Morphometry and active tectonics of the Konkan coast, western India

Abstract

The Indian western coast is petroliferous and draws attention from academicians and industrial experts. In this work, geomorphic indices have been calculated to decode neotectonics of the Konkan onshore region on India's west coast. Earthquake and Bouguer anomaly data have been used along with the present-day stress data from the World Stress Map project. Gravity modeling was performed in order to gain seismotectonic insights. The b-values were determined using Z-MAP 7.1 (2021). Morphometric analysis at both linear and spatial scales were performed using the digital elevation model from the data derived from the Shuttle Radar Topography Mission, analyzed with ArcGIS 10.3 (2014) software. Maps depicting slopes, aspects, and reliefs were created. NW-SE trending lineaments in the Konkan plain guided the major stream courses. Two of the five watersheds, watersheds 4 and 5, reveal high tectonic activity, are landslide-prone and host hot springs. Interestingly, watersheds 4 and 5 show high b-values (except near the rivers' sources), low Bouguer anomalies, and higher Hypsometric integral values (0.18523 and 0.16698) than the other watersheds. A low b-value in watershed 3 indicates stress accumulation. Over a larger area, the gravity trend varies from ∼ −80 to 30 mGal. The lineaments diagram deduced from the first vertical derivative technique shows that the structural fabrics mostly trend ∼ NW-SE at the west of the Western Ghat Escarpment (WGE) while it is NE-SW at the east. The tilt derivative ratio technique reveals a major NE-SW trend to the west of the WGE and an E-W trend to the east. Structural interpretations based on drill-cores around Koyna combined with geophysical studies for deep crust will be required are required for a better understanding of the blind (active) structures in the region.