EERI Special Earthquake Report — January 2005

Learning from Earthquakes Preliminary Observations on the Ken Chuetsu, , Earthquake of October 23, 2004

EERI organized a field investigation significant earthquake to affect Japan more than 100,000 people into tem- team led by Charles Scawthorn of since the 1995 earthquake. porary shelters, and as many as University, which included Forty people were killed, almost 10,000 will be displaced from their Scott Ashford, University of Califor- 3,000 were injured, and numerous upland homes for several years, if nia San Diego; Jean-Pierre Bardet, landslides destroyed entire upland not permanently. Total damages are University of Southern California; villages. Landslides were of all types; estimated by Japanese authorities Charles Huyck, ImageCat Inc.; Rob- some dammed streams, creating at US$40 billion, making this the ert Kayen, U.S. Geological Survey; new lakes likely to overtop their new second most costly disaster in his- Scott Kieffer, Colorado School of embankments at any moment and tory, after the 1995 Kobe earth- Mines; Yohsuke Kawamata, Univer- cause flash floods and mudslides. quake. sity of California San Diego; and Landslides and permanent ground Rob Olshansky, University of Illinois, deformations damaged roads, rail The epicenter was in northwestern Urbana/Champaign and Visiting lines and other lifelines, resulting in , about 80 km south of Professor, . Paul major economic disruption. The nu- Niigata (population 500,000), Somerville, URS Corporation, and merous landslides resulted, in part, well-known as the place liquefac- Jim Mori, Kyoto University, covered from heavy rain associated with tion was first systematically stud- the seismological aspects, but were Typhoon Tokage. At Nagaoka City, ied following the 1964 M7.5 earth- not part of the field investigation. there had been 100 mm (4 inches) on quake. The epicenter was beneath Bardet and Kayen are members October 20 and 13 mm (.5 inch) on the Hills along the Shin- of the Geotechnical Engineering October 21. The earthquake forced anogawa Lowland (Figure 1), an Earthquake Reconnaissance (GEER) Working Group, which organized a second team to focus on landslides, supported by an EERI Beyond Reconnaissance Grant. It was led by Ellen Rathje, University of Texas, and included James Bay, Utah State University; Randy Jibson, U.S. Geological Survey; Keith Kelson, William Lettis and Associates; and Robert Pack, Utah State University. Dr. N. Kishi of AIR participated with the EERI team and contributed to this report.

The EERI team arrived on October 30, and was in the field through No- vember 4. The GEER team was in the field November 15-19. The re- search of both teams and the publi- cation of this report are funded by EERI’s Learning from Earthquakes Program, under National Science Foundation grant #CMS-0347055.

Introduction Figure 1. Aftershock pattern and mechanism. The Unonoma Hills are approxi- The Mw 6.6 earthquake that struck mately outlined by dashed ellipse, and the Shinanogawa Lowland is the white on the evening area to the west (adapted from original figure by Group for Joint Observation, of October 23, 2004, was the most Kyoto and Kyushu Universities).

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alluvial plain that is bisected by the shows almost pure reverse faulting pectively, located 16 km north of the as it flows toward on a fault striking 30 degrees east of epicenter. The peak acceleration re- the . While the 2004 north, dipping down to the northwest corded at Niigata City, at an epicen- earthquake was felt in Niigata, at 54 degrees. The source area is 20- tral distance of 70 km, was 0.11 g. neither significant effects nor lique- 30 km long, with down-dip widths of For comparison, the Mw 7.5 1964 faction was observed there. South about 14 to 25 km. Niigata earthquake, which caused (or upriver) of Niigata, toward the the extensive liquefaction, was epicentral area, there are a number The earthquake occurred near the located offshore at an epicentral of smaller and towns on the Sea of Japan in an area of relatively distance of about 55 km north of plain and some industrial sites; the high seismicity. Within 100 km, there the city, and had a peak value of remainder of the plain is covered by have been five other earthquakes 0.16 g, with a longer duration in

wet rice farmland (i.e. rice paddies). greater than Mjma6 since 1941, includ- Niigata City.

