Quake preparedness

Watch this National Geographic video of the Quake Panic in Chengdu, China filmed on May 14, 2008 … could this happen to us and our kids in Japan?

The deadly magnitude 7.9 earthquake in Beichuan struck on May 12, leveling many parts of Sichuan province in China. The death toll figure was estimated by Chinese officials to be around 50,000 with nearly five million people, homeless

Japanese scientists have said that the fault line that caused the devastating earthquake in China, probably buckled in two stages, and the hardness of the terrain contributed to the wide reach of the damage. Yuji Yagi, a seismologist at Tsukuba University, was reported to have said that data show the 250-kilometer (155-mile) Longmenshan Fault tore in two sections, the first one ripping about seven meters (yards), followed by a second one that sheared four meters (yards). The seismologist said that the damage was very severe because the quake’s epicenter was shallow, and because the quake occurred in densely populated areas.

Vulnerability of schools and children during quakes

In Beichuan, a group of some 40 Japanese rescue workers were at the school for a second day to conduct a more thorough investigation after an initial search found no signs of life. The search by a Japanese relief team for signs of life turned into a grim recovery of bodies Sunday at a school in one of the hardest-hit areas of last week’s earthquake in western China. The bodies of 13 people were found at the junior high school and another at a nearby hospital. The school had an enrollment of about 1,500 students. Of those who were at the school at the time of the quake, about 70 either escaped or were rescued by firefighters. (Source: “Japan team finds bodies at school” Japan Times Monday, May 19, 2008 )

 

9,000 children were killed; 1,869 children orphaned and 7,000 classrooms destroyed (the Straits Times reported in the article “SICHUAN QUAKE: ONE MONTH LATER: Patience running out as questions go begging; One month after quake, parents are no closer to knowing what actually killed their children when schools collapsed”).

Chinese officials have had to send condolences and money to parents of children killed in a school that crumpled in the Sichuan earthquake, in a bid to defuse growing outrage over shoddy buildings and allegations of corruption (see the Straits Times “Money paid to parents of kids killed in school” report.

Closer to home, and still fresh in our minds is the 7.2-magnitude earthquake that rippled through northeastern Japan. It killed at least six people and left about 190 injured in Iwate, Miyagi, Fukushima, Akita and Yamagata prefectures. In Oshu, seven children at a nursery school were injured by shards of glass after the quake shattered its windows (see the Japan Times report “Major quake in Tohoku kills six”).

Japan has 127,164 publicly run schools. The Education ministry has said, of these public schools, 33.9% predate the current building code which means that 43,109 schools (based on April 1 estimates) might not withstand an earthquake such as the one that recently hit Iwate and Miyagi prefectures. In immediate danger are about 8.4% more schools or 10,656 schools that require urgent refortification. In the latest survey (see Yomiuri Shimbun (Jun. 23, 2008)report “Money woes threaten school safety“), 79,215 school buildings were deemed strong enough to resist earthquakes of an upper 6.

The quake resistance of schools varies a great deal from prefecture to prefecture: Kanagawa Prefecture topped the list for the highest proportion of quake-resistant school buildings, with 90.4 percent of buildings assessed as quake-resistant, followed by 86.5 percent in Mie Prefecture, and 86.4 percent in Shizuoka Prefecture. Of the six prefectures in the Tohoku region, Iwate and Miyagi have the highest percentage of quake-resistant school buildings.

The quake improvement aid and subsidies also differ greatly locally: for local governments in areas that have not had major earthquakes, it is still difficult to secure funds for strengthening school buildings against earthquakes because there is no sense of urgency. For instance, in Nagasaki Prefecture, only 39 percent of school buildings are deemed quake-resistant.

It costs 60 million yen to 100 million yen per school building to retrofit them against quakes. On the other hand, it costs 1 billion yen to 2 billion yen to rebuild quake-resistant buildings from scratch. Many local governments in these prefectures have received state subsidies since fiscal 1980 to cover half of the expenses for rebuilding and making school structures quake-resistant as part of the government’s efforts to boost disaster-prevention measures in preparation for a major earthquake in the Tokai region. For local governments outside of the government-designated area, the portion of improvement costs covered by state subsidies was raised from one-third to half in fiscal 1996, one year after the Great Hanshin Earthquake. Unlike for local governments in the Tokai region, the subsidy program covers only costs for improving existing school buildings.

