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Roger Weller, geology instructor
by Alex Jirousek
A Brief History of Landslides
Landslides have been occurring naturally for millions of years, slowly carving
the earth. The presence of man has only contributed to the frequency of
landslides. Humans have built homes on steep slopes, and humans have cut into
already steep slopes to build roads and install utility lines. The picture
below shows a road that has surely contributed to the landslide that occurred on
a severe slope.
before humans, landslides kept a natural balance as the surface of the planet
constantly changed. Volcanoes and tectonic plate activity caused the mountain
ranges to spring up in the first place. Then, over time, through wind, rain,
and other forms of natural erosion(including landslides) the mountains were
steadily reduced creating a constant geological
the reasons landslides have been so hazardous is that they have occurred in
every state in the U.S. More than 25 people have died every year due to
landslides. An estimated $1-2 billion dollars in damage is done every year in
the U.S. alone. The picture below shows someone’s pick-up truck in someone
else’s garage along with several tons of mud. The two vehicles that were
supposed to be in the garage are completely buried.
areas of the U.S. have been considered hotspots for landslides. This is largely
due to the frequency of other natural disasters like floods, earthquakes, even
wildfires. Large mountain ranges and along large rivers are also places where
landslides have occurred frequently. The map below clearly illustrates
high-risk areas for landslides. The Appalachian and Rocky Mountains, the
Mississippi River, and the west coast of the U.S. are all places where
landslides have been common.
is not alone though, landslides have occurred all over the world. Some of the
areas landslides have commonly occurred have been densely populated, such as
southeast Asia. The map below shows that the north and south poles are safest
places on earth, however uninhabitable they might be. The black dots show where
landslides occurred between 2003 and 2006.
millions of years, and an increasing human impact there is no sign of decline
for landslides now. Before building a house on the hillsides of the California
coast, consider the lay of the land and its’ ever-changing surface. After all,
what goes up must come down.