USGS Preliminary Earthquake Report
A strong earthquake occurred at 08:56:00 (UTC) on Saturday, October 23, 2004. The magnitude 6.6 event has been located in NEAR THE WEST COAST OF HONSHU, JAPAN.Table 1. Main shock and after-shocks (data from USGS)
Magnitude Date (m/d/y) UTC Time Latitude Longitude Depth (km) Location 4.0 2004/10/27 12:09:07 37.343 138.823 10.0 Near the west coast of Honshu, Japan 4.4 2004/10/27 03:05:54 37.263 138.873 10.0 Near the west coast of Honshu, Japan 6 10/27/2004 1:40:50 37.264 138.856 15.7 Near the west coast of Honshu, Japan 5.7 10/24/2004 21:04:57 37.296 138.737 11 Near the west coast of Honshu, Japan 4.6 10/24/2004 16:27:52 37.146 138.64 10 Near the west coast of Honshu, Japan 5.3 10/24/2004 15:28:09 37.204 138.645 12.7 Near the west coast of Honshu, Japan 4.8 10/24/2004 7:06:32 37.263 138.781 12.6 Near the west coast of Honshu, Japan 5.1 10/24/2004 5:21:35 37.254 138.68 10 Near the west coast of Honshu, Japan 4.9 10/24/2004 0:28:04 37.211 138.754 16.5 Near the west coast of Honshu, Japan 4.4 10/23/2004 22:08:16 37.147 138.683 50.3 Near the west coast of Honshu, Japan 4.2 10/23/2004 14:54:08 37.392 138.732 10 Near the west coast of Honshu, Japan 5.2 10/23/2004 14:34:46 37.286 138.713 14.1 Near the west coast of Honshu, Japan 4.6 10/23/2004 13:34:57 37.168 138.826 10 Near the west coast of Honshu, Japan 4.3 10/23/2004 13:28:17 37.356 138.725 10 Near the west coast of Honshu, Japan 4.4 10/23/2004 13:26:48 37.39 138.545 10 Near the west coast of Honshu, Japan 5 10/23/2004 12:44:28 37.175 138.942 9.7 Near the west coast of Honshu, Japan 4.5 10/23/2004 11:55:16 37.173 138.805 10 Near the west coast of Honshu, Japan 4.2 10/23/2004 11:20:44 37.394 138.748 10 Near the west coast of Honshu, Japan 4.4 10/23/2004 11:16:55 37.206 138.798 10 Near the west coast of Honshu, Japan 5.9 10/23/2004 10:45:57 37.301 138.659 10 Near the west coast of Honshu, Japan 5.4 10/23/2004 10:36:45 37.206 138.686 10 Near the west coast of Honshu, Japan 4.3 10/23/2004 10:07:32 37.063 138.875 10 Near the west coast of Honshu, Japan 5.3 10/23/2004 9:57:26 37.197 138.765 10 Near the west coast of Honshu, Japan 4.5 10/23/2004 9:53:52 37.343 138.735 10 Near the west coast of Honshu, Japan 4.5 10/23/2004 9:47:02 37.209 138.853 10 Near the west coast of Honshu, Japan 6.3 10/23/2004 9:34:05 37.263 138.818 10 Near the west coast of Honshu, Japan 4.5 10/23/2004 9:28:47 37.225 138.753 10 Near the west coast of Honshu, Japan 5.9 10/23/2004 9:11:57 37.204 138.682 17.1 Near the west coast of Honshu, Japan 5.4 10/23/2004 9:07:31 37.269 138.807 10 Near the west coast of Honshu, Japan 6.1 10/23/2004 9:03:12 37.311 138.835 10.9 Near the west coast of Honshu, Japan 5.8 10/23/2004 8:59:37 37.196 138.944 10 Near the west coast of Honshu, Japan 6.6 10/23/2004 8:56:01 37.231 138.753 16 Near the west coast of Honshu, Japan
Seismic records during the main shock (http://www.k-net.bosai.go.jp/k-net/news/niigata041023/site1.html)
Figure1. Acceleration time histories measured at NIG019 which is the closest station from epicenter (estimated peak compound acceleration: 1500 Gal=1.53 g).
Figure 2. Velocity time histories measured at NIG019 which is the closest station from epicenter (estimated peak compound velocity: 136 cm/sec).
Summary Damage due to the earthquake (as of 26/10/04 11:00) report by Earthquake Disaster Prevention Research Group, Public Works Research Institute (PWRI)
Table 2. Summary Damage due to 2004 Niigata-ken Cyu-etsu Earthquake
Damage Type Details Number River dykes Route 8, 17 & 116 21 National Roads Cracking
Slope failure /Large settlement107
25Land slides 9 Barrages / Water gates 20
Report from Japan Meteorological Agency (JMA)
Table 3. Losses due to 2004 Niigata-ken Cyu-etsu Earthquake (29/10/2004 16:30 local time at epicenter)
No. of dead persons No. of injured persons No. of damaged houses 35 2383 299
