About Us

Seismic Reinforcement against Earthquakes Directly beneath Tokyo Metropolitan Area, and Strengthening of Seismic Observation Systems

East Japan Railway Company

March 6, 2012

In light of past seismic events such as the Great Hanshin Earthquake (January 1995), Sanriku-Minami Earthquake (May 2003) and Niigata Chuetsu Earthquake (October 2004), JR East has been seismically reinforcing its rigid frame viaduct columns, bridge piers, tunnels, station buildings, etc., taking measures to prevent derailing, and installing more seismometers.
In part because of such measures, JR East experienced no major damage to viaducts, tunnels and other structures during the Great East Japan Earthquake of March 11 last year.
We continue to take initiatives such as seismically reinforcing viaduct columns (a secondary seismic reinforcement measure that represents an expansion in scope since FY2009), but we are now taking the earthquake countermeasures described below in addition.

1. As seismic reinforcement measures against an anticipated earthquake directly beneath the Tokyo metropolitan area, we are taking further measures such as reinforcing embankments and moving up our schedule for seismic reinforcement of viaduct columns.
   
2. In light of the Great East Japan Earthquake, we are moving up our schedule for seismic reinforcement of viaduct columns and expanding the scope of this measure.
   
3. We are stepping up our seismic observation system by installing more seismometers, among other measures.
The following table enumerates JR East’s viaduct columns and bridge piers. Data highlighted with indicates structures where seismic reinforcement is complete, while data highlighted with indicates structures where seismic reinforcement is still in progress.

Seismic reinforcement of viaduct columns and bridge piers
: Completed by end of FY2008  : Completion planned by end of FY2013
and : To be newly begun

See Attachment 1 for a map showing the boundaries of the south Kanto area, Sendai, etc. area and other areas.
   
Attachment 1 [PDF/318KB]
Now, JR East will be taking new seismic reinforcement measures against an earthquake directly beneath the Tokyo metropolitan area and further seismic reinforcement measures beyond the scope of those measures.

  1. Seismic reinforcement measures against an earthquake directly beneath the Tokyo metropolitan area

    (1)

    Structures subject to reinforcement

     

    Viaduct columns used by shops, etc. beneath elevated track

       

    (Data highlighted with in Table 1)

     
     

    Embankments, cutouts and bridges on nine line sections, including Yamanote and Chuo Lines (about 220 km)

       

    Embankments and cutouts (survey and design)

    About 8 km

       

    Unreinforced concrete, stacked brick or stone bridge piers

    About 60

       

    Steel girders

    About 120 bridges

     

    Station/platform ceilings (Tokyo Station Shinkansen platforms, etc.)

    About 10 places

    (2)

    Construction cost:

    About 52 billion yen (in the case of embankments and cuts, includes survey and design costs only)

       

    For Shinkansen lines, our aim is to be done in three years, while for conventional lines the schedule is undecided, but we aim to finish as early as possible.

    (3)

    Other:

    In addition to the above, we will hereafter be drafting and implementing plans for brick arch viaduct seismic reinforcement measures, station/platform ceiling and wall collapse prevention measures, electrical pole collapse prevention measures and more.

         
  2. Further seismic reinforcement measures in addition to 1. above

    (1)

    Seismic reinforcement of viaduct columns and bridge piers

       

    (Data highlighted with in Table 1)

    (2)

    Construction cost:

    About 43 billion yen
    Our aim is to be done in five years (subject to change depending on consultations with users below elevated lines, etc.)

    (3)

    Other:

    We will hereafter be drafting and implementing plans for station/platform ceiling and wall collapse prevention measures, electrical pole collapse prevention measures and more.

         
For details, please refer to the following attachment.
   
Attachment 2 [PDF/346KB]
  1. Strengthening seismic observation system

    On Shinkansen lines, the Shinkansen early earthquake detection system was implemented in FY1998, and since then we have been increasing the number of trackside seismometers, among other measures. In FY2009, we implemented a conventional line early earthquake warning system throughout our conventional lines. This system uses Shinkansen P-wave detection seismometers and the Meteorological Agency’s early earthquake warnings.
    Now, JR East is working to strengthen our seismic observation system as below.

    (1)

    Increasing seismometers in the Tokyo metropolitan region and inland areas

     

    Add 30 seismometers to prepare for an earthquake directly beneath the Tokyo metropolitan area and inland earthquakes

     

    Planned start of use: March 9, 2012 on conventional lines, summer 2012 on Shinkansen lines

    (2)

    Implementation of early earthquake warnings (Meteorological Agency) on Shinkansen lines

     

    Planned start of use: Autumn 2012

    (3)

    Construction cost: About 1.2 billion yen

For details, please refer to the following attachment.
   
Attachment 3 [PDF/606KB]
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