Academic Affiliation: University of Colorado at Boulder
2007- Plate kinematics and mechanisms: A perspective on the 20 April 2006 M7.6 Koryakia, Russia earthquake
The occurrence of a Koryakia, Russia magnitude 7.6 earthquake during April 2006 was a mysterious and unusual event. Although the study area is geographically located near two major plates boundaries, the main event and those that followed may support evidence for existence of a microplate. This earthquake and its aftershocks were analyzed using historical seismicity, magnitude, depth, latitude, longitude, and focal mechanisms to determine seismic trends and kinematics. Harvard Centroid Moment Tensors (CMT) and P-axes were produced from the data collected during the events. Building upon existing knowledge of the local plate mechanisms, moment tensor data were analyzed and deformation patterns noted. The results showed trends in significant event epicenters and deformation patterns were used to identify two possible faults that were previously unknown. Data analysis from the events related to the 20 April 2006 shock is intended to add to the body of seismic knowledge for eastern Russia and provide a basis for future research that attempts to clarify microplate plate boundaries and Koryakia’s kinematics.
2008- Uplift, subsidence, or systematic error? Measuring elevation in the Longmont-Denver corridor
The Colorado Department of Transportation (CDOT) and National Geodetic Survey (NGS) conducted a 119 km leveling project that extended from Longmont to Denver International Airport. Up to10 cm elevation differences were observed in the area of Denver International Airport, raising questions about data collection procedures and benchmark stability. A detailed examination of data was conducted to identify possible systematic error. Field notes and the field abstract (a report that summarized recorded observations) were examined to determine how observations were made. Observation times, progression of observation activities, and time lapses between observations were identified as the main sources of systematic error. Data analysis was performed using elevation differences, published values, and loop closures. These provided further evidence that elevation differences were the result of systematic error. This research concluded that systematic error was responsible for the overall observed elevation difference of approximately10 cm and provided a basis for the National Geodetic Survey to finalize and publish elevation data for the benchmarks included in this leveling project. Future impacts of this research will include improvements in field crew training, revised data analysis procedures, and continued monitoring of possible uplift and subsidence through the National Geodetic Survey’s Height Modernization program.