| Autor: |
Jing-Yuan Yin, Wei-Jun Gan, Ai-Lan Zhu, Xi-Wei Xu, Guihua Chen, Yongsheng Zhou |
| Rok vydání: |
2005 |
| Předmět: |
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| Zdroj: |
Chinese Journal of Geophysics. 48:692-700 |
| ISSN: |
0898-9591 |
| DOI: |
10.1002/cjg2.702 |
| Popis: |
We relocated 13367 small earthquakes that occurred in western Sichuan between 1992 and 2002 using a double-difference (DD) earthquake location algorithm to improve the relative location precision. The relocated microseismicity forms highly organized structures that correlate with the surface faulting well: showing the flower structure across the simple strike-slip fault, and the organized but dispersed structure across the pull-apart basin and thrust fault. Beneath thrust fault, there exists an aseismic layer. The seismicity shows segmentation characteristics on active fault zones. Other significant tectonic features that were previously obscured by routine location errors are also revealed by the relocated seismicity. Some blind faults are delineated by lineages of seismicity that are suggestive of faulting structures. A series of large voids in seismicity appear with dimensions of tens of kilometers on the Xianshuihe-Anninghe-Zemuhe fault zone that have been aseismic over the 10-year time interval, suggesting that these segments may be locked and storing strain energy for release in future large earthquakes. A 5km thick aseismic layer appears in most places in western Sichuan plateau at depths of 15~20km. The crustal strength envelopes are calculated for the western Sichuan plateau based on the results from hightemperature and high-pressure experiments. The result shows that the granite at depths of 14 to 19km appears to be ductile, which is in good agreement with the thickness and depth range of the aseismic layer, suggesting that the aseismic layer may be the result of the ductile deformation from the granite in the upper crust. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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