1. slide © UBC-EOSC 2001 The Shaking Earth: mitigation & prediction

2. slide © UBC-EOSC 2001 Outline for “The Shaking Earth” NB: Readings & lectures are complementary - some unique coverage in both. We investigate five aspects of earthquake science: Effects and global distribution Local context, global distribution, effects, plate tectonics. Earthquake sources Forces, types of faults, slip during earthquakes. Seismic waves Ground motion, wave types, wave propagation, using waves to study earthquakes Human impact and engineering What kills?, magnitude vs. intensity, earthquake-resistant structures. Mitigation and Prediction predicting occurrence and effects, minimizing damage

3. slide © UBC-EOSC 2001 Mitigation: Preparedness UBC information –UBC Health, safety, and environment: http://www.hse.ubc.ca/innerContentFrame.php?type=pubsAndProcs &ln=11-Earthquake.PDF Vancouver info: http://www.city.vancouver.bc.ca/fire/emerg_prep.html BC info: http://www.pep.bc.ca/ Canada info: http://www.epc-pcc.gc.ca/ http://www.seismo.nrcan.gc.ca/hazards

4. slide © UBC-EOSC 2001 Mitigation: BC government Risk Management Branch of Ministry of Finance The Seismic Mitigation Program: –$133 million for fiscal years 1999 - 2003 –structural and nonstructural seismic upgrade of schools, post-secondary facilities, hospitals post-disaster facilities Natural Resources Canada - seismic hazard reports: maximum acceleration and velocity (for various probabilities); basis for 2005 National Building Code of Canada

5. slide © UBC-EOSC 2001 Mitigation: Building design Abbott 4th ed, pgs 81 - 83 Damping: Absorb energy caused by moving ground. From University of Bristol, Department of Civil Engineering Earthquake Engineering. http://www.cen.bris.ac.uk/students/eqteach97/welcome.htm Isolation: Let ground move under the building

6. slide © UBC-EOSC 2001 Mitigation: Building design (shear walls)

7. slide © UBC-EOSC 2001 Damping in action (new)

8. slide © UBC-EOSC 2001 Mitigation: construction practices Cosmetic facing can be dangerous Concrete must be reinforced … But it must be done properly!

9. slide © UBC-EOSC 2001 Mitigation: a local example Seymour Falls Dam Seismic Upgrade: Upgrading an earth-filled dam (2003-2008): –The structure is strong, but would fail in a major earthquake by liquefaction of the soil foundation. A new foundation will be made by blasting & dropping large weights (dynamic compaction). –“Blast densification” is new in SW BC. –Explosions cause soil layers to settle and become dense so they won't flow when the BIG ONE comes. http://www.gvrd.bc.ca/water/pdfs/seismic.pdf http://www.gvrd.bc.ca/water/current-projects.htm

10. slide © UBC-EOSC 2001 Earthquake engineering at UBC UBC Department of Civil Engineering Earthquake simulator facility for seismic research and qualification testing. http://www.civil.ubc.ca/home/eq_lab/ Shear-wall test on seismic simulation table. Scale model of a building on the seismic simulation table. Research at UBC in Civil Engineering

11. slide © UBC-EOSC 2001 Prediction Predict... 1. Where earthquakes will occur? 2. When an event will occur? 3. What effects if an event occurs? 4. Specifics about Cascadia? “Since my first attachment to seismology, I have had a horror of predictions and of predictors. Journalists and the general public rush to any suggestion of earthquake prediction like hogs toward a full trough.” Charles Richter, Bulletin of the Seismological Society of America, 1977.

12. slide © UBC-EOSC 2001 Prediction: Geologic faults are complicated. The San Andreas is the most studied fault system ever. “Seismic gaps” are regions “due” for an earthquake. BUT …most fault systems are poorly studied. San Francisco 0km Distance 350km Loma Prieta Dots show 20 yrs of earthquakes Loma Prieta earthquakes: red dots seismic gap

13. slide © UBC-EOSC 2001 Prediction - San Andreas The San Andreas is the most studied fault system ever. But it is a complex system of faults, especially around Los Angeles.

14. slide © UBC-EOSC 2001 “Prediction” using stress patterns Recall we showed stress changes at the 1999 Izmit earthquake: http://quake.wr.usgs.gov/~ross/

15. slide © UBC-EOSC 2001 Red: Stress jumps up after M=7.3 ‘quake (Landers, CA, 1992). Small quakes, plus M=6.5 (Big Bear), in 3 hrs following. Majority of quakes in the next 7 years are in stressed zones. Earthquakes causing more earthquakes http://quake.wr.usgs.gov/~ross/

16. slide © UBC-EOSC 2001 Prediction: When … ? When will a “seismic gap” be filled? Break a stick - exact moment can not be predicted BUT … – Parkfield experiment based on “prediction”. – Chinese “predicted” successfully once, but failed terribly in 1976 (Tangshan - 250,000 fatalities!). – Japan focussed work in early 1990’s on prediction in Tokyo region, then Kobe was struck catastrophically. 2004

17. slide © UBC-EOSC 2001 Prediction: Probability of a quake In spite of progress, prevention of catastrophic effects is often considered more cost-effective than “prediction”. 1. Each fault segment has an average time between events. Probability remains constant. 2. If stress increases gradually, then the chance of a damaging shock grows as time passes. 3. Effects of stress changes caused by nearby earthquakes may cause probabilities of a shock to jump.

