Seismic Hazards - (Japan Earthquake and Tsunami 2011) Flashcards
When and where did the Japan earthquake occur?
On 11th March 2011, at 14:46 local time, a magnitude 9.0 undersea megathrust earthquake struck 70 km off the northeast coast of Honshu, Japan’s main island.
Which areas were most affected by the event?
The Tohoku region of northeast Japan, especially Sendai, Miyagi, and Fukushima Prefectures, suffered the most damage from the earthquake and tsunami.
What type of plate boundary caused the 2011 Japan earthquake?
It was a convergent (destructive) plate boundary. The Pacific Plate is subducting beneath the North American Plate at the Japan Trench.
What tectonic movement caused the earthquake?
A sudden release of strain energy occurred when the subducting Pacific Plate slipped, displacing a huge section of seabed and sending shockwaves and tsunami waves.
How does Japan’s location affect its seismicity?
Japan is located on the Pacific Ring of Fire and is one of the most seismically active countries in the world, experiencing hundreds of small earthquakes annually.
Was the 2011 event predictable?
While seismic risk is well known in Japan, the magnitude 9.0 event exceeded most predictions. It was the largest recorded earthquake in Japan and the fourth largest globally since 1900.
What types of seismic hazards occurred?
Earthquake (moment magnitude 9.0)
Tsunami (up to 40.5 m high)
Liquefaction in parts of Tokyo Bay
Aftershocks (over 800 recorded above M4.5)
Landslides in mountainous areas
What directly caused the 2011 Japan earthquake?
A 160 km section of the Pacific Plate slipped under the North American Plate, causing a 50 m horizontal displacement and 10 m vertical uplift of the seafloor, triggering a tsunami.
How did the Japanese population perceive the event?
Japan had a high level of hazard awareness, but the scale of the disaster shocked the nation. People trusted technology and building codes but were surprised by the magnitude and tsunami height.
How did international perception differ?
Globally, the event highlighted Japan’s vulnerability despite its preparedness and sparked fear due to the Fukushima nuclear disaster that followed.
How many people died or were affected?
Over 19,700 deaths (mostly from the tsunami)
6,000+ injured
470,000 people displaced into shelters
What happened to homes and infrastructure?
Over 120,000 buildings completely destroyed
4.4 million households lost electricity
1.5 million without water
What was the cost of the disaster?
Estimated at $235 billion, making it the costliest natural disaster in history.
What happened to Japan’s economy and industry?
Global supply chains were disrupted
Production at major firms (e.g. Toyota, Sony) temporarily halted
Power shortages from Fukushima impacted manufacturing
What environmental damage occurred?
Massive coastal flooding
Radiation leaks from Fukushima Daiichi Nuclear Plant
Contamination of soil and water
Debris and waste spread across thousands of km
What were the political consequences?
Criticism of TEPCO (Tokyo Electric Power Company) for Fukushima response
Government faced backlash for slow evacuation and information sharing
Long-term energy policy change: shift away from nuclear power
What emergency responses were launched?
100,000 Japanese Self-Defence Force troops mobilised
Rapid deployment of rescue teams and medical aid
Foreign aid from 134 countries
Evacuation of 154,000 people near Fukushima
Emergency shelters, food, and water provided
What reconstruction and recovery efforts took place?
$300 billion+ allocated for reconstruction
New tsunami warning systems installed
29,000 housing units built by 2015 for displaced families
Coastal towns rebuilt on higher ground
What changes were made to Japan’s nuclear policy?
Immediate shutdown of all nuclear reactors
Increased investment in renewables
Stricter nuclear safety regulations
How was Japan prepared before the 2011 earthquake?
Strict building codes for earthquake resilience
Regular earthquake drills and public education
Advanced early warning systems for earthquakes and tsunamis
What mitigation strategies were in place or added after the event?
Sea walls (many of which were overtopped, now being redesigned)
Zoning laws revised to restrict building in tsunami-prone areas
Improvements in emergency planning and nuclear regulation
How did Japan adapt after the disaster?
Rebuilding with disaster-resilient infrastructure
Revising energy policy to reduce nuclear reliance
Increased focus on community preparedness and education
Why was the impact so severe even in a highly developed country?
Magnitude 9.0 quake + massive tsunami overwhelmed defences
Underestimation of tsunami height (some waves reached 40.5 m)
Nuclear vulnerability not sufficiently mitigated
Coastal areas still housed vulnerable populations
