#13 Earthquake Prediction

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Amy Riley
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1 #13 Earthquake Prediction

2 Obvious importance Earthquake Prediction Save lives, reduce damage

3 Earthquake Prediction - Types Long-range prediction - involves EQ probability over long time period (years to decades), some success

4 Earthquake Prediction - Types Short-range prediction Goal is to give: Specific location and magnitude time within few days Completely unable to forecast weeks or more in advance)

5 Earthquake Prediction: Long-Range Determine EQ recurrence (average number of years between EQ of specific magnitude), EQ probability (likelihood of EQ over long time interval, decades); Use historic records of EQs (date and magnitude) and geologic record (paleoseismology)

6 Earthquake Prediction: Long-Range Paleoseismology - look for offset sediment layers or liquefaction evidence, obtain age by C 14 -dating

7 Earthquake Prediction: Long-Range Paleoseismology - look for offset sediment layers or liquefaction evidence, obtain age by C 14 -dating

8 Earthquake Prediction: Long-Range Probability of major EQ changes with time. Why? After major EQ, low probability of another major EQ immediately following, stress needs to build-up over extended time (elastic rebound model).

San Andreas fault at Parkfield, CA experienced moderate EQ (M = ~5.

9 Earthquake Prediction: Long-Range Look for seismic gap, seismically active area, hasn t had major EQ for long time (stress building up) San Andreas fault at Parkfield, CA experienced moderate EQ (M = ~5.5) every 22 years since 1857, Old Faithful ; 2004 EQ - 38 year gap

10 Earthquake Prediction: Long-Range Seismic gaps around world

11 Earthquake Prediction: Long-Range Seismic Gap (M = 9 EQ) - Indonesia (Padang, low-lying coastal city of 800,000)

12 A. Here B. Here C. Here D. Here E. Here Clicker Question: Where on this map would you predict the next major earthquake will occur?

13 Earthquake Prediction: Long-Range Seismic gap (M = 9 EQ) - Pacific Northwest

14 California Earthquakes - Sections of San Andreas Fault (SAF) build up stress over very long time ( years), released in great EQ s (M = ~8; Big One ) Locked sections of SAF: San Francisco (last Major EQ 1906) East of Los Angeles (last one 1857) Clicker question Which section is more likely to have an EQ soon? A. San Francisco area B. East of Los Angeles

15 Earthquake Prediction: Long-Range Seismic Hazard Map - US

16 EQ Prediction: Long-Range Seismic Hazard Map of California Successful long-range prediction: Loma Prieta, 1989

17 EQ Prediction: Long-Range Seismic Hazard Map - California

18 EQ Prediction: Long-Range Seismic Hazard Map - San Francisco Bay area, CA Seismic Hazard Maps are useful for long-term plans (land-use planning, building code rules), not for shortterm planning

19 Announcements Friday 2/17 Web Ex #2 is late Hand in certificates to me in class (Monday is OK) Web Ex #3 is due after Exam #1 Exam #1: Monday Feb. 27 th, 7:15-8:15 (see web site) Request conflict exam by Monday 1PM for best results An old exam is posted in Compass Exam #1: Q+A session Thursday, 2/23 5PM Here

20 EQ Prediction: Short-Range (days - hours) Measure precursor phenomena, events that SOMETIMES precede major EQ, e.g., foreshocks - minor EQs before major EQ; Unfortunately not reliable, most swarms of small EQs aren t followed by major EQ Three major EQs supposedly successfully predicted short-range (controversial) M = 7.3 EQ in Haicheng, China - maybe M = 7.8 EQ in Tangshan, China - no

21 EQ Prediction: Short-Range (days - hours) Other precursor events : ground swelling, changes in electrical conductivity and seismic wave velocities of rocks, high levels of radon gas in groundwater. Peculiar animal behavior? Difficult to use

3, 1990, didn't happen; Claimed to have "predicted 1989 San Francisco EQ.

