Ground-motion predictions in Shillong region, northeast India

Sankar Kumar Nath, Kiran Kumar Singh Thingbaijam, Soumya Kanti Maiti, Avinash Nayak

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

We deliver ground-motion prediction equations for Shillong region, northeast India, based on a database generated by finite-fault stochastic simulations. An examination of the regional seismic source characteristics is carried out beforehand. Micro/minor earthquakes (M W < 5. 0) nucleating at hypocentral depth <21 km in the region recorded at broadband seismic stations are observed to have Brune stress-drop ranging between 2. 8 and 99. 9 bars. Likewise, macroseismic intensity data for the 1897 Shillong Earthquake that nucleated at a hypocentral depth of ~35 km places the associated stress-drop at 100-200 bars. The apparent variation of the stress-drop parameter with depth is considered with two source zones namely lower-crust and upper-crust. Equations for the lower-crust predict higher ground-motion levels and exhibit affinity to those developed for stable continental region of Eastern North America. The ground-motion levels predicted by the equations for the upper-crust are relatively lower but are still higher compared with those predicted for tectonically active regions, viz., the Himalayas and Western North America.

Original languageEnglish
Pages (from-to)475-488
Number of pages14
JournalJournal of Seismology
Volume16
Issue number3
DOIs
StatePublished - 1 Jul 2012
Externally publishedYes

Keywords

  • Ground-motion prediction equation
  • Peak ground acceleration
  • Pseudo-spectral acceleration
  • Shillong
  • Stress-drop

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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