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Crosshole ultrasonic tomography is referred to ray tracing by griding method and image reconstruction by combining the successively linearized iteration with damping least-squares QR decomposition, with which the result has better precision than that with crosshole seismic tomography by using the same inversion method in engineering geological investigation. It has been proved in practice that the investigation with crosshole ultrasonic tomography can clearly show the location and shape of the abnormal geological unit with the volume more than 60 cm when the crosshole distance exceeds 30 m. The result of investigation has been confirmed by the drilling. The crosshole ultrasonic tomography method will be extensively used in the engineering geological investigation.

The Tancheng–Lujiang (Tanlu) fault zone is the most active fault zone in eastern China. In this zone, the Anqiu–Juxian fault represents the most recently active fault and has the clearest surface traces and the highest seismic risk. This study comprehensively analyzes the kinematic characteristics of the Jiangsu segment of the Anqiu–Juxian fault using field geological surveys, trenches, shallow seismic reflection surveys, combined borehole section exploration, and middepth seismic reflection surveys. The results show that the Jiangsu segment of the Anqiu–Juxian fault features a single branch in the bedrock outcrop area, with reverse strike-slip motion near North Maling Mountain and Chonggang Mountain and normal strike-slip motion near South Maling Mountain. The sedimentary zone features two normal strike-slip faults (east and western branches), which represent the synsedimentary boundaries of a half-graben rift basin. The kinematic process is represented by rotational movement along the strike-slip fault with a curved path. The resulting tensile and compressive stresses are accommodated by dip-slip movement at both ends of the strike-slip fault. The activity of the Jiangsu segment of the Anqiu-Juxian fault can be divided into two periods. The first period of activity occurred before the later part of the Late Pleistocene, when movement along this curved segment occurred, forming the western branch of the Xinyi segment and the eastern branch of the Suqian segment. The second period of activity started in the later part of the Late Pleistocene and continues today. It is characterized by activity on the western branch of the Xinyi segment and the western branch of the Suqian segment of the Jiangsu segment, while the eastern branch of the Xinyi segment and the eastern branch of the Suqian segment became inactive and can be considered Late Pleistocene faults. The maximum vertical slip rate of the Jiangsu segment of the Anqiu–Juxian fault since the Pleistocene has been 0.28 mm/a. The Jiangsu segment of the Anqiu–Juxian fault formed via dextral strike-slip faulting, mainly due to the southward movement of the region to the east of the fault.

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