Strong Rayleigh Wave Radiation Toward Southwest From Ionospheric Observations of the Elbistan Earthquake of the 2023 Kahramanmaras, Türkiye, Doublet

The 2023 Elbistan (Mw 7.6) earthquake, the second event of the Kahramanmaraş, Türkiye doublet, occurred by bilateral sub- and supershear fault ruptures toward northeast and southwest, respectively. Utilizing the data from a dense network of global navigation satellite system (GNSS) receivers in Türkiye, we investigated the Rayleigh surface wave signatures in the ionosphere. We found significantly larger signals to the southwest of the epicenter that cannot be explained by the satellite line-of-sight geometry. This strong beam toward southwest, possibly caused by the supershear rupture, was also supported by observations with seismometers and GNSS kinematic solutions. Our finding demonstrates that Rayleigh wave signatures in ionosphere contain rich information on earthquake source processes.