Characterizing%20Fault%20Populations%20and%20Seismicity%20on%20an%20Active%20Plate%20Boundary%20Using%20GIS

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Characterizing Fault Populations and Seismicity
on an Active Plate Boundary Using GIS

• Tip Meckel
• Ph.D. Candidate
• Geological Sciences

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Outline

• Reasons for study
• The Macquarie Ridge Plate Boundary
• Data Sets Involved in Study
• GIS Project
• Results and Significance
• Conclusions

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Why Study Plate Boundaries?

• Seismic Hazard

Better understanding of tectonics is important!
Images courtesy of USGS unless noted otherwise
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What are plate boundaries?

• Basic concepts

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The Macquarie Ridge Plate Boundary

• Benefits of studying this boundary
• Similar to San Andreas Boundary
• It is completely naked!

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Flying over the Macquarie Ridge!
Movie courtesy of the Australian Geological Survey
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Why use GIS?

• Interpretations rely heavily on maps
• advantage to having data incorporated into map in
  table form
• Spatial analysis of features and associated data

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Data sets using

• Entire Dissertation
• Remotely Sensed Data from Ship Bathymetry,
  Sidescan Sonar, Gravity, Magnetics, and Seismic.
• GIS Project
• Line coverage of Faults interpreted on seafloor
• Point coverage earthquake data from USGS
• Bathymetry?

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GIS Project

• Import line drawing into Arc Format
• Convert line drawing to ASCII and import
• Thanks to Christina Massell and Chris McFarlane
• Obtain USGS earthquake data and convert to a
  point coverage in correct latitude /longitude
  projection
• Use data table to color earthquakes according to
  magnitude and depth

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GIS Results I
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GIS Results II
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Faults greater than 0.231 units
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Earthquake occurrence by year
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Earthquake occurrence by depth
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CONCLUSIONS

• The lengths of faults follow an exponential
  distribution - this has not been documented and
  may be suggestive of fundamental processes at
  plate boundaries.
• The spatial occurrence of earthquakes over time
  and with depth is NOT random. This likely
  indicates the current state of stress at the
  plate boundary. There may yet be some hope for
  more complete understanding of tectonics!

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Future Directions

• Incorporate bathymetry, gravity and magnetic data
  into map. This has thus far been stymied by the
  format of the ship data.
• Pursue ideas generated by distribution of fault
  length data. What can the distribution tell us
  about fundamental faulting processes at plate
  boundaries?