In March a landslide in Oso, Washington destroyed a neighborhood, killing 43. This week two scientific analyses were issued (H/T ScienceInsider). On Tuesday the Geotechnical Extreme Events Reconnaissance team (GEER, sponsored by the National Science Foundation), released its report. Earlier today Science reported on the unpublished analysis from the U.S. Geological Survey and researchers at the University of Washington. A notable difference between the two reports deals with the how of the slide.
The GEER team, which is set up to do quick analyses of natural disasters, theorizes that the slide happened in two phases. The first slide was augmented by the collapse of a portion of the mountain when underlying support gave way. One of the USGS researchers explained their theory of the slide (which was significantly larger than the smaller slides that frequent the area) as more compressed. They believe the second spike in the seismic data is not a major event, and that an upper portion of the mountain broke off much sooner. It comes down to debates over the proper analysis of seismic data.
What the GEER report highlights is the absence of systematic assessment of potential for landslides when planning construction. Given what has been achieved for building in areas prone to earthquakes, it’s a little surprising that similar efforts have not taken place for areas with higher potential for landslides. The failure to use detection systems and take advantage of historical data are similarly surprising. Presumably the USGS report, whenever it’s released, won’t be as far apart from the GEER team in terms of recommendations. We’ll have to wait and see.
What you might not want to wait on is to see if you nearest slide area is taking advantage of new detection and monitoring systems. To have the tools and not use them strikes me as tragic, especially given the catastrophic nature of most slide losses (losing one house is a catastrophe – to that family).