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In the context of fluid-induced seismicity, various injection parameters have been shown to affect fault behaviour differently, although existing studies about their effects sometimes show contradictory results. Aseismic slip is also known to affect seismicity, but its exact contribution remains elusive. To address these, we perform numerical modelling to understand the effects of injection volume and rate on long-term seismic and aseismic fault slip behavior. Our results suggest that both parameters can affect various aspects of fault behaviour to different extents, and, in some cases, their roles are interdependent, thus they should be examined simultaneously in order to fully characterize their effects on triggered fault responses. Within the model space, we observe the fault predominantly releasing aseismic energy, which plays a significant role in altering the timing of triggered earthquakes that follow and exhibits lasting impacts in subsequent seismic cycles. In terms of seismic responses, increasing injection rate enhances the size of the triggered cluster, while increasing injection volume increases seismicity rate of the sequence. Detailed characterization of the patterns of earthquake occurrence and moment release with respect to different injection parameters can offer insights into establishing safe bounds of injection operation and potentially mitigate seismic hazard. [ABSTRACT FROM AUTHOR]

The intraplate region of the northern Bay of Bengal has occasional moderate-to-strong earthquakes ranging in depth from 10 to 60 km. This region is known to have a very thick sedimentary cover (~20 km) underlain by the oceanic plate. These intraplate earthquakes occur both within the sedimentary layers and the basement. In order to understand the seismotectonics of this region, we study the source mechanism of recent moderate-to-strong earthquakes (Mw>5.5). We model teleseismic body waveforms (P and SH) to obtain the best fit double couple solution and well constrained centroid depth. The dataset has good azimuthal coverage and clear depth phase. We use a simple source time function which reproduces the main features of the observed waveforms and invert the dataset using linearized least squares algorithm. We also perform uncertainty tests on the modeled source parameters by fixing each parameter to a range of values and allowing the inversion to find the best fit solution. Through this we are able to ascertain the ±1 sigma bound on the modeled parameters. Our results reveal strike-slip faulting in the northernmost Bay of Bengal and normal faulting to its east, close to the Indo-Burman subduction zone. The strike-slip faults originates at depth between 20-30 km, while the normal faulting are shallower than 10 km. We conjecture that the strike-slip faulting occurs on passive margin rift faults within the basement, which are reactivated under oblique N20E motion of India. Whereas the shallow normal faulting close to the Indo-Burman subduction zone occurs due to flexural extension of the top of the downgoing Indian plate. [ABSTRACT FROM AUTHOR]

We study the source properties of the 2005 Kashmir earthquake and its aftershocks to unravel the seismotectonics of the NW Himalayan syntaxis. The mainshock and larger aftershocks have been simultaneously relocated using phase data. We use back-projection of high-frequency energy from multiple teleseismic arrays to model the spatio-temporal evolution of the mainshock rupture. Our analysis reveal a bilateral rupture, which initially propagated SE and then NW of the epicenter, with an average rupture velocity of ~2 km s−1. The area of maximum energy release is parallel to and bound by the surface rupture. Incorporating rupture propagation and velocity, we model the mainshock as a line source using P- and SH-waveform inversion. Our result confirms that the mainshock occurred on a NE dipping (~35°) fault plane, with centroid depth of ~10 km. Integrated source time function show that majority of the energy was released in the first ~20 s, and was confined above the hypocenter. From waveform inverted fault dimension and seismic moment, we argue that the mainshock had an additional ~25 km blind rupture beyond the NW Himalayan syntaxis. Combining this with findings from previous studies, we conjecture that the blind rupture propagated NW of the syntaxis underneath a weak detachment, overlain by infra-Cambrian salt layer, and terminated in a wedge thrust. All moderate-to-large aftershocks, NW of the mainshock rupture, are concentrated at the edge of the blind rupture termination. Source modeling of these aftershocks reveal thrust mechanism with centroid depths of 2–10 km, and fault planes oriented sub-parallel to the mainshock rupture. To study the influence of mainshock rupture on aftershock occurrence, we compute Coulomb failure stress on aftershock faults. All these aftershocks lie in the positive Coulomb stress change region. This suggest that the aftershocks have been triggered by either co-seismic or post-seismic slip on the mainshock fault. • 2005 Kashmir mainshock had a bilateral rupture on NE dipping thrust plane with energy released within 10 km of the surface. • The Mainshock had a surface rupture of ~75 km, and was blind for ~25 km NW of the Himalayan syntaxis beneath a wedge thrust. • The aftershocks NW of the mainshock surface rupture were triggered by co-seismic or post-seismic slip on the mainshock fault. [ABSTRACT FROM AUTHOR]

Northeast India is sandwiched between the seismically active plate boundaries of the Eastern Himalaya to the north and the Indo-Burman subduction zone to the east. This plate boundary system is different from the central Nepal Himalaya, due to oblique convergence across two orthogonal plate boundaries, resulting in a zone of distributed deformation both within and away from the plate boundary. Previous studies of spatial distribution and source mechanism of earthquakes have shown that the N20E convergence between India and Tibet is partitioned into N-S underthrusting and E-W subduction of the Indian plate beneath the Himalaya and Burma micro-plate, respectively. However, south-west of the plate boundaries, the middle-to-lower crust deforms by strike-slip faulting in the Kopilli Fault Zone (KFZ); upper-to-mid crustal strike-slip faulting along the western Brahmaputra Valley; and lower crustal strike-slip faulting beneath the Bengal Basin. Strike-slip faulting in the KFZ also extends northwards beneath the Eastern Himalaya and southeastward beneath the Naga fold-thrust belt. In order to understand the role of these strike-slip faults in accommodating the GPS derived convergence across northeast India, we study the source mechanism of recent earthquakes using teleseismic (for earthquakes with Mw>5) and local (4.0

The article discusses the earthquakes reported by the Indian Meteorological Department (IMD) in the Bengal Basin with no casualties.