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Environmental Geology – Earthquakes vs. humankind
Earthquakes vs. humankind
Reading: This week: Ch 4Next week: Ch 5
Internal processes:
QUESTION
Environmental Geology – Earthquakes vs. humankind
Global seismicity
Environmental Geology – Earthquakes vs. humankind
The earthquake cycle
Environmental Geology – Earthquakes vs. humankind
Loma Prieta and seismic gaps
Locked
Creeping
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Environmental Geology – Earthquakes vs. humankind
San Andreas and North Anatolian faults
Environmental Geology – Earthquakes vs. humankind
North Anatolian slip history
Environmental Geology – Earthquakes vs. humankind
North Anatolian slip history
Izmit1999
Environmental Geology – Earthquakes vs. humankind
Learning the lessons
QUESTION
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Environmental Geology – Earthquakes vs. humankind
Earthquake forecasting
Earthquake forecast issued 1988
Northridge?
Environmental Geology – Earthquakes vs. humankind
The Parkfield experiment
Parkfield on the San Andreas Fault
In 1985 the USGS predicted an earthquake at Parkfield in
January 1988 ± 5 years
…still waiting
Environmental Geology – Earthquakes vs. humankind
Seismic hazard
Environmental Geology – Earthquakes vs. humankind
Building codesEarthquakes don’t kill people, buildings do
4
Environmental Geology – Earthquakes vs. humankind
Building codes
Turkey, 1999:Poor building standards blamed for much of the death
Environmental Geology – Earthquakes vs. humankind
Insurance
Environmental Geology – Earthquakes vs. humankind
The cycle goes on…
Istanbul earthquake 1556
Environmental Geology – Earthquakes vs. humankind
Earthquake prediction
“There will be an earthquake a week from Wednesday at Parkfield”
What is a useful prediction?
There will be an earthquake……in the first week of May…in LA in the first week of May …in LA on Wednesday…in LA on Wednesday greater than magnitude 8…in an hour…in a minute…in 5 seconds
Earthquake early warningan active area of research
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Environmental Geology – Earthquakes vs. humankind
Earthquake prediction in China
Possible earthquake precursors:• Rapid surface deformation• Rapid increase in small earthquake activity• Changes in physical properties of rocks e.g. conductivity, P-velocity• Change in the level of water in wells• Strange animal behavior
Environmental Geology – Earthquakes vs. humankind
Earthquake prediction in China
Success: Haicheng, NE China, February 1975• predicted an imminent earthquake,
evacuation ordered• nine hours later a large earthquake
struck destroying many homes but there was little loss of life
Failure: Tangshan, NE China, 1976• predicted an earthquake in the Tangshan region over the “next
two months”• no immediate precursors, no evacuation• more then 250,000 people died
But, what of false alarms?
Environmental Geology – Earthquakes vs. humankind
The future of earthquake prediction
This is currently being pursued in the US, Russia, China and Japan
…don’t expect results in the foreseeable future
When we are ready to try predictions consider:
• legal implications• political implications• property values• practical implications
…we would need a serious educational campaign
Environmental Geology – Earthquakes vs. humankind
Earthquake warning
Could provide a few to tens of seconds of warning
This is a research effort here at UW!
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Environmental Geology – Earthquakes vs. humankind
“Earthquake control”
Unlocking faults
• fluid injection to “smooth” fault motion
• nuclear explosion to trigger stress release on the fault