Nagaoka (population 194,000) was ing the 1964 Mjma7.5 Niigata earth- the largest city significantly affected quake. All the large earthquakes Aftershock hypocenters are distrib- by the earthquake. It suffered mini- of the present sequence occurred uted over a region that is about 30 mal damage, but had highway and beneath the mountainous region east x 20 km at depths ranging from 15 train service disruptions, school of Ojiya, where there are mapped km to the surface, which roughly closures, and an influx of refugees Neocene-Quaternary folds. Across coincides with the area of the main- from surrounding areas. More the region, there are many shock and larger aftershock rupture seriously damaged areas were the mapped short lineaments city of Ojiya (population 41,000) (1-10 km) trending north- and surrounding rural areas, most east-southwest, along with notably the village of Yamakoshi the recognized Muika-Machi- (population 2,222) and the town Bonchi-Seien fault (Geologi- of Kawaguchi (2000 population cal Survey of Japan). 5,748), which sustained JMA intensity 7, the maximum on that The hypocenter was in the scale (approximately equivalent to central or lower region of the MMI XI-XII). fault, so the rupture propa- gated updip toward the east The Joetsu crosses and along strike in the north- this region in a north/south direc- east and southwest direc- tion and terminates in Niigata. tions, with a duration of of its trains was derailed by the about 10-15 sec. The lar- earthquake. gest amount of slip was in an area about 10 km x 10 km in Seismology and Strong the region of the hypocenter. Ground Motion Strong hanging wall effects were manifested in the large The mainshock at 17:56:00 Japan peak accelerations recorded time (08:56:00 UT) on October 23 above and to the west of the had a moment magnitude Mw 6.6. fault at locations such as The epicenter (lat. 37.30, long. Ojiya, where 1.33 g PGA 138.84) was located 4 km east of and 128.7 cm/sec PGV the city of Ojiya (Figures 1 and 3). were recorded 4 km west of The mainshock was followed by the hypocenter (Figure 2). an aftershock sequence with four The largest recorded peak events of JMA magnitude 6 or lar- acceleration, 1.75 g (and ger, and 12 events of magnitude 53.1 cm/sec PGV), was re- 5 to 5.9 (as of November 28), far corded at Tohkamachi more than usual for an event of (NIG021), located about this magnitude. There was no sur- 20 km south-southwest of face rupture observed with the the epicenter. Peak acceler- earthquake, and the mainshock ations of 0.48 g and 0.89 g Figure 2. Ojiya K-NET Seismograph NIG019. is currently not associated with were recorded at Nagaoka (top) PGA 1.33 g EW, 1.17 g NS, and 0.83 g any mapped fault. The focal and Nagaoka-Shisho, res- UD, and (bottom) 5% damped response spec- mechanism of the main shock tra for two horizontal directions (source: NIED).

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areas. The locations show a complex pattern of westward and eastward dipping structures that are associated with the mainshock and larger after- shocks.

Geotechnical Aspects Landslides, liquefaction, and perman- ent ground displacements accounted for most of the physical and economic effects of the earthquake. Figure 3 shows the distribution of landslides caused by the earthquake, as well as areas where liquefaction was gen- erally observed. The map also shows other effects discussed below.

