indo–us workshop on “intraplate seismicity” - The CERI Blog

oundary faults and an up-­‐welled lower crust. (The precise geometry and seismic potential
of each site depends on its tectonic history and geometry after stress inversion). These
features are sites of local stress concentrations and elevated strain rates, and potential IPE.
To test this model and to predict potential locations of IPE, seismic tomography can be used
to define the weaker lower crust associated with rifted basins, and dense, continuous GPS
observations can be used to identify local pockets of elevated strain rates; and seismicity
and geophysical observations can be used to identify stress concentrators and locations of
IPE.
S1.3
Intra-­‐Plate Dynamics and Active Tectonic Zones of the Indian Plate
S. K. BISWAS
Ex-­‐Director, KDM Institute of Petroleum Exploration, ONGC.
Tectonic framework of Indian Plate started to evolve since the breakup of Gondwanaland in
Late Triassic. It evolved mainly during the time between its separation from the latter in
Early Cretaceous and its collision with the Eurasian plate in the north in Late Middle Eocene
and with the Indosinian plate in the northeast in Late Oligocene. Present active tectonic
zones, responsible for earthquake generation, were created by the collision pattern and
subsequent plate motion. Continued subduction and plate motion due to ridge push and
slab pull are responsible for activation of primordial faults in the inherent structural fabric of
the craton depending on the related stress field. Major tectonic zones of this continental
plate are related to the collision fronts and the reactivated intracratonic faults along the
resurgent paleo-­‐sutures between the proto-­‐cratons. Major Tectonic zones (TZ) are:
Himalayan TZ, Assam-­‐Arakan TZ, Baluchistan-­‐Karakoram TZ, Andaman-­‐Nicobar TZ and Stable
Continental Region (SCR) earthquake zone. The structure of the continental margins
developed during break up of Gondwana continental fragments. Western margin evolved
during the sequential separation of Africa, Madagascar and Seychelles since Late Triassic to
Late Cretaceous time. The Eastern margin structure evolved during separation of Antarctica
in Mid Cretaceous. The Orogenic belt circumscribing the northern margin of the Indian plate
is highly tectonized zone as subduction of the plate continues due to push from the
Carlsberg Ridge in the SW and slab pull towards northeast and east as the subduction of the
plate along the orogenic and island arc fronts continues. This stress pattern induced an