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The Seattle Report Sarah Minson USGS Seattle

Please download animations in the file format of your choice (MPG format is recommended because AVI files are much larger than MPG) August 2010 slow-slip event: ftp://ftp.gps.caltech.edu/pub/minson/chpt_Aug_6-10_2010.avi ftp:// ftp.gps.caltech.edu/pub/minson/chpt_Aug_6-10_2010.mpg

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The Seattle Report Sarah Minson USGS Seattle

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  1. Please download animations in the file format of your choice (MPG format is recommended because AVI files are much larger than MPG) August 2010 slow-slip event: ftp://ftp.gps.caltech.edu/pub/minson/chpt_Aug_6-10_2010.aviftp://ftp.gps.caltech.edu/pub/minson/chpt_Aug_6-10_2010.mpg Full 2010 time series for whole PANGA network:ftp://ftp.gps.caltech.edu/pub/minson/chpt_one_lin_2010.aviftp://ftp.gps.caltech.edu/pub/minson/chpt_one_lin_2010.mpg The Seattle ReportSarah MinsonUSGS Seattle

  2. *Please excuse technical jargon Ongoing Science Stuff*

  3. Earthquake monitoring using GPS • Dense real-time 1 Hz GPS network • Utilize GPS with seismic data to identify and analyze events for which GPS data contribute the most • Hazardous earthquakes • Slow slip events

  4. Rapid response rupture models using real-time GPS • Monte Carlo exploration of fault extent, location, and slip • Okada model • Constraints on fault-finiteness depend greatly on source receiver geometry • Moment is well-determined • Need to detect events and estimate offsets in real-time

  5. Bayesian changepoint detection • Changepoint: the time that at least one model parameter changes • Can use Bayes’ theorem to compute the probability of a changepoint as a function of time, P(changepoint=t|D) • Can also use Bayes’ theorem to assess significance of potential changepoints

  6. Bayesian changepoint detection • It may sound fancy, but it’s not • It’s just Bayesian piecewise linear regression • What is P(t=t0)? • The solution is analytical and ridiculously cheap

  7. Annual Nile Discharge The Nile River & The Aswan Dam Probability of Changepoint

  8. Annual Nile Discharge The Nile River & The Aswan Dam Probability of Changepoint 1898 Aswan 1902

  9. Changepoint Analysis of Cascadia GPS Time Series

  10. Real-time monitoring • That was the retrospectivechangepoint problem • I have a time series. Is there a changepoint or changepoints? If so, when? • For real-time monitoring, need prospectivechangepointanalysis a.k.a. the quickest detection problem • As each new observation arrives, do I now have enough data to identify a changepoint? • Solution is to minimize the Bayes’ risk: • P(false alarm) + c*[average detection delay] • c is tuning parameter

  11. Some complications – or – what we really want are real-time offsets • For slow slip events, we have a functional form for earthquakes • We get offset as part of change-point analysis • For earthquakes, we could get ramps, waveforms, anything • Filter the heck out of the GPS time series until we make it look like a ramp? • Window out the earthquake?

  12. One more thing • If we want to use GPS stations to detect events (to trigger rapid response or for EEW) and/or we want to retrospectively search for deformation events, we have to discriminate between changepoints due to signals and those due to noise • Need to rely on spatio-temporal pattern of stations with possible detections • Could treat triggers at GPS stations like seismic data or could do something new

  13. Seafloor Geodesy in Cascadia Workshop

  14. A little motivation • Need offshore measurements to understand plate locking and ETS, as well as to determininecoseismic slip • Basic science could be done with campaign measurements, but monitoring needs real-time data • Real-time might not be more expensive due to the costs of ship time to retrieve instruments and data • The PBO should extend to the plate boundary • Even better, should go beyond trench to understand deformation of incoming plate

  15. Many kinds of measurements • Mature instrumentation: • GPS-acoustic • Ocean bottom pressure sensors • DART • Seafloor fluid flow • Campaign relative gravity • Japan is deploying 5,100 km of cable to install 154 nodes with OBS/OBP • On the horizon: • Seafloor timelapse gravity (absolute gravity) • Self-calibrating pressure recorders (decreases instrument drift) • Non-electronic seismometer/tiltmeter (decreases instrument drift of tiltmeters) • Seafloor interferometric optical fiber strainmeter

  16. Q. Who pays?A. No clue • When it comes to monitoring, the USGS is the obvious choice • The USGS doesn’t have the money • NOAA might want to expand DART network, install more OBP • FEMA? DHS?

  17. Conference Highlights • Best factoid: • Turbidite flow from Tohoku hit OBP station P03 and moved it about 1 km to the east • Runner-up best factoid: • Largest onshore displacement from Tohoku was 5 m, but largest offshore displacement was 31 m • Best unnecessarily long word: • Seismohydrogeodynamic • Best potential pitfall: • Will the U.S. Navy stand in the way of possible future offshore network to protect secrecy of their submarine positions?

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