As a Math Major and a Geology Minor, I came into the SURE internship with hardly any experience in computer programming. I was equipped only with a desire to learn more about earthquakes and an analytical thought process. My first task was to familiarize myself with the computer programming language, Python. With the guidance of Kevin Milner, I learned the importance and convenience of object-oriented programming, which would later be essential in carrying out my research. Although frustrating at times, I now have a basis of knowledge of Python to take with me into whatever discipline I choose to go into.

After learning the basics of Python, my next task was to program NonLinLoc, an earthquake relocation tool developed by Anthony Lomax, into the Solid Earth Teaching and Research Environment (SEATREE) software developed by my advisor Thorsten Becker. The idea behind SEATREE is to act dually as a teaching tool in the classroom and as a tool for research collaboration. With the NonLinLoc program installed in SEATREE, students can interactively learn how take-off angles, travel-times, and different velocity models affect the process of earthquake relocation and more generally, how they affect wave propagation. It also helps by allowing users to gain an understanding of the structure and patterns of seismicity in an area. By creating a graphical user interface that allows one to toggle with the above-mentioned parameters, one can visually see the affects on the images produced. For visualization, we chose to use MatLibPlot, rather than GMT-produced postscript that is then displayed as a GIF, as MatPlotLib allows us to stay within the Python framework.

Used as a research tool, earthquake relocation (using existing data measured by different stations in a certain area to find, by inversion, where the hypocenter of the event occurred) can later tell us what effects the specific location of an earthquake might have at certain distances from that location. This problem is complicated by three-dimensional variations in wave speed velocities in the crust, and our tool should help with investigations into the trade-offs that are related to such effects. By better understanding earthquake location uncertainty, an improved understanding of fault mechanics may be gained. In the NonLinLoc program, a velocity model is created, a sampling of arrival times at surrounding seismic stations are chosen using a probability density function (or they can be chosen manually), and a sampling of travel take of angles are used. During the event location, the result is an area with the degree of uncertainty represented by various ellipsoidal lines surrounding the location. These uncertainties are due to measurement error in arrival times as well as the assumed fixed velocity mode, which is only an approximation of the real Earth and will lead to flawed predicted travel times.

The goal in implementing the NonLinLoc program enhances the goal of SEATREE to act as a tool for teaching as well as a basis for research. The hope is that NonLinLoc will add to the versatility of SEATREE as a tool for describing and learning more about earthquakes.