ADDTID: An Alternative Tool for Studying Earthquake/Tsunami Signatures in the Ionosphere. Case of the 2011 Tohoku Earthquake

Abstract

In this work, we characterized the ionospheric disturbances generated during the Japan Tohoku earthquake of 11 March 2011, by means of the Atomic Decomposition Detector of Traveling Ionospheric Disturbances (ADDTID) algorithm. This algorithm automatically detects and characterizes Traveling Ionospheric Disturbances (TIDs) from Global Navigation Satellite System (GNSS) measurements. Applying the high-precision estimates of ADDTID, the propagation parameters would make it easier to distinguish TIDs from different origins, in particular the characteristics conforming the acoustic gravity waves driven by the earthquake/tsunami. This method does not assume that disturbances follow a circular pattern of propagation, and can estimate the location by the propagation pattern of tsunami wavefronts and related TIDs. In this work, we present in a single framework a description of phenomena observed by different researchers. By means of the ADDTID algorithm, we detect: (a) simultaneous TIDs of different characteristics, where the detection was robust against the curvature of the wave fronts of the perturbations and the accuracy of the estimated parameters. The results were double-checked by visual inspection from detrended Vertical Total Electron Content (VTEC) maps and keogram plots, and the parameters of the slow-speed TIDs were consistent with the tsunami waveform measurements; (b) different wavefronts between the west and east TIDs around the epicenter, consistent in time and space with the post-earthquake tsunami; (c) complete evolution of the circular TIDs driven by the tsunami during the GNSS observable area; (d) fast and short circular TIDs related to the acoustic waves of earthquake; (e) the pre-seismic activity consisting of a set of fast westward TIDs, and the comparison with neighboring days; (f) the location estimation of the tsunami wavefront along the coast and the possible use as early warning. Finally, we report disturbances that had not been previously published with a possible application to local and real-time detection of tsunamis.

Traveling Ionospheric Disturbances Characteristics during the 2018 Typhoon Maria from GPS Observations

“…Nowadays, denser Global Positioning System (GPS) observations provide important data for the study of ionospheric variations, allowing the continuous monitoring of large-scale ionospheric disturbances caused by typhoons [11][12][13][14] and earthquakes [15][16][17]. The characteristics of traveling ionospheric disturbances (TIDs) are consistent with the theory of gravity waves.…”

Combining Swarm Langmuir probe observations, LEO-POD-based and ground-based GNSS receivers and ionosondes for prompt detection of ionospheric earthquake and tsunami signatures: case study of 2015 Chile-Illapel event

“…Study objective -the ionosphere above Chile-Illapel EQ/tsunami revisited by Swarm, GRACE, ground GNSS and ionosondes Subsequent to the Tohoku 2011 EQ/tsunami, the ionosphere in the vicinity of the epicenter has been intensively investigated, whereas only single preliminary works focused on the ionospheric responses to Chile-Illapel EQ have been shown. The figures of concentric TIDs after Tohoku appear in many studies (Jin et al 2014;Yang et al 2019;Chou et al 2020). The Chile EQ/tsunami event in 2015 has been investigated notably less frequently than Tohoku event, also due to the smaller impact on the ionosphere.…”

“…The presented study includes a number of mathematical techniques, including also spectral analyses by short-term Fourier transform (STFT) and continuous wavelet transform (CWT), which are here applied for the first time to Swarm (LP and POD TEC) and GRACE KBR along-track data. Also, combined lately developed techniques (Yang et al 2019) have been applied in the detection of TIDs. The processing of extended scope of the data with the use of advanced or composed techniques enabled the detection of many interesting pre-seismic and post-seismic ionospheric disturbances of different size, at different distances from the event and within different timeframes.…”

“…In the second stage, we detect and characterize the parameters of TIDs by means of the ADDTID algorithm. ADDTID (see details in Yang et al 2017Yang et al , 2019 uses data from a dense GNSS receiver network, and can detect and characterize TIDs from the IPPs. The algorithm creates a dictionary of possible waves that encompass the geographical area under study.…”

“…The southeastward ionospheric disturbances, possibly resulted from the coupling between tsunami and atmosphere have been also detected (Galvan et al 2012;Occhipinti et al 2013). Different propagation velocities, which are related individually to the seismic Rayleigh waves, acoustic waves and tsunami-generated gravity waves were also discussed in several other works (Heki et al 2006;Jin et al 2014Jin et al , 2015Yang et al 2019). Thus we know that TEC disturbances spread out to almost all directions from the epicenter, with the speed of several hundreds of meters to several kilometers per second.…”