Earthquake seasonality before the 1906 San Francisco earthquake

McClellan, P.H.

doi:10.1038/307153a0

Cited by 24 publications

(28 citation statements)

References 8 publications

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“…For the tectonically unstable and strained NEI region these conditions become increasingly prevalent due to seasonal processes, which might relatively increase shear stress and/or pore pressure or relatively decrease normal stress. MCCLELLAN (1984) has suggested that downward-propagating pulse of pore pressure due to increased infiltration of water from surface and subsurface reservoir/flood by rainfall might trigger seasonal seismicity. He further notes that the above mechanism conceivably could induce a seasonal bias into the time distribution of earthquakes.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Earthquake Dynamics in Northeastern India Regions: A Modern Nonlinear Forecasting Approach

Tiwari

Lakshmi

Rao

2004

Pure and Applied Geophysics

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The Northeastern India (NEI) region, is seismotectonically one of the most active regions of the world. Earlier studies of NEI earthquake data have provided contrasting evidence for the presence of randomness and low-dimensional ''strange attractor.'' Here, in the present study, we assess the dimensionality of an earthquake-generating mechanism by nonlinear predictability analyses on phase portrait constructed by monthly frequency earthquake time series which was obtained from the NOAA catalogue. The result of nonlinear forecasting analyses suggests that the earthquake processes in the NEI region evolve on a non-random high-dimensional chaotic system. Such a complex high-dimensional earthquake behavior is indicative of heterogeneous geological structures in which weak fault zones and/or individual fault interactions might have strength fluctuations due to pore pressure variation. Further, K 2 entropy analysis was performed to isolate the non-random component from the data. The analysis reveals a quasi-coherent time structure, (K 2 % 0.08/month) which corresponds to a seasonal time scale of about 12 months. We argue that stochastic resonance created by seasonality bias may have combined with noise to affect the pore pressure variation leading to subsequent earthquake triggering. It is interesting to note that most earthquakes and swarm activities occurred during or after the monsoon season. Geological and geophysical evidence also reconciles with the above view. Evidence for high-dimensional chaos associated with ''seasonal'' bias in the NEI region may provide useful constraints for testing models and criteria to assess earthquake hazards on a more rigorous and quantitative basis.

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Section: Discussionmentioning

confidence: 99%

Characterization of Earthquake Dynamics in Northeastern India Regions: A Modern Nonlinear Forecasting Approach

Tiwari

Lakshmi

Rao

2004

Pure and Applied Geophysics

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“…It is known that M ≥ 5:5 seismicity in coastal central California from 1855 to 1980 showed a significant bias toward the spring season, while M <5:5 seismicity did not ( fig. 2 of McClellan, 1984); on that basis, small earthquakes would not be expected to contribute significantly to a more general semiannual bias. Along the SAF system, small earthquakes are distributed throughout the thickness of the seismogenic crust, they undoubtedly sample a wide range in the values of physical properties along the fault system (pore pressure, rock type, temperature, pressure, fluid chemistry, mineral hydration, fault-gouge thickness and composition, crack size and orientation, etc.…”

Section: Questions Remainmentioning

confidence: 98%

“…There is no reason to expect a priori that a process of fault dynamics in one seismic zone (e.g., a transform or midplate rift) should be governed by the same minimum rupture size as a similar process at a different plate boundary (e.g., a subduction zone), where the maximum rupture size can differ by orders of magnitude. Further, I previously showed that earthquake seasonality observed along the San Andreas fault (SAF) in coastal central California is explained by the largest events in the record above an empirically determined floor magnitude (McClellan, 1984).…”

Section: Data Selectionmentioning

confidence: 99%

“…Earthquake seasonality (i.e., a bias favoring seismicity in one season) was documented three decades ago along the PNA plate boundary (McClellan, 1984) and has since been reported in almost every other type of plate tectonic setting, including convergence zones in the western Pacific (Matsumura, 1986;Ohtake and Nakahara, 1999;Heki, 2003), the Himalaya (Tiwari et al, 2005;Bettinelli et al, 2008), and the Mediterranean region (Pedrami, 1985;Muço, 1995;Hainzl et al, 2006); transforms in New Zealand and offshore of Oregon (Matsumura, 1986); the Gorda ridge (Matsumura, 1986) and mid-Atlantic spreading zones (Jónsdóttir et al, 2007); and oceanic and continental intraplate areas (Jiménez and García-Fernández, 2000;Costain, 2008).…”

Section: Future Studiesmentioning

confidence: 99%

“…The Schuster test (Schuster, 1897) is commonly used in seismology to assess the tendency for earthquakes to occur near the same time (phase) in a cycle (e.g., Heaton, 1975;Klein, 1976;McClellan, 1984). The time of each earthquake is converted to a vector of unit length with a direction equal to the phase angle of the event within the cycle (360°).…”

Section: Data Selectionmentioning

confidence: 99%

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Semiannual Earthquake Periodicity

McClellan¹

2015

Bulletin of the Seismological Society of America

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Large mainshocks in the Uniform California Earthquake Rupture Forecast (UCERF) catalog appear to have been nonrandom in time in the northern California region. Magnitude M ≥ 6:4 earthquakes clustered significantly in the halfyearly solar declination cycle. The most likely explanation appears to be natural earthquake periodicity, because the semiannual bias (1) persists in historical and instrumental catalog subsets, regardless of foreshocks or aftershocks, (2) is not contradicted by pre-1850 data for northern California, and (3) is replicated in southern California subregions, other plate-tectonic settings, and global seismicity. Alternatively, the UCERF catalog has overlooked many M ≥ 6:4 mainshocks that occurred outside of the observed semiannual clustering phase or contains systematic errors that bias the distribution of large earthquakes in the semiannual cycle. The semiannual clustering in northern California shifted abruptly after the great 1906 earthquake from a phase during the month after equinox to a phase near solstice, with large earthquakes returning to the postequinox phase since about 1980. In some other regions where semiannual clustering is evident, a similar phase shift occurred after a great earthquake. Correspondence between the semiannual phase and the tectonic regime of the clustered earthquakes suggests those two parameters may be related. I speculate that the apparent periodicity is a response of the regional fault network to the semiannual solid-earth tide and explore possible explanations for the shift in its net phase after a great earthquake.

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Multifrequential periodogram analysis of earthquake occurrence: An alternative approach to the Schuster spectrum, with two examples in central California

et al. 2015

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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 Rtrue¯adjusted2: 2.4%). This new MFPA application resolves several periodicities in earthquake catalogs that reveal external periodic forcing.

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Earthquake seasonality before the 1906 San Francisco earthquake

Cited by 24 publications

References 8 publications

Characterization of Earthquake Dynamics in Northeastern India Regions: A Modern Nonlinear Forecasting Approach

Characterization of Earthquake Dynamics in Northeastern India Regions: A Modern Nonlinear Forecasting Approach

Semiannual Earthquake Periodicity

Multifrequential periodogram analysis of earthquake occurrence: An alternative approach to the Schuster spectrum, with two examples in central California

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