Seismic and Tsunamigenic Characteristics of a Multimodal Rupture of Rapid and Slow Stages: The Example of the Complex 12 August 2021 South Sandwich Earthquake

Metz, Malte; Vera, Felipe; Ponce, A. Carrillo; Cesca, Simone; Babeyko, Andrey; Dahm, Torsten; Saul, Joachim; Tilmann, Frederik

doi:10.1029/2022jb024646

Cited by 5 publications

(3 citation statements)

References 73 publications

(133 reference statements)

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“…This observation agrees with the multiple independent technique results presented in Metz et al. (2022), that is, a shallow and slow rupture (1.5–2.1 km/s) that follows the varying strike direction along the trench, as part of a complex rupture also involving a faster propagation on deeper parts of the plate interface.…”

Section: Resultssupporting

confidence: 93%

A Decade of Short‐Period Earthquake Rupture Histories From Multi‐Array Back‐Projection

Vera,

Tilmann,

Saul

2024

JGR Solid Earth

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Teleseismic back‐projection imaging has emerged as a powerful tool for understanding the rupture propagation of large earthquakes. However, its application often suffers from artifacts related to the receiver array geometry. We developed a teleseismic back‐projection technique that can accommodate data from multiple arrays. Combined processing of P and pP waveforms may further improve the resolution. The method is suitable for defining arrays ad‐hoc to achieve a good azimuthal distribution for most earthquakes. We present a catalog of short‐period rupture histories (0.5–2.0 Hz) for all earthquakes from 2010 to 2022 with MW ≥ 7.5 and depth less than 200 km (56 events). The method provides automatic estimates of rupture length, directivity, speed, and aspect ratio, a proxy for rupture complexity. We obtained short‐period rupture length scaling relations that are in good agreement with previously published relations based on estimates of total slip. Rupture speeds were consistently in the sub‐Rayleigh regime for thrust and normal earthquakes, whereas a tenth of strike‐slip events propagated at supershear speeds. Many rupture histories exhibited complex behaviors, for example, rupture on conjugate faults, bilateral propagation, and dynamic triggering by a P wave. For megathrust earthquakes, ruptures encircling asperities were frequently observed, with downdip, updip, and balanced patterns. Although there is a preference for short‐period emissions to emanate from central and downdip parts of the megathrust, emissions updip of the main asperity are more frequent than suggested by earlier results.

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Section: Resultssupporting

confidence: 93%

A Decade of Short‐Period Earthquake Rupture Histories From Multi‐Array Back‐Projection

Vera,

Tilmann,

Saul

2024

JGR Solid Earth

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“…The Sandwich Islands event also presented a shallower rupture for at least part of the rupture propagation. This observation agrees with the multiple independent technique results presented in Metz et al (2022), that is, a shallow and slow rupture (1.5-2.1 km/s) that follows the varying strike direction along the trench, as part of a complex rupture also involving a faster propagation on deeper parts of the plate interface.…”

Section: Rupture Speedsupporting

confidence: 92%

A decade of short-period earthquake rupture histories from multi-array back-projection

Vera¹,

Tilmann²,

Saul³

2021

Preprint

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Teleseismic back-projection imaging has emerged as a powerful tool for understanding the rupture propagation of large earthquakes. However, its application often suffers from artifacts related to the receiver array geometry. We developed a teleseismic back-projection technique that can accommodate data from multiple arrays. Combined processing of P and pP waveforms may further improve the resolution. The method is suitable for defining arrays ad-hoc to achieve a good azimuthal distribution for most earthquakes. We present a catalog of short-period rupture histories (0.5-2.0 Hz) for all earthquakes from 2010 to 2022 with M W ≥ 7.5 and depth less than 200 km (56 events). The method provides automatic estimates of rupture length, directivity, speed, and aspect ratio, a proxy for rupture complexity. We obtained short-period rupture length scaling relations that are in good agreement with previously published relations based on estimates of total slip. Rupture speeds were consistently in the sub-Rayleigh regime for thrust and normal earthquakes, whereas a tenth of strike-slip events propagated at supershear speeds. Many rupture histories exhibited complex behaviors, for example, rupture on conjugate faults, bilateral propagation, and dynamic triggering by a P wave. For megathrust earthquakes, ruptures encircling asperities were frequently observed, with downdip, updip, and balanced patterns. Although there is a preference for short-period emissions to emanate from central and downdip parts of the megathrust, emissions updip of the main asperity are more frequent than suggested by earlier results.

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“…First, on 12 August 2021, a very complex earthquake took place in the South Sandwich Islands. As discussed in detail by Jia et al ( 2022 ) and Metz et al ( 2022 ), the rupture started around 45 km depth, and propagated upwards into a mainshock featuring a very slow rupture velocity (1.2 km/s), suggesting that the sequence may qualify as a tsunami earthquake. This event is remarkable for its total moment release of 3.4 × 10 28 dyn*cm ( M w = 8.3), in an area where no interplate thrust earthquakes with M ≥ 7.1 had been known, thus confirming a new violation to Ruff and Kanamori’s ( 1980 ) now abandoned model for the maximum magnitude of interplate thrust earthquakes at subduction zones.…”

Section: Introductionmentioning

confidence: 86%

Introduction to “Sixty Years of Modern Tsunami Science, Volume 2: Challenges”

Kânoğlu

Rabinovich

Okal

et al. 2023

Pure Appl. Geophys.

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Fifteen papers are included in this PAGEOPH topical issue “Sixty Years of Modern Tsunami Science, Volume 2: Challenges.” The issue starts with a general introduction, and then briefly summarizes all contributions, first papers addressing general topics, and then articles grouped on a regional basis: Northern Pacific, Southeast Pacific, Southwest Pacific and Indonesia, and Mediterranean regions.

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Seismic and Tsunamigenic Characteristics of a Multimodal Rupture of Rapid and Slow Stages: The Example of the Complex 12 August 2021 South Sandwich Earthquake

Cited by 5 publications

References 73 publications

A Decade of Short‐Period Earthquake Rupture Histories From Multi‐Array Back‐Projection

A Decade of Short‐Period Earthquake Rupture Histories From Multi‐Array Back‐Projection

A decade of short-period earthquake rupture histories from multi-array back-projection

Introduction to “Sixty Years of Modern Tsunami Science, Volume 2: Challenges”

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