Noto Peninsula (Japan) Earthquake of March 25, 2007
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EERI Special Earthquake Report — June 2007 Learning from Earthquakes Noto Peninsula (Japan) Earthquake of March 25, 2007 This preliminary report summarizes USGS). The event does not appear with the prefecture’s chief city of available information on the March to have occurred on a known active Kanazawa (pop. 455,000) located in 25, 2007, Mw 6.7 earthquake, and fault. As inferred from the fault plane the coastal plain. The Noto Penin- findings of a damage survey on solution (USGS) and areal distribu- sula is generally mountainous and April 1 in the high-intensity near-epi- tion of aftershocks (see http://www. sparsely populated, with most of the central region. It was prepared for seisvol.kishou.go.jp/eq/2007_03_ population located at river mouths EERI by Shingo Nishida, Charles 25_noto/index.html), the fault mech- along the coast. The nearest major Scawthorn, Junji Kiyono, and Taka- anism is oblique mostly reverse fault- city is Kanazawa (epicentral distance hiro Tsutsumiuchi, all of Kyoto Uni- ing on a plane dipping about 45° to 80 km, no damage); the closest jur- versity. The publication of this report the SE and striking NE. A source mod- isdiction is the township of Monzen is supported by the National Science el has been developed by Y. Yagi (pop. 7,500), and the closest popu- Foundation through EERI’s Learning (Tsukuba University), which has a lated area is the village of Doge, lo- from Earthquakes Program, Grant fault size of 30 km × 5 km, top depth cated approximately 2 km east of #CMMI-0650182. of fault of km, and a focal mecha- the epicenter. Table summarizes nism with strike = 47º, dip angle = 5º the earthquake impacts. Earthquake and Affected and slip angle = 115.8º. Average slip Historic earthquakes near the Noto Area on the fault was m. The seismic mo- peninsula have typically been shal- ment is 2.3 x 0^9 Nm (Mw = 6.8). low events, e.g., 933 and 993 The earthquake struck on Sunday, Maximum observed JMA intensity (Earthquake Research Committee, March 25, 2007, at 00:4:57 (UTC) was 6+ (corresponding to MMI X-XI). 998). The 993 earthquake was or 9:4:57 a.m. (local or JST), with centered farther north and was epicentral coordinates of 37.28°N, The earthquake was centered about caused by reverse faulting (Ito et al., 36.602°E and a depth of 5 km 2 km offshore from the Noto Penin- 994) similar to the current event. (USGS). The magnitude, as deter- sula, Ishikawa Prefecture (pop. .7 mined by the Japan Meteorological million), in the Sea of Japan (Figure ). Agency, was M 6.9 (or M 6.7, The northern part of Ishikawa prefec- Strong Ground Motion j w ture consists of the Noto Peninsula, while the southern part is Though the Mw 6.7 earthquake was wider and consists mostly centered offshore approximately of wooded low mountains, 2 km from the nearest population, in the area closest to the epicenter Figure 1. USGS Community Internet Intensity Map (48 miles N of Kanazawa, Honshu, Japan) EERI Special Earthquake Report — June 2007 Figure 2. Togi site conditions, time history, Fourier amplitude spectra, and 5% damped response spectra (other records available at http://www.kyoshin.bosai.go.jp/k-net/). recorded ground motions were quite 5 m height. No sand boils or other nearby coasts, and waves of 0-20 high. Long-period effects were not direct evidence of liquefaction were cm were observed 30-60 minutes evident. The maximum PGA was observed during our damage survey, later, depending on location. recorded at the Togi K-NET station, although others reported finding such where a single maximum compo- evidence (see Yoshida, 2007, where Performance of Structures nent of 849 gals (three vector com- photographs of sand boils at Wajima Japanese commercial and industrial ponent max PGA 945 gals) was ob- port are presented). However, a num- buildings are typically steel or rein- served. Figure 2 shows the site con- ber of manholes were observed to forced concrete (RC) construction, ditions, time histories, and Fourier have “risen,” and indications of lateral or a combined steel reinforced con- amplitude and acceleration re- spread were observed in a number of struction (SRC). Larger multifamily sponse spectra for this record. locations (Figure 3). residential buildings are typically RC, while smaller residential build- A lateral spread was observed along Geotechnical Effects ings may be steel or wood-frame. a river embankment in the village of Single-family dwellings are almost The geology of the western Noto Doge, and a bridge across the river exclusively wood-frame. Peninsula is rounded hills of 00- about 50 m upstream had abutment 200 m elevation formed of Miocene settlements, but no other damage. Engineered structures performed and Pliocene materials, with young- Many other small bridges at various well, with little or no observed