| Autor: |
Cuiping Zhao, Si-Hua Zheng, Lian-Qing Zhou, Xian Zheng |
| Rok vydání: |
2012 |
| Předmět: |
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| Zdroj: |
Chinese Journal of Geophysics. 55:587-597 |
| ISSN: |
0898-9591 |
| DOI: |
10.1002/cjg2.1752 |
| Popis: |
We present high resolution ambient noise tomography of central and eastern China using vertical- component seismograms recorded by 494 evenly distributed broadband stations from China National Seismic Network and regional networks and 7 IRIS stations. 21 months of continuous data are used from January 2009 to September 2010. We first obtain empirical Green functions (EGF) after cross-correlation and stacking between all possible station-pairs. Then we retrieve about 125000 Rayleigh wave dispersion curves using frequency-time analysis method and reject those with SNR< 10. Finally, we invert for Rayleigh wave group velocity maps from 8 s to 40 s. The resolution can reach about 0.5° at these periods. Our group velocity maps agree well with known geological and tectonic features. Major basins in the study area are delineated by low velocities at short periods (8~20 s), while orogenic belt and uplift areas are manifested by high velocities. The NNE-SSW trending boundary between high and low velocities can be clearly seen at longer periods (25~40 s), which coincides with the well-known Gravity Lineation. North China plain shows remarkable low velocity at group velocity maps below 25 s. The shape of low velocity zone coincides with the block distribution of the plain since Paleogene. A relative high velocity zone is observed in the central part of low velocity Sichuan basin, revealing an uplifted basement beneath the basin. The velocity in northwest of Ordos basin is lower than southeast among the tomography maps under 20 s, revealing the lateral heterogeneity in mid-upper crust. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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