Aftershock Moment Tensor Scattering

Wilding, John D.; Ross, Zachary E.

doi:10.1029/2022gl098473

Cited by 3 publications

(1 citation statement)

References 37 publications

(68 reference statements)

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“…They utilized the James Clerk Maxwell Telescope (JCMT) in Hawaii and the Atacama Large Millimeter Array (ALMA) in Chile, to verify their detection. While this discovery has been contentious in the scientific community (the original study [1] have since reduced their PH 3 estimates and two other studies [2,3] refute their results), it alerted us to the lack of research on PH 3 in the stratosphere of Earth. Our instrument design [Figure 1] aims to improve this lack of data.…”

mentioning

confidence: 99%

Phosphine and Trace Gas Measurement Instrument Design in the Earth's Troposphere and Stratosphere.

Warburton,

El Tarabeishy,

Bapatla

et al. 2023

Goldschmidt2023 Abstracts

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mentioning

confidence: 99%

Phosphine and Trace Gas Measurement Instrument Design in the Earth's Troposphere and Stratosphere.

Warburton,

El Tarabeishy,

Bapatla

et al. 2023

Goldschmidt2023 Abstracts

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Global Characteristics of Observable Foreshocks for Large Earthquakes

Wetzler

Lay

Brodsky

2023

Seismological Research Letters

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Foreshocks are the only currently widely identified precursory seismic behavior, yet their utility and even identifiability are problematic, in part because of extreme variation in behavior. Here, we establish some global trends that help identify the expected frequency of foreshocks as well the type of earthquake most prone to foreshocks. We establish these tendencies using the global earthquake catalog of the U.S. Geological Survey National Earthquake Information Center with a completeness level of magnitude 5 and mainshocks with Mw≥7.0. Foreshocks are identified using three clustering algorithms to address the challenge of distinguishing foreshocks from background activity. The methods give a range of 15%–43% of large mainshocks having at least one foreshock but a narrower range of 13%–26% having at least one foreshock with magnitude within two units of the mainshock magnitude. These observed global foreshock rates are similar to regional values for a completeness level of magnitude 3 using the same detection conditions. The foreshock sequences have distinctive characteristics with the global composite population b-values being lower for foreshocks than for aftershocks, an attribute that is also manifested in synthetic catalogs computed by epidemic-type aftershock sequences, which intrinsically involves only cascading processes. Focal mechanism similarity of foreshocks relative to mainshocks is more pronounced than for aftershocks. Despite these distinguishing characteristics of foreshock sequences, the conditions that promote high foreshock productivity are similar to those that promote high aftershock productivity. For instance, a modestly higher percentage of interplate mainshocks have foreshocks than intraplate mainshocks, and reverse faulting events slightly more commonly have foreshocks than normal or strike-slip-faulting mainshocks. The western circum-Pacific is prone to having slightly more foreshock activity than the eastern circum-Pacific.

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FocMech-Flow: Automatic Determination of P-Wave First-Motion Polarity and Focal Mechanism Inversion and Application to the 2021 Yangbi Earthquake Sequence

Fang

Xiao

et al. 2023

Applied Sciences

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P-wave first-motion polarity is important for the inversion of earthquake focal mechanism solutions. The focal mechanism solution can further contribute to our understanding of the source rupture process, the fault structure, and the regional stress field characteristics. By using the abundant focal mechanism solutions of small and moderate earthquakes, we can deepen our understanding of fault geometry and the seismogenic environment. In this paper, we propose an automatic workflow, FocMech-Flow (Focal Mechanism-Flow), for identifying P-wave first-motion polarity and focal mechanism inversion with deep learning and applied it to the 2021 Yangbi earthquake sequence. We use a deep learning model named DiTingMotion to detect the P-wave first-motion polarity of 2389 waveforms, resulting in 98.49% accuracy of polarity discrimination compared with human experts. The focal mechanisms of 112 earthquakes are obtained by using the CHNYTX program, which is 3.7 times more than that of the waveform inversion method, and the results are highly consistent. The analysis shows that the focal mechanisms of the foreshock sequence of the Yangbi earthquake are highly consistent and are all of the strike-slip type; the focal mechanisms of the aftershock sequence are complex, mainly the strike-slip type, but there are also reverse and normal fault types. This study shows that the deep learning method has high reliability in determining the P-wave first-motion polarity, and FocMech-Flow can obtain a large number of focal mechanism solutions from small and moderate earthquakes, having promising application in fine-scale stress inversion.

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Aftershock Moment Tensor Scattering

Cited by 3 publications

References 37 publications

Phosphine and Trace Gas Measurement Instrument Design in the Earth's Troposphere and Stratosphere.

Phosphine and Trace Gas Measurement Instrument Design in the Earth's Troposphere and Stratosphere.

Global Characteristics of Observable Foreshocks for Large Earthquakes

FocMech-Flow: Automatic Determination of P-Wave First-Motion Polarity and Focal Mechanism Inversion and Application to the 2021 Yangbi Earthquake Sequence

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