Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

New Probabilistic Seismic Hazard Model for Nepal Himalayas Integrating Distributed Seismicity and Major Thrust Faults

Saroj Maharjan
* ,
Antoine Poujol
* ORCID logo ,
Christophe Martin
,
Gabriele Ameri
,
David Baumont
,
Kiana Hashemy
,
Yacine Benjelloun
,
Hussein Shible
ORCID logo
Version 1 : Received: 9 May 2023 / Approved: 9 May 2023 / Online: 9 May 2023 (16:20:12 CEST)

A peer-reviewed article of this Preprint also exists.

Maharjan, S.; Poujol, A.; Martin, C.; Ameri, G.; Baumont, D.; Hashemi, K.; Benjelloun, Y.; Shible, H. New Probabilistic Seismic Hazard Model for Nepal Himalayas by Integrating Distributed Seismicity and Major Thrust Faults. Geosciences 2023, 13, 220. Maharjan, S.; Poujol, A.; Martin, C.; Ameri, G.; Baumont, D.; Hashemi, K.; Benjelloun, Y.; Shible, H. New Probabilistic Seismic Hazard Model for Nepal Himalayas by Integrating Distributed Seismicity and Major Thrust Faults. Geosciences 2023, 13, 220.

Abstract

Nepal is one of the most seismically active regions in the world, as highlighted by the recent devastating 2015, Mw7.8 Gorkha earthquake and a robust assessment of seismic hazard is paramount for the design of earthquake-resistant structures. In this study we present a new probabilistic seismic hazard assessment (PSHA) model for Nepal. We considered data and findings from recent scientific publications, which allowed us to develop a unified homogenized seismicity catalogue, propose alternative Seismic Source Characterization (SSC) models including up-to-date parameters of major thrust faults like Main Frontal Thrust – MFT and Main Boundary Thrust – MBT, while also considering existing SSC models and various hazard modelling strategies within a logic tree framework. The sensitivity analyses show the hazard levels are generally higher for SSC models integrating the major thrust faults, followed by homogenous volume sources and smoothed seismicity approach. The hazard maps covering entire Nepal is presented as well as the Uniform Hazard Spectra (UHS) for 5 selected locations (Kathmandu, Pokhara, Biratnagar, Nepalganj and Dipayal) at return periods of 475- and 2,475-years considering Vs,30=760 m/s. The results obtained are generally consistent with most recent studies. However, a notable variability in hazard levels and several discrepancies with respect to the Nepal Building Code NBC105: 2020 [1] and Global Hazard Model, GEM [2] are noted and possible causes are discussed.

Keywords

Nepal Himalayas; Probabilistic Seismic Hazard Assessment (PSHA); Seismic Source Characterization; Seismogenic Models; Main Himalayan Thrust

Subject

Environmental and Earth Sciences, Geophysics and Geology

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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