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Each time Japan is hit by a serious natural disaster, it has sought to improve its scientific and technological capabilities in preventing and mitigating damage of disasters. Taking into account the lessons learned from the Great East Japan Earthquake, advances are currently being made in research and development into more accurate science and technology to prepare for earthquakes and tsunamis. The Japan Journal's Osamu Sawaji, and Takashi Sasaki and Toshio Matsubara report.

A Hayabusa Shinkansen train running on the Tohoku Shinkansen line. Hayabusa trains will run at a top speed of 320 km/h from March 16.
Shinkansen Trains Brought Safely to a Halt

The Tohoku Shinkansen Line connects Fukushima, Sendai, Morioka and other major cities of the Tohoku region, traveling a distance of 713 km. The Great East Japan Earthquake devastated many train lines in the Tohoku and Kanto regions, and destruction of stations, snapping of overhead wires and other damage resulted. Nineteen Tohoku Shinkansen trains with passengers on board were in operation when the earthquake struck, but all of them stopped without derailing, and no human injury was incurred.

The East Japan Railway Company (JR East Japan) operating the Tohoku Shinkansen has implemented antiseismic measures focusing on the three points of quickly bringing trains in operation to a halt, preventing destruction of structures, and minimizing damage after derailing. For quickly stopping trains in operation, the Earthquake Early Warning System for Shinkansen ("Earthquake Warning System") has been adopted. The system has been put into place on other Shinkansen lines in Japan as well.

"The Earthquake Warning System aims at having the brakes work securely and as fast as possible to safely bring the train to a halt," says Reiko Seki of the Facilities Department of JR East Japan.

The Earthquake Warning System detects earthquakes (seismic waves), automatically terminates power transmission from transformer substations to trains, and automatically activates the train's emergency brake. Seismographs for detecting seismic waves are installed at a total of 127 locations within the area managed by JR East Japan, along the Pacific coast and Japan Sea coast, in inland areas and along Shinkansen lines.

Normally, earthquakes are characterized by the primary wave (P-wave) in a small, vertical motion (initial tremors) that is transmitted quickly and the secondary wave (S-wave) in a large, horizontal motion (primary tremors) that is transmitted slowly. Although influenced also by the earthquake magnitude and the distance from the epicenter, the S-wave normally arrives after a few to several dozen seconds from the arrival of the P-wave. The Earthquake Warning System detects the P-wave with a seismograph close to the epicenter, and the seismograph estimates the distance from the epicenter, direction and magnitude based on past records of earthquake. A warning is then issued to transformer substations in areas where damage to structures are anticipated, referring also to observation data on previous earthquakes, and the transformer substations that received the warning terminate power transmission to the trains.

The Earthquake Warning System also ensures that a warning is issued and Shinkansen trains are brought to a halt when seismographs have detected seismic waves (S-wave) larger than the set level, even when a P-wave was not detected or when a warning was not issued despite detection of P-waves.

"In the past, the warning system only detected S-waves, but since 1998, after the Great Hanshin-Awaji Earthquake, systems that detect P-waves were also put into place," Seki says. "The system that detects both P- and S-waves helped a great deal in safely halting trains during the Great East Japan Earthquake."

When the quake struck, the seismograph located along the Pacific coast in Miyagi Prefecture that was closest to the epicenter detected the S-wave at a scale that exceeds the set level. This led to issuance of a warning, and power transmission was halted over about 170 km along the Tohoku Shinkansen Line. It only took about three seconds to activate the emergency brake after halting power transmission. Two trains were in operation in the section, running at about 270 km/hr. The emergency brake was activated about 10 seconds before the arrival of the tremors that supposed to halt the train. By about 70 seconds before arrival of the strongest tremors, the Shinkansen trains that had been traveling at about 270 km/hr had decelerated to about 100 km/hr. Power transmission was from that point halted sequentially at other sections as well, bringing all Shinkansen trains safely to a halt.

To further enhance antiseismic measures after the earthquake, JR East Japan incorporated emergency earthquake notices issued by the Meteorological Agency, which has installed seismographs for detecting P-waves in larger areas, in the Earthquake Warning System, enabling even more detailed detection of earthquakes.

