Landslides Real Estate: Mass Movements Every Year

Landslides

Real Estate: Mass Movements

Every year the news media seems to contain at least one report of a landslide in the United States or elsewhere in the world. These events are news-worthy because lives are lost and property destroyed. Most landslides leading to the loss of life and property take place in developing countries, where populations have expanded into unregulated, hilly areas around major urban areas (Smith and Petley 155-157). The areas tend to be characterized by steep slopes, seismic activity, and prone to strong storms. Since these factors are also present in the United States, primarily in Southern California and Western Washington, property and loss of life can occur here as well.

Over the past several years, Western Washington has garnered the attention of the U.S. Geological Survey because of the area's propensity for landslides (USGS). This region is hilly and mountainous, densely populated, and typically experiences high levels of rainfall during the winter months. The area is also prone to seismic activity, which means that Western Washington is susceptible to most of the landslide risk factors experienced by some developing countries.

In contrast to the lower United States, which is expected to experience lower than normal rainfall in the future due to global warming, the northern U.S. is expected to experience above normal rainfall levels (EPA sec. "Future Precipitation and Storm Levels). This is relevant to Western Washington because laboratory experiments by Germer and Braun have revealed that rising water tables may represent a significant landslide risk (477). The implications of this finding is that in addition to the landslide risk posed by strong storms, above normal rainfall levels in general can increase landslide risk. For example, generally wet weather and frequent minor rainfalls could combine to increase the water table and thus destabilize slopes from below. Western Washington may therefore experience an increase in landslide activity in the future if rainfall levels continue to increase due to global warming.