Anomalous signals prior to Wenchuan earthquake detected by superconducting gravimeter and broadband seismometers records

Wenbin Shen*, Dijin Wang, Chein-way Hwang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Using 1 Hz sampling records at one superconducting gravimeter (SG) station and 11 broadband seismometer stations, we found anomalous signals prior to the 2008 Wenchuan (chinese source) earthquake event. The tides are removed from the original SG records to obtain the gravity residuals. Applying the Hilbert-Huang transform (HHT) and the wavelet analysis to the SG gravity residuals leads to time-frequency spectra, which suggests that there is an anomalous signal series around 39 h prior to the event. The period and the magnitude of the anomalous signal series are about 8 s and 3×10-8 m/s2 (3 μGal), respectively. In another aspect, applying HHT analysis technique to 11 records at broadband seismometer stations shows that most of them contain anomalous signals prior to the Wenchuan event, and the marginal spectra of 8 inland stations show an apparent characteristic of double peaks in anomalous days compared to the only one peak of the marginal spectra in quiet days. Preliminary investigations suggest that the anomalous signals prior to the earthquake are closely related to the low-frequency earthquake (LFE). We concluded that the SG data as well as the broadband seismometers records might be significant information sources in detecting the anomalous signals prior to large earthquakes.

Original languageEnglish
Pages (from-to)640-651
Number of pages12
JournalJournal of Earth Science
Volume22
Issue number5
DOIs
StatePublished - 1 Oct 2011

Keywords

  • anomalous signals
  • broadband seismometers
  • superconducting gravimeters
  • Wenchuan earthquake

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