Error estimates for seismic body wave delay times in the ISC-EHB Bulletin

Guust Nolet, Suzan Van Der Lee

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We analyse the consistency of the delay time data in the most recent version of the ISC-EHB bulletin published by the International Seismological Centre covering the years 1964-2018. Considering that the delays are influenced by the lateral heterogeneity in the Earth's mantle, we construct a tomographic matrix. We use singular value decomposition of the tomographic matrix for 19 707 dense clusters of earthquakes to compute objective estimates of the standard error from data that project into the null space and should be zero if there were no errors. Using a robust initial estimate of the standard deviation of the clustered delay times, we remove a small fraction of outliers before calculating the ultimate errors. We found that the errors depend on the type of body wave, depth of the earthquake (crust or mantle) and the number of decimals with which the arrival time was reported. Using these parameters, we distinguish 45 different classes of delay times for 11 different types of body waves. The errors of each class so divided generally follow a distribution that is approximately normal with a mean that ranges from 0.32 s for PKPbc waves from mantle earthquakes, to 2.82 s for S waves from shallow earthquakes bottoming in the upper mantle. The widths of the distributions of the errors themselves are small enough to serve in formal statistical quantification of the quality of fit in tomographic experiments.

Original languageEnglish (US)
Pages (from-to)1739-1749
Number of pages11
JournalGeophysical Journal International
Volume231
Issue number3
DOIs
StatePublished - Dec 1 2022

Funding

This research was started while SvdL was on sabbatical at Geoazur when both authors received support from the ERC, advanced grant 226837 'Globalseis'.

Keywords

  • Body waves
  • Error analysis
  • ISC-EHB Bulletin
  • Numerical modelling
  • Seismic tomography

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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