Magnitude 7.7 Earthquake in Northern Chile
Wednesday, November 14, 2007 at 15:40:53 UTC
12:40:53 PM Local time in Chile
7:40:53 AM Pacific Standard
approximately 60 kilometers.
earthquake resulted from the sudden release of strain that had accumulated due
to subduction of the Nazca plate beneath the South American plate. In this area
of the Peru-Chile Trench, the two plates are converging at a rate of about 80
mm per year. The red circle on the left-hand map below indicates the location
of the epicenter of the earthquake. With a depth of 60 km, this earthquake
probably occurred within the subducting Nazca Plate. The arrows on the Nazca
Plate on the right-hand map below show the direction and rate of motion of the
Nazca Plates with respect to the South American Plate. Preliminary indications
are that damage was light, probably because the earthquake occurred 60
kilometers below the Earth’s surface. A similar magnitude earthquake at a
shallow depth would likely have produced much greater damage.
The record of the Chile
earthquake by the University
of Portland seismometer is
shown below. The first seismic waves to reach UP traveled through Earth’s
mantle and required about 12 minutes to travel from the earthquake to
The first-arriving Primary (P) and Secondary (S) waves traveled a long distance
through Earth’s mantle from the earthquake to the base of the crust beneath
then traveled about 40 kilometers through the crust to the Earth’s surface at
the University of
Portland. The S waves
required about 22 minutes to travel from the earthquake to Portland.
The last package of seismic waves to arrive consisted of surface waves (Love
and Rayleigh waves) that started arriving about 42 minutes after the earthquake
occurred in Chile.
These waves traveled the ~9000 kilometer distance from earthquake to
of Portland seismometer
along the Earth’s surface.
Below is a SeismicEruption map of events from 1960 through
today. The region of the cross section in
the next figure is also shown.
Cross section through the Chile
trench showing the relationship of today's event with other in the subduction
zone. 547 events from 1960 through today are shown. Distance and
depth in kilometers.
Video of aftershock
sequence showing the length of the rupture zone.