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A reappraisal of the 1950 (Mw 6.9) Mondy earthquake, Siberia, and its relationship to the strain pattern at the south‐western end of the Baikal rift zone
Author(s) -
Delouis B.,
Déverchère J.,
Melnikova V.,
Radziminovitch N.,
Loncke L.,
Larroque C.,
Ritz J. F.,
San'kov V.
Publication year - 2002
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.2002.00445.x
Subject(s) - geology , seismology , focal mechanism , extensional definition , tectonics , rift , transition zone , fault (geology) , rift zone , inversion (geology) , stress field , active fault , pleistocene , geophysics , paleontology , physics , finite element method , thermodynamics
The precise nature of the transition between the present‐day compressional tectonics in central Mongolia and extensional deformation in the central Baikal rift has still to be determined. For that purpose we have built a comprehensive earthquake focal mechanism data base for the Mongolia – southern Siberia area, from which we map the variations of the stress field. We focus our detailed investigations on the largest seismic event in the transition zone, the 1950 (Mw 6.9) Mondy earthquake, for which several discordant focal mechanisms have been proposed. Using a new approach in source inversion, we resolve the focal mechanism (left‐lateral strike slip type on a steep south‐dipping fault) and depth (14 ± 3 km) of the Mondy earthquake with a satisfactory accuracy. This seismological information, combined with the geological observations, allows us to decipher the connections between the 1950 mainshock, the local stress tensor and the active faults, which strongly suggest a partitioning of the deformation between two faults, namely the Mondy and Ikhe–Ukghun faults.