Microearthquake activity on the Orozco Fracture Zone : preliminary results from Project ROSE
Citable URI
https://hdl.handle.net/1912/10278DOI
10.1575/1912/10278Keyword
Natural disasters; SeismologyAbstract
We present preliminary hypocenter determinations for 52 earthquakes recorded by a large multiinstitutional
network of ocean bottom seismometers and ocean bottom hydrophones in the Orozco Fracture
Zone in the eastern Pacific during late February to mid-March 1979. The network was deployed as
pan of the Rivera Ocean Seismic Experiment, also known as Project ROSE. The Orozco Fracture Zone is
physiographically complex, and the pattern of microeanhquake hypocenters at least partly reflects this
complexity. All of the well-located epicenters lie within the active transform fault segment of the fracture
zone. About lialf of the recorded earthquakes were aligned along a narrow trough that extends eastward
from the northern rise crest intersection in the approximate direction of the Cocos-Pacific relative plate
motion; these events appear to be characterized by strike-slip faulting. The second major group of activity
occurred in the central portion of the transform fault; the microearthquakes in this group do not display
a preferred alignment parallel to the direction of spreading, and several are not obviously associated
with distinct topographic features. Hypocentral depth was well resolved for many of the earthquakes reported
here. Nominal depths range from 0 to 17 km below the seafloor.
Description
Also published as: Journal of Geophysical Research 86 (1981): 3783- 3790