Drowned and partially drowned landslide deposits off Tai O and their engineering implication
MSc in Applied Geosciences
Drowned and Partially Drowned Landslide Deposits off Tai O and Their Engineering Implication
The "stable" inner continental shelf in the territory of Hong Kong provides a record of eustatic sea-level changes dating back almost 0.5 Ma. Because of coastal development, numerous boreholes have been sunk in the offshore region of Hong Kong. This project is based upon the review and reinterpretation of some of these boreholes in order to further test the offshore geological model of Yim (1994). Tai O Bay is chosen as the area of investigation as there are both old and new borehole information available. The cliff exposure of landslide deposits on the coast of Po Chue Tarn is also excellent for exemplifying the effects of Quaternary sea-level changes on landslide deposits now partially drowned.
Two marine units are well-established in many boreholes in the study area. Further review and reinterpretation led to the identification of up to four marine units and four terrestrial units dating back to die third last interglacial period and the fourth last glacial period respectively.
Both pre-Holocene drowned and partially drowned landslide deposits are evident. Landslide deposits are recognized by their poor sorting and coarsening-upwards stratigraphy. The deposits comprise of cobbles and boulders are recognized to represent truly natural landslide deposits long before the appearance of humans on the landscape. These deposits are now either completely drowned or partially drowned along the present day coast. An active system of colluvial-alluvial fans is identified during glacial periods of low sea-level stands. Near Po Chue Tarn, the partially drowned landslide deposits eroded by the present day sea level are recognized to be at least pre-last interglacial in age. Confirmation of the multiple marine transgressions is available through die Vostok ice core in Antarctica while the higher sea level during last interglacial is supported by field evidence.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:landslides china hong kong tai o
Date of Publication:01/01/2000