Duplexing plays important roles in the evolution of fold-and-thrust belts and accretionary
wedges, and causes internal shortening of the system, which then impacts both rates
of frontal advance and seismic-moment deficit. Nevertheless, the significance of this
internal shortening has not yet been highlighted in previous studies in the Himalaya
or elsewhere. We invoke geometric solutions to constrain the ratio of transferred
slip (R; i.e., the ratio of updip slip to downdip slip) for the midcrustal ramp-the
most active ramp within the midcrustal duplex-in the Himalayan wedge. We find that
R is similar to 0.9, and then used this ratio to calculate the accumulating seismic
moment. The reduction in seismic-moment accumulation over the past 1000 yr along the
entire Himalayan arc (similar to 2200 km) is equivalent to at least one similar to
M-w 8.72 earthquake, and potentially reduces the seismic moment deficit by similar
to 23%-54%, which may reconcile the long-term unbalanced seismic moment in the Himalaya.