Landslides: Niigata Prefecture docu- ments 442 individual landslides in this earthquake, although on the ground the number appeared even larger. Heavy rainfall in the days prior to the earthquake likely had a fundamental impact on the distribution and scale of landsliding. Bedrock throughout the area of major landsliding consists of a folded sequence of very weak and friable claystone and siltstone that is fairly nondurable, with interbedded sandstone and minor conglomerate. For the argillaceous bedrock materi- als, high antecedent moisture would tend to cause softening and strength reduction, as well as elevated pore or joint water pressures and seepage forces. Figure 3. Map of affected area showing main effects of mainshock Observed modes of slope failure in- (adapted from KKC aerial photos). cluded translational soil slips, deep- seated rotational slumps, debris flows, slump-flow complexes, and large block The most widespread type of ob- Another commonly observed slides. In some cases, the failures served failure consisted of trans- failure mode was slump-flow were clearly controlled by bedrock lational slip of the regolith and complexes within colluvium-filled structure, while other deep-seated highly weathered bedrock mate- swales and in areas of deep bedrock failures did not have an rials on very steep slopes flanking regolith. If antecedent moisture apparent relation to the bedrock floodplains and along incised riv- conditions had not been so severe, structure. The limited scope of the er and creek channels. This type it is probable that the significant reconnaissance mission did not allow of failure generally involves the flow characteristics commonly for the team to determine how many upper 5-10 feet of soil, and slip exhibited by these failures would of the landslides were reactivated appears generally to be concen- not have been so prominent. Many movements versus first-time move- trated along the interface between debris flows with significant runout ments. However, preliminary observa- significant root growth and under- distances were triggered by the tions indicate that some pre-existing lying highly weathered bedrock. earthquake, as shown in Figure 5. (ancient) deep-seated landslides were Examples of this type of failure In several cases, massive debris not remobilized during the earthquake. are shown in Figure 4. flows blocked natural drainage courses, forming landslide dams.

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(negative impression) of the block is defined by a bedding surface dip- ping at about 300 toward the free face of the slope, along with verti- cal joint release surfaces intersect- ing the right side of the bedding plane. The overlying block of bed- rock traveled on the order of 100- 150 feet, riding over the valley floor. This failure occurred along a hogback ridge, and bedding plane slides of similar or larger size were observed at several locations along the hogback.

A major landslide at Shiroiwa (White Rock) drew international attention because a mother and two young children were buried in their car. They were discovered about four days , with only the four-year old boy Figure 4. North-facing valley wall with extensive translational soil sliding surviving. into valley bottom, Yamakoshi epicentral area (photo: K. Kelson). As the bedrock throughout the area of major landsliding is judged to be These events have already resulted slide material consisted of weakly sufficiently weak under saturated in the flooding of villages and infra- cemented Pliocene and Pleistocene conditions to permit development of structure (Figure 6), and there is sandstone and mudstone that is continuous shear on curved sur- potential for large sudden floods to easily erodible. faces, it is not surprising that deep- initiate if the landslide dams are seated rotational slides occurred, breached in an uncontrolled A classic example of a block slide much like classical soil slumping. manner. can be seen in Figure 7. The mould

An earthquake-triggered landslide dammed a river about 1 km west of Komatsugura. The landslide was a block slide that formed on a dip slope dipping about 15-20o west. As the block moved downslope, a large graben formed at the head of the landslide; the landslide moved across the canyon and completely blocked the drainage. A reservoir several kilometers long formed be- hind the dam and, at the time of the team’s visit (November 19, 2004), the reservoir was rising 15- 20 cm/day despite efforts to pump water over the dam. Several roads and structures had been inundated upstream. An emergency spillway was being constructed to prevent uncontrolled overtopping and cata- strophic failure of the dam, which could inundate downstream com- Figure 5. Typical debris flow, exhibiting a narrow path and long runout munities in ten minutes. The land- (photo: S. Kieffer).

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Figure 8 shows a deep rotational slide, as evidenced by a block of back-rotated trees and agricultural land bordering an approximately 100-foot high headscarp to the left. Farther downslope, similar back- rotated blocks were observed, and the estimated maximum depth of the sliding surface is on the order of several hundred feet.

