Akio Oikawa and Shogo Hara / Yomiuri Shimbun Staff Writers
Reconstruction of an area of Urayasu, Chiba Prefecture, still has a long way to go after 86 percent of the city’s area was affected by liquefaction at the time of the Great East Japan Earthquake.
Liquefaction is a phenomenon where pockets of stable sand underground are shaken by an earthquake and mixed with groundwater. As a result, the soil becomes sludgy and unstable.
In some cases, muddy water reaches the surface. Because the ground foundation suddenly becomes soft, buildings may sink or tilt.
About 9,000 residential buildings were damaged by the liquefaction.
This month, in the Maihama district, which was severely damaged, the city government’s branch office resumed operation, and administrative services have recovered to pre-disaster levels.
But tilted houses still remain, and ripples remain in some roads in the area.
It will take about three years for the water supply and sewerage systems to be fully restored.
Many tasks and hurdles remain before the area’s quiet residential districts can return to their pre-disaster condition.
An administrative service center of the city government reopened Oct. 1 in front of JR Maihama Station, which is the gateway to Tokyo Disney Resort.
The center’s building was tilted due to liquefaction, and was closed until recently.
A 77-year-old man who visited the center to obtain a registration certificate for his personal seal looked relieved and said, “Now I no longer have to go to the next station by train.”
Obvious traces of the disaster can no longer be seen near Maihama Station and on major roads. But in residential districts, “Under repair” signs are prominent in many places beside slightly tilted houses.
In some places, houses sank into the ground and sewer pipes under roads were clogged.
Yuko Shiina, a 47-year-old homemaker, relies on makeshift pumps set up by the city government to keep the sewers flowing.
She said: “Under usual conditions there is no problem at all. But this summer, I worried about what I would do if the pumps stopped due to a blackout or an electric power shortage.”
Most of Urayasu is reclaimed land. In one extreme case, a building sank nearly 90 centimeters into the ground.
Among about 9,000 buildings damaged by the disaster, about 1,400 are severely damaged houses, qualifying the owners to receive subsidies from the central government.
Of that total, more than 60 percent of the homes were repaired or under repair as of the end of September.
But many of about 5,900 houses categorized as “half-collapsed” or “partially collapsed” remained untouched.
The Chiba prefectural government and the Urayasu city government began in July last year providing up to 1 million yen in subsidies to owners of houses who are not eligible to receive state aid. But only about 20 percent of the owners had applied for the local governments’ aid as of September this year.
An official in charge of the issue at the prefectural government said, “There are many people who can’t decide what method to use to reinforce their foundations.”
There are various methods for performing reinforcement work on a building’s foundations. The city government said costs also vary widely from several million yen to 30 million yen.
There are cases where border stones were lost in the liquefaction and land owners became unable to confirm land boundaries.
In other cases, the relative heights of residential land plots and the roads they face changed significantly.
In some such cases, work to restore water supply pipes cannot begin until the land boundaries are confirmed.
Water supply, sewerage systems and other crucial systems in the area were temporarily restored a month after the disaster, but local governments assume they will only be fully restored in fiscal 2015.
This is because the restoration work is done with a certain number of repairs en masse to achieve high efficiency, instead of repairing each gas or water pipe separately.
A long time will also be needed to take measures against liquefaction when restoring sewerage systems.
The city government in June set up an expert panel to discuss which methods are more effective for reinforcing ground foundations.
The city government plans to compile the recommended methods and forecast costs of the work in early November and give explanations to residents.
But a city government official said work to reinforce ground foundations will not be effective if each house owner does the work separately.
The official said, “Unless the work is done with a consistent way in at least one neighborhood association, reinforcement of ground foundations will be difficult to accomplish.”
The city government plans to seek the understanding of residents regarding the issue through explanatory meetings.
The city government also plans to conduct measures to prevent liquefaction in important parts of the sewerage and highway systems that were not damaged by the disaster.