Seasonal modulation of deep slow-slip and earthquakes on the Main Himalayan Thrust

The interaction between seasonally-induced non-tectonic and tectonic deformation along the
Himalayan plate boundary remains debated. Here, 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 explore seasonal mass oscillations by continental
water storage in Southeast Asia and Himalayan arc region using continuous Global
Positioning System measurements and satellite data from the Gravity Recovery and Climate
Experiment. 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.