STATE GEOLOGIC LANDSLIDE PROGRAMS: WHAT IS WORKING AND WHAT ISN'T

Many state geologic surveys have a responsibility or regulatory obligation to provide landslide hazard data to their citizenry. The Association of American State Geologists has adopted a policy advocating geological hazard risk assessments and strong federal-state hazard program partnerships. Landslide hazard programs frequently are not a high priority.

In 35 states landslides are considered a hazard. Fewer than half the 50 state surveys have full or partial landslide inventories and less than 10% have active landslide hazard programs. The inventories vary in scope and completeness from paper copies of decades-old mapping to interactive web based maps and GIS databases.

We examine the efforts of Oregon to develop a landslide hazard program. Oregon’s geology, mountainous terrain, and high precipitation combine to create high landslide hazard. In 1996-97 alone, 3 severe storms caused ~9,500 landslides which resulted in 5 fatalities and $100s millions in damage. This major event increased public perception of landslide hazards in Oregon and prompted the Oregon Department of Geology and Mineral Industries (DOGAMI) to increase landslide studies. In 2007, Oregon sustained ~$30 million in direct losses from landslides triggered from one localized storm.

In 2005, DOGAMI and the USGS Landslide Program entered a 5 year cooperative research agreement. One of the purposes of this collaboration is to increase understanding of landslide hazards in Oregon and provide funding to help setup a permanent landslide program at DOGAMI. The program’s first products are landslide inventories including the Statewide Landslide Information Database (SLIDO) and current Inventory Mapping of Landslide Deposits within local Oregon communities. Both of these products have improved DOGAMI’s ability to collect and distribute data about landslides. These inventories will be used to create susceptibility maps that display areas likely and unlikely to have landslides in the future. After landslide hazards have been identified, the risk can be quantified and mitigation projects identified, prioritized, and implemented.

It required three actions to occur to spur a landslide hazard reduction program in Oregon: public and state recognition of high hazard, strong federal-state partnership, and collection of lidar elevation data.