ken hudnut u.s. geological survey [email protected] 22 november 2013
TRANSCRIPT
Long Term Vision• Install near-field instrumentation to rapidly detect
displacements along major faults like the San Andreas – implement the “Zipper Array” concept
• Improve GPS real-time technology; accuracy, precision, timeliness, robustness, reliability
• Test, procure, and deploy gear on an ongoing basis• Develop new ways to use low-latency displacement
data in EEW algorithms; Slip Sensor & Regional• As a byproduct, obtain data in a future great
earthquake that could potentially revolutionize our understanding of earthquake source physics
Lone Juniper Ranch and Frazier Park High School
Prototype GPS fault slip sensor
Spans the San Andreas fault near Gorman, California
Need robust GPS at all key lifeline crossings
Desirable to include seismic with GPS
Hudnut et al., 2002Hudnut et al., 2002
Proposed a zipper array for early warning and immediate finite-fault source for San Andreas and San Jacinto fault ‘Big Ones’
IOC - 36 quadrilaterals shown @ 30 km spacing (shown)FOC - 100 quads @ 10 km spacing ($5 M init. + $1 M/yr)
LosAngeles
20072007
San Andreas fault
20132013
Observing Static & Dynamic Displacements
Dstatic
Ddynamic
In near-field region, Ddynamic > Dstatic
- very useful for EEW algorithms- e.g., Yamada, Heaton, Aagaard- FinDer (Böse, Heaton & Hauksson, 2012)
Fault slip means displacements are instantaneous right at the fault, move with rupture front
Direct observation of displacement is fastest
Displacements decrease with 1/r2
At distances > 50 km, surface wave amplit.’s will exceed displacements and static will travel out at approx. S-wave velocity
Examine rapid post-seismic behavior (friction law?)
7
Courtesy of M. BöseCISN ShakeAlert
Fault Slip Detector (‘GPSlip’)
Idea: Back-projection of dynamic displacement (at GPS sensor) onto fault to estimate slip
Yamada, Heaton, Aagaard
Example:Application to waveform simulations of M7.8 ShakeOut Scenario by Graves et al., 2008
observed surface slip
estimated slip
along San Andreas Fault
(Böse, Heaton, Hudnut, Felizardo et al.)
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CISN ShakeAlert
Fault Slip Detector (‘GPSlip’)
GPS sensors and estimated
slip
slip legend
(Böse, Heaton, Hudnut, Felizardo et al.)
Slip estimated from back-projection using ShakeOut waveform simulations by Graves et al., 2008
Courtesy of M. Böse
GPS sensor
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Fault Slip Detector (‘GPSlip’)Current Processing:
CISN ShakeAlert
RTK/PPP(AR) using RTNet
software
positiontime series
for each sensor location
(JSON format)GPS
sensor
GPS sensor
.
.
.
Real-time estimation of
fault slip(using back-projection)
USGS Pasadena Caltech
Status:•no 24/7 operation•need to create associator, hardening software•need to connect to other ShakeAlert algs, in particular FinDer
UserDisplay
internal testing
(Böse, Heaton, Hudnut, Felizardo et al.)
raw data
Courtesy of M. Böse
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CISN ShakeAlert
Fault Slip Detector (‘GPSlip’)Future Processing:
GPS sensor
RTK/PPP(AR) using RTNet
software
positiontime series
for each sensor location
(JSON format)
raw data
GPS sensor
GPS sensor
...
Real-time estimation of
fault slip(using back-projection)
USGS Pasadena Caltech
UserDisplay
internal testing
(Böse, Heaton, Hudnut, Felizardo et al.)
GPS sensor
NetR9 with RTX
Real-time conversion to EW tracebuf2
...
~40
site
sTO
PCO
N a
nd o
ther
rece
iver
s
GSOF
Courtesy of M. Böse
Displacementtest resultssimulating 150 cmdynamic and 75 cmstatic earthquakerepeated offsets
… special purchaseby Caltech with newUASI funds for EEWfrom City of LA
10 Hz output to EEW- position- velocity
Deploy to ‘zipper’ arrayas upgrades under way
Real-timeoutput fromGPS receiver…
“paradigm shift”“revolutionary”
Fielddeploymenthalf-waycompleted:
NetR9 RTX fieldperformance at~10 mm RMS horiz.~20 mm RMS vert.is even better thanexpected (due toGLONASS & revisedreceiver configurationsettings)
Governor Signs California Earthquake Early Warning Bill
Governor Jerry Brown signed the California earthquake early warning bill, SB 135, on September 24, 2013. The bill calls for Cal OES in collaboration with USGS, CISN, State agencies and private partners to “develop a comprehensive statewide earthquake early warning system in California.” Cal OES has until January of 2016 to identify funding for the system “through single or multiple sources of revenue that shall be limited to federal funds, funds from revenue bonds, local funds, and private grants.” State General Funds are specifically excluded as a source.
Senator Padilla andDoug Given, USGS
