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Three-dimensional modelling of the crustal structure in the contact zone between Antarctic Peninsula and South Pacific from seismic data

100%

Środa P. , Środa P.

nr 2

Crustal velocity structure in Borneo Island using receiver function inversion

86%

Syuhada S. , Pranata B. , Anggono T. , Ramdhan M. , Zulfakriza Z. , Febriani F. , Prasetio A. D. , Dewi C. N. , Hasib M. , Sulaiman A.

2022

tom Vol. 70, no 6

2529--2553

Borneo is an island situated in a tectonically complex region and characterised by multiple arcs and continental blocks accreted during the Mesozoic and early Cenozoic. We analyse receiver functions of teleseismic events from 12 seismic stations around the island. In general, these stations sample a variety of geological environments, including Meratus Complex, Eastern Borneo, South–Western Borneo, North–Western Borneo, and Sabah Zones. We then derive the shear wave velocity models from the inversion of receiver functions using the stochastic non-linear approach. Inversion results indicate that the island is covered by sedimentary layers with thickness ranging from 1 to 3 km thick. The inversion solutions for most stations also show that the crustal thickness varies between 26 and 36 km around the region. The variation in the average crustal Vp/Vs values obtained for each seismic station addresses the geological diversity of the study area. Furthermore, the lowvelocity zone with high and low Vp/Vs in the lower crust observed beneath some seismic stations may be associated with the tectonic evolution and development of Borneo Island. The results inferred from our inversion are generally consistent with other previous geological and geophysical studies conducted in this region.

Seismic crustal structure of the Bransfield Strait, West Antarctica

86%

Janik T.

nr 3-4

Lithospheric structure of the Arabian Shield from joint inversion of P- and S-wave receiver functions and dispersion velocities

58%

Al-Amri A. M.

tom Vol. 65, no. 2

227--243

New velocity models of lithospheric thickness and velocity structure have been developed for the Arabian Shield by three tasks: 1) Computing P-Wave Receiver Functions (PRFs) and S-Wave Receiver Functions (SRFs) for all the broadband stations within the Saudi seismic networks. The number of receiver function waveforms depends on the recording time window and quality of the broadband station. 2) Computing ambient noise correlation Green’s functions for all available station pairs within the Saudi seismic networks to image the shear velocity in the crust and uppermost mantle beneath the Arabian Peninsula. Together they provided hundreds of additional, unique paths exclusively sampling the region of interest. Both phase and group velocities for all the resulting empirical Green’s functions have been measured and to be used in the joint inversion. 3) Jointly inverted the PRFs and SRFs obtained in task 1 with dispersion velocities measured on the Green’s functions obtained in task 2 and with fundamental-mode, Rayleigh-wave, group and phase velocities borrowed from the tomographic studies to precisely determine 1D crustal velocity structure and upper mantle. The analysis of the PRFs revealed values of 25 - 45 km for crustal thickness, with the thin crust next to the Red Sea and Gulf of Aqaba and the thicker crust under the platform, and Vp/Vs ratios in the 1.70 – 1.80 range, suggesting a range of compositions (felsic to mafic) for the shield’s crust. The migrated SRFs suggest lithospheric thicknesses in the 80-100 km range for portions of the shield close to the Red Sea and Gulf of Aqaba and near the Arabian Gulf. Generally, the novelty of the velocity models developed under this paper has consisted in the addition of SRF data to extend the velocity models down to lithospheric and sub-lithospheric depths.

Huge contrasts of the lithospheric structure revealed by new generation seismic experiments in Central Europe

58%

Guterch A. , Grad M. , Keller R. G.

tom Vol. 52, nr 8/2

753-760

Beginning in 1997, Central Europe, between the Baltic and Adriatic Seas, has been covered by an unprecedented network of seismic refraction experiments (Fig.1A). These experiments — POLONAISE’97, CELEBRATION 2000, ALP 2002, and SUDETES 2003—have only been possible due to a massive international cooperative effort. International Consortium consisted of more than 30 institutions from 16 countries in Europe and North America—Austria, Belarus, Canada, Croatia, Czech Republic, Denmark, Finland, Germany, Hungary, Lithuania, Poland, Russia, Slovakia, Slovenia, Turkey, and the United States. The majority of the recording instruments was provided by the IRIS /PASCAL Instrument Center and the University of Texas at El Paso (USA), the Geological Survey of Canada, and other countries. For example, in the CELEBRATION experiment, the total number was 1230 stations and 147 shot points located along seismic lines of a total length of about 9000 km. A large number of seismic sources and stations in all experiments means that besides 2-D approach along profiles, also 3-D approach could be implemented in data interpretation. Total length of seismic profiles in all experiments is about 20,000 km.