Historic Earthquakes

Near Napoopoo, Hawaii
1951 August 21 UTC
Magnitude 6.9

This earthquake probably was caused by movement on the Kealakekua fault. It inflicted property damage that extended from Holualoa on the north to Honuapo on the southeast, a distance of 80 km. Damage was most severe in the central Kona district, along a 16 km stretch from Captain Cook to Hookena. Here, several houses, churches, and a school building were damaged severely, and about 200 water tanks were demolished or damaged beyond repair (mainly owing to damage to footings). Many stone walls were thrown down. Roads were partly blocked by small rock slides; road pavement and shoulders were cracked badly; and telephone communications and electric power were disrupted. Tombstones were shifted, rotated, or overturned in many cemeteries in the area.

The earthquake was felt strongly throughout the island of Hawaii and slightly on Maui and Oahu (at Honolulu, about 290 km from the epicenter). Many aftershocks, all of lower intensity, occurred through September 1951. A small tsunami was observed at Hilo, Honolulu, and the Kona Coast area (maximum at Napoopoo-0.9 meters). Residents of Naalehu and Pahala reported bright flashes of white light at the time of the earthquake.

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.