A major question remains regarding the influence of prior rainfall on slope stability. The extent of landsliding is very large, and the authors are not aware of other earthquakes of similar magnitude that have caused slope instability to this extent. If the earthquake had struck under normal soil moisture conditions, or relatively dry conditions, it is likely that the Figure 7. Block slide formed by bedding plane (sliding surface) and extent of landsliding would have two sets of vertical joint release surfaces (photo: S. Kieffer). been significantly less. Liquefaction: Clear evidence of settlement on the order of tens of This emphasizes that risk of prior liquefaction was widespread but centimeters along the Uono and rainfall should be considered in any sporadic, and was primarily confined Shinano rivers, along with levee evaluation of seismically induced to rice fields along the Shinano slumping, could have resulted from slope instability. Due to the sparse River and to backfill around sewer liquefaction. Ultimately, the amount population in the mountainous pipelines. Some sand boils were of liquefaction and associated epicentral region, the number of observed under the Shinkansen ground failure was less than that resultant casualties was surprisingly viaduct (Figure 9) near the site of anticipated by members of the small. However, seismically induced the derailment, and under a few EERI reconnaissance team. landslides under saturated ground bridges. However, there was much conditions in areas of the San Fran- indirect evidence of liquefaction. Hillside fills: The hillside residen- cisco Bay and Los Angeles would Liquefaction may have contributed tial area of Takamashi, located on cause similar damages and many to the many ground failures, partic- the eastern edge of Nagaoka, more casualties. ularly near Kawaguchi, though no experienced significant slope fail- sand boils were observed. Ground ures during the earthquake. Taka- machi is located on a natural hill at the edge of the Shinano valley and the native soil consists of early Pleistocene sand and silt. It is assumed that the area was constructed by cutting the top of the Figure 6. hillside and using this material as Inundation fill along the edges. In most places, of homes the fill was confined by a 4-m high upstream of rigid, concrete retaining wall. Four landslide dam large sections of retaining wall (photo: failed catastrophically, with the soil K. Kelson). sliding a significant distance down- slope. Figure 10 shows one of the large failures, extending across the road and close to the adjacent homes. Four segments of the con- crete retaining wall translated sig- nificantly during the earthquake,

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Within the interior of the hillside area, only green-tagged structures were encountered. It appears that all of the structural damage in Takamachi can be attributed to the deformations and failures of the hillside slopes.

Buildings As a generalization, building damage in this earthquake was surprisingly light given the high apparent ground motions. Traditional single-family Japanese houses are one- and two-story wood post and lintel with reinforced mud infill and heavy fired clay tile roofing. They perform very poorly in earthquakes, being prone to pancake collapse, as seen in Figure 8. Deep rotational slump, indicated by a block of back-rotated trees the 1995 Kobe earthquake. In the and agricultural land, beneath an approximately 100 foot high headscarp Niigata region, houses tend to have (photo: S. Kieffer). larger and more numerous interior columns and heavier roof beams, caused significant damage to struc- including one that came to rest with- due to the heavy snows (up to 3 m) tures. No failures or ground cracking in the trees downhill. every winter. A substantial number were observed in areas that did not of these buildings collapsed in have a retaining structure. In addition to the catastrophic fail- Kawaguchi, although the effects of ures, severe cracking due to slope shaking and PGD were hard to The yellow and red-tagged struc- and retaining wall deformations was differentiate. Damage in Ojiya was tures within the Takamachi area observed in many areas along the lighter, although there were still were almost completely concen- edge of the hill. As much as 1 m of some collapses and heavily dam- trated in areas with adjacent slope downslope movement was ob- aged houses. There was very little failures and ground cracking. served, and these deformations to no damage to houses of this type in Nagaoka.

Within the last two decades, a new- er type of residential construction has been increasingly built in the region, presumably due to the snow accumulations, in which the entire ground floor exterior wall is of reinforced concrete, with second and third stories of more traditional wooden construction. These build- ings are significantly taller and lar- ger than more traditional housing, and are more like U.S. housing in that they have shingle roofing rather than heavy clay tile. They fared very well in the earthquake, having benefited from more modern building codes and construction practices. Figure 9. Sand boils at the derailing site of the Johetsu Shinkansen (Oct. 25) (photo: K. Kiyono).

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at over 6,000 locations throughout the region. Virtually all roads in the Uonoma Hills were cut by landslides (Figure 11) and many pavements in the lowland areas were disrupted by floating manholes, settlements at culverts and bridge abutments, and general disruption of the paved surface.

