GPS detection of ionospheric Rayleigh wave and its source following the 2012 Haida Gwaii earthquake

Abstract

The processes and sources of seismo‐ionospheric disturbances are still not clear. In this paper, coseismic ionospheric disturbances (CIDs) are investigated by dual‐frequency GPS observations following the Mw = 7.8 earthquake as results of the oblique‐thrust fault in the Haida Gwaii region, Canada, on 28 October 2012. Results show that the CIDs with an amplitude of up to 0.15 total electron content units (TECU) are found with spreading out at 2.20 km/s, which agree well with the Rayleigh wave propagation speed at 2.22 km/s detected by the bottom pressure records at about 10 min after the onset. The CIDs are a result of the upward propagation acoustic waves trigged by the Rayleigh wave in sequence from near field to far field. The strong correlation is found between the CIDs and the vertical ground motion recorded by seismometers nearby the epicenter. The total electron content (TEC) series from lower‐elevation angle GPS observations have higher perturbation amplitudes. Furthermore, the simulated ionospheric disturbance following a vertical Gauss pulse on the ground based on the finite difference time domain method confirms the ionospheric Rayleigh wave signature in the near field and the vertical ground motion dependence theoretically. The vertical ground motion is the dominant source of the ionospheric Rayleigh wave and affects the CID waveform directly.

Ionospheric Detection of Natural Hazards

“…The near‐field CSID represent ionospheric response to acoustic waves generated directly by coseismic vertical crustal displacements (e.g., Afraimovich et al, ; Afraimovich et al, ; Afraimovich et al, ; Astafyeva & Heki, ; Cahyadi & Heki, ; Calais & Minster, , ; Heki & Ping, ; Jin et al, ; Komjathy et al, ; Li et al, ; Lognonné et al, ; Zettergren & Snively, ). The far‐field CSID are usually associated with the propagation of the Rayleigh surface waves (Astafyeva et al, ; Ducic et al, ; Kakinami et al, ; Liu, Tsai, Ma, et al, ; Rolland et al, ; Jin et al, ) or of the air surface waves (Astafyeva & Afraimovich, ; Liu, Tsai, Chen, et al, ). In addition, large earthquakes can be accompanied by the acoustic resonance signatures in the ionosphere (Choosakul et al, ; Liu et al, ; Rolland et al, ; Saito et al, ).…”

Long‐time variations of precipitable water vapour estimated from GPS, MODIS and radiosonde observations in Turkey

“…While traditional techniques are difficult to obtain high‐resolution and high‐accuracy PWV and its variations, particularly in Turkey with the complex weather variability around the Black Sea and the Mediterranean Sea. Since atmospheric delay is one of the main errors in satellite techniques, it can be estimated in contrast and widely used nowadays (Chaboureau et al ., ; Jin et al ., , , , , , , ; Afraimovich et al ., ; Wu et al ., ). Firstly, the global positioning system (GPS) plays a significant role in determining continuous and precise Zenith tropospheric delay (ZTD) and PWV with the high temporal resolution (Jin and Luo, ; Jin et al ., , ) and high accuracy (1–2 mm) (Ware et al ., ).…”

Two‐Mode Ionospheric Disturbances Following the 2005 Northern California Offshore Earthquake From GPS Measurements

“…The smaller amplitude with about 0.04 TECU is found for station P267 and satellite 08 in the left panel with the elevation angle range of 40–80°, while the larger amplitude around 0.10 TECU is found for station HOTK and satellite 10 in the right panel with the elevation angle range of 15–25°. The GPS TEC observation with lower elevation angle is sensitive to coseismic ionospheric disturbances induced by Rayleigh waves (e.g., Jin, Jin, & Li, ).…”

“…The magnitude of GPS signal code delay and phase advance in the Earth's ionosphere is related to the ionospheric electron density on the raypath and the carrier frequency. Using dual‐frequency GPS observations, the precise ionospheric TEC could be extracted from combining code‐phase measurements with ignoring the high‐order ionospheric effects as (Brunini & Azpilicueta, ; Jin et al, ; Jin, Jin, & Li, ): where TEC is the total electron content, L 1 and L 2 are the GPS phase measurements, P 1 and P 2 are the GPS code measurements, N is the ambiguity, f 1 and f 2 are the frequency of GPS ( f 1 = 1,575.42 MHz, f 2 = 1,227.60 MHz), d 1 and d 2 are the differential code biases, and ε is the residual. In order to estimate the temporal‐spatial distribution of seismo‐ionospheric disturbances, the slant TEC along the GPS line of sight (LOS) is converted into the vertical TEC ( vTEC ) using the mapping function as where H is the thin shell height of the ionosphere (here H is set as 300 km), R is the Earth's radius, and z is the zenith distance of the line of sight (LOS) from the receiver to GPS satellites.…”