Seasonal Modulation of Deep Slow-slip and Earthquakes on the Main
Himalayan Thrust
Abstract
We explore seasonal mass oscillations by continental water storage in
Southeast Asia and Himalayan arc region using continuous Global
Positioning System (cGPS) measurements and satellite data from the
Gravity Recovery and Climate Experiment (GRACE). While the interaction
between seasonally induced non-tectonic and tectonic deformation along
the Himalayan plate boundary is still debated, we propose that tectonic
deformation along this plate boundary can be significantly influenced by
the deformation induced by the non-tectonic hydrological loading cycles.
We suggest that the substantially higher transient displacements above
the base of the seismogenic zone indicate a role of changes in aseismic
slip rate on the deep megathrust that may be controlled by seasonal
hydrological loading. We invoke modulation of aseismic slip on the
megathrust down-dip of the seismogenic zone due to a fault resonance
process induced by the seasonal stress changes. This process modulates
mid-crustal ramp associated micro-seismicity and influences the timing
of Central Himalayan earthquakes.