What are my risks?

• Seismic Hazard Ranking for Oahu
• History of earthquakes in Oahu

Seismic Hazard Zones in Oahu

In 1997, Oahu upgraded their Uniform Building Code seismic risk zone ranking from a 1 to a 2A. The UBC contain six seismic zones, ranging from 0 (no chance of severe ground shaking) to 4 (10% chance of severe shaking in a 50-year interval).

The risk from living in a seismically active area, unlike that of living in an area prone to being covered by lava, also depends to a large degree on the type of construction used in a given home. Earthquake shaking may damage certain types of houses, while leaving other types of construction unscathed. For all of these reasons, earthquake hazards are highly localized, and it is difficult to define broad zones with the same relative degree of hazard.

For more information about Seismic Hazards in Hawaii click here.

History of Earthquakes on Oahu

Each year thousands of earthquakes occur in Hawaii, with the majority of them too small to be felt except by highly sensitive instruments. However, there have been earthquakes that jolted the islands. The island of Hawaii has experienced numerous earthquakes of magnitude 5 or greater.

Earthquakes are not only concentrated on the Big Island. The Oahu Earthquake of 1948, which occurred along the Diamond Head Fault, was measured between 4.8 and 5.0 and resulted in broken store windows, plaster cracks, ruptures in building walls, and a broken underground water main.

In 1871, the Lanai Earthquake had a magnitude of 7 or greater. Massive rockfalls and cliff collapse occurred on Lanai as well as damages to homes. A house and churches were flattened on the island of Maui and Molokai. Two houses were reported to have split open on Oahu. And ground fractures and land slippage was reported in Waianae and Lahaina.

History of Earthquakes in Hawaii, M6 and Greater, 1868-Present

History of Earthquakes in Hawaii, M6 and Greater, 1868-Present

Source: Atlas of Hawaii, Third Edition, 1998