The potential for the next quake calamity in Japan?

Japan is one of the most earthquake prone countries in the world as it sits on top of an offshore ocean-trench structure that causes earthquakes when ocean trench plates sink or jolt against each other.

The 1891 Nobi Earthquake registered magnitude 8–as strong as the Sichuan tremor–when the 80-kilometer Neodani fault in western Gifu Prefecture shifted, killing 7,273 people as a result.

In the past 10 years, there have been six fatal inland earthquakes, including the 2004 Niigata Prefecture Chuetsu Earthquake and the 2007 Niigata Prefecture Chuetsu Offshore Earthquake that damaged the Kashiwazaki -Kariwa nuclear power plant.

Then there was the most recent 7.2-magnitude earthquake that struck northeastern Japan but which did relatively little damage and injury in Iwate, Miyagi, Fukushima, Akita and Yamagata prefectures…relative to the Chinese earthquake, that is.

Japan’s most destructive and frightening quake in recent times was the 7.3-magnitude temblor in the western city of Kobe, which killed more than 6,400 people in January 1995.

The death toll of the Chinese quake was 50,000 compared to 6,400 for the Kobe earthquake. Why was this so?

Most Chinese have blamed the large death toll and damage on the shoddy construction methods used in China. However, other explanations have been put forth.

Yuji Yagi, a seismologist at Tsukuba University explained to AFP’s reporter that it was the shallowness of the epicenter – only 10 kilometers (6 miles) – that contributed most to the temblor’s destructive power. The energy level of the China quake was calculated to have been 30 times that of the one that struck Kobe.

Another seismologist of Tokyo University, Teruyuki Kato attributed the quake’s force to the firmness and hardness of the terrain and strata in the quake-hit region in central China, which allowed seismic waves to travel large distances without losing their power. Kato said the hardness of the land in China contrasted with Japan, where patches of soft terrain can often blunt the reach of earthquakes.

But will another Big One strike again?

Masayuki Takemura of Kajima Corp., a major construction firm, was quoted saying, while magnitude-8 earthquakes are unlikely to strike the nation, the possibility of strong magnitude-7 tremors hitting plain regions, where foundations are soft, cannot be ruled out. However, based on records kept on damage to buildings, Takemura believed there have been 10 magnitude-7 earthquakes since the beginning of the Meiji era (1868-1912). Of them, nine were inland quakes, Takemura said.

The ministry in charge of education and science estimated based on records that there is a 30 percent chance of a magnitude 6.7 to 7.2 temblor occurring in the tectonic plates of the southern Kanto region within the next decade, and a 70 percent chance within the next 30 years. Other areas believed to be facing the possibility of a major earthquake in the near future include Shizuoka, Gifu, Yamanashi and Aichi prefectures.

A Tokyo University research team led by Kunihiko Shimazaki, a seismology professor at the university’s Earthquake Research Institute, concluded that major earthquakes outside the Niigata-Kobe region are likely. Using data from sources such as old documents to classify data in five time periods on the epicenters of 52 inland earthquakes with a magnitude of 6.8 or more that have struck since 1596, as well as Global Positioning System data, the team determined that the seismic zone stretched from Niigata and ran past Kobe as far as southern Kyushu, and by superimposing the position of this longer zone on the Niigata-Kobe belt, they statistically calculated that more than half of 20 quakes that occurred between 1896 and 2007 had struck outside the Niigata-Kobe zone–one example being the Noto Peninsula Earthquake. This contrasted with the picture that almost all of 20 quakes that struck between 1729 and 1914 were inside the Niigata-Kobe zone. The team concluded the subduction of seismic plates has caused the build up of “invisible” seismic strain, which causes major inland earthquakes, and consequently has prompted a shift in the distribution of earthquakes from the commonly acknowledged Niigata-Kobe zone (source: “Scientists question earthquake zone theory” Yomiuri Shimbun Dec 30, 2007).

 

The effectiveness of earthquake resistance is the key to preventing damage.

