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利用北京—丰镇及其邻区三分向宽角反射／折射ＤＳＳ剖面（总长３４０．０ｋｍ）所获信息和利用数字处理技术，充分识别、提取了地壳和上地幔顶部的多种Ｓ波折射、反射震相（波组）．结合Ｐ波解释结果，计算了包括Ｓ波速度ｖＳ和泊松比μ在内的二维物性结构，并综合近垂直反射、地质及其它地球物理等资料，给出了该区内深部构造轮廊和相应的解释推断：该剖面的地壳厚度由东边顺义的３５．０ｋｍ左右向西呈增加之势，至丰镇以东为４２．０ｋｍ左右，壳内于延庆以东的下地壳和延庆至涿鹿间的中地壳以及天镇以西的上地壳内各存在一低速体；地壳中由东向西有一厚约５．０～９．０ｋｍ的壳幔过渡带；大部分地区上、中地壳的μ值为０．２５，下地壳的μ值一般为０．２７，上地幔顶部的μ值为０．２８．表明了该区上、中地壳整体呈脆性，下地壳和上地幔顶部整体呈塑性的特征；延庆至涿鹿间，上地壳的低μ值，可能反映该处岩体裂隙（孔隙）发育且呈干燥充气状态，而中地壳的高μ值，则可能反映该处岩体充液（或呈部分熔融状）；根据震相特点、μ值的横向变化特征，确定了该区数条深部断裂．地震大多发生在断裂附近，即μ值显著变化处，并集中于μ值较低一侧的脆性岩体中．
Using the information obtained from the wide-angle reflex / refraction DSS profile (340.0km in total length) in Beijing-Fengzhen and its neighbors, and using digital processing techniques, various S-wave reflections at the top of the crust and the upper mantle were fully extracted , Reflection phase (wave group). Combined with the results of P wave interpretation, the two-dimensional physical structure including S-wave velocity vS and Poisson's ratio μ is calculated. Based on the data of near-vertical reflection, geology and other geophysics, The corresponding interpretation deduces that the thickness of the crust in this section increases from 35.0 km east of Shunyi in the east to about 42.0 km east of Fengzhen, and the crust in the lower crust to the east of Yanqing and Yanqing to Demol Between the middle crust and the upper crust west of the town, there is a low-velocity body. The crust has a crust-mantle transitional zone with a thickness of 5.0-9.0 km from east to west. In most areas, the μ Is 0.25, the value of the lower crust is generally 0.27, and the value of the top of the upper mantle is 0.28. It shows that the upper and middle crusts in the area are brittle, and the top of the lower crust and upper mantle are plastic as a whole. The low μ value of the upper crust between Yanqing and Zhuolu may reflect the development of cracks (pores) in the rock mass Dry and inflated state, while the high μ value of the middle crust may reflect that the rock mass is filled with liquid (or partially melted). According to the characteristics of seismic phases and the lateral variation of μ value, several deep faults in this area are determined. Most of the earthquakes occurred near the fault, that is, the value of μ was significantly changed and concentrated in the brittle rock mass on the lower μ side.