GNSS TEC‐Based Detection and Analysis of Acoustic‐Gravity Waves From the 2012 Sumatra Double Earthquake Sequence

Abstract

Introduction Acoustic-Gravity Waves From EarthquakesIonospheric disturbances following seismic events arising due to surface-atmosphere coupling have been studied previously (Calais & Minster, 1995;K. Davies & Baker, 1965). Earthquakes result in vertical and horizontal ground displacement. Normal and reverse thrust fault earthquakes result in mostly vertical while strike-slip faults result in mostly horizontal displacement. These ground movements can induce acoustic-gravity waves in the atmosphere (Rolland, Lognonné, & Munekane, 2011;Rolland, Occhipinti, et al., 2010). Waves originating from the source region first propagate obliquely upward and then spread horizontally as acoustic-gravity waves (Mikumo & Watada, 2010).There are four different pathways for atmospheric wave generation due to earthquakes (Mikumo & Watada, 2010;Occhipinti, 2016;ReVelle, 2008). The first is low-frequency (less than Brunt-Väisälä frequency) gravity waves generated at the source and propagating upward to long distances (Afraimovich, Perevalova, et al., 2001). The second one is higher-frequency infrasonic or acoustic waves (higher than acoustic cutoff frequency) also generated at the source (Bolt, 1964). These infrasonic waves can get reflected or diffracted due to topography (Young & Greene, 1982) or sound velocity variations (Drob, Picone, & Garcés, 2003) during propagation. The third case is also infrasonic waves but generated due to coupling of atmosphere with seismic Rayleigh waves along the ground surface (Donn & Posmentier, 1964). Coupling of the atmosphere with Rayleigh surface waves is found to be most effective at frequency ∼3.7 mHz. Ionospheric disturbances corresponding to Rayleigh waves travel at ∼3-4.5 km/s, much higher than direct acoustic waves from the source (∼1 km/s at 400 km altitude) (Ducic et al., 2003;Heki & Ping, 2005). Thus, two kinds of acoustic infrasonic waves are generated by earthquakes (Le Pichon et al., 2002). Some simulations (Artru et al., 2005) suggest that trapping of acoustic waves with periods between 4 and 6 min can occur in lower atmosphere. The fourth case is generation of gravity waves by ocean tsunami waves that are themselves generated from large earthquakes. These waves occur due to coupling of the atmosphere with ocean surface displacement and are detected in the ionosphere a few hours after the earthquake (Artru et al., 2005;Occhipinti, Lognonné, et al., 2006) as opposed to ∼10 min for waves due to seismic Rayleigh origin.

Statistical Study of Global Lightning Activity and Thunderstorm‐Induced Gravity Waves in the Ionosphere Using WWLLN and GNSS‐TEC

“…Besides, geomagnetic storms and earthquakes are also vital in generating atmospheric GWs. Previously, many authors detected the intensification of atmospheric GW, 1 week before the large earthquakes using fast Fourier transform (FFT) and wavelet analysis of GNSS‐TEC data, space‐based instruments SABER/TIMED satellite data, and ERA5 model reanalysis data (Kundu et al., 2022; Row, 1967; Sasmal et al., 2021; Srivastava et al., 2021; Yang et al., 2019). Atmospheric GWs are generally thought to be generated by tropospheric overshoot and/or from latent heating associated with rainfall within the thunderstorm.…”

A Nonlinear Numerical Model for Comparative Study of Acoustic‐Gravity Wave Propagation in Planetary Atmospheres: Application to Earth and Mars

“…Gravity waves can be generated by ocean tsunami waves that are themselves generated from large undersea earthquakes. These waves occur due to coupling of the atmosphere with ocean surface displacement and are detected in the ionosphere a few hours after the earthquake (Artru et al., 2005; Inchin et al., 2020; Occhipinti et al., 2006; Srivastava et al., 2021). Here, we apply our model to simulate gravity waves resulting from the 2004 Sumatra tsunami.…”

A study of gravity waves on planetary atmospheres

“…Direct measurements of neutral atmospheric densities and winds GWs (Potter et al, 1976) from satellite-based instruments have been used to detect thermospheric GWs. GWs can also be identified using ionospheric total electron content data obtained from ground based Global Positioning System (GPS) receiver arrays (Azeem and Barlage, 2018a;Dautermann et al, 2009;Nayak and Yigit, 2018;Rolland, Lognonné, Astafyeva, Kherani, Kobayashi, Mann and Munekane, 2011;Srivastava et al, 2021). Different observation techniques have specific limitations on resolution and the range of wave scales that can be observed, thus multi-sensor profiling is common.…”

“…Gravity waves can be generated by ocean tsunami waves that are themselves generated from large undersea earthquakes. These waves occur due to coupling of the atmosphere with ocean surface displacement and are detected in the ionosphere a few hours after the earthquake (Artru et al, 2005b;Inchin, Heale, Snively and Zettergren, 2020;Occhipinti et al, 2006;Srivastava et al, 2021). Here we apply our model to simulate gravity waves resulting from the 2004 Sumatra tsunami.…”