The scatter of time-delays in shear-wave splitting above small earthquakes

Stuart Crampin, Sheila Peacock, Yuan Gao, Sebastien Chastin

Research output: Contribution to journalArticlepeer-review

Abstract

Measurements of time-delays in seismic shear-wave splitting above small earthquakes typically display a scatter of often as much as ±80 per cent about the mean. Changes in the average time-delay appear to be related to changes of stress, but applications of this potentially powerful tool have been handicapped by the previously inexplicable scatter in time-delays above earthquakes. In contrast, measurements of shear-wave time-delays in controlled-source exploration seismics are typically well controlled and display little scatter. Previous estimates of possible causes of scatter cannot produce sufficient variation specifically above earthquakes. Here we show that 90°-flips in shear-wave polarizations due to fluctuating high pore-fluid pressures on seismically-active fault planes are the most likely cause of the scatter.
Original languageEnglish
Pages (from-to)39-44
Number of pages6
JournalGeophysical Journal International
Volume156
Issue number1
DOIs
Publication statusPublished - 1 Jan 2004

Keywords

  • crack-critical systems
  • critically-high pore-fluid pressures
  • scatter in time-delays
  • shear-wave splitting
  • 90°-flips

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