Earthquake rupture below the brittle-ductile transition in continental lithospheric mantle

Prieto, G. A.; Froment, B.; Yu, Chunquan; Poli, Piero; Abercrombie, Rachel E.

doi:10.1126/sciadv.1602642

Cited by 63 publications

(57 citation statements)

References 56 publications

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“…Of course, the general observation that emerges from examining the stereonet projections is the same as that of the top plots of each column in Figure , but this visualization technique is particularly informative with respect to the possible role of the takeoff angle as discussed in Boatwright (). This information is fundamental for constraining the subhorizontal versus the subvertical character of rupture propagation (Poli et al, ; Prieto et al, ; Warren & Shearer, ). In a stereonet visualization, the largest amplitudes at the smallest takeoff angles denote subvertical ruptures (Boatwright, ).…”

Section: Analysis Methodsmentioning

confidence: 99%

Rupture Directivity of the Strongest 2016–2017 Central Italy Earthquakes

2017

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The along‐strike rupture directivity of 16 of the strongest earthquakes (4.4 ≤ Mw ≤ 6.5) within the 2016–2017 central Italy seismic sequence is estimated by investigating high‐frequency S wave amplitude variations versus source azimuths with an empirical Green's function deconvolution approach. The results confirm that an along‐strike rupture directivity is a persistent feature of normal‐faulting earthquakes in the Apennines. The preferred rupture directions of the 2016–2017 earthquakes and of similar‐magnitude events from the 1997 Umbria‐Marche and 2009 L'Aquila‐Campotosto seismic sequences show a significant spatial consistency. Different sectors of the Apennines show an alternating trend of preferential along‐strike rupture propagation directions with significant spatial and temporal stabilities independent of the magnitude. These results, if confirmed by further data, could lead to more refined hazard assessments of the investigated region.

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Section: Analysis Methodsmentioning

confidence: 99%

Rupture Directivity of the Strongest 2016–2017 Central Italy Earthquakes

2017

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“…source duration) as in most of previous studies. Similar ideas based on source time function stretching has also been exploited recently (Zhan et al 2015;Prieto et al 2017). However, they still rely on EGF deconvolution to obtain ASTFs first before stretching them to search for directivity, which causes additional challenges for the more automated goal we have in mind.…”

Section: Introductionmentioning

confidence: 99%

Toward automated directivity estimates in earthquake moment tensor inversion

Huang

Aso

Tsai

2017

Geophysical Journal International

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S U M M A R YRapid estimates of earthquake rupture properties are useful for both scientific characterization of earthquakes and emergency response to earthquake hazards. Rupture directivity is a particularly important property to constrain since seismic waves radiated in the direction of rupture can be greatly amplified, and even moderate magnitude earthquakes can sometimes cause serious damage. Knowing the directivity of earthquakes is important for ground shaking prediction and hazard mitigation, and is also useful for discriminating which nodal plane corresponds to the actual fault plane particularly when the event lacks aftershocks or outcropped fault traces. Here, we propose a 3-D multiple-time-window directivity inversion method through direct waveform fitting, with source time functions stretched for each station according to a given directivity. By grid searching for the directivity vector in 3-D space, this method determines not only horizontal but vertical directivity components, provides uncertainty estimates, and has the potential to be automated in real time. Synthetic tests show that the method is stable with respect to noise, picking errors, and site amplification, and is less sensitive to station coverage than other methods. Horizontal directivity can be properly recovered with a minimum azimuthal station coverage of 180 • , whereas vertical directivity requires better coverage to resolve. We apply the new method to the M w 6.0 Nantou, Taiwan earthquake, M w 7.0 Kumamoto, Japan earthquake, and M w 4.7 San Jacinto fault trifurcation (SJFT) earthquake in southern California. For the Nantou earthquake, we corroborate previous findings that the earthquake occurred on a shallow east-dipping fault plane rather than a west-dipping one. For the Kumamoto and SJFT earthquakes, the directivity results show good agreement with previous studies and demonstrate that the method captures the general rupture characteristics of large earthquakes involving multiple fault ruptures and applies to earthquakes with magnitudes as small as M w 4.7.

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“…The 1988 Mw 6.8 event, another lower crustal event having similar source characteristics as that of the 2011 Sikkim earthquake, also generated a comparable stress drop of 9.63 MPa (Ghimire & Kasahara, ). The unusually slow rupture propagation and the comparably high stress drop value imply that a larger portion of the potential energy of 2011 event is dissipated in and around the source region (e.g., Prieto et al, ).…”

Section: Discussionmentioning

confidence: 99%

Rupture of the Indian Slab in the 2011 Mw 6.9 Sikkim Himalaya Earthquake and Its Tectonic Implications

et al. 2019

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Unlike the other Himalayan plate boundary segments, the eastern Nepal to Bhutan Himalayan region is not known to have generated prominent shallow thrust faulting earthquakes, typical of the ongoing convergence. This region features strike‐slip earthquakes over the depth ranges of 40–120 km, indicating intraslab deformation. Here we present for the first time a slip distribution model for the largest recorded intraslab strike‐slip earthquake in this region, the Mw 6.9 Sikkim event that occurred on 18 September 2011. Relying on kinematic source process modeling, our results indicate a NE‐SW trending, steeply dipping sinistral source zone within the underthrusting Indian slab. The rupture propagated radially, with a low rupture velocity of 1.7 km/s, breaking a large asperity of 20 × 20 km2 with a maximum slip of 1.6 m. The rupture nucleated at a depth of 45 km and reached upper mantle depths. The computed coseismic stress drop value is 13.6 MPa. We suggest that most of the aftershocks occurred on the conjugate plane, possibly due to stress triggering. Stress inversion of focal mechanisms indicates a transpressive stress regime throughout the crust and pure strike‐slip regime in the upper mantle. We observed a unimodal distribution of earthquakes beneath the Higher Himalaya. This indicates a strong, brittle Indian slab and unravels a scenario of an eventual breakup of the lithosphere; the key trigger might be variation in the convergence rates along the Himalayan arc.

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Earthquake rupture below the brittle-ductile transition in continental lithospheric mantle

Abstract: The slow and inefficient deep Wyoming earthquake ruptured in the ductile regime of the upper mantle.

Cited by 63 publications

References 56 publications

Rupture Directivity of the Strongest 2016–2017 Central Italy Earthquakes

Rupture Directivity of the Strongest 2016–2017 Central Italy Earthquakes

Toward automated directivity estimates in earthquake moment tensor inversion

Rupture of the Indian Slab in the 2011 Mw 6.9 Sikkim Himalaya Earthquake and Its Tectonic Implications

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