Answer:
An initial estimate of the size of the rupture that caused the earthquake
is obtained from the length of the aftershock zone, the dimensions of
historical earthquakes, and a study of the elastic waves generated by the
earthquake. The aftershocks suggest that the earthquake rupture had a
maximum length of 1200 -- 1300 km parallel to the Sunda trench and a width
of over 100 km perpendicular to the earthquake source. An early estimate
from the study of elastic waves show the majority of slip was concentrated
in the southernmost 400 km of the rupture.