er Holocene deposits in the valleys. locations sustained similar abutment damage, including a number of Relatively few landslides were ob- settlements, which were quickly larger buildings strengthened after served in the hills, the largest being repaired (Figure 4). the 995 Hanshin earthquake. an arcuate rotational slump with ap- Older Japanese wood-frame build- A tsunami advisory was immediately proximate dimensions of 00 m width ings were the most significant issued for the Noto Peninsula and at the bottom at the roadway, and a segment of the built environment 2 EERI Special Earthquake Report — June 2007 Figure 4. Bridge abutment settle- ment and temporary repairs to bridge in Doge (photo: Scawthorn). School and municipal buildings in Monzen (the closest location to the epicenter) typically performed very well. The worst problem appears to have been settlement and lateral spreading on the west side of the main building of the middle school, adjacent to a drainage channel (Figure 6). An intensity meter at this location registered IJMA 6+ (equivalent to MMI X). Several of these buildings had been seismically Figure 5. Collapse of steel industrial strengthened, and appear to have building, Doge (photos: Scawthorn). performed very well. Residential wood-frame dwellings. In Japan, wood-frame houses fall in- to three categories: ) the traditional Figure 3. Lateral spread and man- Japanese house (post and beam, hole deformation in minor roadway mud walls), 2) an intermediate type built over rice paddy, village of Doge with stucco over wood lath walls, (photos: Scawthorn). and 3) a recent primarily post-Kobe type, having continuous or mono- lithic foundations, bolted wood con- damaged by the earthquake, with a nections with hold-downs and/or number of collapses. some steel framing, and lightweight Figure 6. Monzen Middle School: ground settlements around under- Engineered buildings. Despite the roofs and cladding. Wood buildings high recorded ground motions, en- in Monzen varied in their seismic ground tanks west of main building gineered buildings generally per- performance; Figure 7 shows perfor- (photo: Scawthorn). formed well. An exception was an mance of various wood-frame build- older steel-framed industrial shed ings. If a modicum of bracing was tilever structure was notable for no building at a lumber yard in Doge, provided, most buildings did well; signs of rocking. Immediately adja- which collapsed (Figure 5). It had modern housing performed excel- cent to the structure were utility steel columns with tie rod bracing, lently, with no signs of distress of poles, which appeared to have wood secondary framing, and a any kind. disturbed foundations. heavy tile roof. Failure appeared to Other Structures. About km dis- Traditional Japanese stone monu- be due to shear in the single bolt tant from the Togi instrument was a ments throughout the region sus- connections of the tie rod bracing. modern, approximately 80 m-tall tained minor to moderate damage. Whether the building had actually windmill, which appeared undam- Typical was a shrine where the wood been engineered is questionable. aged. The foundation of this tall can- building was undamaged, but the 3 EERI Special Earthquake Report — June 2007 City reported 28 households lost facilities for a total of 55 persons. water service, as of April 2, with 87 Anamizu opened two shelters for a having decreased pressure. In Shika total of 57 persons. Shika Town district, 52 households lost service. opened three shelters for a total of Sewerage damage was 220 m in 45 persons. Yoda town, 86 m in Nakahata, and Agriculture, forestry, and fishery 330 m in Bungome. Electric power losses totaled approximately 5.6 was lost for 110,000 households in billion Yen (approximately US$50 Ishikawa Prefecture and 50,000 in million). Farm facilities were dam- Toyama Prefecture, with service re- aged in three prefectures at 72 stored by 4 p.m. the next day. locations, totaling .2 billion Yen There were numerous minor distur- (US$0 million). Forestry assets bances to local roads due to minor were damaged in four prefectures ground failure. As of April 6, the Noto at 345 locations, totaling .6 billion toll road from Tokudaotsu to Anamizu Yen (US$3 million). Fishery facili- was closed. Route 249 sustained a ties at 35 harbors sustained damage major landslide, with damage at a totaling 2.6 billion Yen (US$20 mil- total of seven locations. Limited ser- lion) (MAFF, 2007). vice was restored to all roads by April 6, with the exception of the Noto toll References road. Earthquake Research Committee, JR West reported some displaced 998. Seismic Activity in Japan, rails on the Nanao line, but no dam- Headquarters for Earthquake age to the Hokuriku line. Service was Research Promotion, Prime Min- restored by the next day. The Noto ister’s Office, Government of Rail line sustained some significant Japan, p.