22 EQ Forecasting: Iben Browning Climatologist who forecast 50% probability of major EQ on New Madrid fault Dec. 3, 1990, didn't happen; Claimed to have "predicted 1989 San Francisco EQ. Basis for EQ prediction involves gravitational pull of Sun and moon to create EQ susceptibility. No scientific basis for method

23 Question For Thought (Earthquake Prediction) Assume that in future, we can predict with given probability when and where a large, damaging earthquake will occur, as we do today for hurricanes. At what level of probability should general public be informed of EQ forecast for next day? >90% probability? >50%? >10%? >1%? What if EQ forecast is for next 2 months? Defend your answer in terms of the positive and negative impacts on society. The most important things to consider are positive and negative consequences of EQ forecast in terms of impact on society.

economic impact (people avoid job, tourists stay away, property values drop, insurance rates rise,

24 Merits of Informing Public of EQ Prediction Positive consequence = possibility of saving lives by evacuating a city and reducing damage (nuclear reactors on high alert) Negative consequences = major economic impact (people avoid job, tourists stay away, property values drop, insurance rates rise, evacuation cost, reduced public services); boy who cried wolf, i.e., people ignore future warnings after unsuccessful predictions

short-term warning before 2009 EQ in L'Aquila Italy where

25 Informing Public of EQ Prediction In 2012 Italian scientists convicted of manslaughter for not providing short-term warning before 2009 EQ in L'Aquila Italy where >300 deaths occurred; in 2014 convictions overturned for 6 out of 7

26 Earthquake Mitigation Mapping and zoning Improve building codes

27 Earthquake Mitigation Mandatory insurance Monitoring precursors

28 Earthquake Mitigation Develop warning systems - EQ detected by seismometer, send radiowave transmission ahead with a sec lead time to major cities

29 Clicker Question Which of the following is NOT a good example of current efforts to decrease death and destruction caused by earthquakes? A. Creation of earthquake probability maps B. Creation of earthquake warning systems that alert societies when a major earthquake has occurred C. Recently developed, excellent ability to use foreshocks to detect earthquakes shortly before they happen D. Laws that require earthquake insurance in some areas E. Laws that require earthquake-safe building codes

30 What s with Oklahoma????

31 Earthquakes - Human-Induced In 1960s Rocky Mountain Arsenal (chemical weapons maker) injected 10s of thousands of m 3 of liquid wastewater deep in subsurface (> 3 km). High levels of injection were associated with increased EQ activity.

32 Earthquakes - Human-Induced Injection of water to produce geothermal energy also correlates with increased EQ activity

associated with oil production Wastewater disposal wells

33 Earthquakes - Human-Induced Oklahoma experienced few EQs until recently due to increased wastewater injection associated with oil production Wastewater disposal wells (purple) and M 3 EQs (orange) from (left) and 2014 (right)

34 Earthquake Control? Merits of attempting EQ control (deep subsurface injection of fluid along faults) in California? Don t understand EQ control well enough to use it Probably requires HUGE number of small EQs to reduce pressure of large one; Potential legal problems if you generate EQ that causes significant destruction and any deaths

35 What to do during EQ? If indoors - do NOT run outside during shaking Drop, Cover, Hold On; door frame no stronger than rest of house

36 What to do in an EQ? if outdoors - Stay away from buildings, turn off gas supply (if safe) If driving - Stop in safe area

37 Exam 1 Coverage Ends Here

Earthquakes. Earthquake Magnitudes 10/1/2013. Environmental Geology Chapter 8 Earthquakes and Related Phenomena

Earthquakes. Earthquake Magnitudes 10/1/2013. Environmental Geology Chapter 8 Earthquakes and Related Phenomena Environmental Geology Chapter 8 Earthquakes and Related Phenomena Fall 2013 Northridge 1994 Kobe 1995 Mexico City 1985 China 2008 Earthquakes Earthquake Magnitudes Earthquake Magnitudes Richter Magnitude