Climate change may make terrible mudslides more common – ‘The slide is about a mile wide. Entire neighborhoods are just gone. When the slide hit the river, it was like a tsunami.’Posted by Jim at Wednesday, March 26, 2014
By Eric Holthaus
26 March 2014
The stories emerging are the definition of heart-rending. Here’s one, from the Seattle Times:
One volunteer firefighter who had stopped working around 11:30 p.m. Saturday night said many tragic stories have yet to be told. He watched one rescuer find his own front door, but nothing else—not his home, his wife or his child.
They’re in the “missing” category along with many it is feared will eventually be listed as dead.
“It’s much worse than everyone’s been saying,” said the firefighter, who did not want to be named. “The slide is about a mile wide. Entire neighborhoods are just gone. When the slide hit the river, it was like a tsunami.”
The most immediate cause of the mudslide is a near-record pace of rainfall for the area so far in the month of March.
The Pacific Northwest has had an exceptionally wet finish to its rainy season, as storms that historically would have hit California were re-routed northward by a semi-permanent dome of high pressure that’s been mostly responsible for the intensifying drought there.
This particular mudslide wasn’t just a freak event brought about by heavy rain, although this month’s deluge surely speeded the process. Another mudslide happened on this very same hillside just eight years ago.
In fact, the State of Washington recently completed a project aimed at preventing future mudslides, just short distance away from the site of this weekend’s deadly tragedy. Only problem is? It was on the other side of the river. Again, from the Seattle Times:
Sixteen months ago, the Washington State Department of Transportation (WSDOT) completed a $13.3 million project, called the Skaglund Hill Permanent Slide Repair, to secure an area just west of Saturday’s slide, on the opposite side of the Stillaguamish River.
That project covered about a half-mile stretch of Highway 530, from mile marker 36.25 to 36.67. It secured a hill south of the river. Saturday’s slide collapsed a hill north of the river and sent mud crashing into the Stillaguamish and across Highway 530 between mile markers 37 and 38, according to WSDOT.
This weekend’s tragedy reminds me of a similar pair of mudslides that occurred in 1995 and 2005 along the coast of California, in the tiny town of La Conchita. In 2005, heavy rains caused groundwater levels to rise, re-mobilizing the previous debris flow and creating a repeat tragedy.
Like in La Conchita, this weekend’s disaster occurred in an area known for its landslides. There are surely other, more remote areas where this process happens with less tragic results.
One of the most well-forecast and consequential components of human-caused climate change is the tendency for rainstorms to become more intense as the planet warms. As the effect becomes more pronounced, that will make follow-on events like flooding and landslides more common. [more]