This week we are discussing 'mass wasting' events...aka, landslides, mudslides, rockslides, etc. These are very related to flooding and rain events, so is very relevant to our news!
These hazards are connected to others like earthquakes or flooding or wildfires.... although mass wasting events do not need any triggers (just gravity!). As an example, a 7.3 magnitude earthquake hit NE Japan and provoked several landslides and rockslides (image below).
Landslides in the United States cause approximately $3.5 billion in damage and kill between 25-50 people annually. The US Landslide inventory map below shows these hazards widespread within the country.
The largest landslide in modern U.S. history (in terms of volume) was most likely one that occurred in 2013 in Bingham Canyon outside of Salt Lake City, Utah. It had a slide mass of 55 million cubic meters (compared to an estimated 10 million cubic meters during the Oso event in 2014).
Landslides impact California’s terrain often. These are generally related to precipitation patterns, in particular if there has been previous months of drought conditions. In January 2019, Pacific storms brought a lot of rainfall to the state. The heavy rain forced residents to evacuate from wildfire-ravaged areas. The “high risk” areas for mudslides are so because they are adjacent to steep slopes or are located at the base of drainage areas. Recent examples are the ‘Woolsey’ and the ‘Hill’ fire burn areas, which will be subject to high volume of mud and debris flow moving forward.
Dr. Garcia-Garcia, it is a big contrast between USA and Mongolia, with respect to resources and mitigation plans. Our USGS provides us with extensive resources to investigate local risks across our country. I was unable to find any specific mass wasting plan in English for Mongolia, but I did find a page about the general risk mitigations, which said that Mongolia's risk analysis and mitigation communication plans are implement at the local level - and therefore very spotty. Nonetheless, like the USA, Mongolia experiences many mass wasting events each year. Luckily Mongolia is less densely populated than the USA, so any one mass wasting event has less likelihood to cause widespread damage and harm to humans and other animals.
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