A meteor shockwave event recorded at seismic and infrasound stations in northern Taiwan

Abstract

Three mysterious explosion sounds were heard in the coastal towns of Tamsui, west of Taipei in northern Taiwan, in the early evening of December 5, 2013. The event left clear signals that are identified in the recordings of 12 regional seismometers and 3 infrasound sensors and processed by means of travel time analysis. The apparent velocity of ~330 m/s of the signals confirms that the energy transmission was through the atmosphere, and the characteristics of the waveforms suggest the meteor-generated shockwaves. We use the graphical method as well as the Genetic Algorithm optimization approach to constrain the trajectory of the meteor and to locate its projected intercept with the ground-(25.33 N, 121.26 E), approximately 20 km off the coast of Tamsui. The trajectory has azimuth (measured from north in a map view in the clockwise direction) of 303° and (near-vertical) elevation angle of 70°. From the observed period of 1.3 s at the maximum amplitude of the infrasound signal, we estimate by conventional scaling law that the meteor in question had impact energy on the order of 5 × 10 10 J (equivalent to an earthquake of local magnitude 4) or roughly a size of ~0.5 m across.

Exclusive Seismoacoustic Detection and Characterization of an Unseen and Unheard Fireball Over the North Atlantic

“…Using a constant‐velocity, straight‐ray approximation, we derived a first‐order source and trajectory model. This approach has been previously employed in studies of fireballs recorded by seismic networks (Che et al., 2016; Ishihara et al., 2003; Kumar et al., 2017; Yamada, 2021; Yamada & Mori, 2012). By optimizing the source parameters using the Genetic Algorithm (Kumar et al., 2017) and considering all recorded arrival times, we determined the origin time, 3‐D source position, trajectory azimuth and inclination angle, and meteoroid velocity.…”

“…This approach has been previously employed in studies of fireballs recorded by seismic networks (Che et al., 2016; Ishihara et al., 2003; Kumar et al., 2017; Yamada, 2021; Yamada & Mori, 2012). By optimizing the source parameters using the Genetic Algorithm (Kumar et al., 2017) and considering all recorded arrival times, we determined the origin time, 3‐D source position, trajectory azimuth and inclination angle, and meteoroid velocity. To improve optimization, our polarization analysis results constrained the source position range (Table S1 in Supporting Information ).…”

“…Studies on meteoroids primarily rely on initial visual and/or audible human observations (Brown, ReVelle, et al., 2002; Brown et al., 2003, 2011; D’Auria et al., 2006; Hughes et al., 2022; Ishihara et al., 2003; Kumar et al., 2017; Langston, 2004; Llorca et al., 2005; Pujol et al., 2005; Stich et al., 2022; Vera Rodriguez et al., 2022; Walker et al., 2010; Yamada, 2021; Yamada & Mori, 2012), leading to an observational bias toward populated areas, such as on the continents. Observations over oceans and islands are notably scarce, particularly without all‐sky cameras (Silber & Brown, 2014).…”

“…Two main methods are commonly used. One assumes straight rays and a constant velocity of sound through the atmosphere (Ishihara et al., 2003; Kumar et al., 2017; Langston, 2004; Pujol et al., 2006; Yamada, 2021; Yamada & Mori, 2012). The other involves ray‐tracing in realistic atmospheric models while accounting for wind effects (Walker et al., 2010) to reconstruct the acoustic raypath in the atmosphere (Brown et al., 2003; Hedlin et al., 2010; Stich et al., 2022).…”

Natural and Anthropogenic Sources of Seismic, Hydroacoustic, and Infrasonic Waves: Waveforms and Spectral Characteristics (and Their Applicability for Sensor Calibration)

“…In addition, an apparent velocity of about 330 m/s is evident (e.g. Ishihara et al 2003 ; Langston 2004 ; Kumar et al 2017 ). Second, if the shock wave is strong enough, its energy couples with the ground and generates ground-coupled acoustic waves that can be measured at the sensors (e.g.…”