve this objective, surface wave dispersion curves from noise cross-correlations in rotated coordinates were used to create group velocity maps in 0.5-5 s periods. The group velocity dispersions from map bins were inverted for shear wave velocity ([Formula: see text]) and [Formula: see text] radial anisotropy (ξ) maps down to 5 km depth. The [Formula: see text] and ξ till 1 km depth are correlated with topographical features in agreement with the basement depth estimates. Large earthquakes in the region are marked by negative ξ with negative [Formula: see text] anomaly or [Formula: see text] anomaly contrast, suggesting shear strength could be an important control on their genesis. A large negative [Formula: see text] anomaly southwest of the Koyna reservoir is linked with reservoir water migration to greater depths, part of a larger interconnected system of pathways extending across the reservoirs. These results, set decades post reservoir impoundment, can help understand the evolution of RTS around dam sites elsewhere.

Source: Scientific Reports

DOI: 10.1038/s41598-025-12099-z

Authors: Pratul Ranjan, Prakash Kumar, Biswajit Mandal, Periyasamy Karuppannan

Institutions: National Geophysical Research Institute, Academy of Scientific and Innovative Research

Language: English

Topic: Seismic Waves and Analysis

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,690

Funder: Ministry of Earth Sciences