tohuku tsunami Flashcards
- what was the cause of the earthquake?
the radioactive decay in the core causing the hot magma to flow in convection currents which causes movements of the tectonic plates.
- what do the convection currents cause
a subduction zone
- what is a subduction zone
converging of moving plates towards eachother, forming a convergent plate boundary.
- what did the pacific plate do?
submerged under the Eurasian plate and Japan
- what did the subducting plates cause
one of the most powerful earthquakes
- where is Japan situated
along the pacific ring of fire, sitting upon 3 different tectonic plates; pacific, eurasian, Philippine
- what is position is Japan in and what are they extremely prone to
vulnerable position
disaster
- what did the earthquake rupture do to the seafloor
pushed the seafloor upwards with S waves which was a seismic wave on the Pacific Ocean floor as the water became displaced above which resulted in the tsunami
- what happened 20 minutes after the earthquake
the tsunami waves were as tall as 40 meters, struck the coasts if the Iwate prefecture, and one hour later hit Fukushima, Ibaraki and Chiba.
- what did humans greatly intensify and create
the impacts
an entirely different issue for Japan to handle with
- what horrible choice did Japan make
the choice of building a nuclear power plant so close to the coast.
- what did the 14 meter tsunami prove to much to be for
the breakwaters couldn’t handle the tsunami and it came overwhelmingly down on Fukushima
- what did the tsunami disable
the emergency power supply and cooling to the 3 reactors, which caused a significant nuclear reaction
- what happened before the tsunami even hit the coast
the systems at the nuclear power plant detected the quake and automatically shut down the nuclear reactors, emergency diesel generators turned on to keep coolant pumping around the cores
- what happened when the emergency power shut down
the 3 cores melted within the first 3 days, which sparked a major disaster
- why did the exclusive zone grow larger
there was leaking radiation from the plant and more than 150 000 people had to evacuate the area
- where did the radioactive material begin leaking into
the atmosphere and Pacific Ocean
- what caused the damage to buildings
several chemical explosions injuring 16 workers and exposing radiation to several workers.
- what could have avoided the the nuclear accident
better planning and consideration of Japan being situated on tectonic plates.
- what else did humans build on their coast
many coastal towns and prefectures which the tsunami proved to be too much for the infrastructure
2.how much of the Japanese coastline did the tsunami hit
200 miles
- other than the tsunami damage what else did the earthquake cause
structural damage due to the severe ground motion which continued for such a long duration
- in what accordance were all the damaged buildings were designed in
old building codes which lacked the seismic strength, short column shear failure due to the source wall and the breast wall or the eccentricity of structural elements
- what happened to the buildings that were fitted with appropriate seismic reinforcement
they were mostly free of damage, indicating these seismic reinforcements were effective
- what did the lack of human awareness cause when planning buildings
destruction to building and left many Japanese devastated
- why did Japan have mitigation strategies in place
because they had prior knowledge and were well prepared
- did it prevent the tsunami
no but it lessens the impact and provided them with more time
- why was Japan motivated to develop coastal protection infrastructures
due to previous 1959 typhoon and 1960 earthquake
- what did they do to protect communities
built 10 meter high seawalls along the coast to protect communities that were greatly devastated through the years
- where was the very first breakwater constructed
the mouth of Ofunato Bay in the Iwate prefecture, where the maximum depth of the bay was 36m
- how was the functionality of the breakwater investigated
through numerical analysis and was the first stage of using computer simulations in tsunami science and engineering
- what breakwater is 63m deep and what does it protect
the Kamaishi tsunami breakwater which is designed to protect the densely populated area in Kamaishi city
- was the Kamaishi breakwater able to protect the population
no but it bought them 6 minutes of time before the tsunami penetrated Kamaishi city
- what did the Kamaishi breakwater reduce
the height of the tsunami by 40% and limited the fatalities in the city to 1253
- was Japan considered well prepared
yes
- how were hazard maps determined
by long term evaluation of seismic activities
- what did 30 years of monitoring and measuring seismic activity uncover
Japan’s seismotectonic structure
- what did these hazard maps suggest
that the tohuku region in the pacific plate was moving westward and subducting beneath the northern American plate at the Japan trench
- what was predicted maximum potential earthquake caused by
the thrust faulting at the plate boundary between the Pacific and North American plates as expected
- was the quake larger than expected
yes
- compare the 2004 and 2011 event
the 2004 Sumatra-Andaman Earthquake killed 220 000, while the 2011 Tohuku event caused over 18 000 fatalities
- why was there a striking level of difference between the 2004 and 2011 event
the level of preparedness
- what did the national cabinet office publish in 2004
‘tsunami and storm surge hazard map manual’
- what did the hazard map display
previously flooded areas by past tsunamis and most likely tsunamis to occur in the future
- what have many coastal communities conducted
regular evacuation drills and held workshops to learn which areas are at risk
- what were the people of Sanriku taught
‘tsunami tendenko’ - people should run without taking care of others even family members
- what did tsunami tendenko encourage
individual decisions and taking personal responsibility of survival
- what was one of the functional aspects of hazard maps
inform people that they were at risk, but it did backfire
- why did hazard maps backfire
they failed to offer accurate prediction in some areas and may have increased the number of fatalities due to people not evacuating soon enough