18. slide © UBC-EOSC 2001 Prediction: Effects? We can predict how the ground will move. East-west & north-south ground motion for two Parkfield earthquakes, recorded at Berkeley, CA. http://quake.wr.usgs.gov/research/parkfield/berkeleyrecords.html Therefore we can design buildings to survive, and develop emergency response procedures.

19. slide © UBC-EOSC 2001 Prediction: Cascadia? Where? When? How large? Recurrence relation gives one way of estimating how often `quakes might occur. Gutenberg / Richter curve. Queen Charlotte Fault Cascadia Earthquake magnitude, M Earthquakes per year > M Queen Charlotte Fault DATA: - Many ‘quakes with M < 6 - 4 ‘quakes with M ~ 7.5-8 - 1 ‘quake M ~ 8-9 (1700)

20. slide © UBC-EOSC 2001 Prediction: Cascadia? Evidence: Mega-quake, 9:00PM, January 26, 1700 – Tsunami in Japan on January 27. Mega-quakes every 400-600 years – tree rings/drowned forests, ocean landslides Real-time tectonic deformation (GPS) Conclusion? A Megathrust earthquake in Cascadia is likely. Therefore we must prepare to deal with it.

21. slide © UBC-EOSC 2001 "The water also went into the pine trees of Ego. The receding water went out very fast, like a big river. It came in about seven times before 10 a.m. of that day and gradually lost its power…Because the way the tide came in was so unusual, and was in fact unheard of, I advised the villagers to escape to Miho Shrine…It is said that when an earthquake happens, something like large swells result, but there was no earthquake in either the village or nearby." Tsunami from a Cascadia earthquake: 1700 -account from the head of Miho village, near Tokyo

22. slide © UBC-EOSC 2001 Drowned forests - evidence of Cascadia mega-earthquake Oregon coast wood fragments sandwiched between sand layers where land surface dropped suddenly and killed a mature forest photos by Steve Carlson

23. slide © UBC-EOSC 2001 As Vancouver Island is squashed, stresses are building on the subduction zone... Henton et al., 2001

24. slide © UBC-EOSC 2001 Prediction recap … 1. Where will earthquakes occur? 3 aspects of prediction, & some complications for each. 2. Exactly When will an event occur? > 3 ways to estimate probability - include evolving stress patterns. > Reliable, detailed records exist for only ~100yrs. 3. What effects can be anticipated if an event occurs? > Knowing ground motion permits better buildings. What about Cascadia? - Large quakes have occurred. - Recurrence rate of large quakes is ~400-600 years. - Plate dynamics is being studied. - Preparation and hazard mitigation can be done. > Faults, but geometry and physics is complicated.

25. slide © UBC-EOSC 2001 That concludes Earthquakes Earthquakes kill thousands world-wide every year. They are a factor in S.W. BC. Understanding causes /effects /patterns is pre-requisite for –Minimizing tragedy –Reducing costs

26. slide © UBC-EOSC 2001 Active Research in Earthquake Science Examples of current research topics: –Earth’s internal processes, chemistry & structures. –Physics of tectonic plate behaviour. –Using seismic waves to image Earth’s interior. –Earthquake-earthquake & earthquake-volcano interactions. –Hazard mitigation & management. At UBC’s EOS Department: –Global structure, Crustal structure (Cascadia). –Fault physics, earthquake stresses, interaction, prediction. –Clowes, Hearn, Bostock, Herrmann, Ellis, and students.

27. slide © UBC-EOSC 2001 EOS courses with geophysics EOSC110 & EOSC111: The Solid Earth - A Dynamic Planet EOSC114 & EOSC115: The Catastrophic Earth - Natural Disasters EOSC210: Earth Science for Engineers EOSC250: Geophysical Fields and Fluxes I EOSC251: Geophysical Fields and Fluxes II EOSC252: Introduction to Experimental Geophysics EOSC350: Environmental, Geotechnical, & Exploration Geophysics I EOSC351: Environmental, Geotechnical, & Exploration Geophysics II EOSC352: Geophysical Continuum Dynamics EOSC353: Seismology EOSC354: Analysis of Geophysical Time Series EOSC450: Potential Methods EOSC451: Applied Potential Field and Borehole Methods EOSC452: Applied Electromagnetic Methods EOSC453: Advanced Physics of the Earth EOSC477: Geophysical Fluid Dynamics

28. slide © UBC-EOSC 2001 Outline for “The Shaking Earth” We investigate five aspects of earthquake science: Effects and global distribution Local context, global distribution, effects, plate tectonics. Earthquake sources Forces, types of faults, slip during earthquakes. Seismic waves Ground motion, wave types, wave propagation, using waves to study earthquakes Human impact and engineering What kills?, magnitude vs. intensity, earthquake-resistant structures. Mitigation and Prediction predicting occurrence and effects, minimizing damage

29. slide © UBC-EOSC 2001 This is just the beginning! Our Planet - understanding is the key to survival.