Oso, Washington Mudslide
Storm Damage

Oso, Washington Mudslide

Cleanup continues after a disastrous and deadly mudslide in Washington state. On March 22, 2014, a mudslide covered an area of about one square mile, killing 39 with 4 still missing. Our hearts and prayers go out to their surviving families.

As previously posted, mudslides are almost always unpredictable.

Mudslides are a subcategory of landslides, basically a moving river of rock, earth, and debris that has become saturated with water. Mudslides can vary in speed, although they do grow in size as they move along and their momentum allows them to easily pick up trees, cars, houses, and anything else that gets in their way.  Mudslides occur year round, in all kinds of weather condition, and usually, strike with little or no advance warning.

What Causes a Mudslide?

Mudslides may be the result of earthquakes, volcanic eruptions, changes in levels of groundwater, freezing and thawing cycles, and slopes caused by erosion. There may also be man-made causes, such as the reckless modification of land for development and construction.

Because different geographical locations have different compositions of soil, not to mention different slopes and other characteristics, it is very difficult to determine exactly how prone a given area is to a mudslide, much less predict when one will occur.  Many mudslides occur on the west coast due to the proliferation of earthquakes, rainfall and wildfires that crop up every year. California actually has a mudslide season that runs from December to April during which time the rainfall levels are fairly predictable.

California wildfires often leave behind charred slopes, making the area susceptible to mudslides as a result both during and immediately following severe storms.  More than 100 Californians have been killed by mudslides over the last quarter century, most of which were buried by debris flows as they slept in lower floor bedrooms that were located near hazardous areas.

Any time conditions are favorable for a mudslide, the appropriate response is to evacuate. Outrunning a mudslide is not advisable since it is a race you are likely to lose. Seek higher ground until the slide has passed and then wait for rescue personnel to arrive.

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