报 告 人：曾祥方 博士 Department of GeoscienceUniversity of Wisconsin-Madison 报告时间：2016年1月18日（周 一）15:00—17:00 报告地点：中科院计算地球动力学重点实验室会议室 中国科学院大学科研楼西楼106室 报告简介： To refine the 3D seismic velocity model in the greater Parkfield, California region, a new dataset including regular earthquakes, shots, quarry blasts, and low-frequency earthquakes (LFEs) was assembled. Hundreds of traces of each LFE family at two temporary arrays were stacked with time-frequency domain phase weighted stacking (tf-PWS) method to improve signal-to-noise ratio. We extend our model resolution to lower crustal depth with LFE data. Our result images not only previously identified features but also low velocity zones (LVZs) in the area around the LFEs and the lower crust beneath the southern Rinconada fault. The former LVZ is consistent with high fluid pressure that can account for several aspects of LFE behavior. The latter LVZ is consistent with a high conductivity zone in magnetotelluric studies. A new Vs model was developed with S picks that were obtained with a new auto-picker. At shallow depth, the low Vs areas underlie the strongest shaking areas in the 2004 Parkfield earthquake. A high Vp/Vs zone in the middle crust on the northwest side of the San Andreas Fault was also revealed. We relocate LFE families and analyze the location uncertainties with the Non-Linear-Location and tomoDD. Both methods provide similar results. The attenuation tomography result will be introduced too. 报告人简介： Education: University of Science and Technology of China (USTC) Ph D., Sept. 2006 – Jul. 2012 Major: Geophysics University of Science and Technology of China (USTC) Bachelor of Science, Sept. 2002 – Jul. 2006 Major: Geophysics Minor: Finance Experience: Nov. 2013 -- Postdoctoral Associate Department of Geoscience, University of Wisconsin-Madison Feb. 2012 -- Postdoctoral CAS Key Lab of Computational Geodynamics, University of Chinese Academy of Sciences Sept.2006 – Jan. 2012 Graduate student School of Earth and Space Sciences, University of Science and Technology of China Sept. 2008 – Sept. 2009 Visiting student Earth Resource Laboratory, Massachusetts Institute of Technology Sept. 2002 – Jul. 2006 Undergraduate student School of Earth and Space Sciences, University of Science and Technology of China Professional Societies: American Geophysical Union, Student member (2008- ) Research Fields: Seismic structure Distributed acoustic sensing Source parameters of earthquake Seismic ambient noise source Publications: 2015 Zeng, X., C. Thurber, and D. Shelly et al. (2015) Three-dimensional P- and S-wave velocity structure and low-frequency earthquake locations in the Parkfield, California region. Submitted to Geophysical Journal International. Zeng, X. and C. Thurber (2015) A graphic processing unit implementation for time-frequency phase-weighted stacking, Seismological Research Letters, doi:10.1785/0220150192. Harrington, R., E. Griffiths, E. Cochran, X. Zeng and C. Thurber (2015) Earthquake relocations along the San Andreas Fault near Cholame, California suggest along-strike variations in fault frictional properties, Bulletin of the Seismological Society of America, in press. Zeng, X., J. Xie, and S. Ni (2015) Ground truth location of earthquakes by use of ambient seismic noise from a sparse seismic network: a case study in western Australia. Pure and Applied Geophysics, 172(6): 1397-1407. Luo, Y., L. Zhao, X. Zeng and Y. Gao. (2015) Focal mechanisms of the Lushan earthquake sequence and spatial variation of the stress field. Science China Earth Sciences, 58(7):1148-1158. Xia, Y., S. Ni, X. Zeng, J. Xie, B. Wang and S. Yuan. (2015) Synchronizing intercontinental seismic networks using the 26 s persistent localized microseismic source. Bulletin of the Seismological Society of America, 105(4): 2101-2108. 