Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short‐Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions

Berg, Elizabeth; Lin, Fan‐Chi; Schulte-Pelkum, V.; Allam, A. A.; Qiu, Hongrui; Gkogkas, K.

doi:10.1029/2021gl092626

Cited by 9 publications

(6 citation statements)

References 77 publications

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“…Based on microseismicity and anisotropy studies, this outer region exhibits significant tectonic earthquakes, tectonic fractures, and fissure swarms (Bacon et al., 2022; Greenfield et al., 2020; Winder, 2021). Anomaly III is mainly concentrated in the highly fractured zones, between Askja and Herðubreið in this case, which is similar to observations in the San Andreas fault and Eastern California Shear Zone (Berg et al., 2021; Fang et al., 2018; Lin et al., 2007). In particular, Vs is found to be sensitive to highly fractured rocks (Catchings et al., 2020), but this diminishes with depth as cracks begin to close, which is also supported by studies of seismic anisotropy (Bacon et al., 2022).…”

Section: Resultssupporting

confidence: 87%

Evidence of a Shallow Magma Reservoir Beneath Askja Caldera, Iceland, From Body Wave Tomography

Han,

Rawlinson,

Greenfield

et al. 2024

Geophysical Research Letters

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In August 2021, Askja caldera switched to reinflation following ∼40 years of continuous deflation that was first measured some 20 years after its last eruption in 1961. Various lines of evidence, including from geodetic modeling, suggest that both the deflation and reinflation events are related to a shallow magma body. To better understand the subsurface plumbing system, we derive P‐wave velocity (Vp), S‐wave velocity (Vs), and Vp/Vs models of the mid‐upper crust by leveraging a new local earthquake traveltime data set. A cylindrical low‐velocity zone, ∼3 km wide and extending to ∼8 km below sea level (bsl), was imaged beneath the caldera. Within it, two distinct lower velocity and higher Vp/Vs anomalies are illuminated, one centered at ∼0.5 km and the other at ∼6 km bsl. The shallower anomaly lies directly beneath the zone of uplift and is likely associated with the current reinflation event.

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Section: Resultssupporting

confidence: 87%

Evidence of a Shallow Magma Reservoir Beneath Askja Caldera, Iceland, From Body Wave Tomography

Han,

Rawlinson,

Greenfield

et al. 2024

Geophysical Research Letters

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“…Given separate Vp and Vs model structures, one possible approach is to calculate the Vp/Vs from independently generated Vp and Vs models, but this suffers from potential bias from the different resolutions between independently created Vp and Vs models (Berg et al., 2021). Direct measurements of Vp/Vs for the Southern California crust are possible, and generally fall into three categories: (a) receiver functions H‐κ stacking (Lowry & Pérez‐Gussinyé, 2011; Purevsuren, 2014; Zhu & Kanamori, 2000); (b) Compressional (P) and shear (S) wave arrival time difference analysis (Allam & Ben‐Zion, 2012; Hauksson, 2000; Hauksson & Haase, 1997); (c) inversion of 3‐D seismic velocities (Fang et al., 2019; Lee et al., 2014).…”

Section: Introductionmentioning

confidence: 99%

“…The ratio between the compressional and shear wave speed (Vp/Vs) provides constraints on the crustal physical and chemical properties (Christensen, 1996). For southern California, seismic models have constrained the elastic properties (e.g., compressional wave speed [Vp], shear wave speed [Vs]) and these separate measurements have been used to inform crustal composition and viscosity (Berg et al, 2018(Berg et al, , 2021Shaw et al, 2015;Shinevar et al, 2018;Wu et al, 2022). However, directly-measured Vp/Vs ratio, a more direct indicator of crustal composition (Lowry & Pérez-Gussinyé, 2011;Sui et al, 2022) has not been used to infer the crustal strength.…”

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confidence: 99%

Crustal Architecture Across Southern California and Its Implications on San Andreas Fault Development

Sui

Shen

Holt

et al. 2023

Geophysical Research Letters

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In this study, we perform a 2‐frequency sequential receiver function stacking investigation in Southern California. The resulting Moho depths exhibit similar patterns to previous studies while the crystalline crustal Vp/Vs values show more regional variations. Most Vp/Vs variations can be explained by compositional differences. We observe a dichotomy in Moho depth, Vp/Vs, and crustal strain rates between the Peninsular Ranges and Southern San Andreas Fault system. Comparisons between strain rates, Vp/Vs, and temperature suggest that crustal compositional variations may have played a more critical role in influencing the crustal strain rate variations in the Peninsular Ranges and Southern San Andreas than temperature. The structural and compositional variations provide a new insight into the causes of the migration of the Southern San Andreas Fault system and the formation of the “Big Bend.”

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“…9d) by dividing the Vp by Vs models. To mitigate for potentially extreme inaccuracies and numerical artefacts due to simply dividing the Vp by Vs models obtained from data with differing resolutions (Berg et al 2021), we resampled the Vp model based on the Vs model's grid setting before dividing the Vp by Vs models. In addition, we calculated the S-wave velocity perturbation model (Fig.…”

Section: Vp/vs Model Construction and Correlation With Geological Obs...mentioning

confidence: 99%

Upper crustal structure beneath the Qin-Hang and Wuyishan metallogenic belts in Southeast China as revealed by a joint active and passive seismic experiment

Zheng

Lü

et al. 2022

Geophysical Journal International

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Summary Southeast China is one of the most important polymetallic metallogenic provinces in the world. However, distinct differences in the type and origin of the mineral deposits are present between the major metallogenic belts in this province. To deepen our knowledge of this regional metallogenic setting, investigate the factors controlling its metallogenic differences, and explore the feasibility of active and passive seismic imaging, we performed a multibatch seismic experiment using active and passive sources with the help of 437 short-period seismographs deployed across the Qin-Hang and Wuyishan metallogenic belts in Southeast China. We resolved the S-wave velocity structure beneath the profile using ambient noise tomography and derived a Vp/Vs model by combining with a published P-wave model. A good correlation between the obtained seismic velocity models and geological observations are observed. The Proterozoic volcanic-sedimentary rock series and the Fuzhou-Yongfeng sedimentary basin are identified by low P- and S-wave velocities, high Vp/Vs ratios, and low S-wave velocity perturbations. Within the core of the Wuyishan Metallogenic Belt, several narrow, elongated, and low seismic velocity anomalies are considered to be signs of the nearby fault zones, and these anomalies provide reference information on the extension and pattern of these faults at depth. Combined with the geological and mineralogical evidence, we propose that theses faults function as ore-guiding structures and facilitate the formation of regionally representative mineral species and metal assemblages.

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Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short‐Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions

Cited by 9 publications

References 77 publications

Evidence of a Shallow Magma Reservoir Beneath Askja Caldera, Iceland, From Body Wave Tomography

Evidence of a Shallow Magma Reservoir Beneath Askja Caldera, Iceland, From Body Wave Tomography

Crustal Architecture Across Southern California and Its Implications on San Andreas Fault Development

Upper crustal structure beneath the Qin-Hang and Wuyishan metallogenic belts in Southeast China as revealed by a joint active and passive seismic experiment

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