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WRRCTR No.8 Electromagnetic Mapping of Hawaiian Lava Tubes
|Title:||WRRCTR No.8 Electromagnetic Mapping of Hawaiian Lava Tubes|
|Authors:||Von Seggern, David|
Adams, William M.
|Keywords:||Kaumana Lava Tube|
|LC Subject Headings:||Lava tubes -- Hawaii -- Hawaii Island.|
|Date Issued:||Aug 1967|
|Publisher:||Water Resources Research Center, University of Hawaii at Manoa|
|Citation:||Von Seggern D, Adams WM. 1967. Electromagnetic mapping of Hawaiian lava tubes. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC technical report, 8.|
|Series:||WRRC Technical Report|
|Abstract:||A portable, electromagnetic loop-coupling device has been built to locate points on the earth's surface over points in an underground cavity and to determine the depth to the cavity. This method presently requires both an underground and a surface operator who each carry a motorcycle battery, a twenty-inch diameter loop antenna, and a compact transceiver circuit. The underground unit transmits to the surface a l200 hz signal which is essentially unattenuated and undistorted. The surface operator locates the transmitter by a nulling procedure. Three methods of determining depth are described. The accuracy of the location and the depth determination with the loop-coupling device is checked with a transit survey.
The device was applied with success to Kaumana Lava Tube on the island of Hawaii. Locations confirmed suspicions that the tube ran under roads and buildings. The roof of the tube was found to average about 25 feet thick. The accuracy of a compass-and-tape survey 4400 feet into the tube was checked by locations with the loop-coupling method and found to be in error by 20 feet.
Lava tubes are significant as conduits of water and as geologic hazards.
|Pages/Duration:||vi + 27 pages|
|Appears in Collections:||
WRRC Technical Reports|
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