Tip Meckel Ph.D. Candidate Geological Sciences Characterizing Fault Populations and Seismicity on an Active Plate Boundary Using GIS Tip Meckel Ph.D. Candidate Geological Sciences

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

Why Study Plate Boundaries? Seismic Hazard Better understanding of tectonics is important! Images courtesy of USGS unless noted otherwise

What are plate boundaries? Basic concepts

The Macquarie Ridge Plate Boundary Benefits of studying this boundary Similar to San Andreas Boundary It is completely naked!

Flying over the Macquarie Ridge! Movie courtesy of the Australian Geological Survey

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

Data sets using: Entire Dissertation: GIS Project: 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?

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

GIS Results I

GIS Results II

Faults greater than 0.231 units

Earthquake occurrence by year

Earthquake occurrence by depth

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!

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?