THE STUDY OF BEIJING GROUND FISSURE BY SHALLOW REFLECTION SEISMIC SURVEY

摘要

The ground fissures are widely distributed in the northeast of Beijing, China. Which are a kind of geohazard related to active faults, earthquakes or groundwater withdrawals in loess areas and plains covered by recent sediments. The hazard made the building wall and basement dehiscence, the surface of runway and highway disconnected. The cause of ground fissuresn is unclear and heated debated. We design the shallow reflection experiment to survey the active structure and the stratum subsidence feature. The grid high density seismic lines had been layout on the ground fissure distribution area. The acquisition parameters are: trace interval 2m, shot interval 4m, line apace 20m. After data processing we get 20 high resolution seismic profiles. Then the precision interpretation been executed and got the shallow stratum and the deep structure character information. The result show that the factor of the ground fissure are complicate. One part of the ground fissure created by the deep active fault, and the other come from the composite element of the deep structure and the groundwater withdrawals.