Abstract:
This research performs a Probabilistic Seismic Hazard Assessment (PSHA) for Gilgit
Baltistan, utilizing US National Seismic Hazard Mapping project methodologies. This study
uses smoothed seismicity to determine and quantify the risk of seismic activity within the
region. According to the Global Earthquake Model (GEM) database, 42 crustal faults are
identified in the study area, out of which 30 faults are active and have been modeled in 3D.
PSHA uses a logic tree technique to addressing epistemological uncertainties related to
characterization of sources and Ground Motion Attenuation Relationships (GMARs). Seismic
Hazard Maps have been developed for the PGA and SA at 0.2 seconds (Ss) and 1.0 seconds
(S1). These maps represent Design Basis Earthquake (DBE) level, which has a 10% probability
of exceedance (PE) in 50 years, and Maximum Considered Earthquake (MCE) level, which
has a 2% probability of exceedance (PE) in 50 years. Seismic Hazard in Gilgit-Baltistan
regarding PGA varies between 0.10 g to 1.10 g for DBE level and from 0.30 g to 2.20 g for
MCE level. For spectral acceleration at 0.2 seconds (Ss), the hazard values for DBE level range
from 0.30 g to 2.10 g, while for MCE level, it ranges from 0.70 g to 4.20 g. Alternatively, for
the spectral acceleration at 1.0 seconds (S1), the hazard values range from 0.10 g to 0.60 g for
DBE level and from 0.30 g to 1.30 for MCE level. Furthermore, a Uniform Hazard Spectrum
has also been prepared for Gilgit City. This research provides a thorough assessment of seismic
hazards for Gilgit-Baltistan region and might benefit decision-makers who are interested in
reducing seismic risks.
