EESA06H3 Lecture Notes - Lecture 7: Seismology, Soil Horizon, Eurasian Plate
**** how the pacific ocean is dying (basically)
How plates interact with e/o around the Pacific Rim
● 3 types
○ Ocean crust vs ocean crust (subduction) → island arcs
○ Ocean crust vs continental crust (subduction) → magnetic arcs
○ Oceanic or continental crust simply slide past each other (transform)
● The older and thicker the plates are, more that they’ll get subducted
JAPAN: SUBDUCTION CENTRAL
● Where 3 different plates meet
○ Pacific plate (underneath pacific ocean) is being pushed down below Philippine
plate
○ Eurasian plate is over both of them
● NOTED FOR it’s major earthquakes and volcanoes as well
● Japan’s active volcanoes
○ Earthquakes used to be believed to be caused by weathering conditions
● If it’s been longer than 100 years that there’s been no major earthquake then there’s
trouble
○ There will be a gap filling earthquake → major earthquake
○ Seismic gap is a place where there’s no movement occuring between plates
■ Plates are locked → strain is accumulating and then released when plates
uncouple → energy is released as major earthquake
NOBI earthquake 1991
● No one really knew what triggered earthquakes
● Used to believe unusual weather creating earthquakes
● First one to be studied scientifically
● NEODANI FAULT → movement of this fault caused earthquake
● Beginning of the science of seismology
● Key earthquake in Japan
○ Japan was modernizing and brought in Western engineers
○ A lot of buildings were destroyed bc of earthquake and realized these buildings
were catastrophic
○ Japanese culture became more militaristic and anti-Western
Tokyo After the The Great Kanto Earthquake (and fire) - Sept 1 1923
● Leveled Tokyo
● Fire that destroyed wooden and paper buildings
● These earthquakes occur every 100 years so some ppl have not experienced these
○ A lot of effort to educate students on how to be better prepared in case every
year on this day
● Uplift and subsidence
Document Summary
**** how the pacific ocean is dying (basically) How plates interact with e/o around the pacific rim. Ocean crust vs ocean crust (subduction) island arcs. Ocean crust vs continental crust (subduction) magnetic arcs. Oceanic or continental crust simply slide past each other (transform) The older and thicker the plates are, more that they"ll get subducted. Pacific plate (underneath pacific ocean) is being pushed down below philippine plate. Eurasian plate is over both of them. Noted for it"s major earthquakes and volcanoes as well. Earthquakes used to be believed to be caused by weathering conditions. If it"s been longer than 100 years that there"s been no major earthquake then there"s trouble. There will be a gap filling earthquake major earthquake. Seismic gap is a place where there"s no movement occuring between plates. Plates are locked strain is accumulating and then released when plates uncouple energy is released as major earthquake. No one really knew what triggered earthquakes.
