Acknowledgments
The author acknowledges support from the National Science Foundation, NSF EAR 0310232: “Real-time Monitoring, Enhanced Visualization and Temporal Analysis of Tectonic and Geophysical Data.” The work benefited from discussions and interaction with students Heather Melanson, Liz Wilson, Arancha Pinan, Liam Morley, Nathan Williams, and Akanksha Sharma.