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Damage Estimation of Earthquake

What is damage estimation?
Basic data that estimates damage from a hypothetical earthquake and is used for disaster management.
The TMG created “Damage Estimates of an Earthquake with an Epicenter in the Tokyo Metropolitan Area” (May 2006).

Damage Estimates of an Earthquake with an Epicenter in the Tokyo Metropolitan Area (May, 2006)
  1. Background
    • With a growing number of skyscrapers and increasing urban population, etc. Tokyo's urban structure is changing on a grand scale.
    • In February 2005, The Central Disaster Prevention Council's Expert Examination Committee on Measures for Earthquakes (hereon Expert Examination Committee) announced the first national study on damage estimates of an earthquake with an epicenter in the Tokyo metropolitan area.
  2. Goals
    Together with promotion of earthquake disaster preparedness for the TMG and municipalities, it is intended to be a source for increasing disaster awareness in the citizens of Tokyo.
  3. Features
    1) Estimates on high frequency earthquakes
    • The Expert Examination Committee theorized about hypothetical earthquakes directly under North Tokyo Bay and directly under Tama.
    • The Expert Examination Committee theorized about hypothetical earthquakes at a 7.3 magnitude, and because of the higher frequency of M6 class earthquakes, this level was also studied. (M6.9)
    2) Estimates on realistic weather conditions
    • The Expert Examination Committee theorized about hypothetical fire-fueling winds at 3m/sec and at 15m/sec, as well as winter month average wind speed at double speed, or 6m/sec.
      Note: the Expert Examination Committee's hypothesis on 15 m/sec was based on the wind speed during the Great Kanto Earthquake and is considered an especially rare wind speed condition.
    3) Application of factual data
    • In order to practically apply earthquake disaster countermeasures, the TMG as well as municipalities, made estimates using practical data on the ground, sloping areas, buildings, and highways, done individually by municipality.
    • Examining the activities of individual departments/disaster prevention organizations helps anticipate the need for secondary fire-fighting services, etc.
    4) Urban type disaster estimates
    • Based on urban type disaster, the number of stuck elevators, the number of people finding difficulty in returning home using major railway stations, etc. was estimated.
    5) TMG's first new damage estimates
    • The first Tokyo damage hypothesis revisions ever done based on damage estimates by the Expert Examination Committee.
      * Successive damage estimate reports on all prefectures are based on this Tokyo damage estimate report.
  4. Prerequisites
    1) Assuming earthquake
    [Damage Estimates]
      Earthquake estimates
    Name North Tokyo Bay Earthquake Tama Epicenter Earthquake
    (Plate boundary Tama earthquake)
    Epicenter North Tokyo Bay Tokyo's Tama area
    Magnitude M6.9 and M7.3
    Epicenter depth approximately 30-50km
    2) Climate conditions
    • The season, time of day, and weather conditions have a great influence on the amount of damage an earthquake can cause. High expected damage seasons, times and weather conditions were selected in estimates.
  5. Damage estimates based on magnitude scale
    • This shows the largest damage estimates for a North Tokyo Bay M7.3 earthquake (occurring in winter at 6:00PM).

Seismic intensity map

North Tokyo Bay M7.3 earthquake damage estimates
[North Tokyo Bay M7.3 earthquake damage estimates]
  TMG Disaster Prevention Conference Central Disaster Prevention Conference
Conditions Scale North Tokyo Bay M7.3 earthquake
Season and time of day Winter, 6:00PM
Personal
damage		 Wind speed 6m/sec 15m/sec 15m/sec
Deaths 5,638 6,413 7,800
Cause Structure collapse due to ground foundation liquefaction 1,737 Same as on the left 2,200
Fire caused by earthquake 2,742 3,517 4,700
Inclines, falling objects,
concrete block walls		 769 Same as on the left 900
Vehicle/transportation damage 390 Same as on the left -
Injured persons (severely injured persons) 159,157
(24,129)		 160,860
(124,501)		 -
Cause Structure collapse due to ground foundation liquefaction 73,472 Same as on the left -
Moving/toppling of indoor items 54,501 Same as on the left -
Fire caused by earthquake 15,336 17,039 -
Inclines, falling objects,
concrete block walls		 9,027 Same as on the left -
Vehicle/transportation damage 6,821 Same as on the left -
Physical damage Buildings damaged 436,539 471,586 530,000
Cause Structure collapse due to ground foundation liquefaction 126,523 Same as on the left 120,000
Fire caused by earthquake 310,016 345,063 410,000
Traffic Highway 607 places Same as on the left About 720 places
Railways 663 places Same as on the left About 620 places
Essential services Electric power facilities Outage 16.9% - Outage: 1.10million homes
Communication facility Offline 10.1% - Offline 0.74million lines
Gas providers Service stoppage 17.9% - Service stoppage: 1.10million homes
Waterworks facilities Water outage 34.8% - Water outage: 3.90million people
Sewage facilities Sewage service damage 22.3% - Sewage service damage: 0.13million people
Other Incidents of people experiencing trouble returning home 4,476,259 Same as on the left About 3,900,000
Incidents of evacuees
(Peak: After one day)		 3,854,893 3,990,231 About 3,100,000
Incidents of stuck elevators Maximum estimate 9,161 Same as on the left -
Deaths of vulnerable members 1,732 2,009 about 2,900
People experiencing difficulty escaping by themselves 22,713 Same as on the left About 32,000
Waste due to earthquake 40.65 million tons 41.83 million tons About 67million ton

*Decimal points are rounded up to match whole estimates.