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David Oppenheimer Presented to CISN Steering and Advisory Committees at Caltech, 27 September 2007

When Good Quakes Go Bad Or How Do Small Quakes End Up Being Big And Why Can’t Something Be Done About It?. David Oppenheimer Presented to CISN Steering and Advisory Committees at Caltech, 27 September 2007. Where do Noise Events Come from?. Case 1

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David Oppenheimer Presented to CISN Steering and Advisory Committees at Caltech, 27 September 2007

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  1. When Good Quakes Go BadOrHow Do Small Quakes End Up Being BigAndWhy Can’t Something Be Done About It? David Oppenheimer Presented to CISN Steering and Advisory Committees at Caltech, 27 September 2007

  2. Where do Noise Events Come from? • Case 1 • Bad radio repeater at Oroville causes interference on 7 stations • Automated picks associate into Cape Mendocino “quake” • Coda durations last for 300-400s (M5)

  3. Where do Noise Events Come from? • Case 2 • Small quake occurs at Geysers • Automated “picks” are ok, but Oroville noise adds 2 bad picks. • No codas on BG stations. Oroville again causes codas of 300-400s (M5)

  4. Chronology of Event #40201796

  5. Solutions • Make picker smarter • RT differentiation of noise from signal • Squash bad magnitudes faster • Stifle ShakeCast generation

  6. Making systems smarter

  7. Making systems smarter

  8. Making systems smarter… Or, better, eliminate the problem

  9. What have we learned? • Fine tune criteria for generating ShakeMaps • ShakeCast needs to get smarter • Need to dynamically remove bad stations from system • Clients ascribe (too?) high level of reliability to CISN products. • CISN staff should work with clients to explain limitations

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