Theory and Observations - Seismic Tomography and Inverse Methods

Thurber, C. H.; Ritsema, Jeroen

doi:10.1016/b978-0-444-53802-4.00009-9

Cited by 11 publications

(7 citation statements)

References 308 publications

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“…The interested reader is referred to a few other comprehensive reviews on this topic, e.g., Dziewonski and Romanowicz (2007), Kind and Li (2007), Lay (2007), Romanowicz and Mitchell (2007), Thurber and Ritsema (2007), Rawlinson et al (2010), and Montagner (2011). Hence, in this chapter I draw mainly on the global tomographic studies in which I was involved.…”

Section: Discussionmentioning

confidence: 99%

Multiscale Seismic Tomography

Zhao

2015

100

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Section: Discussionmentioning

confidence: 99%

Multiscale Seismic Tomography

Zhao

2015

100

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“…This means that we need to rely upon the statistics of large samples and trust that the ~35,000 P diff station pairs will average out much of the noise, but also remember to interpret final anomaly maps only at large spatial wavelengths. We also rely upon the many whole‐mantle tomographic studies that show that the spectral power of lateral heterogeneities is significantly greater in the lowermost few hundred kilometers than in the rest of the midmantle and lower mantle, allowing us to make the assumption that traveltime and amplitude anomalies are more likely to arise at the base of the mantle than above it [ Megnin and Romanowicz , ; Thurber and Ritsema , ; Koelemeijer et al , ]. And last, our study makes the assumption throughout that if the paths of the two waves are geographically similar, then any anomalies accrued will be similar for both and will not remain in differential measurements.…”

Section: Methodsmentioning

confidence: 99%

Geographic variations in lowermost mantle structure from the ray parameters and decay constants of core‐diffracted waves

Euler

Wysession²

2017

JGR Solid Earth

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We introduce an array‐based approach for constraining seismic velocity structure in the lowermost mantle by measuring the frequency dependence of the ray parameter p and decay constant γ for core‐diffracted waves (Pdiff and SHdiff). The approach uses an iterative multichannel cross‐correlation algorithm that solves for relative arrival times and amplitudes of core‐diffracted waveforms from multiple peaks in normalized correlograms from pairs of coazimuthal stations. The approach is applied to 60 mb ≥ 5.8 earthquakes for Pdiff and 36 for SHdiff during 2001–2002, with nearly 50,000 unique profile station pairs with epicentral‐distance differences of Δd ≥ 10° and azimuth differences of Δφ ≤ 10°, sampling a significant portion of the lowermost mantle. Cap‐averaging the resulting ray parameter estimates produces geographic variations that are largely consistent with the distribution of lowermost mantle large low‐velocity provinces and seismically fast slab‐accumulation regions seen in seismic tomography models, whose locations also strongly influence the geographic distribution of heat flow out of the core. Geographic variations in station‐pair diffracted‐wave decay constants differ from those of the ray parameters, suggesting that variations in the decay of core‐diffracted waves are more linked to lowermost mantle seismic velocity gradients than absolute values of seismic velocity. The ray parameters and decay constants of core‐diffracted waves are strongly frequency‐dependent, and these frequency variations also vary significantly with geographic location. Combining lateral and vertical seismic‐velocity variations with mineral‐physics data on elasticity and conductivity of lowermost mantle species can provide constraints on D″ composition and CMB heat flux.

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“…We assume that (a) each S‐wave path between two points has a corresponding P‐wave path; (b) the P‐ and S‐wave paths taken between two different points are identical and have similar Fresnel zones. Under these assumptions, the inverse problem is linear, as any lateral heterogeneity will cause a divergence of the P‐ and S‐ray paths (Eberhart‐Phillips & Reyners, 2012; Thurber, 1993; Walck, 1988). The method requires common P‐ and S‐arrival times, so rays with only S‐phases or P‐phases will be removed.…”

Section: Methodsmentioning

confidence: 99%

Seismic Tomography of Nabro Caldera, Eritrea: Insights Into the Magmatic and Hydrothermal Systems of a Recently Erupted Volcano

et al. 2023

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Modeling the crustal architecture of a volcano is of fundamental importance; interactions between magmatic and hydrothermal systems play a central role in volcanic unrest and eruption (e.g., Chouet & Matoza, 2013;Pritchard et al., 2019;Wilks et al., 2020). However, these systems are often poorly characterized, both due to their complexity and to the difficulty of probing the crust in sufficient detail. Further motivation for investigation is that volcanic-hosted hydrothermal systems may be a source of geothermal energy production (Reinsch et al., 2017) or metal-rich brines (Blundy et al., 2021).

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Theory and Observations - Seismic Tomography and Inverse Methods

Cited by 11 publications

References 308 publications

Multiscale Seismic Tomography

Multiscale Seismic Tomography

Geographic variations in lowermost mantle structure from the ray parameters and decay constants of core‐diffracted waves

Seismic Tomography of Nabro Caldera, Eritrea: Insights Into the Magmatic and Hydrothermal Systems of a Recently Erupted Volcano

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