Seismic ground motions from a bolide shock wave

Abstract

An intensely brilliant bolide accompanied by an audible sonic boom occurred on the night of 3 November 2003 (∼2150 LT or 4 November 2003, 0350 UT) in northeastern Arkansas. The sonic boom was well recorded by 22 three‐component stations of the Center for Earthquake Research and Information Cooperative Seismic Network. Arrival times and wave polarizations were used to reconstruct the acoustic wave front propagating across the network and to estimate trajectory parameters of the bolide. A grid search location technique constrains the trajectory and gives a reference height of 50–100 km above the southern edge of the network, an azimuth of propagation of 270°–290° toward the northwest and a plunge of 38°–48° downward. The trajectory and date of the bolide event are consistent with a Taurid shower meteor. Transient ground motions from the sonic boom were studied using plane wave, Cagniard‐deHoop, and propagator matrix theory for an incident pressure pulse impinging on a layered elastic Earth model. General characteristics of the vertical and radial polarization and wave frequency content require acoustic coupling within a thin (∼10 m) near‐surface layer with low P wave (∼0.25 km/s) and S wave (∼0.125 km/s) velocities. Ground motions are generally confined to this near‐surface layer, are not sensitive to deeper Earth structure within the Mississippi embayment unconsolidated sediments, and display both “leaky” mode PL (a type of dispersed, P‐type seismic wave) and “locked” mode Rayleigh wave propagation. Acoustic wave/ground motion coupling studies may be a useful way to analyze near‐surface site responses to determine velocity structure in earthquake shaking hazard studies.