Great Hanshin earthquake

Great Hanshin Earthquake

UTC time	??
Magnitude	Mw 6.8 (USGS) Mj 7.3 (revised JMA scale)
Epicenter	Awaji Island, Japan
Areas affected	Japan
Casualties	6,434 killed, around 300,000 left homeless

The Great Hanshin Earthquake, or Kobe earthquake as it is more commonly known outside of Japan, was an earthquake in Japan that occurred on Tuesday January 17, 1995 at 5:46 a.m. JST in the southern part of Hyōgo Prefecture. It measured Mw 6.8 on the Moment magnitude scale (USGS), and Mj7.3 on the revised (7.2 on the old) JMA magnitude scale. The tremors lasted for approximately 20 seconds. The focus of the earthquake was located 16 km beneath its epicenter, on the northern end of Awaji Island, 20 km away from the city of Kobe.

Approximately 6,434 people lost their lives (final estimate as of December 22, 2005); about 4,600 of them were of Kobe. Among major cities, Kobe with its population of 1.5 million was the closest to the epicenter and hit by the strongest tremors. This was the worst earthquake in Japan since the Great Kantō earthquake in 1923, which claimed 140,000 lives. It caused approximately ten trillion yen or $200 billion USD in damage, 2.5% of Japan's GDP at the time. It is listed in the Guinness Book of Records as the "costliest natural disaster to befall any one country."

Seismic intensity

This earthquake was the first case with any area where seismic intensityTemplate:Ref harv (震度, shindo) was certified as the scale 7, which was introduced in 1949.

Through the field research, the seismic intensity was certified as

Scale 7 at some areas in:

Hokudan, Ichinomiya, and Tsuna towns (now Awaji City);

cities of Kobe, Ashiya, Nishinomiya, and Takarazuka.

At observatory points, the seismic intensity was estimated at

Scale 6 at points in:

cities of Sumoto (Awaji Island) , and Kobe.

Scale 5 at points in:

cities of Kyōto, Hikone (Shiga Pref.), and Toyooka(Hyōgo Pref.).

Scale 4 at points in:

prefectures of Hyōgo, Shiga, Kyōto, Fukui, Gifu, Mie, Osaka, Nara, Wakayama, Tottori, Okayama, Hiroshima, Tokushima, Kagawa, and Kōchi.

(Source)

^Note Note : Seismic intensity

Seismic intensity represents the strength of ground motion. JMA use the scales of 0 to 7.

0, 1, 2, 3, 4, 5 (lower, upper), 6 (lower, upper), 7.

By April, 1996, observations were fully automated nationwide. Now the scale 7 could be measured with seismic intensity meters.

The scales 5 and 6 were each divided in October, 1996.

(More info on JMA's site)

Foreshocks and aftershocks

This earthquake of Mj 7.3 struck at 5:46 a.m. JST.

There were four foreshocks, beginning with the largest of Mj 3.7 at 6:28 p.m. the previous day.

Within 5 weeks, about 50 aftershocks (of Mj 4.0 or more) were observed.

By May 23, 1995: 1983 aftershocks in total, 249 felt.

By Oct. 31, 1995: 2309 aftershocks in total, 302 felt.

By Oct. 31, 1996: 2522 aftershocks in total, 408 felt.

Damage

Fatality rates
Nada-ku, Kobe	0.703%
Higashinada-ku, Kobe	0.692%
Nagata-ku, Kobe	0.596%
Ashiya	0.468%
Hyōgo-ku, Kobe	0.365%
Nishinomiya	0.239%
source

File:阪神淡路大震災343.jpg

Damage at Minatogawa, Kobe

File:阪神淡路大震災（東急ハンズあたり）337.jpg

Damage at Sannomiya, Kobe

Damage in cities and the suburbs

The majority of deaths, over 4000, occurred in cities and the suburbs in Hyōgo Prefecture. Ruptured gas lines ignited, fueled by the wooden construction material, and broken water mains hampered firefighters' efforts to combat them. Most of the older traditional houses had heavy tiled roofs which weighed around 2 tons, intended to resist the frequent typhoons that plagued Kobe, but they were only held up by a light wood support frame. When the wood supports gave way, the roof crushed the unreinforced walls and floors in a "pancake" collapse. Newer homes have reinforced walls and lighter roofs to avoid this. One in five of the buildings in the worst-hit area were completely destroyed (or rendered uninhabitable). 22% of the offices in the CBD were unusable and over half of the houses in that area were deemed unfit to live in.

