Prospects for Larger or More Frequent Earthquakes in the Los Angeles Metropolitan Region

Dolan, James F.; Sieh, Kerry; Rockwell, T.; Yeats, Robert S.; Shaw, John H.; Suppe, John; Huftile, Gary J.; Gath, Eldon

doi:10.1126/science.267.5195.199

Cited by 158 publications

(119 citation statements)

References 49 publications

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“…To encompass a reasonable earthquake recurrence interval for the Los Angeles basin faults (Ward and Valensise, 1994;Dolan et al, 1995;McNeilan et al, 1996;Grant et al, 1997;Dolan et al, 2000a;Oskin et al, 2000;Dolan et al, 2003), and to ensure infinitesimal strain, we simulate 5000 years of deformation. This time span bridges the gap between geodetically inferred active slip rates (Յ10 years) and geologically determined late-Quaternary (Յ10,000 years) slip rates.…”

Section: Fault Surfaces and Host Rock Propertiesmentioning

confidence: 99%

How Sensitive Are Fault-Slip Rates in the Los Angeles Basin to Tectonic Boundary Conditions?

Griffith

Cooke

2005

Bulletin of the Seismological Society of America

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Section: Fault Surfaces and Host Rock Propertiesmentioning

confidence: 99%

How Sensitive Are Fault-Slip Rates in the Los Angeles Basin to Tectonic Boundary Conditions?

Griffith

Cooke

2005

Bulletin of the Seismological Society of America

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“…Since joint geodetic and seismological analyses are not yet standardized, it is unclear how exceptional triggering of the type observed in the Harnai doublet is. A comparison between geological slip rates and historical earthquake occurrence suggests that multi-segment earthquakes with larger-than-expected magnitudes may be rather frequent amongst the reverse faults of the Los Angeles basin and surroundings 48 . Our results indicate that multiple-fault ruptures (as opposed to merely multiple-segment ones), such as sequential failure of the Sierra Madre and Puente Hills thrusts which are separated by ~20 km, are also mechanically feasible if both systems are critically stressed.…”

Section: Triggering Mechanismmentioning

confidence: 99%

Limitations of rupture forecasting exposed by instantaneously triggered earthquake doublet

et al. 2016

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Earthquake hazard assessments and rupture forecasts are based on the potential length of seismic rupture and whether or not slip is arrested at fault segment boundaries. Such forecasts do not generally consider that one earthquake can trigger a second large event, near-instantaneously, at distances greater than a few kilometers. Here we present a geodetic and seismological analysis of a magnitude 7.1 intra-continental earthquake that occurred in Pakistan in 1997. We find that the earthquake, rather than a single event as hitherto assumed, was in fact an earthquake doublet: initial rupture on a shallow, blind 2 reverse fault was followed just 19 seconds later by a second rupture on a separate reverse fault 50 km away. Slip on the second fault increased the total seismic moment by half, and doubled both the combined event duration and the area of maximum ground shaking. We infer that static Coulomb stresses at the initiation location of the second earthquake were probably reduced as a result of the first. Instead, we suggest that a dynamic triggering mechanism is likely, although the responsible seismic wave phase is unclear. Our results expose a flaw in earthquake rupture forecasts that disregard cascading, multiple-fault ruptures of this type.Continental earthquakes typically rupture diffuse systems of shallow fault segments, delineated by bends, step-overs, gaps, and terminations. The largest events generally involve slip on multiple segments, and whether or not rupture is arrested by these boundaries can determine the difference between a moderate earthquake and a potentially devastating one.Compilations of historical surface ruptures suggest that boundary offsets of ~5 km are sufficient to halt earthquakes, regardless of the total rupture length 1,2 . This value is incorporated into modern, fault-based earthquake rupture forecasts such as the UCERF3 model for California 3,4 , whose goals include anticipating the maximum possible rupture length and magnitude of future earthquakes within known fault systems.However, if earthquakes could rapidly trigger failure of neighbouring faults or fault segments, at distances larger than ~5 km, then such scenario planning could be missing an important class of cascading, multiple-fault rupture. Here we exploit the combination of spatial 3 information captured by satellite deformation measurements and timing information of successive fault ruptures from seismology, to reveal how near-instantaneous, probably dynamic triggering may lead to sequential rupture of multiple large earthquakes separated by distances of 10s of kilometers.The destructive Harnai earthquake occurred on 27 February 1997 at 21:08 UTC (02:08 on 28February, local time) in the western Sulaiman mountains of Pakistan 5 (Figure 1a). Published source catalogues ascribe it a single, largely (85% 99%) double-couple focal mechanism with gentle ~N-dipping and steep ~S-dipping nodal planes and a moment magnitude M w of 7.0 7.1 (Supplementary Table 1 The south-eastern fringe ellipse is caused by slip on another NE-di...

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“…First, in 1975 we had only rudimentary knowledge of the frequency of moderate and large seismic events. In California and many other areas we now realize that great earthquakes occur with average repeat intervals of 100 years or so (Dolan et al, 1995;Sieh, 1996). Although moderate earthquakes of M ϳ ‫ם6‬ affect smaller geographic areas, they are more numerous and may dominate the local seismic hazards for an area.…”

Section: Introductionmentioning

confidence: 99%

Earthquake Prediction by Animals: Evolution and Sensory Perception

Kirschvink¹

2000

Bulletin of the Seismological Society of America

104

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Animals living within seismically active regions are subjected episodically to intense ground shaking that can kill individuals through burrow collapse, egg destruction, and tsunami action. Although anecdotal and retrospective reports of animal behavior suggest that although many organisms may be able to detect an impending seismic event, no plausible scenario has been presented yet through which accounts for the evolution of such behaviors. The evolutionary mechanism of exaptation can do this in a two-step process. The first step is to evolve a vibrationtriggered early warning response which would act in the short time interval between the arrival of P and S waves. Anecdotal evidence suggests this response already exists. Then if precursory stimuli also exist, similar evolutionary processes can link an animal's perception of these stimuli to its P-wave triggered response, yielding an earthquake predictive behavior. A population-genetic model indicates that such a seismic-escape response system can be maintained against random mutations as a result of episodic selection that operates with time scales comparable to that of strong seismic events. Hence, additional understanding of possible earthquake precursors that are presently outside the realm of seismology might be gleaned from the study of animal behavior, sensory physiology, and genetics. A brief review of possible seismic precursors suggests that tilt, hygroreception (humidity), electric, and magnetic sensory systems in animals could be linked into a seismic escape behavioral system. Several testable predictions of this analysis are discussed, and it is recommended that additional magnetic, electrical, tilt, and hygro-sensors be incorporated into dense monitoring networks in seismically active regions.

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Prospects for Larger or More Frequent Earthquakes in the Los Angeles Metropolitan Region

Cited by 158 publications

References 49 publications

How Sensitive Are Fault-Slip Rates in the Los Angeles Basin to Tectonic Boundary Conditions?

How Sensitive Are Fault-Slip Rates in the Los Angeles Basin to Tectonic Boundary Conditions?

Limitations of rupture forecasting exposed by instantaneously triggered earthquake doublet

Earthquake Prediction by Animals: Evolution and Sensory Perception

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