Earthquake nucleation and fault slip complexity in the lower crust of central Alaska

Tape, Carl; Holtkamp, S. G.; Silwal, Vipul; Hawthorne, J. C.; Kaneko, Yoshihiro; Ampuero, Jean‐Paul; Ji, Chen; Ruppert, N. A.; Smith, Kyle; West, M. E.

doi:10.1038/s41561-018-0144-2

Cited by 113 publications

(94 citation statements)

References 54 publications

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“…The model might imply an accelerating crescendo of seismicity or an emergent initiation of seismic waves. However, other than a few notable cases (Bouchon et al, 2011;Tape et al, 2013;Tape et al, 2018) by fault sections with larger L c . In this model, brittle patches can rupture to create small events that, in some cases, ignite dynamic rupture in the surrounding fault and cause larger ruptures without a large nucleation.…”

Section: Preslip Model: Large Nucleation On the Order Of Kilometersmentioning

confidence: 94%

“…The model might imply an accelerating crescendo of seismicity or an emergent initiation of seismic waves. However, other than a few notable cases (Bouchon et al, ; Tape et al, ; Tape et al, ), such observations are rarely reported. This model also has trouble accounting for observations that small and large earthquakes initiate and grow similarly (McLaskey & Lockner, ; Okuda & Ide, ; Uchide & Ide, )…”

Section: Scaling Up To Natural Faultsmentioning

confidence: 95%

“…In a few cases, upper bounds on L c have been made from borehole strain measurements (e.g., Johnston et al, 2006), but this disqualifies only nucleation zones larger than 10 km and only at specific fault locations. Instead, seismic measurements such as foreshocks, tremors, and initial P wave signatures primarily shape our understanding of earthquake initiation (Bouchon et al, 2011(Bouchon et al, , 2013Chen & Shearer, 2013;Dodge et al, 1995;Ellsworth & Bulut, 2018;Kato et al, 2012;Ruiz et al, 2017;Tape et al, 2018). A coalescence of seismicity is sometimes observed (Savage et al, 2017) in a source volume near the eventual hypocenter of a larger earthquake.…”

Section: Scaling Up To Natural Faultsmentioning

confidence: 99%

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Earthquake Initiation From Laboratory Observations and Implications for Foreshocks

2019

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This paper reviews laboratory observations of earthquake initiation and describes new experiments on a 3‐m rock sample where the nucleation process is imaged in detail. Many of the laboratory observations are consistent with previous work that showed a slow and smoothly accelerating earthquake nucleation process that expands to a critical nucleation length scale Lc, before it rapidly accelerates to dynamic fault rupture. The experiments also highlight complexities not currently considered by most theoretical and numerical models. This includes a loading rate dependency where a “kick” above steady state produces smaller and more abrupt initiation. Heterogeneity of fault strength also causes abrupt initiation when creep fronts coalesce on a stuck patch that is somewhat stronger than the surrounding fault. Taken together, these two mechanisms suggest a rate‐dependent “cascade up” model for earthquake initiation. This model simultaneously accounts for foreshocks that are a by‐product of a larger nucleation process and similarities between initial P wave signatures of small and large earthquakes. A diversity of nucleation conditions are expected in the Earth's crust, ranging from slip limited environments with Lc < 1 m, to ignition‐limited environments with Lc > 10 km. In the latter case, Lc fails to fully characterize the initiation process since earthquakes nucleate not because a slipping patch reaches a critical length but because fault slip rate exceeds a critical power density needed to ignite dynamic rupture.

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Section: Preslip Model: Large Nucleation On the Order Of Kilometersmentioning

confidence: 94%

Section: Scaling Up To Natural Faultsmentioning

confidence: 95%

Section: Scaling Up To Natural Faultsmentioning

confidence: 99%

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Earthquake Initiation From Laboratory Observations and Implications for Foreshocks

2019

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“…Theoretical models and observational evidence suggest that the onset of instabilities responsible for earthquakes, landslides, and volcanic eruptions is often preceded by slowly evolving, low‐amplitude initiation phases (Bouchon et al, ; Brenguier, Campillo, et al, ; Johnson & Jia, ; Scuderi et al, ; Tape et al, ). Both high temporal resolution and high precision measurement of crustal deformation are therefore crucial for hazard prediction and early warning.…”

Section: Introductionmentioning

confidence: 99%

High Temporal Resolution Monitoring of Small Variations in Crustal Strain by Dense Seismic Arrays

Mao

Campillo

Hilst

et al. 2019

Geophysical Research Letters

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We demonstrate the feasibility of detecting very weak deformation in the shallow crust with high temporal resolution by monitoring the relative changes in seismic wave velocity (dv/v) using dense arrays of seismometers. We show that the dv/v variations are consistent between independent measurements from two seismic arrays. Dominant peaks in the observed dv/v spectrum suggest that tides and temperature changes are the major causes of daily and subdaily velocity changes, in accordance with theoretical strain modeling. Our analysis illustrates that dv/v perturbations of the order of 10−4, corresponding to crustal strain changes of the order of 10−8, can be measured from ambient seismic noise with a temporal resolution of 1 hr. This represents a low‐cost technique for high precision and high time‐resolution monitoring of crustal deformation that is complementary to existing geodetic measurements and is instrumental in both the detection and understanding of low‐amplitude precursory processes of natural catastrophic events.

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“…On the other hand, detecting nucleation processes for natural faults by means of seismological and geodetic observations remains unsuccessful. Although several observations reported preceding slip before some earthquakes (e.g., Bouchon et al, 2011;Kato et al, 2012;Tape et al, 2018), whether the reported slow slip events are the nucleation processes of mainshocks is an open question.…”

Section: Introductionmentioning

confidence: 99%

Longer Migration and Spontaneous Decay of Aseismic Slip Pulse Caused by Fault Roughness

Ozawa

Hatano

Kame

2019

Geophysical Research Letters

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It has been known that natural faults possess rough profiles, which may play a vital role in earthquake dynamics. Here we examine the effect of fault roughness in the earthquake nucleation process using the rate and state friction law with the slip evolution law. The nucleation process on rough faults behaves as accelerating and migrating aseismic slip pulse, which is similar to previous studies for flat faults. However, the migration distance on rough faults is much larger than flat faults. The effect of fault roughness on the aseismic slip pulse migration is described by a single parameter known as the roughness drag, which depends on the amplitude, the minimum wavelength, and the Hurst exponent of the fault roughness profile. We also show that aseismic slip pulse cannot accelerate to dynamic rupture and ceases spontaneously if the roughness drag exceeds the static stress drop.

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Earthquake nucleation and fault slip complexity in the lower crust of central Alaska

Cited by 113 publications

References 54 publications

Earthquake Initiation From Laboratory Observations and Implications for Foreshocks

Earthquake Initiation From Laboratory Observations and Implications for Foreshocks

High Temporal Resolution Monitoring of Small Variations in Crustal Strain by Dense Seismic Arrays

Longer Migration and Spontaneous Decay of Aseismic Slip Pulse Caused by Fault Roughness

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