Real-time GPS in Cascadia and its application to hazards reduction

Pacific Northwest Geodetic ArrayDept. of Geological Sciences

Central Washington Universitywww.panga.org

Tim MelbourneMarcelo Santillan

Craig ScrivnerWalter Szeliga

CS481 Team Risc (GPS Cockpit)

Frank Webb (JPL)

Support: NASA ROSES NNH07ZDA001N and USGS NEHRP

Overview1. (L1) Cascadia real-time GPS Station Network (PANGA + PBO)

2. (L2) GPS processing (phase+psuedorange data -> position estimates)

3. (L3) EEW products derived from rtGPS position streams

4. Example earthquakes as examples – 2010 Sierra El Mayor, 2010 Maule, 2011 Tohoku-Oki

5. GPS Cockpit Project: Managing rtGPS time series and derived products

SeattleM6-7 crustal

faults not well known, <1m

EEWM8-9: megathrust, <5m EEW

450 rtGPS stations: PANGA (~220) + PBO (~230)

Latency: most data arrives in less than 1 secondPANGA telemetered to CWU

PBO telemetered to UNAVCO, then to CWU

Arrival at CWU Arrival at Boulder

Relative Positioning Absolute (Point) Positioning(L2) Real-time processing strategies

Higher relative precisionRequires stable reference

stationRequires dense network

Primarily commercial RTK

Lower absolute precision (improving)

Single station-capableLinear wrt station #

Requires rt orbit + clock corrections

Requires extensive data editing

- (1) Relative positioning: Trimble commercial product (joint w/ WSRN and OGRN RTK processing)

- (2) Real-time GIPSY Point positioning:

- (3) Developing standard GIPSY (not RTG) processing with clock and orbit correction streams from DLR (German Aerospace Center, Munich, Hauschild)

2. PANGA/CWU real-time processing

(Method 1) Trimble T4D operated jointly with WSRN & OGRN

Trimble T4D operated jointly with WSRN & OGRN

Method 2: JPL GDGPS RT-GIPSY SYSTEM (Bar-Sever)

Requires clock corrections streamed over Ntrip (DLR, IGS

Method 3: CWU short-arc real-time processing with GIPSY

IGS Final

Method 3: CWU real-time processing with GIPSY

Method 3: CWU real-time processing with GIPSY-Requires extensive phase-level data QC-Less than 5s latency

BREW

CNCR

CABL

TRND

CHZZ

~10cm deviations are common in all methods

2010 Maule Chile M8.8

Mike Bevis, UNAVCO

4. Example Earthquakes

2010 Maule: Absolute point positioning of CONZ

2010 Chile M8.8

east

north3m

Sierra El Mayor, 4/4/2010

Good agreement between GPS PP and Accelerometer Data

CWU, pp., 5 minutes

http://www.panga.cwu.edu/events/baja/

PBO, relative p., 24+24 hr

http://supersites.earthobservations.org/baja.php

Absolute vs. relative positioning

pgDisplacement- 2010 Sierra El Mayor

GPS PGD Seismic PGA

2011 Tohoku-Oki Earthquake

GEONET GPS ARRAY

+15s:Seismic Detection

JMA: M6.8

NEIC W phase:M9.0~20 minutes

2011 Tohoku-Oki 3d GPS displacements (3x speed)

+60s: Mw 8.47

GPS Moment Estimate

+90s: Mw 8.80

GPS Moment Estimate

+120s: Mw 9.04

GPS Moment Estimate

+180s: Mw 9.05

GPS Moment Estimate

+15s:Seismic Detection

JMA: M6.8

NEIC W phase:M9.0~20 minutes

60s:M8.5 90s:M8.8 120s:M9.04

5. GPS Cockpit

-Time Series viewer (interactive): negation of false positives-Data Aggregator (Perl, modular, talk to Craig Scrivner)-Many new derived products:

-DefMaps-Inversions-GPS ShakeCast

-Assimilation into seismic EEW not obvious

GPS CockpitDefMap Slip

GPS CockpitGPS Cockpit

GPS CockpitGPS Cockpit

Time for a demo!

Conclusions1. Cascadia has mature real-time GPS networks (PANGA + PBO)

2. Data analysis is evolving rapidly

3. EEW products based on rtGPS position streams are also improving

4. Recent earthquakes show the importance of rtGPS in hazards monitoring

5. GPS Cockpit: First release on March 15