Animated visualization techniques for three-component seismic array data

Traditional seismic displays are dimensionally inadequate for displaying seismic motion recorded over time by an areally distributed array of 3-component seismometers. The development of a new, portable, 3-component recording system has led to a number of proposals for non-traditional, temporary, seismic array experiments, requiring new techniques for visualizing seismic data. The first of these experiments, using a small-aperture array of 60 seismometers at spacings of only a few meters, produced the first detailed, unaliased record of the high-frequency, seismic wavefield generated by local earthquakes.;Scientific visualization is a process of transforming data into pictures. High-speed workstations combined with object-oriented graphics and interactive, animated displays are the basis for a number of new visualization techniques. Time-domain animations using vectors and hodograms illustrate wavefield particle motion in three dimensions. F/K displays use surface displacement and color to show spectral behavior of the wavefield animated over time. Animated displays based on frequency-domain beamforming illustrate arrival azimuth and apparent velocity of seismic energy crossing the array.;The viewer gains an immediate, fundamentally different perspective on the nature of ground motion. Particle motion is generally elliptical and far more chaotic than indicated by either theoretical development or more conventional display techniques. The spatial variability of the wavefield, observable on a scale of only a few meters, is largely attributed to near-surface, near-receiver scattering and mode conversion. In addition, P and S-wave polarizations suggest velocity anisotropy at depth. Frequency-domain animations show constantly changing apparent velocity, arrival azimuth, and wavefield spectral content throughout the seismic coda, strongly supporting the time-domain indications of substantial scattering from near-surface heterogeneity. Animated visualization techniques demonstrate increased flexibility and capability for interactively displaying the multidimensional complexity of a 3-component seismic wavefield. The wavefield characterization obtained using these visualization techniques is more complete and allows more attention to detail than would be possible using traditional static display ideas.