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What
are my risks?
What
areas are prone to landslides?
Areas
generally more prone to landslides are those located at:
- previous
landslides
- base of
slopes
- base of
minor drainage hollows
- base or
top of an old, filled slope
- base or
top of a steep, cut slope
- developed
hillsides with leach-field septic systems.
SOURCE:
State of California Department of Conservation, Sacramento,
CA and National Landslide Information Center, U.S. Geological
Survey, Denver, CO
Recent
Oahu Landslides
On March 6,
2000, rock and debris fell onto Kamehameha Highway at
Waimea Bay. A new, $4 million stretch of highway has been
constructed 38 feet makai to mitigate future risk to motorists.
In May 1999,
boulders and other debris slid down the right slope, dropping
500 feet at Sacred Falls State Park in Hauula, Oahu, killing
9 people. Geologists speculate dry conditions may have
separated the clay from the mountainside, loosening the
rock front.
A mudslide
in Makaha swept away several cars and bikes and left rocks
and mud in the lobby of the Makaha Valley Towers condominium
in November 1996.
On Woodlawn
street in Manoa Valley a whole series of houses were sliding
down the hill.
At the now
defunct Kailua Drive on the Windward side of Oahu, they
had oversteepened the slope, and for many years after
the drive in opened, every time it rained, parts of the
cliffs would collapse and block the entrances.
Back in the
1960s in Aina Haina and Niu Valley 7 houses were sliding
downhill.
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