Highway bridge structures generally performed well in the earthquake series, with the exception that sig- nificant settlement of approach fills was observed on many bridges. Most had been repaired with as- phalt by the time the EERI team Figure 10. Failure of hillside fill in Takamachi residential area (photo: E. Rathje). arrived in the area. Several highway bridges suffered damage to piers and bearings, but closure of the Commercial and institutional build- ways were damaged at numerous lo- bridge was not required. A unique ings generally performed well, with cations, with similar damage to rail feature of the region are pipes, car- some exceptions. A surprising suc- lines. An historic first was the derail- rying water at 13° C, embedded in cess was a three-story 1960s vin- ment at full speed of a Shinkansen concrete along many streets and tage RC frame school building in (bullet) train. With that exception, roads; the water is sprayed on snow Ojiya about 100 yards from the transportation structures performed in the winter to melt it. Over 600 km 1.33 g PGA seismograph recording. generally well in this series of earth- of such piping exists in the region, The building was completely un- quakes. There were no collapses; and much of it was damaged. Since damaged, with the exception of a damages appeared to be limited and that damaged the pavement, the cracked brick chimney. Another repairable, and not surprising given success story was a large three- the level of ground mo- story hotel complex situated on the tions. The EERI team ridge directly above Kawaguchi. visited every bridge struc- Despite having a landslide imme- ture crossing the Uono diately adjacent, the building sus- and Shinano Rivers in the tained no damage, with the excep- epicentral region. All tion of some minor pounding at a but two of the highway seismic joint between two parts. bridges were open for at least limited traffic; Large "big-box" stores are increas- the two that were closed ingly prevalent in Japan, and two appeared to be open for were observed in Ojiya with precast emergency vehicles. cladding having fallen away from steel frames. Entry was denied, but An unusual aspect of this extensive salvage and repair opera- earthquake was damage tions were observed. A ten-story to transportation tunnels. concrete-clad building was ob- Water and power systems served to have classic shear crack- sustained some damage, ing of columns, and an electronic but were back in service chip fab plant was reported to have within hours, except in the sustained heavy nonstructural hardest hit areas. damage. Roads and Highways: Lifelines Landslides and perman- ent ground displacements After landslides, damage to life- of varying magnitudes lines was the most notable result of Figure 11. Damage to road in Uonoma Hills. Note seriously damaged roads this earthquake. Roads and high- abandoned car in distance (photo: J.P. Bardet).

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In the town of Kawaguchi, the Joet- su Shinkansen railway bridge was damaged. Piers supporting the Wanazu Bridge over the suffered a flexural failure due to a reinforcement discontinuity, as shown in Figure 13. Several columns of a viaduct section just south of the bridge also failed. Re- pairs were underway at both loca- tions by the end of the team’s time in the area. Tracks of the JR Joetsu Line were also damaged due to mi- nor fill settlement in the Wanazu area. In Kawaguchi, rails were buckled in numerous locations, and several plain concrete piers of the JR were damaged, while the superstructure remained intact.

Figure 12. Derailed Shinkansen (Oct. 31) (photo: C. Scawthorn). Tunnels: Several tunnels were damaged in this event, including the town of Kawaguchi removed it and tion of elevated, level viaduct through 8.6 km Shinkansen tunnel, which put down gravel. However, snow- rice farms. The viaduct, constructed had fallen lining at about mid-length, plows cannot operate on such in the 1970s, is composed of several and buckled track. Spalled lining roads, so considerable disruption is different types of segments with vary- occurred in the Wanatsu Tunnel of expected this winter when the deep ing heights and section design, some National Route 17. snows come. of which were damaged in the earth- quake. Ground cracking, ground set- Utilities: The earthquake cut off all Railroads: There was extensive tlement, and signs of significant soil power, gas, water, and telephone damage to roadbeds caused by softening were observed at many lo- service to Ojiya city. Upwards of ground failures. Significant damage cations along the viaduct (Figure 9). 300,000 households in the region was observed on the Shinkansen elevated viaduct, as well as on some local railway lines, but all ap- peared to be repairable. The Joetsu Shinkansen line carries 360,000 passengers per day, and was scheduled to restore service on December 28, 2004. A northbound Shinkansen train derailed just south of Nagaoka City (Figure 12). As the train traveling over 200 km/hr was exiting a tunnel, the driver felt the earthquake and applied the brakes. The train passed under a 300-m- long covered section, and began to derail along a viaduct, approximate- ly 500 m from the exit of the tunnel. The train engine came to rest ap- proximately 1.9 km from the tunnel exit, taking over 1.5 km to stop. There were no reported injuries as a result of the derailment, which oc- Figure 13. Damaged piers of Joetsu Shinkansen Wanazu Bridge curred entirely along a straight sec- (Nov. 1) (photo: S. Ashford).