In Japan, the 1981 revised Building Standards Law stipulated a new earthquake-resistance standard that requires structures to be able to withstand an earthquake with a seismic intensity of 6 on the Japanese scale.

When the Great Hanshin Earthquake struck, relatively little damage was caused to houses built using the new standard.

Modern structures and condominiums have been built with seismic isolation designs capable of withstanding tremors. But the problem is how to deal with buildings erected before 1981.

According to estimates by the Construction and Transport Ministry (see “Can Japan’s Buildings Survive Big Quake” Yomiuri Shimbun May 24, 2008), about 25 percent of about 47 million houses in the country do not meet the new resistance requirements.

The government is still mid-task in terms of bolstering the earthquake resistance of school facilities, which serve as shelters in disasters. According to the Education, Science and Technology Ministry, of about 130,000 public school facilities across the country, about 54,000 either do not meet the current quake-resistance standard or have not been examined to see whether they are earthquake-proof. An official of the ministry’s local facilities aid division also said there are about 10,000 buildings that could collapse due to a strong earthquake.

Early Warning Systems and Preparedness

A year before the Sichuan earthquake, a scientific study had warned that the Chinese region was ripe for a major quake. Scientists had issued a warning after examining satellite images and conducting on-the-ground inspections of deep, active faults in Sichuan Province for more than a decade. “The faults are sufficiently long to sustain a strong ground-shaking earthquake, making them potentially serious sources of regional seismic hazard,” the Chinese, European, and U.S. geoscientists wrote in the mid-July 2007 edition of the journal Tectonics. They concluded that clashing tectonic forces were growing in Beichuan, ready to burst in an explosion of seismic energy.

On 1 October 2007, the Japan Meteorological Agency (JMA) started providing residents in Japan with Earthquake Early Warnings(or “緊急地震速報 (Kinkyu Jishin Sokuho)” in Japanese), new prompt earthquake alerts to be issued immediately over TV or radio after the occurrence of earthquakes, in order to secure time to protect yourself before strong tremors arrive.

However, despite Japan owning the most sophisticated and expensive quake research and quake alert system in the world, its early warning alert system has come under fire. The Meteorological Agency has so far detected only two magnitude-7 earthquakes–the 1995 Great Hanshin Earthquake and the 2004 Niigata Prefecture Chuetsu Earthquake. See National Geographic News’ report “Shaky Start for New Quake Alert System in Japan

How prepared are you for the next Big One?

According to Japan Times, 70% of those evacuated during and surveyed said they weren’t prepared for the earthquake. Are you prepared for an earthquake? Because experts on every side say the Big One is about to strike Japan.

Have you:

 

  1. Told your children their evacuation routes (on foot) and meeting place in the event of an earthquake?
  2. Prepared your emergency food rations and other disaster supplies kit (containing necessities)
  3. Minded yourself and family members when the time comes to:
  • where the safest place to be (in the home or school, etc.)
  • switch off utilities by turning off the main gas valve and electric circuit breakers;
  • not to touch electric wires;
  • put up a sign in front of house indicating safety and whereabouts or place of contact;
  • to look for and to follow instructions given by local authorities, police or firefighters during an evacuation.
  • have easily available in your home “shoes with strong soles in case of shattered glass and fallen objects”

(Source of quake tips: Booklet by City of Kawasaki and Kawasaki International Association)

Sources and related links:

Schools work around problems posed by risky buildings The Yomiuri Shimbun (Jun. 23, 2008)

Money woes threaten school building safety (Jun. 23, 2008) Yomiuri Shimbun

“Shaking Japan to the very core” Tuesday, June 3, 2008 Japan Times

“Study Warned of China Quake Risk Nearly a Year Ago” May 16, 2008 National Geographic News

“China Quake Delivered Seismic One-Two Punch” May 15, 2008 National Geographic News

Can Japan’s buildings survive big quake? The Yomiuri Shimbun (May. 24, 2008)

34% of nation’s school buildings would fall in Iwate-strength quake (Kyodo News) Source: Japan Times

Quake resistance of one-third of old public schools in doubt June 20 (AP) – (Kyodo)

