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.