Rapid earthquake rupture duration estimates from teleseismic energy rates, with application to real-time warning

Convers, J. A.; Newman, A. V.

doi:10.1002/2013gl057664

Cited by 10 publications

(9 citation statements)

References 19 publications

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“…During an earthquake, the timescales of faulting are usually on the order of seconds, rarely exceeding 2 minutes (Geller, 1976;Convers and Newman, 2013). On these short timescales, frictional heating is much faster than conductive heat loss, so we can approximate frictional melting as an adiabatic process, wherein no heat is lost from the shear zone (Spray, 1992;Fialko and Khazan, 2005;Spray, 2010).…”

Section: Thermodynamics Of Earthquakesmentioning

confidence: 99%

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Geochemistry and thermodynamics of an earthquake: A case study of pseudotachylites within mylonitic granitoid

Jiang

Lee

Morgan

et al. 2015

Earth and Planetary Science Letters

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Pseudotachylites are melts produced by frictional heating during seismic slip. Understanding their origin and their influence on slip behavior is critical to understanding the physics of earthquakes. To provide insight into this topic, we conducted a case study in the proto-mylonitic to mylonitic Asbestos Mountain granitoid in the eastern Peninsular Ranges Batholith (California), which records both ductile (mylonites) and brittle deformation features (pseudotachylites and ultracataclasites). U-Pb chronology and Zr thermometry of titanite porphyroblasts in the mylonites indicate that mylonitization of the plutons occurred at near solidus conditions (~750 o C) over a 10 Ma interval from 89 to 78 Ma. Mylonitization resulted in recrystallization of quartz, plagioclase and biotite, with the biotite concentrated into biotiterich foliation planes. Subsequent brittle deformation is superimposed on the ductile fabrics. Micro-XRF elemental mapping and in situ LA-ICPMS analyses on these brittle deformation products show that the pseudotachylites are more mafic (lower Si, but higher Fe) and K-rich than the host mylonite, while the ultracataclasites are intermediate between the host and the pseudotachylites. Inverse mass balance calculations show that both brittle deformation products are depleted in quartz but enriched in biotite, with the pseudotachylites showing the most significant enrichment in biotite, indicating preferential involvement of biotite during brittle deformation. We suggest that biotite-rich layers generated during

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Section: Thermodynamics Of Earthquakesmentioning

confidence: 99%

“…However, on earthquake timescales (less than 2 min) (Geller, 1976;Convers and Newman, 2013), only biotite can be completely melted. Some fraction of plagioclase can be melted if the slip rate is high (v > 1 m/s).…”

mentioning

confidence: 99%

Geochemistry and thermodynamics of an earthquake: A case study of pseudotachylites within mylonitic granitoid

Jiang

Lee

Morgan

et al. 2015

Earth and Planetary Science Letters

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“…We define the shorter of the two durations as the source duration. We compare our determined source durations (Figure S2 and Table S1) with those obtained by W‐phase inversion [ Duputel et al , ], Global centroid moment tensor (CMT) inversion [ Ekström and Nettles , ], and energy duration [ Convers and Newman , ] (Figure ). Notice that the source durations derived from W‐phase inversion and Global CMT inversion are approximated by 2 times of the centroid time delays [ Duputel et al , ].…”

Section: Methodsmentioning

confidence: 99%

“…In addition to methods that involve inversions, other approaches use empirical relations to estimate earthquake magnitudes, usually for large earthquakes [e.g., Convers and Newman , ; Hara, ; Katsumata et al , ; Lomax and Michelini , ; Noda et al , ; Tsuboi et al , , ]. Their simple implementation and straightforward calculation made these approaches widely applied by many institutions such as the Pacific Tsunami Warning Center, Japan Meteorological Agency, and USGS.…”

Section: Introductionmentioning

confidence: 99%

Automated determination of magnitude and source length of large earthquakes using backprojection andPwave amplitudes

Wang

Kawakatsu

Zhuang

et al. 2017

Geophysical Research Letters

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Fast estimates of magnitude and source extent of large earthquakes are fundamental for disaster mitigation. However, resolving these estimates within 10–20 min after origin time remains challenging. Here we propose a robust algorithm to resolve magnitude and source length of large earthquakes using seismic data recorded by regional arrays and global stations. We estimate source length and source duration by backprojecting seismic array data. Then the source duration and the maximum amplitude of the teleseismic P wave displacement waveforms are used jointly to estimate magnitude. We apply this method to 74 shallow earthquakes that occurred within epicentral distances of 30–85° to Hi‐net (2004–2014). The estimated magnitudes are similar to moment magnitudes estimated from W‐phase inversions (U.S. Geological Survey), with standard deviations of 0.14–0.19 depending on the global station distributions. Application of this method to multiple regional seismic arrays could benefit tsunami warning systems and emergency response to large global earthquakes.

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“…Scaling laws would predict a constant value of the ratio E/T 3 R , while all known 'tsunami earthquakes' indeed feature significant deficiencies (of the order of 1-1.5 orders of magnitude) in that ratio. In this framework, Convers & Newman [67] have explored several strategies to define a source duration from P waves, including through an analysis of the evolution of the energy contained in a time window moving through the P wavetrain. [66] approach was able to identify the source slowness of the 2010 Mentawai earthquake as early as 17 min after origin, during the developmental stages of their algorithm.…”

Section: (D) Quantifiers and Discriminants Based On Durationmentioning

confidence: 99%

The quest for wisdom: lessons from 17 tsunamis, 2004–2014

Okal¹

2015

Phil. Trans. R. Soc. A.

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Since the catastrophic Sumatra–Andaman tsunami took place in 2004, 16 other tsunamis have resulted in significant damage and 14 in casualties. We review the fundamental changes that have affected our command of tsunami issues as scientists, engineers and decision-makers, in the quest for improved wisdom in this respect. While several scientific paradigms have had to be altered or abandoned, new algorithms, e.g. the W seismic phase and real-time processing of fast-arriving seismic P waves, give us more powerful tools to estimate in real time the tsunamigenic character of an earthquake. We assign to each event a ‘wisdom index’ based on the warning issued (or not) during the event, and on the response of the population. While this approach is admittedly subjective, it clearly shows several robust trends: (i) we have made significant progress in our command of far-field warning, with only three casualties in the past 10 years; (ii) self-evacuation by educated populations in the near field is a key element of successful tsunami mitigation; (iii) there remains a significant cacophony between the scientific community and decision-makers in industry and government as documented during the 2010 Maule and 2011 Tohoku events; and (iv) the so-called ‘tsunami earthquakes’ generating larger tsunamis than expected from the size of their seismic source persist as a fundamental challenge, despite scientific progress towards characterizing these events in real time.

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Rapid earthquake rupture duration estimates from teleseismic energy rates, with application to real-time warning

Cited by 10 publications

References 19 publications

Geochemistry and thermodynamics of an earthquake: A case study of pseudotachylites within mylonitic granitoid

Geochemistry and thermodynamics of an earthquake: A case study of pseudotachylites within mylonitic granitoid

Automated determination of magnitude and source length of large earthquakes using backprojection andPwave amplitudes

The quest for wisdom: lessons from 17 tsunamis, 2004–2014

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