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lost electric power. As of Sunday settlements, and the plant had sus- power down from 63kv to 1500 volts evening, the day after the earth- tained piping damage and was in- (the service voltage for the Shinkan- quake, 98,000 homes in Ojiya and stalling temporary piping. The plant sen catenaries). Transformers in the Nagaoka still lacked electric power. was back in operation in hours. From substation were significantly tilted Water supplies were cut through the plant, water is pumped to two due to liquefaction, but still operat- most of the affected area, and the large hilltop reservoirs, one on each ing, and otherwise the substation lack of telephone service added to side of the Shinano. The EERI team was undamaged. the isolation of the mountain areas visited the reservoir on the west bank, cut off by landslides. Many areas which is a circular concrete partially Social Impacts received water from tank trucks, embedded tank, approximately 25 m dispatched from neighboring areas. in diameter. Some ground settlements The most seriously affected areas had occurred around the tank, and were small towns and villages near Electric power was restored stead- entry structures had collapsed, but Nagaoka, especially the village of ily, but as of October 26, 34,000 the tank was largely undamaged Yamakoshi, the town of Kawaguchi, households were still without pow- and in operation. The hilltop location and the city of Tokamachi. As is true er, mostly in Nagaoka and Ojiya. is within 1 km of the 1.33 g PGA in rural areas throughout much of Tohoku Power employed 1,900 recording in Ojiya, and the hilltop had Japan, the population has been in repair workers, but they were im- sustained landsliding and damage decline, with Yamakoshi and Kawa- peded in some places by damaged to nearby houses, and clearly had guchi declining by 11.9% and 5.9%, roads. Water and gas service took undergone very strong shaking. respectively, from 1995 to 2000. longer to restore, and as of Octo- Nearly 40% of Yamkoshi residents ber 26, 108,000 households still Approximately 23 km from the epi- and 25% of Kawaguchi residents remained without running water center is the Kashiwazaki- are elderly. Although the earthquake and 56,000 without gas. Access Nuclear Power Station, at 8,300 MW occurred in mid-autumn, winter was was impeded by all the road clo- (7 units) the world’s largest NPS. The rapidly approaching, and Niigata sures. By November 3, power was October 23 mainshock reportedly had Prefecture is known to receive some restored to all but 2,300 house- no effect on the NPS, but a magni- of the heaviest snowfall in Japan. holds, mostly in evacuated parts of tude 5.2 on November 4 caused Unit Yamakoshi and Ojiya. 7 to shut down automatically (other Because landslides cut off transpor- units operated at the rated thermal tation and communication to many Nagaoka City receives its water power). In Kawaguchi, the Shin- areas, it took some time for emer- from the Shinano River, upstream kansen has a substation stepping gency services to identify damage of the city. Water level in the river is raised by lowering gates across the river, and water is diverted into a pipe that carries the water to a treatment plant downstream of the gates. The earthquake disrupted power to the gates and also caused some damage to the wire rope machinery used to raise the gates, so the gates could not be lowered and the treatment plant received no water. As a result, the plant had to resort to emergency drafting from the Shinano River (Figure 14).

