Seismic fault zone trapped noise

Hillers, Gregor; Campillo, Míchel; Ben‐Zion, Yehuda; Roux, Philippe

doi:10.1002/2014jb011217

Cited by 43 publications

(62 citation statements)

References 102 publications

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“…Ben-Zion & Aki 1990;Igel et al 1997Hillers et al 2014). These phases have been observed in various fault and geologic settings in California (Li et al 1994;Peng et al 2003;Lewis & Ben-Zion 2010) including the SJFZ (Li & Vernon 2001;Lewis et al 2005;Qiu et al 2017), Turkey , Italy (Rovelli et al 2002;Calderoni et al 2012;Avallone et al 2014), Japan (Mizuno & Nishigami 2006) and New Zealand (Eccles et al 2015).…”

Section: Methodsmentioning

confidence: 95%

Internal structure of the San Jacinto fault zone at Blackburn Saddle from seismic data of a linear array

Ben‐Zion

Ross

et al. 2017

Geophysical Journal International

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S U M M A R YLocal and teleseismic earthquake waveforms recorded by a 180-m-long linear array (BB) with seven seismometers crossing the Clark fault of the San Jacinto fault zone northwest of Anza are used to image a deep bimaterial interface and core damage structure of the fault. Delay times of P waves across the array indicate an increase in slowness from the southwest most (BB01) to the northeast most (BB07) station. Automatic algorithms combined with visual inspection and additional analyses are used to identify local events generating fault zone head and trapped waves. The observed fault zone head waves imply that the Clark fault in the area is a sharp bimaterial interface, with lower seismic velocity on the southwest side. The moveout between the head and direct P arrivals for events within ∼40 km epicentral distance indicates an average velocity contrast across the fault over that section and the top 20 km of 3.2 per cent. A constant moveout for events beyond ∼40 km to the southeast is due to off-fault locations of these events or because the imaged deep bimaterial interface is discontinuous or ends at that distance. The lack of head waves from events beyond ∼20 km to the northwest is associated with structural complexity near the Hemet stepover. Events located in a broad region generate fault zone trapped waves at stations BB04-BB07. Waveform inversions indicate that the most likely parameters of the trapping structure are width of ∼200 m, S velocity reduction of 30-40 per cent with respect to the bounding blocks, Q value of 10-20 and depth of ∼3.5 km. The trapping structure and zone with largest slowness are on the northeast side of the fault. The observed sense of velocity contrast and asymmetric damage across the fault suggest preferred rupture direction of earthquakes to the northwest. This inference is consistent with results of other geological and seismological studies.

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Section: Methodsmentioning

confidence: 95%

Internal structure of the San Jacinto fault zone at Blackburn Saddle from seismic data of a linear array

Ben‐Zion

Ross

et al. 2017

Geophysical Journal International

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“…Since the body waves are of higher frequencies than the FZTW, the body waves sampling the FZ may resolve the FZ structure in higher resolution. Another advantage of this method is that it allows us to trace individual seismic rays that travel through and bounce back multiple times from the FZ boundaries, as the synthetic travel times and waveforms are computed using the Generalized Ray Theory (GRT) (Helmberger 1983). In addition, this technique can well constrain the depth extent of the LVZ if it is combined with the waves that are diffracted from the base of the LVZ (Fig.…”

Section: Fz Wavesmentioning

confidence: 99%

Recent advances in imaging crustal fault zones: a review

Yang

2015

Earthq Sci

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Crustal faults usually have a fault core and surrounding regions of brittle damage, forming a low-velocity zone (LVZ) in the immediate vicinity of the main slip interface. The LVZ may amplify ground motion, influence rupture propagation, and hold important information of earthquake physics. A number of geophysical and geodetic methods have been developed to derive high-resolution structure of the LVZ. Here, I review a few recent approaches, including ambient noise cross-correlation on dense across-fault arrays and GPS recordings of fault-zone trapped waves. Despite the past efforts, many questions concerning the LVZ structure remain unclear, such as the depth extent of the LVZ. High-quality data from larger and denser arrays and new seismic imaging technique using larger portion of recorded waveforms, which are currently under active development, may be able to better resolve the LVZ structure. In addition, effects of the alongstrike segmentation and gradational velocity changes across the boundaries between the LVZ and the host rock on rupture propagation should be investigated by conducting comprehensive numerical experiments. Furthermore, high-quality active sources such as recently developed large-volume airgun arrays provide a powerful tool to continuously monitor temporal changes of fault-zone properties, and thus can advance our understanding of fault zone evolution.

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“…Jeppson et al 2010;Zoback et al 2011;Townend et al 2013). To cover a larger volume in the upper few kilometres, seismic fault-zone trapped noise has been effectively utilized to obtain estimates of fault-zone properties (Hillers et al 2014;Ben-Zion et al 2015;Liu et al 2015;Roux et al 2016). Excluding some very deep drilling projects the above methods are unable to image fault zones at greater than a few km deep.…”

Section: M P L I C At I O N S F O R M O D E L L I N G F Z T W Smentioning

confidence: 99%

“…This data allows seismic noise studies (e.g. Hillers et al 2014) . The top row shows the dispersion curve produced by setting the anisotropy parameters = 0.15 in the country-rock, = 0.3 is the maximum value in the fault zone and δ = /4.…”

Section: M P L I C At I O N S F O R M O D E L L I N G F Z T W Smentioning

confidence: 99%