Outline of the Ocean Bottom Seismic and Tsunami Network along the Japan Trench
A fiber optic cable (pink line) measuring approximately 5,600 km long and having 150 observation points (dots) will be submerged in the inner part of the Japan Trench and in the outer part of the Japan Trench (blue region) from Chiba Prefecture to Hokkaido.
More Accurate Forecasting of Tsunamis

The Pacific plate is sinking westward beneath the North American plate, on which Tohoku and Hokkaido sit, beginning its descent at the Japan Trench that extends from south to north for around 800 km from just off the coast of the Boso Peninsula in Chiba Prefecture on Honshu to just off the coast of southeast Hokkaido. At its deepest, this trench is 8,020 m.

Massive colliding plates in this area have made it the epicenter of not only the Great East Japan Earthquake on March 11, 2011, but of many other large earthquakes that have occurred in the past too. However, the majority of the more than 1,500 seismic observation stations in Japan are on land, with only 55 observation stations in the ocean (both these figures are as of the time of the Great East Japan Earthquake). To compensate for the gap in this network of observation stations in the ocean, in 2011 an improvement project for the "Ocean Bottom Seismic and Tsunami Network along the Japan Trench" was launched.

Toshihiko Kanazawa, professor emeritus at the University of Tokyo and head of the Ocean Bottom Seismic and Tsunami Network Laboratory at the National Research Institute for Earth Science and Disaster Prevention, had the following to say:

"At the time of the Great East Japan Earthquake there were two observation devices installed just off the coast of Sanriku for collaborative research by the Earthquake Research Institute of the University of Tokyo to which I belong and Tohoku University. The land-based station that was installed on the coast was destroyed by the tsunami in the earthquake, interrupting data collection, but the movement and size of the tsunami during the period until it reached the coast had been accurately captured. Although the devices were for research purposes only, some researchers believe that if this real time data had been reflected in the warnings the extent of the damage may have been slightly different."

While only two observation devices were installed on the ocean floor, their position was optimal for observing the tsunami in the Great East Japan Earthquake, and as such they have yielded precious data.

Illustration shows a section of the fiber optic cable belonging to the Ocean Bottom Seismic and Tsunami Network along the Japan Trench.
A capsule called an "observation node" will be installed on the ocean floor of the Pacific in the Ocean Bottom Seismic and Tsunami Network along the Japan Trench. This stores a seismometer, a tsunami gauge (water-pressure gauge), a power source, and so forth, together with ocean bottom fiber optic cables that link these together. These will be submerged in the inner part (western side) of the Japan Trench and in the outer part (eastern side) of the Japan Trench from Chiba Prefecture to Hokkaido. This means that it will attempt to cover a wide area of sea on the eastern side of the Japanese archipelago by forming an extensive observation network on either side of the Japan Trench. There will be a total of 150 observation points, with the total length of the ocean bottom cable approximately 5,600 km.

The observation node is cylindrical in shape measuring 32 cm in diameter and 2.3 m long, and is divided into an open part that measures water pressure and an airtight part that stores the other devices. The body of the node is made of high strength beryllium copper. Further, the airtight part into which the devices have been placed is sealed using laser beam welding rather than packing, which can age over time allowing seawater to penetrate. Even if trouble were to occur, such as the fiber optic cable breaking at some point, or part of the observation equipment or land-based station being destroyed, it employs redundant design so as to operate continuously.

The observation node is 32 cm in diameter and 2.3 m long.
"The observation devices have a life of more than thirty years," says Professor Kanazawa. "To secure durability and a high level of reliability is indispensable for a disaster prevention system."

The data collected in this way is sent in real time not only to the National Research Institute for Earth Science and Disaster Prevention but also to the Japan Meteorological Agency and other bodies, enabling it to be used in a range of disaster prevention scenarios, including earthquake information and tsunami information. It could be also useful for local government evacuation orders, and public transport traffic control.

Previously, when a tsunami was approaching, it could only be estimated from the epicenter or size of the earthquake, but if actual observation data can be obtained offshore using multiple observation devices, highly precise forecasts can be sent out swiftly. Further, since seismic waves can be caught close to the epicenter, an earthquake early warning can be technically circulated as much as about 30 seconds earlier than previously, in the case of an earthquake that occurs on the bottom of the ocean near the Japan Trench.

The construction work for the observation network will begin in April this year at the earliest, starting with the coast off Boso in Chiba Prefecture and the northern part of the coast off Sanriku in Miyagi Prefecture, with partial trial operation beginning around July. Full-scale operation will commence approximately two years later when all the construction work is completed. Not only will it be able to provide accurate and speedy information on earthquakes and tsunamis, but if the collection of highly precise data reveals the mechanism of earthquakes that have occurred deep in the ocean floor, it is expected to help predict earthquakes in the future, as well as contribute to urban planning and disaster damage prevention planning in the Tohoku region.