Damage was more extensive at the Ojiya water treatment plant, which also draws its water from the Shinano via an intake structure and over the levee on an approximately 70-m long steel truss bridge. Differ- ential displacements of the sup- ports damaged the bridge, but did not cause collapse. In the plant, Figure 14. Emergency drafting of water from Shinano River for Nagaoka City there were obvious signs of ground Water Treatment Plant (photo: C. Scawthorn).

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and assess needs. There were re- were evacuated and taken to three November 8 again stopped the bul- ports of family and neighbors rescu- sites in Nagaoka. The national gov- let train and closed a portion of the ing people from collapsed homes. ernment applied the disaster relief expressway to . Continued By the morning after the Saturday law to 29 localities, which meant that rain during the ten days following evening earthquake, the Self- government would cover the cost of the earthquake raised concerns Defense Forces (SDF) opened a relief and shelter. about water behind the landslide disaster headquarters in Ojiya to dams in Ojiya and Yamakoshi. The coordinate relief efforts, and used Many people spent the first night in Japan Meteorological Agency set up 300 personnel, 21 helicopters, and their cars, but by the day after the alarm units and surveillance cam- 65 vehicles to transport food and earthquake, 82,000 were staying in eras at five landslide dams, the pre- water to evacuation sites. They emergency shelters. In Ojiya, 14,500 fecture prepared pumps to lower the also evacuated tens of thousands people took refuge at 93 different water levels, and the prefecture of residents to emergency shelters, evacuation centers, mostly school recommended evacuation of 101 and used helicopters to airlift gymnasiums and public halls. Even households containing 439 resi- stranded villagers from the hamlet in lightly damaged Nagaoka, more dents. of Shiotani. than 34,000 people were evacuated to temporary shelters (Figure 15). On As of November 28, authorities at- More difficult was reaching the iso- Monday, October 25, thousands were tributed 40 deaths to the earth- lated towns of Kawaguchi and airlifted from about 60 mountainous quake. Although most died from Yamakoshi, which initially depend- communities, which remained closed building collapses, approximately ed on airlifted food and water until to road access. Thirty police and SDF 14 deaths were from stress-related they could be rescued the following helicopters were needed to evacuate illnesses following the earthquake. day. In Kawaguchi, about 300 peo- residents of seven municipalities. By One hospital patient died when an ple took refuge in an elementary Tuesday, October 26, about 320 peo- artificial respirator detached during school and awaited assistance. By ple were still stranded in five hamlets. the earthquake. Five died from com- Monday evening, relief supplies plications due to living in their cars, were coming in over the roads, Aftershocks and landslide dams including blood clots from inactivity. but still with not enough food for posed continuing problems. A M5.2 As a result, the prefecture encour- the population. In Yamakoshi, 250 aftershock on November 4 halted the aged people to move into SDF tents residents spent two nights in a bullet train line between Niigata and or to stay in accommodations far- gymnasium without power or water Nagaoka. It also closed down a sec- ther away. Elderly residents were before being evacuated. All but six tion of the bullet train tracks that had especially susceptible to exposure of Yamakoshi’s 2,200 residents just reopened. A M5.9 aftershock on and stress-related illnesses.

Economic Effects Agricultural activities in Yamakoshi were disrupted by the earthquake, and residents fear permanent con- sequences. The village’s main in- dustry is the raising of carp, which it provides to decorative ponds throughout Japan. The cattle indus- try is another concern. Residents had to leave behind 1,000 cattle. In order to save his business, the lar- gest cattle owner began ten days after the earthquake to airlift 700 cattle out of the village by heli- copter, at considerable expense.

