Source Parameter Scaling for Small Earthquakes Observed at the Western Nagano 800-m-Deep Borehole, Central Japan

Stork, A.; Ito, Hisao

doi:10.1785/012002214

Cited by 58 publications

(37 citation statements)

References 57 publications

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“…The present understanding of earthquake source scaling has divided the seismologists into two groups. One group believes a constantly scaled energy (=E R /M o ) (Ide and Beroza 2001;Ide et al 2003;Pérez-Campos and Beroza 2001;Choy and Boatwright 1995;McGarr 1999;Prieto et al 2004), while other group advocates that radiated energy increases with M o (Abercrombie 1995;Kanamori et al 1993;Mayeda and Walter 1996;Prejean and Ellsworth 2001;Richardson and Jordan 2002;Mori et al 2003;Mayeda et al 2005;Stork and Ito 2004). In this paper, we have made an attempt to obtain stable and reliable scaling relationships of earthquake source parameter estimates for small to moderate earthquakes occurring in Kachchh, Gujarat.…”

Section: Introductionmentioning

confidence: 92%

Evidence for non-self-similarity in the M w 7.7 2001 Bhuj earthquake sequence

et al. 2014

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Scaled energy, apparent stress, seismic moments, stress drops and corner frequencies are measured through the Levenberg-Marquardt nonlinear inversion modeling of S-wave displacement spectra for 489 selected earthquakes (M w 2.05-5.52) from the 2001 M w 7.7 Bhuj earthquake sequence. The iterative inversion scheme is formulated based on the x-square source spectral model, which enabled us to estimate stable source parameters. The estimated seismic moment (M o ) and source radius (r) vary from 1.5 9 10 12 to 2.4 9 10 17 to N m and 139.1-933.9 m, respectively, while estimated stress drops (Dr) and the multiplicative factor (E mo ) values range from 0.1 to 14.4 MPa and 1.0-4.1, respectively. The corner frequencies (f c ) are found to be ranging from 1.4 to 9.3 Hz. The mean standard deviation for f c , r and Dr are estimated to be 0.7 Hz, 91.4 m and 2.9 MPa, respectively. The radiated seismic energy and apparent stresses range from 2.1 9 10 5 to 4.1 9 10 13 Joule and 0.005-8.0 MPa, respectively. Our estimated corner frequencies and seismic moments satisfy the relation M o ? f c -(3?e) , where e (measure for a deviation from self-similarity) is found to be 1.33 for the larger earthquakes (M o C 2 9 10 15 N m), while the parameter e is estimated to be 6.74 for smaller earthquakes (M o \ 2 9 10 15 N m). We feel that the larger value of e may require to satisfy the increasing trend of scaled energy with moment for smaller earthquakes. We also notice that stress drops increase with seismic moment, approximately as Mo 3 (DrµM o 3 ) for smaller events (M o \ 10 15.3 N m), while for larger earthquakes (M o C 2 9 10 15 N m) stress drop increases approximately with M o 1 (DrµM o 1 ). Adding credence to this non-self-similar theory, our estimated seismic moments and source radii (r) also reveal a break in the linear self-similar source scaling at M o = 2 9 10 15 N m and r = 300 m, which is attributed to constant source radius for smaller earthquakes. Further, a comparative study between apparent stresses and static stress drops suggests a probable frictional overshoot mechanism for larger earthquakes, while smaller shocks are showing both partial stress drop and frictional overshoot Electronic supplementary material The online version of this article (mechanisms. We hypothesize that larger events are probably subject to the regional stateof-stress and fluid flow in the fault zone, whereas smaller earthquakes are sensitive to the local state-of-stress associated with material heterogeneities and fluid flows within the fault zone. We also propose that the relations developed in this study could be useful for accessing proper seismic hazard in the region.

