Report No. : GEO Report No. 337

Report Title : Review of Alert Criteria In Respect of Natural Terrain Hazards (2018), 20p.

Author : F.W.Y. Ko

Abstract

This study reviews the Alert Criteria in respect of natural terrain hazards as stipulated in GEO Report No. 138 with due regard to the latest landslide data. The review examines the travel angles, toe slope angles and runout distances beyond ≤ 15° ground slope of all recent landslides in the Enhanced Natural Terrain Landslide Inventory (ENTLI), and makes recommendations on possible improvements.

The Alert Criteria have been reviewed using the most up-to-date landslide data in the ENTLI and the 1:1000-scale topographic maps, together with the latest Geographic Information System technology. The resolution and accuracy of the measurements of the travel angles, toe slope angles and runout distances beyond ≤ 15° ground slope are greatly enhanced. As a result, the findings of the review are more reliable and representative.

The findings of the review indicate only minor variations (about 1%) in the cumulative percentages of natural terrain landslides covered by the two criteria under the Alert Criteria, as compared to the previous study. Change to the Alert Criteria is considered not necessary at this stage.

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