Multifrequential periodogram analysis of earthquake occurrence: An alternative approach to the Schuster spectrum, with two examples in central California. Issue 12 (28th December 2015)

• Record Type: Journal Article
• Authors: Dutilleul, Pierre; Johnson, Christopher W.; Bürgmann, Roland; Wan, Yongge; Shen, Zheng‐Kang
• Is Part Of: Journal of geophysical research. Volume 120:Issue 12(2015:Dec.)
• Page Start: 8494
• Page End: 8515
• Publication Date: 2015-12-28
• Subjects: seismicity -- periodicity -- earthquake triggering -- MFPA -- time series; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2015JB012467
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Periodic earthquake occurrences may reflect links with semidiurnal to multiyear tides, seasonal hydrological loads, and ~14 month pole tide forcing. The Schuster spectrum is a recent extension of Schuster's traditional test for periodicity analysis in seismology. We present an alternative approach: the multifrequential periodogram analysis (MFPA), performed on time series of monthly earthquake numbers. We explore if seismicity in two central California regions, the Central San Andreas Fault near Parkfield (CSAF‐PKD) and the Sierra Nevada‐Eastern California Shear Zone (SN‐ECSZ), exhibits periodic behavior at periods of 2 months to several years. Original and declustered catalogs spanning up to 26 years were analyzed with both methods. For CSAF‐PKD, the MFPA resolves ~1 year periodicities, with additional statistically significant periods of ~6 and ~4 months; for SN‐ECSZ, it finds a strong ~14 month periodic component. Unlike the Schuster spectrum, the MFPA has an exact modified statistic at non‐Fourier frequencies. Informed by the MFPA period estimates, trigonometric models with periods of 12, 6, and 4 months (Model 1) and 14.24 and 12 months (Model 2) were fitted to time series of earthquake numbers. For CSAF‐PKD, Model 1 shows a peak annual earthquake occurrence during August‐November and a secondary peak in April. Similar peaks, or troughs, are found in annual and semiannual components of pole tide and tide‐induced stress model time series and fault normal‐stress reduction from seasonal hydrological unloading. For SN‐ECSZ, the dominant ~14 month periodicity prevents regular annual peaking, and Model 2 provides a better fit (Δ R ¯ adjusted 2 : 2.4%). This new MFPA application resolves several periodicities in earthquake catalogs that reveal external periodic forcing. Key Points: Systematic analysis of seasonal periodicity observed in California earthquake records Multifrequential periodogram analysis indicates a significant annual period First application of multifrequential periodogram analysis with earthquake catalog data