Schools a big risk in earthquakes and not just in China May 14, 2008 IHT

Jun 21 “EARTHQUAKE! Get Out of the School” Bill Belew June 21, 2008 TheBizofKnowledge.com

Massive Earthquake Rocks Japan July 16, 2007 National Geographic News

Early-warning system passes test with Hokuriku quake March 31, 2007 Japan Times

Shaky Start for New Quake Alert System in Japan by Julian Ryall in Tokyo
for National Geographic News, May 30, 2008 Source: National Geographic.com

Japan formally launches earthquake early warning system (AP) Tuesday August 1, 2006 (Source: thestar.com)

5.2 earthquake jolts Okinawa; warning system fails Tuesday, April 29, 2008 See also virtualreview.org

Japan Times

“SICHUAN QUAKE: ONE MONTH LATER: Patience running out as questions go begging
One month after quake, parents are no closer to knowing what actually killed their children when schools collapsed” Straits Times

Quake-zone parents still looking for lost children” by TORU MAKINODA for Yomiuri Shimbun Thursday, May. 22, 2008

Major quake in Tohoku kills six Japan Times

Japanese scientists say China quake struck in two stages By Shino Yuasa for AFP news Friday, May 16.

*****

Can Japan’s buildings survive big quake?

(May. 24, 2008) Yomiuri Shimbun

 

The recent catastrophic earthquake in China’s Sichuan Province was typical of an inland epicentral jolt caused by a shift in the giant faults.

Will Japan be buffeted by a similar jolt? This country is known for an offshore ocean-trench structure that causes earthquakes when ocean trench plates sink.

The 1891 Nobi Earthquake registered magnitude 8–as strong as the Sichuan tremor–when the 80-kilometer Neodani fault in western Gifu Prefecture shifted, killing 7,273 people as a result.

In the past 10 years, there have been six fatal inland earthquakes, including the 2004 Niigata Prefecture Chuetsu Earthquake and the 2007 Niigata Prefecture Chuetsu Offshore Earthquake that damaged the Kashiwazaki -Kariwa nuclear power plant.

Masayuki Takemura of Kajima Corp., a major construction firm, said while magnitude-8 earthquakes are unlikely to strike the nation, the possibility of strong magnitude-7 tremors hitting plain regions, where foundations are soft, cannot be ruled out.

The Meteorological Agency has so far detected only two magnitude-7 earthquakes–the 1995 Great Hanshin Earthquake and the 2004 Niigata Prefecture Chuetsu Earthquake.

However, based on records kept on damage to buildings, Takemura believes there have been 10 magnitude-7 earthquakes since the beginning of the Meiji era (1868-1912). Of them, nine were inland quakes, Takemura said.

The effectiveness of earthquake resistance is the key to preventing damage.

Taking previous strong temblors into consideration, the Chinese government set standards requiring each region to build structures capable of withstanding tremors equivalent to a seismic intensity of 4 to 6 on the Japanese earthquake scale.

However, since little progress was made in reinforcing existing structures in China, weak houses collapsed, crushing many people to death when the earthquake hit Sichuan.

In Japan, the 1981 revised Building Standards Law stipulated a new earthquake-resistance standard that requires structures to be able to withstand an earthquake with a seismic intensity of 6 on the Japanese scale.

When the Great Hanshin Earthquake struck, relatively little damage was caused to houses built using the new standard.

Modern structures and condominiums have been built with seismic isolation designs capable of withstanding tremors. But the problem is how to deal with buildings erected before 1981.

According to estimates by the Construction and Transport Ministry, about 25 percent of about 47 million houses in the country do not meet the new resistance requirements.

Meanwhile, the government is still mid-task in terms of bolstering the earthquake resistance of school facilities, which serve as shelters in disasters. According to the Education, Science and Technology Ministry, of about 130,000 public school facilities across the country, about 54,000 either do not meet the current quake-resistance standard or have not been examined to see whether they are earthquake-proof.

An official of the ministry’s local facilities aid division said there are about 10,000 buildings that could collapse due to a strong earthquake.

In light of this, the ministry must reinforce such buildings as soon as possible.

(May. 24, 2008) Yomiuri Shimbun

1 thought on “Quake preparedness”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s