The vertical propagation of disturbances triggered by seismic waves of the 11 March 2011 M9.0 Tohoku earthquake over Taiwan

Abstract

In this paper, concurrent/colocated measurements of seismometers, infrasonic systems, magnetometers, HF‐CW (high frequency‐continuous wave) Doppler sounding systems, and GPS receivers are employed to detect disturbances triggered by seismic waves of the 11 March 2011 M9.0 Tohoku earthquake. No time delay between colocated infrasonic (i.e., super long acoustic) waves and seismic waves indicates that the triggered acoustic and/or gravity waves in the atmosphere (or seismo‐traveling atmospheric disturbances, STADs) near the Earth's surface can be immediately activated by vertical ground motions. The circle method is used to find the origin and compute the observed horizontal traveling speed of the triggered infrasonic waves. The speed of about 3.3 km/s computed from the arrival time versus the epicentral distance suggests that the infrasonic waves (i.e., STADs) are mainly induced by the Rayleigh waves. The agreements in the travel time at various heights between the observation and theoretical calculation suggest that the STADs triggered by the vertical motion of ground surface caused by the Tohoku earthquake traveled vertically from the ground to the ionosphere with speed of the sound in the atmosphere over Taiwan.

Nonlinear acoustic waves in the viscous thermosphere and ionosphere above earthquake

“…Similar shapes of wave packets and frequency contents of v z and w (f D ) fluctuations were also observed for the 2015 Nepal earthquake by the CDSS in the Czech Republic and Taiwan [Chum et al, 2016]. Liu et al [2016] used collocated measurements by seismometers, infrasound sensors, magnetometers, continuous Doppler sounding, and dual-frequency GPS receivers in Taiwan to demonstrate that the time delays between observations of coseismic disturbances at various heights are consistent with the vertically propagating infrasound waves generated locally in Taiwan by the vertical component of seismic waves triggered by the 2011 Tohoku earthquake. The coseismic perturbations caused by vertically propagating infrasound waves were also confirmed by independent sounding techniques; Maruyama and Shinagawa [2014] showed that the disturbances observed in the ionograms are consistent with the ionospheric perturbations generated by the vertically propagating infrasound.…”

An observing system simulation experiment for FORMOSAT-5/AIP detecting seismo-ionospheric precursors

“…The data are designed for monitoring the ionospheric space weather and also for detecting precursors (i.e., SIPs) and co-seismic disturbances (i.e., seismotraveling ionospheric disturbances) induced by worldwide earthquakes (cf. Liu et al 2016).…”

Co-seismic signatures in magnetometer, geophone, and infrasound data during the Meinong Earthquake

“…Nevertheless, the long lasting co-seismic pulsations appearing at the CC station might be due to the ground water and underground structure around Meishan fault being complex (Yen et al 2008;Ching et al 2011;Wilcox et al 2011). By contrast, researchers (Iyemori et al 2005;Hao et al 2013;Yen et al 2015;Liu et al 2016a) observe that seismo-magnetic pulsations with much longer period (low frequency) constantly lag seismic wave pulses by about 200+ minutes, suggesting that ionospheric conductivity affects magnetic fields. Since there is almost no time lag between magnetic pulsations and seismic waves at each co-located station, the co-seismo magnetic pulsation is unlikely related to the ionospheric conductivity.…”

“…6). Liu et al (2016a) study the vertical propagation of disturbances triggered by seismic waves of the 11 March 2011 M 9.0 Tohoku earthquake over Taiwan. However, they find that there is no time lag between co-seismic infrasound fluctuations and the colocated seismic waves.…”

“…Sometimes STADs could further travel into the ionosphere and interact with the ionized gas resulting in seismo-traveling ionospheric disturbances (STIDs) [see papers listed in Davies (1990)]. Traditionally, seismometers (also geophones) record seismic waves monitoring the Earth's surface motion (Shearer 1999), and infrasound systems measure atmospheric pressure changes induced by the Earth's surface motion and/or seismic waves, mainly Rayleigh waves, on the ground (Mutschlecner and Whitaker 2005;Liu et al 2006Liu et al , 2010Liu et al , 2016a. Meanwhile, scientists report magnetic pulsations triggered by seismic waves (Iyemori et al 1996(Iyemori et al , 2005Honkura et al 2002;Abdul Azeez et al 2009;Widarto et al 2009;Hao et al 2013;Gao et al 2014;Yen et al 2015;Liu et al 2016a).…”