Fine Structure of the Landers Fault Zone: Segmentation and the Rupture Process

Li, Yonggang; Aki, Keiiti; Vidale, John E.; Lee, William H. K.; Marone, Chris

doi:10.1126/science.265.5170.367

Cited by 98 publications

(57 citation statements)

References 30 publications

(2 reference statements)

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“…a shear modulus ratio of ∼0.2). This estimate is consistent with measurements from guided seismic waves (Li et al 1994(Li et al , 2007Peng et al 2003) that indicate shear modulus ratios between 0.1 and 0.4, corresponding to 80 per cent of our models. On the other hand, these studies suggest relatively small damage zone widths of a few hundred meters, which is narrower than our estimates.…”

Section: Discussionsupporting

confidence: 92%

Revisiting the 1992 Landers earthquake: a Bayesian exploration of co-seismic slip and off-fault damage

Gombert¹,

Duputel²,

Jolivet

et al. 2017

Geophysical Journal International

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S U M M A R YExisting models for the distribution of subsurface fault slip associated with the 1992 Landers, CA, earthquake (M w = 7.3) show significant dissimilarities. In particular, they exhibit different amounts of slip at shallow depths (<5 km). These discrepancies can be primarily attributed to the ill-posed nature of the slip inversion problem and to the use of physically unjustifiable smoothing or regularization constraints. In this study, we propose a new coseismic model obtained from the joint inversion of multiple observations in a relatively unregularized and fully Bayesian framework. We use a comprehensive data set including GPS, terrestrial geodesy, multiple SAR interferograms and co-seismic offsets from correlation of aerial images. These observations provide dense coverage of both near-and far-field deformation. To limit the impact of modelling uncertainties, we develop a 3-D fault geometry designed from field observations, co-seismic offsets and the distribution of aftershocks. In addition, we account for uncertainty in the assumed elastic structure used to compute the Green's functions. Our solution includes the ensemble of all plausible models that are consistent with our prior information and fit the available observations within data and prediction uncertainties. Using near-fault high-resolution ground deformation measurements and the density of aftershocks, we investigate the properties of the damage zone and its impact on the inferred slip at depth. We attribute a part of the inferred slip deficit at shallow depth to our models not including the impact of a damage zone associated with a reduction of shear modulus in the vicinity of the fault.

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Section: Discussionsupporting

confidence: 92%

Revisiting the 1992 Landers earthquake: a Bayesian exploration of co-seismic slip and off-fault damage

Gombert¹,

Duputel²,

Jolivet

et al. 2017

Geophysical Journal International

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“…The manner and the conditions under which faults coalesce are the subjects of many studies because of their importance in earthquake investigation (SIBSON, 1985;DENG et al, 1986;BARKA and KADINSKY-CADE, 1988;WESNOUSKY, 1989;KNUEPFER, 1989;HARRIS and DAY, 1993;LI et al, 1994;STIRLING et al, 1996) and structural geology (SEGALL and POLLARD, 1980;AYDIN and NUR, 1985;AYDIN and SCHULTZ, 1990;LIN and LOGAN, 1991). It is a common observation that two faults can link together either under tension or compression (SIBSON, 1985;DENG et al, 1986;KNUEPFER, 1989).…”

Section: Introductionmentioning

confidence: 99%

Maximum Link Distance between Strike-slip Faults: Observations and Constraints

1997

Pure appl. geophys.

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The maximum fault link distance (lateral separation) between two interacting strike-slip faults is studied in relation to fault length (combined length of the two interacting faults). Data collected for laboratory generated strike-slip faults indicate that fault linkage takes place when the lateral separation between two strike-slip faults is less than one tenth of the combined length of the two faults. Strike-slip faults developed in clay models require a smaller link distance than those developed in gouge materials. About 98% of the data collected for natural strike-slip faults and 93% of earthquake rupture data derived from KNUEPFER (1989) follow the rule. These observations support a simple scaling relationship for strike-slip faults, i.e., W 50.1 L where W is lateral link distance and L the combined fault length (AN and SAMMIS, 1996a). Two possible explanations are discussed. Assuming a fault continues to be dominantly strike-slip after various fault coalescences, the fault link distance for both compressional coalescence (leading to restraining bend) and extensional coalescence (leading to releasing bend) can be constrained within 0.134 L. Assuming fault coalescence is caused by interaction between breakdown zones at fault tips, then the scaling relationship b =0.1 l between the size of a breakdown zone, b, and the individual fault length, l (SCHOLZ et al., 1993), leads to the scaling relationship W max = 0.1 L where W max is the maximum link distance.The above observed relationship between W max and L may not hold if faults coalesce through preexisting faults, if a fault has a mixed mode other than strike-slip, or if a fault bend is caused by cross faulting rather than fault coalescence. Limited exposure of natural fault traces may also lead to errors in link distance measurements.

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“…It is known that segmentation is a fundamental feature of fault development [4,[30][31][32][33][34]. A similar segmented structure of fault zones extends throughout the seismogenic depth, deeper that 10 km in the earth's crust [33,34].…”

Section: Frictionless Model Of Complex Shear Rupturesmentioning

confidence: 99%