Mapping Motion Direction to Color in Ground-Motion Visualizations—A Tool with Potential Applications in Different Settings

Abstract

Abstract The increase in seismometer density on a continental scale since the start of the EarthScope project has enabled the community to produce visualizations of the propagating wavefield from local and teleseismic events. Previous work has shown that these animations generate much interest yet have limitations and can be confusing to novices. Here, we present a new type of visualization in which the color, position, and size of the symbols representing each seismometer are time dependent and determined by the instantaneous proportion of motion in the Z, R, and T components. This color-mapping scheme has the advantage of automatically producing different colors for different wave types and results in vibrant animations. The color mapping is based on transforming the value of the envelopes of the filtered velocity traces to red–green–blue values and subsequently boosting the color saturation in the hue–saturation–value color space. Animations in map view and along great-circle paths have been produced and used in a formal classroom setting and have also been shared with the broader public through social media channels. In both formal and informal settings, the animations have succeeded in garnering attention and stimulating discussion.