Area industries were also affected. Hokuetsu Paper Mills plant in Na- gaoka shut down for several days, as did Matsushita Electric’s chip production center. The Niigata Figure 15. Interior of shelter in Nagaoka City (Nov. 6) (photo: C. Scawthorn). Sanyo Electric Plant in Ojiya, which

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employs 1,500 workers and is Oji- An example of structural damage cap- Acknowledgments ya’s largest employer, is closed tured by the USGS LiDAR unit is pre- The two teams were generously indefinitely. An auto parts plant has sented in Figure 16, collected in the assisted by numerous Japanese been unable to resume its speed- damaged portal of the Juetsu railroad colleagues, including Professor H. ometer assembly line, which caused tunnel, north of Horinouchi town. The Iemura of Kyoto University, who act- Honda Motor Company to halt auto portal is founded on a poorly compact- ed as senior advisor. Technical as- production at four plants elsewhere ed embankment fill that failed during sistance was provided by Professors in Japan. Other plants shut down for the earthquake. The portal pulled away M. Hamada, Waseda University; K. approximately one week, including from the tunnel, settling vertically, slid- Ishihara, (Emer- Panasonic Communications, and ing downslope, and rotating. In the itus); Kazuo Konagai, University of Alps Electric Company. photograph, the offset in the portal can Tokyo; T. Kaino, Nagaoka University be seen along the left wall of the tun- of Technology; Y. Yamakawa, Naga- The Tokyo Stock Exchange fell on nel, and the rotation can be seen in oka University of Technology; Y. the Monday following the earth- the ceiling. An oblique view of the Tanaka, ; I. Towhata, quake, with the largest losses to LiDAR point-cloud data can be seen on University of Tokyo; T. Sato, Kyoto Japan Rail East, companies with the right. The left-lateral offset in the University; H. Hayashi, Kyoto Uni- production facilities in the area, and portal is clearly visible in the LiDAR versity; K. Kiyono, Kyoto University; insurers. On the positive side, the model. In the LiDAR imagery, precise S. Sawada, Kyoto University; Y. Japan Times reported that shares centimeter-scale measurements can Ono, Kyoto University; Y. Takahashi, of construction-related companies be made of the three-dimensional Kyoto University; R. Honda, Kyoto increased sharply November 1 deformation of the structure. on the Tokyo Exchange, because University; N. Inukai, Nagaoka Uni- versity of Technology; T. Kokusho, investors anticipated a supplemen- GPS also played an important role in ; and Mr. Hajime tary national budget to pay for re- this reconnaissance. Figure 17 shows Tanaka of the University of Tokyo construction following the earth- the VIEWS (Visualizing Impacts of and Ms. M. Wada of Kyoto Univer- quake and recent typhoons. How- Earthquakes With Satellites) system, sity. The team also thanks the JR ever, reconstruction will be a chal- which allows full cataloging of ground East Railway Company for access lenge to homeowners, since only video and still imagery geo-referenced to the Shinkansen site; public offi- 11.2 % of households in Niigata to aerial photographs. A user can cials of Niigata Prefecture, Nagaoka Prefecture have earthquake in- switch from the aerial photo to a close- City, and the city of Ojiya for their surance, compared to 17.2 % up video or to still images. VIEWS is assistance; and the people of the nationally. developed by ImageCat Inc., and its affected region for their generosity use is gratefully acknowledged. and patience. IT/GIS/GPS aspects This earthquake reconnaissance effort provided an opportunity to apply new IT/GIS/GPS tools. Both teams used such high-tech tools as GPS, satellite imagery, and LiDAR (Light Detection And Ranging).

For the first time, the EERI team utilized LiDAR, a 3-D scanning- laser that can create high-resolu- tion, three-dimensional, digital ter- rain models of any surface, includ- ing earthquake-related ground, structural, and lifeline deformations. Approximately 30 laser scans of damaged roadways, structures, and displaced ground were taken with a tripod-mounted LiDAR apparatus, a portable device that models sur- Figure 16. Photograph (left) and LiDAR image (right) of damage to the faces to a measurement accuracy Juetsu Railroad portal at Kita-Horinouchi from the portal entrance. Lateral of 1-2 cm. displacement of the portal in the photo is visible and measurable in the LiDAR scan. (Source: R. Kayen)

10 11 EERI Special Earthquake Report — January 2005

▲ Figure 17. (a) Screen shot from VIEWS, showing aerial-photo-referenced ground shots (VIEWS: C. Huyck).

◄ (b) Map with GPS-referenced photos (GPS: J. P. Bardet).

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