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Cycle 1 (2011 Deadline)
Earthquake-generated landslide hazard in Lebanon
PI: Grace Abou-Jaoude, Lebanese American University
US Partner: Joseph Wartman, University of Washington
Project Dates: May 2012 - April 2014
Project Overview
Lebanon is located in a relatively high seismic zone and has a rugged topography, making it vulnerable to hazards from earthquakes and landslides. Records about seismic events in the country go back to 303 AD and contain descriptions about such damages as houses and monuments destroyed and widespread fires, but they offer few if any details about collateral damages from landslide hazards associated with earthquakes. Although Lebanon has not experienced any major earthquake since 1956, the recent discovery of an active thrusting fault close to its coastline has significantly raised its risk of being hit by a high magnitude earthquake. Past studies on seismic hazards in Lebanon have focused on seismic zoning and its impact on structural engineering design. Although many researchers have assessed slope stability hazards in Lebanon based on various static conditions, no effort has been undertaken as yet to assess the impact of a seismic event on triggering landslide hazards in the country.
This project aims to produce a hazard map of Lebanon that clearly shows the critical areas prone to earthquake-induced landslides. This goal will be achieved through three major activities to be conducted over a period of two years. The first task will be mapping the landslide prone zones in the Geographic Information Systems (GIS) framework, followed by a detailed geological field survey. The second task will focus on numerical modeling of slopes, including seismic slope stability analyses in order to evaluate the failure potential of sloping terrains when subjected to different seismic loading events. The third task will be to produce an up-to-date earthquake-induced landslide hazard map, taking into consideration the effects of the active faults in the country, the general terrain parameters, and the seismic slope stability analyses. Ultimately the project should help Lebanese cities to identify areas with high natural hazard potential so they can plan urban growth appropriately, thus preventing damage to critical infrastructure and saving lives in the event natural disasters strike.
Summary of Recent Activities
The tasks conducted during the first quarter of 2013 included (1) interpretation of the first Newmark analysis (an engineering method used to calculate the permanent displacements of soil slopes) that was performed on ArcGIS using the 1:200,000 geology map of Lebanon, (2) completion of the digitization of the 1:50,000 geology maps and faults map of Lebanon, and (3) Dr. Abou-Jaoude’s visit to the U.S. partner Dr. Wartman at the University of Washington and subsequent attendance at the GeoCongress 2013. Work is ongoing to identify soil strength parameters for the new geologic units revealed through the 1:50,000 scale geology maps of Lebanon. Threshold slope angles will be set between the three categories of expected mass movements, and sensitivity analyses will be conducted on slope angle and slope height or failure surface. Dr. Abou-Jaoude and her group will also conduct a literature review to check their results against available threshold slope angles considered by other researchers. By the end of the next quarter, the team plans to obtain a new map of Lebanon where every expected category of mass movement can be identified. This map will form the basis of the refined analysis planned for the upcoming months.
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