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Section: Introductionmentioning

confidence: 92%

Evidence for non-self-similarity in the M w 7.7 2001 Bhuj earthquake sequence

et al. 2014

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“…Allmann & Shearer 2009;Duputel et al 2013), it has also been a subject of debate, especially for small earthquakes (Abercrombie 1995;Ide et al 2004;Stork & Ito 2004;Oye et al 2005;Venkataraman et al 2006;Yamada et al 2007). Conventionally, the source duration of an event is determined from the spectral corner frequency by considering a frequency-dependent (Stork & Ito 2004;Oye et al 2005) or frequency-independent Q-model to remove path effects. It has been suggested that incomplete removal of path effects and an inappropriate instrumental bandwidth affect observed scaling relations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Evidence for non-self-similarity of microearthquakes recorded at a Taiwan borehole seismometer array

et al. 2016

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S U M M A R YWe investigate the relationship between seismic moment M 0 and source duration t w of microearthquakes by using high-quality seismic data recorded with a vertical borehole array installed in central Taiwan. We apply a waveform cross-correlation method to the threecomponent records and identify several event clusters with high waveform similarity, with event magnitudes ranging from 0.3 to 2.0. Three clusters-Clusters A, B and C-contain 11, 8 and 6 events with similar waveforms, respectively. To determine how M 0 scales with t w , we remove path effects by using a path-averaged Q. The results indicate a nearly constant t w for events within each cluster, regardless of M 0 , with mean values of t w being 0.058, 0.056 and 0.034 s for Clusters A, B and C, respectively. Constant t w , independent of M 0 , violates the commonly used scaling relation t w ∝ M 1/3 0 . This constant duration may arise either because all events in a cluster are hosted on the same isolated seismogenic patch, or because the events are driven by external factors of constant duration, such as fluid injections into the fault zone. It may also be related to the earthquake nucleation size.

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“…In contrast, Kinoshita (1994) demonstrated that 1/Q S ( f ) decreases with frequency as f −0.7 /130. Recently, Kinoshita (2008) and Stork and Ito (2004) found that Q S is larger than or equal to Q P , confirming the tomography results by Hauksson and Shearer (2006). Although Q P is usually larger than Q S because shear motion is more dissipated, there are reports of Q P lower than Q S (Hauksson and Shearer, 2006).…”

Section: Introductionmentioning

confidence: 54%

Near surface velocity and QS structure of the Quaternary sediment in Bohai basin, China

Chong

2009

Earthq Sci

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Heavily populated by Beijing and Tianjin cities, Bohai basin is a seismically active Cenozoic basin suffering from huge lost by devastating earthquakes, such as Tangshan earthquake. The attenuation (Q P and Q S ) of the surficial Quaternary sediment has not been studied at natural seismic frequency (1−10 Hz), which is crucial to earthquake hazards study. Borehole seismic records of micro earthquake provide us a good way to study the velocity and attenuation of the surficial structure (0−500 m). We found that there are two pulses well separated with simple waveforms on borehole seismic records from the 2006 M W 4.9 Wen'an earthquake sequence. Then we performed waveform modeling with generalized ray theory (GRT) to confirm that the two pulses are direct wave and surface reflected wave, and found that the average v P and v S of the top 300 m in this region are about 1.8 km/s and 0.42 km/s, leading to high v P /v S ratio of 4.3. We also modeled surface reflected wave with propagating matrix method to constrain Q S and the near surface velocity structure. Our modeling indicates that Q S is at least 30, or probably up to 100, much larger than the typically assumed extremely low Q (~10), but consistent with Q S modeling in Mississippi embayment. Also, the velocity gradient just beneath the free surface (0−50 m) is very large and velocity increases gradually at larger depth. Our modeling demonstrates the importance of borehole seismic records in resolving shallow velocity and attenuation structure, and hence may help in earthquake hazard simulation.

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Source Parameter Scaling for Small Earthquakes Observed at the Western Nagano 800-m-Deep Borehole, Central Japan

Cited by 58 publications

References 57 publications

Evidence for non-self-similarity in the M w 7.7 2001 Bhuj earthquake sequence

Evidence for non-self-similarity in the M w 7.7 2001 Bhuj earthquake sequence

Evidence for non-self-similarity of microearthquakes recorded at a Taiwan borehole seismometer array

Near surface velocity and QS structure of the Quaternary sediment in Bohai basin, China

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