Thunder‐induced ground motions: 2. Site characterization

Abstract

[1] Thunder-induced ground motion, near-surface refraction, and Rayleigh wave dispersion measurements were used to constrain near-surface velocity structure at an unconsolidated sediment site. We employed near-surface seismic refraction measurements to first define ranges for site structure parameters. Air-coupled and hammer-generated Rayleigh wave dispersion curves were used to further constrain the site structure by a grid search technique. The acoustic-to-seismic coupling is modeled as an incident plane P wave in a fluid half-space impinging into a solid layered half-space. We found that the infrasound-induced ground motions constrained substrate velocities and the average thickness and velocities of the near-surface layer. The addition of higher-frequency near-surface Rayleigh waves produced tighter constraints on the near-surface velocities. This suggests that natural or controlled airborne pressure sources can be used to investigate the near-surface site structures for earthquake shaking hazard studies.

Characterizing Thunder‐Induced Ground Motions Using Fiber‐Optic Distributed Acoustic Sensing Array

“…In addition, as qualitatively shown in Figure 4, the amplitude versus offset and spectrogram of Event e4 shows that waveforms are dispersive and attenuated around Channel 2000, which may indicate a more dispersive medium around the site Channel 2000. A pioneer study by Lin and Langston (2009b) used a seismometer-microphone recording of thunders to estimate substrate velocities and the average thickness and velocities of the near-surface layer. This could be particularly useful in the areas of less earthquake seismicity, for example, the eastern United States, where few local earthquakes are insufficient to constrain high-resolution images of the near surface and/or upper crust.…”

“…We find that the apparent velocity of all signals is 325-970 m/s and averaged at 440 m/s. This implies that most of the recorded waves are not direct air waves and are likely to be the air-coupled Rayleigh wave caused by the trapped propagating wave in the substrate layer (Lin & Langston, 2009b). Figure 8.…”

Manuscript accepted for publication

“…Earthquakes, volcanic disturbances, chemical and nuclear explosions, and artificial energy sources such as vibration-producing trucks or even handheld hammer blows can provide seismic wavefields that can be modeled to determine the physical characteristics of the Earth over scales from meters to 10,000 km. Impulsive atmospheric sources such as explosions (e.g., Matoza et al, 2022), bolide sonic booms (D'Auria et al, 2006;Langston, 2004;Le Pichon, 2002), or even thunder (Lin and Langston, 2009a;Lin and Langston, 2009b), can be interesting in their own right as well as providing for new wavefields for investigating Earth structure using records from seismometers.…”

Tracking Lightning Through 3D Thunder Source Location With Distributed Acoustic Sensing

“…The plane wave assumption is valid only for the far-field observation, which may obscure the precise thunder location. Some thunder recordings from the seismometers were explained as air-Rayleigh coupling surface waves (Lin & Langston, 2007, 2009a and were used for subsurface velocity imaging (Lin & Langston, 2009b). Recently, studies using seismic arrays provided more details of thunder signals, where the seismometer recorded signals were considered to be seismic waves converted from acoustic waves near the receiver side (Hong et al, 2022) or pure acoustic waves (Lythgoe et al, 2021).…”