GPS, scaling exponent and past seismicity for seismic hazard assessment in Garhwal–Kumaun, Himalayan region

Abstract

The world’s most geologically complex Himalayan arc is well known for its tectonic and seismic activities due to the collision of Indian and Eurasian plates. Based on these elements [global positioning system (GPS) deformation measurements, scaling exponent (D) of the tectonic elements and past seismicity] studied here can contribute to better understanding of dynamics and complexities of earthquakes occurrence in any region. In the present paper, the crustal deformation is analyzed with the 3-year campaign and continuous GPS sites data. The velocity vectors of the sites with IGS05 reference frame ranges from 35 to 50 mm/year and give strain-rate measurements up to 130 9 10 -9 strain/year. Further, the study region was divided into number of blocks of 1° 9 1° that gives different D value based on the presence and distribution of tectonic elements in a particular block. One of the blocks was identified with very high D value of 1.82, where the least seismic activity and extensive convergence due to strain accumulation in comparison with other blocks of higher capacity dimensional value has been observed. Particularly this block lying between latitude 29°N–30°N and longitude 79°E–80°E is considered to be the probable highest seismic hazard zone in the study area. Significance of the combined application of GPS study, scaling exponent and the characteristics of seis- micity are stated as helpful methods in the identification of hazardous zone in the Eastern part of the central seismic gap in the Himalaya or in any active areas of the world