U.S.-Philippines SGER Planning Visit: Reconnaissance Survey of the February 17 2006 Leyte, Philippines, Landslide

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Schaefer0630446This award supports a project to enable Dr. Vernon Schaefer of the Iowa State University in Ames and Dr. Marte Gutierrez of the Virginia Polytechnic Institute in Blacksburg to meet with Dr. Gil Cardiel in the School of Earth and Material Science at Mapua Institute of Technology in Manila, Philippines. They plan to undertake a reconnaissance survey of the February 17, 2006 Southern Leyte, Philippines landslide. This landslide was one of the most significant to have occurred in the world over the past several decades. The town of Guinsaugon located at the foot of Mt. Can-abag with a population of about 1,857 was completely inundated by the slide debris and at least 1,328 persons are missing and presumed dead. The slide followed extensive rain with an accumulated rainfall of 674 mm from February 8 to 17, which is about five times higher than during normal rainy seasons. Unlike most landslides where a block-like failure occurs, this was a mud/debris flow where massive amounts of material flowed downhill at an incredible speed. Because so many areas of the world are prone to landslides like this, it is important to gather information about each major event. The United States has considerable losses from landslides each year. The survey will consist of geological mapping, surveying and characterization of the scarp and the debris, in situ testing and soil/rock sampling. The survey will be facilitated by the use of advanced technologies such as Global Positioning System (GPS), digital photogrammetry, LIDAE and portable testing devices. Soil and rock classification and laboratory tests for index, physical properties, permeability and shear strength will be carried out on samples to be collected from the site. Finally, 3D slope stability analysis will be performed to back-calculate shear strength and water conditions in the site, and to predict future movements at the site. A particular benefit expected from the project is improving the understanding of rainfall-induced slope failures in partly saturated weathered and fractured rock masses. The study will also help improve the understanding of the geological effects of severe weather conditions due to global warming. Determining the causes for the landslide could lead to predictive techniques that can be used to identify other areas where landslides are likely, and ways to identify critical factors that trigger this type of landslide. In addition the PIs will endeavor to make presentations in schools, civil defense and emergency management and other government officials to explain catastrophic slope failures and what can be done to reduce their occurrence and mitigate their impact. In addition, several US graduate students will be involved in the project and will be working in demanding conditions and environments in remote areas of the Philippines. It is anticipated that, following this project, the US and Philippine researchers will continue long-term collaborations in this important geohazards research area.