Historic Earthquakes: Tectonic Summary
Magnitude 6.8 NEAR THE COAST OF CENTRAL CHILE
2003 June 20 13:30:38 UTC
Tectonic Setting
This earthquake occurred in the Chilean subduction zone, in which the
dominant tectonic process is the subduction and underthrusting of the Nazca
plate to the east beneath the South American plate at a rate of about 8
cm/yr. The currently available location and moment-tensor of the
earthquake imply that the shock occurred as a sudden slippage on the
thrust-fault boundary between the plates. The hypocenter of this event
is located within a segment of the plate boundary that was ruptured in 1943
by a magnitude 7.9 earthquake.
