CS: Tohoku, Japan EQ 2011

Question 1

General

Answer 1

• on March 11th, 2011, a 9 magnitude EQ, w a 30km epicentre, struck off Eastern coast of Japan, on main island of Honshu, severely impacting region of Tohoku
• most powerful recorded EQ in Japanese history, + most expensive natural disaster in history (est. $235B)
• Japan is a dev. country, w a GDP of $4.97 trillion

Question 2

What hazards resulted from EQ?

Answer 2

• shaking (primary impact)
• landslides (primary impact)
• soil liquefaction (primary impact)
• tsunami (secondary impact)

Question 3

Describe how shaking is a hazard resulting from EQ.

Answer 3

• EQ generated shockwaves, resulting from sudden release of built up pressure from friction between tectonic plates at a convergent plate boundary
  
  • caused severe ground shaking in Tohoku region, which led to damage, or collapse of buildings + infrastructure in major cities like Tokyo (e.g. 30 homes + buildings were destroyed + 1000 were damaged)
  • also, caused several nuclear power stations to suffer from fractures, + so shut down + lost power

Question 4

Describe how landslides is a hazard resulting from EQ.

Answer 4

• severe ground shaking disrupted stability of slopes, + triggered landslides in Mt regions, that buried villages, farmland + blocked transport routes, further disrupting communication, + causing a delay in aid + emergency response

Question 5

Describe how soil liquefaction is a hazard resulting from EQ.

Answer 5

• ground shaking also led to minor soil liquefaction, by inc water pressure between soil particles in saturated soil, + so dec soil friction, making it behave like a liquid
  
  • meant soil couldn’t support foundations of buildings, caused underground pipes to fracture + vehicles to sink, resulting in further damage to buildings, roads + infrastructure

Question 6

Evaluation of primary impacts from EQ.

Answer 6

• overall, despite large magnitude of EQ, damage + deaths (ab. 700 ppl) from EQ itself was low

Question 7

Describe how tsunami is a hazard resulting from EQ.

Answer 7

• EQ jolted oceanic crust, which displaced a large volume of water + generated a wave w a low amplitude, that travelled at high speeds across deep ocean
• as wave travelled towards coast, water became shallower + friction w seabed caused wave to slow down, compress, + inc in height
• this triggered a massive tsunami, w waves reaching 40m in some areas, that exceeded protective sea walls built on past experience of smaller tsunamis

Question 8

What were the secondary impacts resulting from tsunami?

Answer 8

• this led to widespread flooding + destruction of infrastructure, killing 16,000 ppl, injuring 6150 ppl, + leaving 450,000 ppl homeless from destruction of 12,000 buildings
• also, it caused a power failure at Fukushima Daiichi Nuclear Power Plant, bc disabled back up generators needed for cooling reactors, so led to meltdown of 3 plant reactors
• this released radioactive materials into air + ocean, causing widespread contamination of surrounding areas, + so >200,000 ppl were evacuated from the vicinity

Question 9

Prediction

Answer 9

• although EQs + their magnitudes are impossible to predict, bc of their random strength, Japan uses historical data + seismic activity (e.g. frequency + magnitude) to predict probability of EQs in specific areas
• seismic gaps (areas along a fault line w/o recent experience of EQs) are also used as a forecasting method, bc suggest stress is building up, inc risk of an EQ

Question 10

Hazard mapping

Answer 10

• Japan used EQ hazard maps, which predict severity + frequency of EQs in specific areas, for land-use planning + to dev EQ resistant infrastructure + buildings

Question 11

Preparedness + perception of risk

Answer 11

• buildings in Japan are designed to be EQ resistant, w v strict building codes, so can withstand intense shaking from EQs
  
  • many had strong, flexible frames + shock absorbers, enabling energy to be absorbed + dispersed, so buildings moved w/o collapsing, + deep foundations reinforced w concrete, to stabilise + prevent buildings shifting when ground shook
  • e.g. in Sendai, >70% of buildings were EQ resistant, dec collapse + casualties
• Japanese gov ensured public was informed ab EQ + tsunami safety, by carrying out public education campaigns, inc sig of emergency safety kits, + evacuation drills
• Japan invested heavily in constructing large sea walls along 14,000km of its coastline, to protect inland from tsunami waves

Question 12

Response + recovery

Answer 12

• bc Japan was highly prepared, its response + recovery was highly organised + efficient, w rescue workers + 100,000 members of Japan Self-Defence Force helping in search + rescue operations, providing medical care + delivering supplies, within hrs of tsunami
• also, although rebuilding took yrs, affected areas were rebuilt w stronger infrastructure + stricter measures to improve Japan’s preparedness for future disasters

Question 13

Monitoring

Answer 13

• Japan’s EQ Early Warning System, detected initial shock waves, providing Ms of ppl w a few seconds warning before stronger shaking occurred, allowing many to evacuate buildings + trains to stop, mitigating impacts
• Japan Meteorological Agency issued tsunami warnings 3 mins after EQ, allowing effective evacuation + response measures that mitigated impacts + minimised casualties
  
  • tsunami warning system involved a network of buoys in ocean, w sensors to detect offshore EQs + monitor tsunami waves, allowing it to predict areas most at risk + send alerts to these areas

Question 14

Conclusion/evaluation

Answer 14

• although Japan was relatively well-prepared for EQ, sheer scale of event revealed limitations in its disaster preparedness systems, highlighting that even sophisticated plans can be insufficient when facing such extreme natural disasters
• however, bc of Japan’s financial stability, it successfully mitigated impacts + diverted social impacts to eco. impacts
• also, this led to further strengthening of Japan’s preparedness + disaster planning, ensuring resistance is improved for future natural disasters