Volcano Watch: Seismic event devastated Ka‘u 150 years ago

Left, this cross-section through the south part of the Island of Hawaii illustrates the hypocenter of the 1868 great Kaʻū earthquake (red star), located on the décollement (bold black line) between Mauna Loa (brown) and the ancient ocean floor (tan). Earth’s lithospheric mantle and the ocean are represented in green and blue, respectively. [Right] The striped pattern on this map of Hawaii Island indicates the areas of Mauna Loa and Kilauea that must have moved along the décollement to produce the magnitude-7.9 Kaʻū earthquake in 1868. Red lines depict the rift zones on Mauna Loa (left) and Kilauea (right). The approximate epicenter of the earthquake is shown as a yellow dot, and the direction of slip along the décollement is shown with black arrows. Graphics are modified from Max Wyss, Bulletin of the Seismological Society of America, 1988.
Destruction caused by the 1868 great Ka‘u earthquake included the Wai‘ohinu church, shown here, in the Ka‘u District of Hawaii Island. With a magnitude estimated at 7.9, the earthquake is the largest in Hawaii’s recorded history. Photo by Henry L. Chase, published in “Volcanoes of Kilauea and Mauna Loa on the Island of Hawaii” by W.T. Brigham, Bishop Museum Press, 1909.

This week marks 150 years since the largest earthquake to strike Hawaii in the last two centuries. Estimated to have been at least magnitude-7.9, this earthquake struck near Pahala in the Ka’u District of the Island of Hawaii on April 2, 1868.