Kohala (mountain)
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| Kohala Mountains | |
|---|---|
 A view of Kohala Volcano from the slopes of Mauna Kea |
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| Elevation | 5,480 ft (1,670 m) |
| Location | Hawaii, USA |
| Range | Hawaiian Islands |
| Coordinates | |
| Topo map | USGS Kamuela |
| Type | Shield volcano |
| Age of rock | 460,000-120,000 yr |
Kohala, also known as the "Kohala Mountains," is the name of an extinct volcano on Hawaii Island in the state of Hawaii. At its highest elevation, Kohala is 5,480 feet (1,670 meters) above sea level.
Kohala is believed to be the oldest volcano that makes up Hawaii Island. It is thought to have breached sea level about 500,000 years ago. Its eruptive activity began to wane about 300,000 years ago. At about this time, it is thought that the volcano was about twice as wide as it is today. However, because the island of Kohala is slowly sinking into the Pacific Ocean's seafloor, the volcano began to sink faster than new eruptions could replace what was being lost to subsidence. Thus, the volcano's size began to recede as it sank below sea level. Kohala's activity continued to wane and it is thought that the volcano last erupted about 120,000 years ago.
As Kohala slowly waned, its southern flanks were buried by the two younger volcanoes, Mauna Kea and Mauna Loa. Since Kohala'a southern flanks are buried, it is difficult to determine the size and shape of the volcano when it was at its prime.
About 250,000 to 300,000 years ago, a large landslide on the northeastern flank of the volcano removed a massive portion of the mountain, estimated to be as much as a section 20 kilometers wide. The part of the mountain removed by the landslide collapsed into the ocean at a very high speed and traveled as much as 130 kilometers across the ocean floor. The large seacliffs on the northeast flank of the volcano mark the headwall of this landslide.
Kohala is named after the district of Kohala, which exists on the volcano's southwest flank.
