The<i>S</i>-velocity structure of the East Asian mantle from inversion of shear and surface waveforms

Friederich, Wolfgang

doi:10.1046/j.1365-246x.2003.01869.x

Cited by 164 publications

(142 citation statements)

References 44 publications

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“…3d) wavespeeds beneath the Baikal region are relatively low, with the lowest values north of the rift. The lateral and vertical extent of the Siberian-Platform lithosphere inferred from our tomography is consistent with inferences from other high-resolution models constrained with surface waves (e.g., [40]); the low-velocity anomaly in the transition zone has been observed in P-velocity [41] and S-velocity [42] regional studies.…”

Section: Upper-mantle Heterogeneitysupporting

confidence: 89%

Asthenospheric flow and origin of volcanism in the Baikal Rift area

Lebedev

Meier

Hilst

2006

Earth and Planetary Science Letters

110

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The origin of low-volume, hotspot-like volcanism often observed in continental rift areas is debated, as is the nature of the flow in the mantle beneath. In this paper we assemble seismic constraints on the mantle flow below the Baikal Rift Zone. We combine new evidence from upper-mantle tomography and from a radially anisotropic shear-velocity profile measured beneath and SE of the rift with published shear-wave-splitting constraints on azimuthal anisotropy. Fast directions of azimuthal anisotropy are perpendicular to the rift on both of its sides. Stable Siberian-Platform lithosphere on the northern side extends down to 200 km; on the southern side, the lithosphere is only 60-70 km thick. This asymmetry, with the thick cratonic root forming a barrier to convective flow, inhibits a mid-ocean-ridge-like flow pattern. The radially anisotropic profile yields evidence for horizontal flow in the upper asthenosphere (60-100 km) SE of the rift but no evidence for vertical flow. These results are consistent with horizontal asthenospheric flow NW to SE perpendicular to the rift, from beneath the thick Siberian towards the thin Baikal-Mongolian lithosphere. When asthenosphere ascends from the 200-km depth beneath the craton to shallower depths beneath the rift, decompression melting of embedded veins of enriched rock can produce the hotspot-like basaltic volcanism observed. The occurrence of such veins of enriched mantle in sub-cratonic asthenosphere has been predicted by geochemical mantle models; we propose that sub-horizontal asthenospheric flow from beneath cratons is a common cause for hotspot-like volcanism in continental rift zones.

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Section: Upper-mantle Heterogeneitysupporting

confidence: 89%

Asthenospheric flow and origin of volcanism in the Baikal Rift area

Lebedev

Meier

Hilst

2006

Earth and Planetary Science Letters

110

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“…This puts restrictions on the type of seismic imaging that can be performed and the scale of the structure that can be resolved. Surface wave tomography studies show pronounced high-velocity continental roots beneath several Precambrian tectonic units (e.g., Ordos Plateau, Songliao Basin, Sichuan Basin) of SE Asia (Lebedev and Nolet, 2003;Debayle et al, 2005;Lebedev et al, 2005) and a seismically fast Indian lithosphere under southeastern Tibet (Friederich, 2003). These features can also be inferred from global shear-wave velocity models (e.g., Trampert and Woodhouse, 1995;Ekström et al, 1997;Shapiro and Ritzwoller, 2002).…”

Section: Introductionmentioning

confidence: 95%

Constraining P-wave velocity variations in the upper mantle beneath Southeast Asia

Hilst

Toksöz

2006

Physics of the Earth and Planetary Interiors

178

135

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We have produced a P-wave model of the upper mantle beneath Southeast (SE) Asia from reprocessed short period International Seismological Centre (ISC) P and pP data, short period P data of the Annual Bulletin of Chinese Earthquakes (ABCE), and long period PP-P data. We used 3D sensitivity kernels to combine the datasets, and mantle structure was parameterized with an irregular grid. In the best-sampled region our data resolve structure on scale lengths less than 150 km. The smearing of crustal anomalies to larger depths is reduced by a crustal correction using an a priori 3D model. Our tomographic inversions reveal high-velocity roots beneath the Archean Ordos Plateau, the Sichuan Basin, and other continental blocks in SE Asia. Beneath the Himalayan Block we detect high seismic velocities, which we associate with subduction of Indian lithospheric mantle. This structure is visible above the 410 km discontinuity and may not connect to the remnant of the Neo-Tethys oceanic slab in the lower mantle. Our images suggest that only the southwestern part of the Tibetan plateau is underlain by Indian lithosphere and, thus, that the upper mantle beneath northeastern Tibet is primarily of Asian origin. Our imaging also reveals a large-scale high-velocity structure in the transition zone beneath the Yangtze Craton, which could have been produced in multiple subduction episodes. The low P-wave velocities beneath the Hainan Island are most prominent in the upper mantle and transition zone; they may represent counter flow from the surrounding subduction zones, and may not be unrelated to processes beneath eastern Tibet.

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“…Complex propagation effects may be at least partly corrected for when the source and receivers are located within the study area (e.g. Snieder 1986;Friederich 2003;Chen et al 2007;Fichtner et al 2013) or when the local structure is imaged below a large array (e.g. Friederich & Wielandt 1995;Bruneton et al 2002;Chevrot & Zhao 2007;Lin & Ritzwoller 2011;Salaün et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Arrival angle anomalies of Rayleigh waves observed at a broadband array: a systematic study based on earthquake data, full waveform simulations and noise correlations

et al. 2015

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S U M M A R YDeviation of seismic surface waves from the great-circle between source and receiver is illustrated by the anomalies in the arrival angle, that is the difference between the observed backazimuth of the incident waves and the great-circle. Such arrival angle anomalies have been known for decades, but observations remain scattered. We present a systematic study of arrival angle anomalies of fundamental mode Rayleigh waves (20-100 s period interval) from 289 earthquakes and recorded by a broadband network LAPNET, located in northern Finland. These observations are compared with those of full waveform synthetic seismograms for the same events, calculated in a 3-D Earth and also compared with those of seismograms obtained by ambient noise correlation. The arrival angle anomalies for individual events are complex, and have significant variations with period. On average, the mean absolute deviation decreases from ∼9 • at 20 s period to ∼3 • at 100 s period. The synthetic seismograms show the same evolution, albeit with somewhat smaller deviations. While the arrival angle anomalies are fairly well simulated at long periods, the deviations at short periods are very poorly modelled, demonstrating the importance of the continuous improvement of global crustal models. At 20-30 s period, both event data and numerical simulations have strong multipathing, and relative amplitude changes between different waves will induced differences in deviations between very closely located events. The source mechanism has only limited influence on the deviations, demonstrating that they are directly linked to propagation effects, including near-field effects in the source area. This observation is confirmed by the comparison with seismic noise correlation records, that is where the surface waves correspond to those emitted by a point source at the surface, as the two types of observations are remarkably similar in the cases where earthquakes are located close to seismic stations. This agreement additionally confirms that the noise correlations capture the complex surface wave propagation.

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TheS-velocity structure of the East Asian mantle from inversion of shear and surface waveforms

Cited by 164 publications

References 44 publications

Asthenospheric flow and origin of volcanism in the Baikal Rift area

Asthenospheric flow and origin of volcanism in the Baikal Rift area

Constraining P-wave velocity variations in the upper mantle beneath Southeast Asia

Arrival angle anomalies of Rayleigh waves observed at a broadband array: a systematic study based on earthquake data, full waveform simulations and noise correlations

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