Displays of Fujinokuni Joint Information System and Network (FUJISAN) in the Shizuoka Prefectural Government Office in Shizuoka City. Officers can see the real-time situation of disasters via electronic maps and cameras.
Harnessing Cloud Computing for Disaster Prevention

In the Tokai region facing Suruga Bay in the Pacific Ocean, on the western side of Mount Fuji, massive earthquakes with their epicenter off the coast have struck every 100–150 years, and it is speculated that there is a high possibility of a magnitude 8 earthquake occurring in the near future. Because of this, Shizuoka Prefecture, which is situated in this area, is devoting a great deal of effort to various disaster prevention measures in respect of earthquakes and tsunamis, with local governments in the prefecture at the center of such initiatives.

One such measure is Japan's first disaster prevention system utilizing cloud computing, which commenced operation in July 2011, the Fujinokuni Joint Information System and Network (FUJISAN). ("Fuji-san" is the Japanese for "Mount Fuji.")

Prior to introducing FUJISAN, Shizuoka Prefecture had constructed a disaster prevention system using two dedicated servers located in the prefectural office building. Through this system, Shizuoka Prefecture collected information from the municipalities on the extent of damage which was used for rescue and relief activities, as well as being conveyed to the national government. However, there were a number of major problems with this system. Firstly, while the prefectural office building is exceedingly earthquake resistant, if by any chance it were to sustain a level of damage that destroyed the building there was a danger that the system itself would cease to operate. Also, in a prefectural trial run, it became clear that when 800 members of staff access the disaster prevention system at the same time the system stops. What is more, even during normal use the volume of data is large, so the electronic maps displaying various types of information do not work smoothly.

To resolve these problems using independent servers would require the investment of enormous sums of money. So the solution that emerged was to switch to cloud computing. Preparations began in April 2010, and in March 2011, when the construction of the new system was in its final stages, the Great East Japan Earthquake struck. Shizuoka Prefecture was untouched by the disaster. However, in the disaster-affected areas, the destruction of disaster-prevention facilities and the disruption of communications networks caused existing disaster-prevention information systems to cease functioning, making the problem that had been feared in Shizuoka a reality.

By utilizing the Internet to decentralize information processing, cloud computing made it possible to process large volumes of data speedily. As a result, electronic maps work a great deal more smoothly with FUJISAN. Theoretically, simultaneous access too is almost limitless. As a result, various disaster-related data can now be confirmed speedily using electronic maps, and even people unfamiliar with the area or people with little experience of dealing with disasters can now easily comprehend the extent of the disaster. Further, since the data is stored on the cloud, the system would continue to run even if the prefectural office building were damaged.

When building the system, emphasis was placed on the collection and dissemination of information necessary for rescue and relief activities within 72 hours after a disaster occurs. The information handled mainly relates to earthquakes and damage caused by wind or flood, and in addition to information on damage and requests for assistance, four important databases for roads, heliports, evacuation centers, and first-aid stations have been developed. Further, a system was introduced (area e-mail) whereby when a disaster occurs a disaster emergency announcement is delivered simultaneously to mobile phone holders in the entire prefecture through mobile phone companies.

FUJISAN can be used by prefectural government bodies and other municipal agencies within the prefecture, and when a disaster occurs members of staff can use their smartphones or mobile phones from their workplace to view detailed disaster information. Staff who are at the scene of a disaster can now also send photographs and latitude and longitude information, which are instantly reflected on electronic maps.

"This is a specialized system to collect the information that is required by the prefecture and send out requests for assistance without delay to surrounding areas and the national government," says Takefumi Watanabe of Shizuoka Prefectural Government's Emergency Management Strategic Division that supervised the building of the FUJISAN system. "As far as uploading information on damage from the scene of the disaster is concerned, detailed rules and regulations have also been put in place regarding who should upload information and when, in order to avoid confusion."

New initiatives for the future too have already begun. For example, investigations are in progress in order to display information about road restrictions and information about evacuation orders when a disaster occurs on FUJISAN and car navigation systems simultaneously, by linking ITS, the state-of-the-art road information communications system, and FUJISAN via a network. Further, although citizens currently cannot access FUJISAN, in 2013 Shizuoka Prefecture will launch a service on its website enabling the public to check electronic map information in real time. This electronic map will display information on the establishment of emergency response headquarters, damage in each area, opening of evacuation centers, and official evacuation warning announcements.