Immediate foreshocks: time variation of the b-value

Molchan, G.; Kronrod, T.; Nekrasova, Anastasia

doi:10.1016/s0031-9201(98)00163-0

Cited by 76 publications

(27 citation statements)

References 10 publications

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“…Some studies reported that the b value is significantly smaller for foreshocks than for background seismicity (e.g., Molchan et al 1999). However, our analysis does not detect such trend significantly.…”

Section: Consistency Between the Estimated Energy Release Rate And Thcontrasting

confidence: 99%

Preliminary estimation of high-frequency (4–20 Hz) energy released from the 2016 Kumamoto, Japan, earthquake sequence

Sawazaki

Nakahara

Shiomi

2016

Earth Planets Space

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We estimate high-frequency (4-20 Hz) energy release due to the 2016 Kumamoto, Japan, earthquake sequence, within a time period from April 14 to 26 through envelope inversion analysis applied to the Hi-net continuous seismograms. We especially focus on energy releases after each of the April 14 M JMA 6.5 and the April 16 M JMA 7.3 earthquakes. The cumulative energy release from aftershocks of the April 14 event reaches 60% of that from the April 14 event itself by the lapse time of 27 h (pre-April 16 period). On the other hand, the cumulative energy release from aftershocks of the April 16 event reaches only 11 and 13% of that from the April 16 event itself by the lapse times of 27 h and 10 days (post-April 16 period), respectively. This discrepancy in the normalized cumulative energy release (NCER) indicates that the April 14 event was followed by much larger relative aftershock productivity than the April 16 event. Thus, NCER would provide information that reflects relative aftershock productivity and ongoing seismicity pattern after a large earthquake. We also find that the temporal decay of the energy release rate obeys the power law. The exponent p E of the power-law decay is estimated to be 1.7-2.1, which is much larger than the typical p value of the Omori-Utsu law: slightly larger than 1. We propose a simple relationship given by p E = βp/b, where p value, b value of the Gutenberg-Richter law, and β value of the magnitude-energy release relationship are combined.

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Section: Consistency Between the Estimated Energy Release Rate And Thcontrasting

confidence: 99%

Preliminary estimation of high-frequency (4–20 Hz) energy released from the 2016 Kumamoto, Japan, earthquake sequence

Sawazaki

Nakahara

Shiomi

2016

Earth Planets Space

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“…Strong variations of b across different stress regimes imply that this parameter acts as a stress meter that depends inversely on differential stress (e.g., Schorlemmer et al, 2005;Narteau et al, 2009, and references therein). Observations of seismic sequences have shown that b usually drops and becomes significantly lower in foreshocks than in aftershocks or in background seismicity (Papazachos, 1975;Jones and Molnar, 1979;Main et al, 1989;Molchan et al, 1999;Enescu et al, 2001;Nanjo et al, 2012). This was also the case with L'Aquila (Papadopoulos et al, 2010;De Santis et al, 2011).…”

Section: Discussionmentioning

confidence: 77%

Foreshocks and short-term hazard assessment of large earthquakes using complex networks: the case of the 2009 L'Aquila earthquake

Daskalaki

Spiliotis

Siettos

et al. 2016

Nonlin. Processes Geophys.

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Abstract. The monitoring of statistical network properties could be useful for the short-term hazard assessment of the occurrence of mainshocks in the presence of foreshocks. Using successive connections between events acquired from the earthquake catalog of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) for the case of the L'Aquila (Italy) mainshock (M w = 6.3) of 6 April 2009, we provide evidence that network measures, both global (average clustering coefficient, small-world index) and local (betweenness centrality) ones, could potentially be exploited for forecasting purposes both in time and space. Our results reveal statistically significant increases in the topological measures and a nucleation of the betweenness centrality around the location of the epicenter about 2 months before the mainshock. The results of the analysis are robust even when considering either large or off-centered the main event space windows.

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“…Experimental studies which have shown that the b value of acoustic emissions decrease prior to rock fracture (MOGI, 1962;SCHOLZ, 1968) and studies on foreshock and aftershock sequences (PAPAZACHOS et al, 1967;GIBOWICZ, 1973;MOLCHAN et al, 1999) indicate that changes in b values are inversely related to changes in stress and that the mean fracture size increases as gross failure approaches (SCHOLZ, 1990). LI et al (1978) studying the b value temporal behavior found a decrease of this value two years before the 1976 Tangshan earthquake.…”

Section: Discussionmentioning

confidence: 99%

Time Variation of Parameters Related to the Accelerating Preshock Crustal Deformation in the Aegean Area

Karakaisis¹,

Savvaidis²,

Papazachos³

2003

Pure and Applied Geophysics

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-The time variation of two parameters related to accelerating seismic deformation before strong earthquakes in the Aegean area is examined. The first is the b parameter of the Gutenberg-Richter relation and the second is the curvature parameter C, which is a measure of deviation of the accelerating preshock deformation from a linear time variation of this deformation. Following two different procedures, it was found that the b value exhibits a decreasing trend prior to the oncoming earthquake, in agreement with the results of laboratory experiments and other independent observations. C values also show a decreasing trend before main shocks. These results indicate that such time variations of these parameters can be considered as precursory phenomena of ensuing strong earthquakes.

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Immediate foreshocks: time variation of the b-value

Cited by 76 publications

References 10 publications

Preliminary estimation of high-frequency (4–20 Hz) energy released from the 2016 Kumamoto, Japan, earthquake sequence

Preliminary estimation of high-frequency (4–20 Hz) energy released from the 2016 Kumamoto, Japan, earthquake sequence

Foreshocks and short-term hazard assessment of large earthquakes using complex networks: the case of the 2009 L'Aquila earthquake

Time Variation of Parameters Related to the Accelerating Preshock Crustal Deformation in the Aegean Area

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