Area Affected by Earthquakes at Kapoho, Hawai‘i, in Apr., 1925

Prior to the May 1924 explosive eruption of Kīlauea Volcano, magma drained from the summit of the volcano and moved down the east rift zone to lower Puna. The magma intruded upward toward the surface, producing more than 20 gaping cracks extending from Kapoho village up rift to Pu`u Ki`i and down rift to the east tip of the island. The zone of cracks paralleled the east rift zone and was some 6.5 km (4 miles) long and 1.5 km (1 mile) wide. The broken zone was bounded by faults with vertical movement. A zone of cracks formed the south side of the 0.8 km wide (0.5 mi wide) sunken block, a "graben" geologically speaking. The graben extended down rift to the coastline at a place called Kapele northwest of Cape Kumukahi, dropping the shore about 3.7 m (12 feet) and forming a new lagoon 2-2.5 m (8-12 feet) deep that reached inland 60 m (200 feet). This deformation produced hundreds of earthquakes in the Kapoho region in April 1924.