Upwarped high velocity mafic crust, subsurface tectonics and causes of intraplate Latur-Killari (M 6.2) and Koyna (M 6.3) earthquakes, India - A comparative study

O. P. Pandey, K. Chandrakala, G. Parthasarathy, P. R. Reddy, G. Koti Reddy

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37 Scopus citations

Abstract

A unique attempt is made to understand the genesis of intraplate seismicity in the Latur-Killari and Koyna seismogenic regions of India, through derived crustal structure by synthesizing active and passive seismic, magnetotelluric, gravity and heat flow data. It has indicated presence of relatively high velocity/density intermediate granulite (and amphibolite) facies rocks underneath the Deccan volcanic cover caused mainly due to a continuous geodynamic process of uplift and erosion since Precambrian times. These findings have been independently confirmed by detailed borehole geological, geochemical and mineralogical investigations. The crystalline basement rock is found to contain 2 wt% of carbon-di-oxide fluid components. The presence of geodynamic process, associated with thermal anomalies at subcrustal depths, is supported by a high mantle heat flow (29-36 mW/m2) beneath both regions, although some structural and compositional variations may exist as evidenced by P- and S-wave seismic velocities. We suggest that the stress, caused by ongoing uplift and a high mantle heat flow is continuously accumulating in this denser and rheologically stronger mafic crust within which earthquakes tend to nucleate. These stresses appear to dominate over and above those generated by the India-Eurasia collision. The role of fluids in stress generation, as advocated through earlier studies, appears limited.

Original languageEnglish
Pages (from-to)781-795
Number of pages15
JournalJournal of Asian Earth Sciences
Volume34
Issue number6
DOIs
StatePublished - 20 May 2009
Externally publishedYes

Keywords

  • Crustal structure
  • Geochemical data
  • Granulites
  • Intraplate seismicity
  • Killari borehole
  • Latur and Koyna earthquakes
  • Mantle heat flow
  • Regional uplift

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