[IGSMAIL-0453] Northridge Earthquake Update

[Yehuda]

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IGS Electronic Mail      Fri Jan 21 10:22:36 PST 1994      Message Number 0453
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Author: Yehuda Bock, Peng Fang, Keith Stark and Jie Zhang
Subject: Northridge Earthquake Update

The Northridge Earthquake (surface wave magnitude 6.6) struck the San Fernando
Valley on January 17, 04:30 AM Pacific Standard Time, 12:30 UT. The epicenter
is located at 34 13 N (dm) and 118 33 W (dm) at a depth of 14.6 km
(ref: 17 January memo by Lucy Jones, Caltech/USGS).

The closest PGGA stations to the epicenter are JPLM and PVEP.  Expected
displacements at these sites according to yet incomplete elastic dislocation
models are less than 1 cm of motion at both of these sites.  The other
PGGA sites (including the primary IGS site at Goldstone) are expected
to have negligible displacements.  GPS field crews from Caltech, JPL, SIO, 
UCLA and USGS are now surveying sites in the area with 10-30 cm of
displacements expected near the epicentral region.

The PGGA data collection for the period of the earthquake was nearly 100%
complete.  The only problem was an 80% loss of data from JPLM on 15 January.
All data (raw and RINEX data, and solutions) can be retrieved from the SIO 
archives (RINEX data should be available from  CDDIS, when they are back on line). As a reminder:

To access SIO GARNER archive:
 ftp toba at ucsd.edu (132.239.152.80)
 login: anonymous
 password: your name
 directories: rinex, raw, solutions, products
Direct problems to: kstark at ucsd.edu, bock at pgga.ucsd.edu

The SIO facility has completed the PGGA/IGS solutions up to January 17,
the day of the earthquake.  We expect to have January 18 and 19 solutions
in a few hours. At that time we will report on any observed displacements.

Our response to the earthquake has been aided immensely by the rapid 
availability of global data from the IGS network.  

Please contact us for any additional information.