Crustal thickness and average V_p/V_s ratio variations in southwest Yunnan, China, from teleseismic receiver functions

Abstract

[1] Recently, many portable broadband three-component seismic stations have been deployed in Yunnan, China. We use teleseismic receiver functions to determine the crustal thickness (H) and the crustal average compressional to shear wave velocity (V p /V s ) ratio (k) variations beneath in southwest Yunnan. By comparing the synthetics generated from dipping Moho models with those from a flat Moho model, it reveals that for the rays traveling along or around the updip direction, the differential arrival times of Ps and multiples generated at the dipping Moho are comparable with those generated at the flat Moho and the result from stacking with these synthetics is a better estimate of model structure. For the synthetics traveling along or around the downdip direction, the differential arrival times of Ps and multiples generated at dipping Moho are smaller than those generated at flat Moho and make the H-k stacking results deviate from the model structure. Thus, the ambiguity induced by dipping Moho can be reduced significantly by only stacking with the rays traveling along or around the updip direction. Applying this technique to 19 stations, we obtained that H ranges from ∼35-42 km and the k ranges from ∼1.66-1.78. From the central Simao basin, H increases northward and northeastward; k increases significantly northeastward across the Ailao Shan-Red River shear zone.

Magnitude and symmetry of seismic anisotropy in mica‐ and amphibole‐bearing metamorphic rocks and implications for tectonic interpretation of seismic data from the southeast Tibetan Plateau

“…The Ailao Shan‐Red River fault zone is a tectonic boundary separating the Indochina block with an average crustal thickness of 36–37 km on the southwest and the Yangtze block with an average crustal thickness of 40–42 km on the northeast [ Sun et al , ]. The thickness of the crust beneath west Yunnan between the Ailao Shan‐Red River fault zone and the Nabang fault zone increases northward [ Sun et al , ; Wang et al , ]. The thickness of the lithosphere beneath west Yunnan [ Hu et al , ] is about 80–100 km, which is much thinner than that beneath Sichuan (140–180 km).…”

Receiver function structure beneath four seismic stations in the Sumatra region

“…The inversion of teleseismic receiver functions is a strategy that is commonly employed to determine the velocity structure beneath three-component seismic stations, e.g., Langston (1977), Ammon and Zandt (1993), Searcy et al (1996), Midzi and Ottemoller (2001), Park et al (2009), Wang et al (2010). The receiver function technique exploits the fact that P-to-S converted waves have higher amplitudes in the radial component than in the vertical.…”

Seismic evidence for the stratified lithosphere in the south of the North China Craton

“…The PRF studies of Langston and Hammer [] revealed that the complex structures beneath sedimentary basins may induce strong P wave coda and interfere with the deconvolution. The strong multiples (especially PpPp ) generated by dipping interfaces would result in the failure of the deconvolution as well [ Wang et al ., ]. The Shanxi rift is covered by thick sediments, and the complex structures below cause the failure of calculating PRF (Figure b).…”