chapter 4 Flashcards
what is the difference between a forecast and prediction?
a forecast is a general statement about the possibility of something happening.
prediction is a more precise statement about the possibility of a future event.
it is possible to forecast an earthquake but it is not possible to predict one
what is the relationship between building heights, ground oscillation frequency, building oscillation frequency and building damage during an earthquake?
during an earthquake a tall building located on sediment will experience maximum earthquake effect because of the frequency of the ground is matched by the frequency of the building. in the same way a short building would also experience a maximum effect
explain how changes in ground levels and ground water level may be used to predict an earthquake
the water table and the movement of ground water may change as the stress causes cracks in the ground (porosity and permeability) to open and close
explain how radon gas may be used to predict an earthquake
a radioactive gas (naturally occurring) the rate of gas escape from the ground will depend upon the grounds porosity and permeability
changes in stress that might be related to earthquakes activity may change porosity and permeability and rate of gas escape
explain how seismic gaps and migrating earthquakes may be used to predict an earthquake
a seismic gap is a section of fault that has not experienced an earthquake in a significant period of time.
seismic gaps will help narrow the search for where the next earthquake will/may occur
explain how earthquake regularity may be used to predict an earthquake
the regular occurrence of earthquakes @ certain times and places may be useful in predicting their behaviour
explain how paleoseismology may be used to predict an earthquake
the long term earthquake history of an area as recorded in the reck record. this may include tsunami deposits and evidence of movement on a fault. this not only provides information from other sources and areas not regularly monitored.
explain how animal behaviour may be used to predict an earthquake
its generally accepted that many animals “sense” things differently than humans.
example: elephants in a zoo constantly pacing suggesting a certain unease
there have been notable examples of successful earthquake predictions. describe one. when was it and on what basis was a successful prediction and warning made?
Feb 1975, China.
a warning was issued and people were ordered to remain outside. shorty after a 7.3 magnitude earthquake happened which caused considerable damage but minimal loss of life.
what is a seismic gap and why is it significant? describe in detail an example
a section of the fault that has not yet experienced an earthquake in an ____ amount of time. a seismic gap may indicate a behaviour of a fault.
what is a blind fault?
is a fault that does not show on the surface
can earthquakes be triggered by the introduction of fluids such as water into a fault zone? explain and give an example
yes, an earthquake was accidentally triggered in Colorado when they disposed of liquid waste underground. a series of unknown faults were “lubricated”. this reduced the friction between rock bodies which allowed them to move and cause earthquakes
if earthquakes could be deliberately triggered by injecting fluids (water) into a fault zone, what are some of the ramifications?
it is not possible to reliably map a fault, predict where the fluid will go or what it will do. it earthquakes you hope for may or may not occur. it may not be of the size you intended. it may takes place @ a time or location that was not predicted
describe the earthquake hazard in turkey
in Turkey the main type of plate margin is a right Lateral Strike-Slip or transform margins
describe the earthquake hazard in Chile. why is the area so important for British Columbia?
Chile is located along the coast near a subduction plate as British Columbia. it caused a tsunami which is what were also expecting here.
