Earthquake nucleation and triggering on an optimally oriented fault

Tape, Carl; West, M. E.; Silwal, Vipul; Ruppert, N. A.

doi:10.1016/j.epsl.2012.11.060

Cited by 51 publications

(54 citation statements)

References 54 publications

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“…6) mainshocks, even though Love-wave triggering is also predicted by the Coulomb triggering model, because the waves from both earthquakes have near strike-parallel incidence on the EDF (Hill, 2012). Specifically for the Indian Ocean mainshock, we could not confirm Love-wave triggering visually due to overlapping seismic waves from the triggered M w 3.9 Nenana earthquake in central Alaska (Tape et al, 2013). Nor could we identify evidence for triggered tremor in a higher frequency band (see Ⓔ Fig.…”

Section: Discussioncontrasting

confidence: 48%

“…The Indian Ocean mainshock has triggered many microearthquakes and tremor around the world (e.g., Wu et al, 2012), as well as a transient global increase of M w ≥ 5:5 earthquakes (Pollitz et al, 2012). Its Love wave also triggered an M w 3.9 earthquake in central Alaska (Tape et al, 2013), which was recorded by stations in our study region at ∼2700 s after the Indian Ocean mainshock. We observed consecutive bursts of tectonic tremor triggered by the long-period Rayleigh wave between 3500 and 4000 s after the Indian Ocean mainshock in the 1-10 Hz frequency band (Fig.…”

Section: Additional Observations Of Triggered Tremormentioning

confidence: 93%

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Triggered Seismic Events along the Eastern Denali Fault in Northwest Canada Following the 2012 Mw 7.8 Haida Gwaii, 2013 Mw 7.5 Craig, and Two Mw>8.5 Teleseismic Earthquakes

Aiken¹,

Zimmerman²,

Peng³

et al. 2015

Bulletin of the Seismological Society of America

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We conduct a systematic search for remotely triggered seismic activity along the eastern Denali fault (EDF) in northwest Canada, an intraplate strike-slip region. We examine 19 distant earthquakes recorded by nine broadband stations in the Canadian National Seismograph Network and find that the 2012 M w 7.8 Haida Gwaii and 2013 M w 7.5 Craig, Alaska, earthquakes triggered long duration (> 10 s), emergent tremor-like signals near the southeastern portion of the EDF. In both cases, tremor coincides with the peak transverse velocities, consistent with Love-wave triggering on right-lateral strike-slip faults. The 2011 M w 9.0 Tohoku-Oki and 2012 M w 8.6 Indian Ocean earthquakes possibly triggered tremor signals, although we were unable to locate those sources. In addition, we also identify many short-duration (< 5 s) bursts that were repeatedly triggered by the Rayleigh waves of the 2012 M w 7.8 Haida Gwaii earthquake. Although we were unable to precisely locate the short-duration (< 5 s) events, they appear to be radiating from the direction of the Klutlan Glacier and from a belt of shallow historical seismicity at the eastern flank of the Wrangell-St. Elias mountain range. The fact that these events were triggered solely by the Rayleigh waves suggests a different source mechanism as compared with triggered tremor observed along the EDF and other plate boundary regions.Online Material: Description of Rayleigh-wave polarization detection; figures of spectograms, S-wave amplitudes, polarization analysis, and static stress changes; tables of earthquake catalogs and velocity model; and animations of tremors and bursts.

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Section: Discussioncontrasting

confidence: 48%

Section: Additional Observations Of Triggered Tremormentioning

confidence: 93%

Triggered Seismic Events along the Eastern Denali Fault in Northwest Canada Following the 2012 Mw 7.8 Haida Gwaii, 2013 Mw 7.5 Craig, and Two Mw>8.5 Teleseismic Earthquakes

Aiken¹,

Zimmerman²,

Peng³

et al. 2015

Bulletin of the Seismological Society of America

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“…[53] These lab observations may provide some physical insight into the mechanics of foreshocks, particularly short-term foreshocks and tremor-like signals sometimes observed to emanate from the eventual hypocenter of a larger earthquake [e.g., Bouchon et al, 2011;Tape et al, 2013]. Stressing rate dependence to frictional stability may help explain the radiation of tectonic tremor and certain characteristics of repeating earthquake sequences [Matsuzawa et al, 2012].…”