The extent of the damage was considerably greater than in the Northridge earthquake, which, by coincidence, had occurred exactly one year before. The difference in the amount of damage experienced was in part due to the kind of ground Kobe was located on and the construction of its buildings (e.g. many unreinforced masonry buildings collapsed). Also, the intensity of the quake was considerably greater at ~7.2 vs. ~6.6 at Northridge. The immediate population bases of the two areas (Kobe area and San Fernando Valley of Los Angeles) were roughly the same -- ~ 2 million.

Transportation infrastructure damage

The damage to highways and subways was the most graphic image of the earthquake, and images of the collapsed elevated Hanshin Expressway made front pages of newspapers worldwide. Most people in Japan believed those structures to be relatively safe from earthquake damage by design. Though the initial belief was negligence, it was later shown that most of the collapsed structures were constructed properly to the building codes in the 1960s. However, the 1960s regulations were discovered to be inadequate and revised several times, the latest in 1981 which did prove effective but it only applied to new structures.

Ten spans of the Hanshin Expressway Route 43 in three locations in Kobe and Nishinomiya were knocked over, blocking a link that carried forty percent of Osaka-Kobe road traffic. Half of the elevated expressway's piers were damaged in some way, and the entire route was not reopened until September 30, 1996. Three bridges on the less heavily used Route 2 were damaged, but the highway was reopened well ahead of Route 43 and served as one of the main intercity road links for a time. The Meishin Expressway was only lightly damaged, but was closed during the day until February 17, 1995 so that emergency vehicles could easily access the hardest-hit areas to the west. It wasn't until July 29 that all four lanes were open to traffic along one section (Kitamura, Yamamoto & Fujii 1998:240). Many surface highways were clogged for some time due to the collapse of higher-capacity elevated highways.

Most railways in the region were also damaged. In the aftermath of the earthquake, only 30% of the Osaka-Kobe railway tracks were operational. Daikai Station on the Kobe Rapid Railway line collapsed, bringing down part of National Route 30 above it. Wooden supports collapsed inside supposedly solid concrete pilings under the tracks of the Shinkansen high-speed rail line, causing the entire line to shut down. However, the railways rebounded quickly after the quake, reaching 80% operability in one month.

Artificial islands in the Port of Kobe suffered some subsidence due to liquefaction of the soil; the water breaking to the surface did not come from the sea. However, the newly-completed artificial island supporting Kansai International Airport was not significantly affected, due to being further away from the epicenter and because it was built to the latest standards. The Akashi Kaikyo Bridge, under construction near the earthquake's epicentre, was not damaged but was reportedly lengthened by a full meter due to horizontal displacement along the activated tectonic fault.

Response

In the aftermath, both citizens and specialists lost faith in the technology of their early warning systems and earthquake construction techniques. The national government of Japan was criticised for not acting quickly enough to save many people, for poorly managing Japanese volunteers, and for initially refusing help from foreign nations, including the United States, South Korea, Mongolia, and the United Kingdom. The language barriers and the obvious lack of Japanese medical licensing by foreign volunteers were cited as justification.

Local response

Local hospitals struggled to keep up with demand for medical treatment, largely due to collapsed or obstructed "lifelines" (roads) that kept supplies and personnel from reaching the affected areas. People were forced to wait in corridors due to the overcrowding and lack of space. Some people had to be operated on in waiting rooms and corridors.

Approximately 1.2 million volunteers were involved in relief efforts during the first three months following the earthquake. Retailers such as Daiei and 7-Eleven used their existing supply networks to provide necessities in affected areas, while NTT and Motorola provided free telephone service for victims. Even the Yamaguchi-gumi yakuza syndicate was involved in distributing food and supplies to needy victims.

