Fig. 8
From: Reconstruction of a 2D seismic wavefield by seismic gradiometry
Wavefield and propagation direction analyzed by seismic gradiometry at elapsed times of t = 20 s (a), t = 130 s (b), and t = 230 s (c). Each panel shows the observed vertical-component displacement amplitude (color scale) at stations in the 25–50 s period band (left), the continuous displacement wavefield reconstructed by seismic gradiometry (center), and propagation direction and its slowness estimated from the gradiometry parameters (right). The absolute value of slowness is shown by the color scale. Arrow length is proportional to the absolute value of the slowness. The star in the right panel shows the epicenter location. An MP4-formatted movie of the time-dependent wavefield is included in Additional file 3: Movie S3