Section: Resultsmentioning

confidence: 99%

“…In some cases, clusters or swarms of small earthquakes have been detected within a few kilometers of the eventual hypocenter of a main shock in the weeks to seconds before earthquakes [e.g., Dodge et al 1995, 1996, Zanzerkia et al, 2003, Bouchon et al, 2011, Chiaraluce et al, 2011, Miyazaki et al, 2011Ando and Imanishi, 2011;Marsan and Enescu, 2012;Tape et al, 2013]. While they are termed foreshocks, the precise physical connection between foreshocks and main shocks is not well established.…”

Section: Introductionmentioning

confidence: 99%

Foreshocks during the nucleation of stick‐slip instability

2013

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[1] We report on laboratory experiments which investigate interactions between aseismic slip, stress changes, and seismicity on a critically stressed fault during the nucleation of stick-slip instability. We monitor quasi-static and dynamic changes in local shear stress and fault slip with arrays of gages deployed along a simulated strike-slip fault (2 m long and 0.4 m deep) in a saw cut sample of Sierra White granite. With 14 piezoelectric sensors, we simultaneously monitor seismic signals produced during the nucleation phase and subsequent dynamic rupture. We observe localized aseismic fault slip in an approximately meter-sized zone in the center of the fault, while the ends of the fault remain locked. Clusters of high-frequency foreshocks (M w~À 6.5 to À5.0) can occur in this slowly slipping zone 5-50 ms prior to the initiation of dynamic rupture; their occurrence appears to be dependent on the rate at which local shear stress is applied to the fault. The meter-sized nucleation zone is generally consistent with theoretical estimates, but source radii of the foreshocks (2 to 70 mm) are 1 to 2 orders of magnitude smaller than the theoretical minimum length scale over which earthquake nucleation can occur. We propose that frictional stability and the transition between seismic and aseismic slip are modulated by local stressing rate and that fault sections, which would typically slip aseismically, may radiate seismic waves if they are rapidly stressed. Fault behavior of this type may provide physical insight into the mechanics of foreshocks, tremor, repeating earthquake sequences, and a minimum earthquake source dimension.

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“…A clue to the triggering power of the April 2012 event lies in the apparent triggering of a foreshock sequence ∼20 s prior to an M 3.9 dynamically triggered aftershock in Alaska (Tape et al, 2013). This suggests that source patches that are close to failure may exhibit a gradual precursory slip prior to generating a larger triggered event.…”

Section: Introductionmentioning

confidence: 99%

The Profound Reach of the 11 April 2012 M 8.6 Indian Ocean Earthquake: Short-Term Global Triggering Followed by a Longer-Term Global Shadow

Pollitz

Bürgmann

Stein

et al. 2014

Bulletin of the Seismological Society of America

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The 11 April 2012 M 8.6 Indian Ocean earthquake was an unusually large intraoceanic strike-slip event. For several days, the global M ≥ 4:5 and M ≥ 6:5 seismicity rate at remote distances (i.e., thousands of kilometers from the mainshock) was elevated. The strike-slip mainshock appears through its Love waves to have triggered a global burst of strike-slip aftershocks over several days. But the M ≥ 6:5 rate subsequently dropped to zero for the succeeding 95 days, although the M ≤ 6:0 global rate was close to background during this period. Such an extended period without an M ≥ 6:5 event has happened rarely over the past century, and never after a large mainshock. Quiescent periods following previous large (M ≥ 8) mainshocks over the past century are either much shorter or begin so long after a given mainshock that no physical interpretation is warranted. The 2012 mainshock is unique in terms of both the short-lived global increase and subsequent long quiescent period. We believe that the two components are linked and interpret this pattern as the product of dynamic stressing of a global system of faults. Transient dynamic stresses can encourage shortterm triggering, but, paradoxically, it can also inhibit rupture temporarily until background tectonic loading restores the system to its premainshock stress levels.

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Earthquake nucleation and triggering on an optimally oriented fault

Cited by 51 publications

References 54 publications

Triggered Seismic Events along the Eastern Denali Fault in Northwest Canada Following the 2012 Mw 7.8 Haida Gwaii, 2013 Mw 7.5 Craig, and Two Mw>8.5 Teleseismic Earthquakes

Triggered Seismic Events along the Eastern Denali Fault in Northwest Canada Following the 2012 Mw 7.8 Haida Gwaii, 2013 Mw 7.5 Craig, and Two Mw>8.5 Teleseismic Earthquakes

Foreshocks during the nucleation of stick‐slip instability

The Profound Reach of the 11 April 2012 M 8.6 Indian Ocean Earthquake: Short-Term Global Triggering Followed by a Longer-Term Global Shadow

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