To help speed the recovery effort, the government closed most of the Hanshin Expressway network to private vehicles from 6.00am to 8.00pm daily and limited traffic to buses, taxis and other designated vehicles (Kitamura, Yamamoto & Fujii 1998:260). To keep the light rail system running even though it had quite severely damaged sections, shuttle buses were commissioned to transfer patrons to stations around damaged sections (Kitamura, Yamamoto & Fujii 1998:256).

Other effects

Economic aftershocks

It caused approximately ten trillion yen or $200 billion in damage, 2.5% of Japan's GDP at the time. It listed in the Guinness Book of Records as the "costliest natural disaster to befall any one country." Most of the losses were uninsured, as only 3% of property in the Kobe area was covered by earthquake insurance, compared to 16% in Tokyo.

The sheer size of the earthquake caused a major decline in Japanese stock markets, with the Nikkei 225 index plunging by a thousand points in one day following the quake. This financial damage was the chief cause for the collapse of Barings Bank due to the actions of Nick Leeson, who had speculated vast amounts of money on Japanese and Singaporean derivatives.

Revaluation of volunteerism

The fact that many Japanese volunteers ran to help victims was, so to say, an epoch-making thing on the history of volunteerism in Japan. The year 1995 is sometimes called "ボランティア元年" (Borantia gannen; the beginning year of volunteerism).

The government set a day and a week of "防災とボランティア" (Bōsai To Borantia; disaster prevention and volunteerism), the former on the anniversary January, 17 and the latter at January, 15-21. It was agreed at a Cabinet meeting on December, 15, 1995. (Source in Japanese)

Local memorial in Kobe

Effect on disaster prevention planning

The earthquake proved to be a major wake-up call for Japanese disaster prevention authorities. Japan installed rubber blocks under bridges to absorb the shock and rebuilt buildings further apart to prevent them from falling like dominoes. The national government changed its disaster response policies in the wake of the earthquake, and its response to the 2004 Chūetsu earthquake was significantly faster and more effective. The Ground Self-Defence Forces were given automatic authority to respond to earthquakes over a certain magnitude, which allowed them to deploy to the Niigata region within minutes. Control over fire response was likewise handed over from local fire departments to a central command base in Tokyo and Kyoto.

In response to the widespread damage to transportation infrastructure, and the resulting effect on emergency response times in the disaster area, the Ministry of Land, Infrastructure and Transport began designating special disaster prevention routes and reinforcing the roads and surrounding buildings so as to keep them as intact as possible in the event of another earthquake. Hyōgo's prefectural government invested millions of yen in the years following the quake to build earthquake-proof shelters and supplies in public parks.

Elsewhere in Japan, the Tokyo metropolitan government set up an emergency food and water supply network based around petrol stations, which were mostly unaffected in the Hanshin earthquake. However, citizens' groups have taken up the bulk of disaster planning, partly out of distrust for the government still held after the disaster in Kobe.

Memorials

1.17 memorial in Kobe

The Kobe Luminarie, a small city of Christmas lights, is set up in the middle of Kobe City, as well as near Shin-Kobe Station every December in commemoration of the earthquake. Large "1.17" digits are illuminated at Higashi Yuenchi Park next to Kobe City Hall on January 17 of each year.

Naming in Japanese

Japan Meteorological Agency officially named within in a few days this earthquake "平成７年兵庫県南部地震" (Heisei-Shichinen Hyōgo-ken-Nanbu jishin; 1995 Southern Hyōgo Prefecture Earthquake #1).

In the first 10 days, many news media of Japan began to use an ambiguous area name "阪神" (Hanshin) to refer to the disaster #2; however, calling the disaster only with "阪神" was unpopular among some people including 2 mayors of towns in northern Awaji Island, beneath which this earthquake arose. (Asahi Shimbun, January 28, 1995)

Finally in February, 1995, the government officially named the disaster "阪神・淡路大震災（阪神淡路大震災）" (Hanshin-Awaji Dai-shinsai; Great Hanshin-Awaji Earthquake Disaster).

