Last week, the M=6.6 Hokkaido earthquake struck the southern region of Hokkaido island, near the city of Sapporo in Japan. The earthquake caused widespread electricity blackouts and multiple large landslides.
International Gravity Standardization Net 1971 . The world-wide network of the gravity base stations providing a reference frame for the absolute gravity measurements using the same type of gravimeters. Supersedes the Potsdam system that was defined by pendulum measurements in 1906.
split-barrel sampler . A steel tool for sampling soil that is driven into the formation. The split barrel is held together by a bit at one end and a head at the other. The bit and head are removed to permit separation of the two sides of the split barrel to expose the sampled soil. Samplers commonly have core catchers made of plastic or steel that are located between the bit and the split barrel. Cf: penetration test. Syn: split-spoon sampler.
fan shooting . Seismic shooting in which detectors are laid out along an arc so that each detector is in a different direction at roughly the same distance from a single source point. It was used in the 1920s and 1930s to detect the presence of shallow salt domes intruding low-velocity sediments. Syn: arc shooting.