VISUALIZING EARTHQUAKE DATA TO IMPROVE COMMUNICATION ABOUT SEISMIC HAZARDS

Digital technologies routinely deliver continuous, high precision data streams to potential users from satellites, buoys, stream gaging stations, GPS sensors, and more. Due to the high rate of data acquisition, almost all data processing is performed by automated computer algorithms developed by technical experts, raising questions about how effectively scientific results and their implications, such as environmental hazards, are being communicated to the larger scientific community, students, and the public. We consider data gathered by seismometers and archived by IRIS and the USGS, focusing on records from the 2017 M 8.1 earthquake and aftershocks off the SW coast of Mexico.

One objective was to reintegrate seismic velocities recorded as North, East, and vertical components into waveforms that can be rotated in three dimensions to reveal the arrival directions and characteristic motions of body and surface waves via animation. Viewing the motion in selected two-dimensional sections improves understanding of the waves as experienced during a seismic event. We studied data received by West Chester University’s seismometer (WUPA) as well as others in different positions relative to the epicenter. We used Excel to integrate the velocity records, filter out instrumental drift, select arrivals, rotate the data, and display the results in charts. After removing drift we subsampled the original 10 millisecond data stream at 50 milliseconds to reduce computation time.

Another objective was to create a three-dimensional visualization of the main shock, which resulted from normal faulting, and its aftershocks in relation to the subduction zone. We used ArcMap to display geospatial relationships between stations and earthquake locations, generate surficial datasets, such as buffers, and to qualitatively categorize data to find potential patterns in magnitude. ESRI 3D Analyst capabilities enabled exploration of depth and magnitude associations and three-dimensional rotation of the data to better understand the geometry of the subduction zone on which they occurred.