1. Other translations exist.
2. The first "阪" (han) comes from "大阪" (Osaka) and the second "神" (shin) from "神戸" (Kobe).

Plate tectonics

Brief on arising mechanisms of earthquakes in Japan

"Earthquakes occur not only around the plate boundary but also in the plates." (Source Y-p.23=p.21 of the booklet)

Japan is located on two sea plates, i.e. Philippine Sea Plate and Pacific Plate, and one or two land plates, i.e. Eurasian Plate (and North American Plate #1). Each of the sea plates is subducting beneath another plate. (See a plate map in Source X-p.3)

Within the Japanese Archipelago, compressions exist in northwest-southeast or east-west directions. (Source X; Source Z) Sometimes the release of the energy causes earthquakes.

1. Some consider that northeastern Japan is on the North American Plate. (Source X)

Sorting earthquakes in Japan by arising mechanism

By arising mechanism, Kobe earthquake is sorted into Type C of the below.

Type A is so to say "plate-boundary type." 1923 Great Kantō earthquake was of this type, for example.

The edge of a land plate is dragged along as a sea plate subducts, and the land plate finally pushes up when the stress has reached its limit, releasing the energy. (Source Z) This type corresponds to Type (1) explained in Source X-p.5, and Type 1) or 2) in Subsection 2-4-(1) of Source Z.

Type B is so to say "inside-sea-plate type." 1933 Sanriku earthquake was of this type, for example.

Extensive collapse occurs within a subducing sea plate, releasing the energy. (Source Z) This type corresponds to Type (2) explained in Source X-p.6, and Type 3) in Subsection 2-4-(1) of Source Z.

Type C is so to say "shallow-inland type." Kobe earthquake (1995 Southern Hyōgo Prefecture Earthquake) was of this type.

An active fault (活断層, Katsu-dansō) in a land plate can be the origin of this type. An active fault is such a fault #1 at which it's considered there have been and will be repeated activities of slipping the earth's surface. Even when the magnitude is not extremely high, an earthquake which arises from shallow inland active faults can result in large scale of disaster. This type corresponds to Type (3) shown in Source X-p.7, and the type explained in Subsection 2-4-(2) of Source Z.

The active fault at which Kobe earthquake arose was several tens of kilometers in length. Its part in Kobe lies beneath the surface, and its part in northern Awaji Island appears on the surface, the latter is known as Nojima Fault (野島断層, Nojima-dansō).

1. Here "fault" means "a place where there is a break that is longer than usual in the layers of rock in the earth's crust." (Oxford Advanced Learner's Dictionary, the 6th edition)

Sources for "Plate tectonics" section:

Source X (in Japanese): 「我が国で発生する地震」 on Cabinet Office web site.

Source Y (in English): "Earthquake and Tsunami - Monitoring and Information" by Japan Meteorological Agency.

Source Z (in English): "Seismic Activity in Japan" by the Headquarters for Earthquake Research Promotion, Earthquake and Disaster-Reduction Research Division, the Research Promotion Bureau of MEXT.

See also

• National Geographic Seconds From Disaster episodes

External links

• The Great Hanshin-Awaji Earthquake Statistics and Restoration Progress
• Great Hanshin Earthquake Restoration
• "Earthquake and Tsunami - Monitoring and Information" by Japan Meteorological Agency
• Hanshin Earthquake Information Database (in Japanese only)
• Anderson, "The Kobe Earthquake of 1995"
• Chang & Nojima, "Measuring Post-Disaster Transportation System Performance: The 1995 Kobe Earthquake in Comparative Perspective"
• Kunii et al., "The Medical and Public Health Response to the Great Hanshin-Awaji Earthquake in Japan: A Case Study in Disaster Planning"
• Sawada and Shimizutani, Are People Insured Against Natural Disasters? Evidence from the Great Hanshin-Awaji (Kobe) Earthquake in 1995
• Somerville, "Kobe Earthquake: An Urban Disaster"