2014 Zeng X., H. Zhang, and X. Zhang et al. (2014) Surface microseismic monitoring of hydraulic fracturing of a shale‐gas reservoir using short-period and broadband seismic sensors. Seismological Research Letters, 85(3): 668-677 Zeng. X. and S. Ni (2014) Evidence for an independent 26-s microseismic source near the Vanuatu islands. Pure and Applied Geophysics, 171(9): 2155-2163. Zeng X., L. Han, and Y. Shi (2014) The April 24, 2013 Changning Ms4.8 earthquake: a felt earthquake that occurred in Paleozoic sediment. Earthquake Science, 27(1): 107-115. Han L., X. Zeng, and C. Jiang et al. (2014) Focal mechanisms of the 2013 Mw 6.6 Lushan, China earthquake and high resolution aftershock relocations. Seismological Research Letters, 85(1): 8-14. Thurber C., X. Zeng, A. Thomas and P. Audet (2014) Phased-weighted stacking applied to low-frequency earthquakes, Bulletin of the Seismological Society of America, 194(5): 2567-2572. 2013 Zeng X. and S. Ni (2013) Constraining shear wave velocity and density contrast at the inner core boundary with PKiKP/P amplitude ratio. Journal of Earth Sciences, 24(5): 716-724. Luo Y., X. Zeng, and S. Ni (2013) Progress on the determination of focal depth. Progress in Geophys.(in Chinese), 27(5): 1881-1889. Zeng X., L. Han, S. Ni and Y. Shi (2013) The source parameters of June 24, 2012 Ninglang-Yanyuan Ms5.7 earthquake, Earthquake (in Chinese), 33(4): 196-296. Zeng X., Y. Luo, L. Han, and Y. Shi (2013) The Lushan Ms7.0 earthquake on 20 April 2013: A high-angle thrust event. Chinese J. Geophys. (in Chinese), 56(4): 1418-1424. Zeng X., L. Han, and Y. Shi (2013) Focal mechanism of Lushan Ms7.0 earthquake, April 20, 2013, Science and Technology Review (in Chinese), 31(14): 5-8. Xia Y., S. Ni, and X. Zeng (2013) Twin enigmatic microseismic sources in the Gulf of Guinea observed on intercontinental seismic stations. Geophys. J. Int., 194(1): 363-366. 2012 Zeng X., S. Ni, and Y. Xia (2012) Estimated Green’s Function extracted from long time continuous seismic records. Progress in Geophys. (in Chinese),27(5): 1881-1889. Wu W. S. Ni, and X. Zeng (2012) Evidence for P’P’ asymmetrical scattering at near podal distances. Geophys. Res. Letts., 39, L11306. Yu Z., S. Ni, S. Wei, X. Zeng, W. Wu, and Z. Li (2012) An iterative algorithm for separation of S and ScS waves of great earthquakes., Geophys. J. Int.,191(2): 591-600. Xie, J., S. Ni, and X. Zeng (2012). 1D shear wave velocity structure of the shallow upper crust in central Sichuan Basin. Earthquake Research in Sichuan (in Chinese), 143(2): 20-24. Liu L., M. Gong, B. Hu, X. Zeng, and Y. Luo (2012) Preliminary study of shear wave velocity structure of Huabei and surrounding areas from ambient seismic noise. Earthquake (in Chinese), 32(4): 103-112. 2011 Zeng X.,Z. Zhan, and Y. Zheng (2011) Estimated Green’s function extracted from superconducting gravimeters and seismometers. Earthquake Science, 24(2): 143-150. Xie J., X. Zeng, W. Chen, and Z. Zhan (2011) Comparison of ground truth location of earthquake from InSAR and from ambient seismic noise: A case study of the 1998 Zhangbei earthquake. Earthquake Science, 24(2): 239-247. Luo Y., S. Ni, and X. Zeng et al., (2011), The M5.0 Suining_Tongnan(China) earthquake of 31 Juanuary 2010: A destructive earthquake occurring in sedimentary cover, Chinese Sci. Bull., 56(6): 521-525. Xia Y., S. Ni, and X. Zeng (2011), Polarization research on seismic noise before Wenchuan Earthquake, Chinese J. Geophys. (in Chinese), 54(10): 2590-2596. 2010 Zeng X. and S. Ni (2010) A persistent localized microseismic noise source near Kyushu Island Japan. Geophys. Res. Lett., 37,L24307. Luo Y., S. Ni, X. Zeng, Y. Zheng, Q. Chen, and Y. Chen (2010) A shallow aftershock sequence in the north-esatern end of the Wenchuan earthquake aftershock zone. Sci China D: Earth Sci., 53(11): 1655-1664. Chong J. S. Ni, and X. Zeng (2010) sPL, an effective seismic phase for determining focal depth at near distance, Chinese J. Geophys. (in Chinese), 53(11): 2620-2630. Wan K., S. Ni, X. Zeng, and P. Sommerville (2009) Real-time seismology for the 05/12/2008 Wenchuan earthquake of China, a retrospective view. Sci China D: Earth Sci., 52(2): 155-165.