paluzzi@pioneer.arc.nasa.gov (Peter Paluzzi- ZeroOne) (04/11/90)
April Meeting and Technical Presentation
Santa Clara Valley
Geoscience and Remote Sensing Society
Analyzing Earthquake Aftershocks
Dr. Susan Schwartz
University of Santa Cruz
Thursday April 26, 1990
Dinner - 5:45 pm at Sundance Mining Company,
1921 El Camino, Palo Alto
Presentation - 7:30 pm at 450 Durand Building,
Stanford University
Within a matter of a few hours following the magnitude 7.1
Loma Prieta earthquake, 21 instruments belonging to Incor-
porated Research Institutions for Seismology (IRIS) were
deployed in the epicentral region to record the abundant
aftershock activity. These instruments, along with the hun-
dreds of permanent stations comprising the Calnet array,
make the aftershock sequence of this earthquake one of the
best instrumented in the history of seismic observations.
Dr. Susan Schwartz, a University of California President's
Fellow at UC Santa Cruz and a seismic researcher, led the
deployment of the IRIS instruments, and is currently using
the data collected in an effort to understand the sub-
surface geometry of the many active faults in the Loma
Prieta aftershockzone. Dr. Schwartz will be the featured
speaker at the April 26 meeting of the Santa Clara Valley
Geoscience and Remote Sensing Society.
The IRIS instruments consisted of 16-bit data loggers and
sensors that recorded three-component ground motion in the
frequency range between 1-40 hz. These instruments were
previously used in experiments designed to image crustal and
upper mantle velocity structure. The Loma Prieta aftershock
deployment was the first opportunity for this equipment to
be used in aftershock study.
The data collected during the aftershock sequence are
presently being analyzed by many universities and research
institutions. Some of the important questions being
addressed are: was this earthquake characteristic for this
region of the San Andreas Fault, and does its occurrence
help us with future predictions; what is the sub-surface
velocity structure in an active fault zone; and what did the
magnitude of ground-shaking caused by this earthquake vary
so greatly and what factors affect this magnitude? Progress
made on these and other important questions will be dis-
cussed in the presentation.
Reservations for dinner can be made by calling the IEEE
Council Office at (415) 327-6622.
Peter Paluzzi, Sr. Graphics Analyst, Sterling Software, ZeroOne Group
Advanced Computing Facility, NASA/Ames Research Center, Mail Stop 233-3
Moffett Field, CA 94035
paluzzi@ames.arc.nasa.gov (415) 604-4589