HR: 14:50h
AN: S42F-05 INVITED     [PDF]
TI: Strong Motion Network as Infrastructure
AU: * Aoi, S
EM: aoi@bosai.go.jp
AF: National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki, 305-0006 Japan
AU: Kunugi, T
EM: kunugi@bosai.go.jp
AF: National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki, 305-0006 Japan
AU: Fujiwara, H
EM: fujiwara@bosai.go.jp
AF: National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki, 305-0006 Japan
AB: After the 1995 Hyogoken-Nanbu earthquake, NIED (National Research Institute for Earth Science and Disaster Prevention) installed the K-NET that uniformly covers all Japan with more than one thousand strong-motion accelerometers on the ground surface. In addition to the K-NET, NIED constructed uphole/downhole observation network, KiK-net, with approximately 660 stations. Each KiK-net station has a borehole of 100m or more in depth and strong-motion seismographs have been installed both on the ground surface and at the bottom of the boreholes. The velocity profiles and geological information are widely accessible on the website as well as the observed records. We are coming into an era where we can obtain the data immediately when the earthquakes occur, as we are able to obtain water in every house by just turning on a water faucet. These networks recorded strong-motion waveforms near the source-region. In fact, for most of large inland earthquakes, strong motion records were obtained within 15 km of epicenter and largely contributed to investigating both source processes and ground motion characteristics. For example, approximately 800 stations were triggered by the 2003 Off-Miyagi earthquake (Mw 7.0), an intra-slab earthquake that occurred at 70 km deep. At three stations, PGA (peak ground acceleration) exceeded 1g (980 gal). During the crustal earthquake in July of 2003 at Miyagi prefecture, the other governmental seismograph network for measuring seismic intensity recorded more than 1.5 - 2g at very near-fault stations. The dense network showed that the large accelerations were not accidental phenomena, although they were observed at spatially limited area. When the observation is sparse, it is difficult to judge whether the large ground motions are caused just by locally special situation like the effects of topography and fill-up ground or not. Accumulation of the near-source strong-motion data is very important for evaluating the ground-motion both for the past and future earthquakes.
UR: http://www.k-net.bosai.go.jp/
DE: 7212 Earthquake ground motions and engineering
DE: 7294 Instruments and techniques
SC: Seismology [S]
MN: 2003 Fall Meeting