Old Rocks
Diamond Member
Honolulu Star-Bulletin article on Hawaiian slumps
Unlike the debris avalanches, which are fast-moving and affect only the surface of the islands, slumps are slow and jerky, and involve blocks of earth as much as six miles thick, Moore wrote. Kealakekua, on the edge of this slump area, was the source of a major 6.8 magnitude earthquake in 1951.
Volcano observatory geologist Reggie Okamura remembers feeling that quake in Hilo, on the other side of the island.
"I felt it strongly," he said. "I was on the third story of Hilo High School."
Wright said he thinks that kind of force, though far smaller than the energy released by the debris avalanches, could still cause serious problems with the giant cracks in the Riviera area.
Wright's comments at the Land Use Commission followed testimony by Riviera geologists, so those experts had no immediate opportunity to respond, says Riviera attorney Ben Tsukazaki. The hearings are expected to last many more months and Riviera geologists may be called back to respond later, he said.
Besides the West Hawaii slump, Moore linked a giant East Hawaii slump to major earthquakes in 1823, 1868, and 1975. The 1975 quake, with a 7.2 magnitude, dropped land as much as 11 feet for 40 miles along the Puna-Kau coast and moved it seaward as much as 26 feet, he said.
Two people died in that quake. The 1868 quake, estimated at magnitude 8, killed 31 people and 500 animals, according to the Atlas of Hawaii.
Unlike the debris avalanches, which are fast-moving and affect only the surface of the islands, slumps are slow and jerky, and involve blocks of earth as much as six miles thick, Moore wrote. Kealakekua, on the edge of this slump area, was the source of a major 6.8 magnitude earthquake in 1951.
Volcano observatory geologist Reggie Okamura remembers feeling that quake in Hilo, on the other side of the island.
"I felt it strongly," he said. "I was on the third story of Hilo High School."
Wright said he thinks that kind of force, though far smaller than the energy released by the debris avalanches, could still cause serious problems with the giant cracks in the Riviera area.
Wright's comments at the Land Use Commission followed testimony by Riviera geologists, so those experts had no immediate opportunity to respond, says Riviera attorney Ben Tsukazaki. The hearings are expected to last many more months and Riviera geologists may be called back to respond later, he said.
Besides the West Hawaii slump, Moore linked a giant East Hawaii slump to major earthquakes in 1823, 1868, and 1975. The 1975 quake, with a 7.2 magnitude, dropped land as much as 11 feet for 40 miles along the Puna-Kau coast and moved it seaward as much as 26 feet, he said.
Two people died in that quake. The 1868 quake, estimated at magnitude 8, killed 31 people and 500 animals, according to the Atlas of Hawaii.
