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Using IRIS and other seismic data resources in the classroom

Explore the IRIS Earthquake Browser, estimate seismic hazard, analyze earthquake data, visualize waveforms, and study regional tectonics. Use data to compare seismic hazard in different regions and determine the safest location for a manufacturing plant.

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Using IRIS and other seismic data resources in the classroom

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  1. Using IRIS and other seismic data resources in the classroom John Taber, Incorporated Research Institutions for Seismology

  2. Overview • IRIS Earthquake Browser • Estimating seismic hazard • Exploring seismicity in Oklahoma • Visualizations, animations, and waveforms • Recording and analyzing data from an educational or research-grade seismometer • Viewing a set of seismograms from an earthquake • Exploring regional tectonics using focal mechanisms • USArray ground motion visualizations

  3. Yesterday’s Earthquake

  4. As recorded in the US

  5. As a story • Jointly produced with Univ. of Portland, • collaborative content from USGS, UNAVCO and others

  6. Tectonics http://www.iris.edu/hq/retm

  7. IRIS Earthquake Browser - www.iris.edu/ieb My_link_for_this_image

  8. IRIS Earthquake Browser - www.iris.edu/ieb • Can use for introduction to plate tectonics • Explore plate boundaries • Turn plate boundary lines on and off • Interactive 3D viewer • General exploration of spatial distribution of local and regional seismicity

  9. Estimating seismic hazard You have been asked to compare the seismic hazard in two regions to determine which is safer for building a new manufacturing plant. 1.What type of data would you need to collect to make the comparison? 2. How could you express your findings in a quantitative way?

  10. Earthquake hazard from a single fault • Would like to know • How often do the biggest earthquakes occur? • When will the next big one occur? • Extend earthquake history with geologic record

  11. Earthquake recurrence along a single fault With a partner: Determine when the next Pallett Creek earthquake is going to occur. Can you estimate the uncertainty in your answer? Sieh et al., 1989

  12. Earthquake recurrence along a single fault can be highly variable: probabilities hard to assess M >7: mean = 132 yr Standard deviation = 105 yr Estimated probability of next earthquake in 30 yrs is 7-51% -> Nearly Random! Sieh et al., 1989

  13. How can we deal with unpredictable • nature of individual faults? • Try regional approach • Use the rate of earthquake occurrence • in one time period to forecast earthquake • activity in another time period • Combine results from multiple faults • Consider more than just the biggest • earthquakes

  14. IRIS Earthquake Browser - www.iris.edu/ieb

  15. Estimating seismic hazard Steps: • Select a region of the world that is of interest to you • Interrogate the earthquake catalog to determine the number of events that occur in a 25 year period • Set the Time Range • Set the Magnitude Range • In an Excel spreadsheet, record the total number of events for each magnitude range • Determine the number of earthquakes/year for each magnitude range • Plot the magnitude range vs the number of earthquakes/year

  16. Questions to discuss with a partner • Given the range of the data, what sort of plot gives the clearest representation of the data? • Do you see any patterns or trends in your data? • How does your plot compare to your partner’s plot of a different region? • What is the likelihood of earthquakes of magnitude 6.0 or greater and 7.0 or greater occurring in the next year in the 2 regions? • What is the likelihood of these events occurring in the next 100 years in each region?

  17. Earthquakes, Magnitude >3.5, 1973-2007

  18. Earthquakes, Magnitude >3.5, 1973-2007

  19. California (blue) and Eastern US Earthquakes (red) Earthquakes/year Magnitude

  20. How often does a M6 earthquake occur?

  21. How often does a M7 earthquake occur?

  22. Real, imperfect data set

  23. Interpretation questions • How can you use the seismicity information to estimate which of your two regions would be a safer choice for the manufacturing plant mentioned at the beginning of the exercise? • What are some assumptions, limitations, and potential sources of error in drawing conclusions about long-term seismic hazard using the above technique?

  24. Customizable USGS Seismic Hazard Maps http://geohazards.usgs.gov/eqprob/2009/index.php Submitted draft exercise explores hazard map

  25. Oklahoma seismicity - www.iris.edu/ieb • For Oklahoma: • Compare 5/1/95-5/1/05 and 5/1/05-5/1/15 • Magnitude 2 and greater • Count the earthquakes

  26. Rapid Earthquake Viewer • Determine global travel times and infer Earth structure • Rapid Earthquake Viewer • Developed and maintained by Univ S. Carolina

  27. Recording and analyzing seismic data Jamaseis • Real time data streaming and simple analysis • Simple filtering, arrival picking, locations, magnitudes

  28. Recordings from the Global Seismic Network

  29. Exploring regional tectonics using focal mechanisms • Visual sorting of normal, reverse, and strike-slip mechanisms • Can explore distribution in a subduction zone • IRIS main menu: Data and Software > Products • Select Moment Tensors, then Quick links • http://www.iris.edu/spud/momenttensor • Focal mechanism animation available

  30. Investigating Earth structure using tomographic models • Select a region and a submitted velocity model and generate a cross section • Fate of slabs • Crustal and upper mantle thickness under mountain ranges

  31. USArray Ground Motion Visualizations • Visualizations exist for all parts of lower 48

  32. EPO web page fromwww.iris.edu • Feedback? • Comments? • Questions?

  33. EXTRAS

  34. Selection from focal mechanism animation

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