Since February 2019, the InSight mission has returned seismic and meteorological data from Mars. We conducted horizontal to vertical spectral ratio (HVSR) analysis to the InSight seismic data recorded both on the lander and on the ground. Horizontal to vertical spectral ratio curves of ground data show multi‐peak characteristics at frequencies between 1 and 30 Hz with the highest peak appearing at around 11.7 Hz. The HVSR results of the Very Broad Band (VBB) and Short Period (SP) data differ greatly for frequencies over 10 Hz due to the difference in vertical component. The onboard SP data have the same highest H/V peak as the ground SP data. We conducted numerical modeling of HVSR and confirmed that the wind‐induced lander vibrations are the major sources to the InSight seismic ground motion in high frequencies. The HVSR curves of the continuous ground SEIS data show diurnal variation and are highly correlated with local meteorological conditions. The particle motions are investigated through the polarization analysis and the random decrement method. Generally, the ground motions above the self‐noise level are linearly polarized in the horizontal plane around the highest H/V peak. The damping analysis demonstrated the mechanical origins of the highest HVSR peak, while the 2.4 Hz mode is the most likely one having natural origin. Finally, most marsquake signals analyzed in this study generally highlight the 2.4 Hz trough but cause no significant change on the shape of the H/V curves. Our study explores the possible existence of natural sources in relatively high frequencies of Mars' background noise.

Studying the source characteristics of marsquakes can not only help to reveal the current geological features and thermal state (temperature and pressure) of the marsquake source regions, but also provide information on the evolution history of the corresponding regions. NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission (Banerdt et al., 2020;Banfield et al., 2020;Lognonné et al., 2020) has revealed that Mars is seismically active today, with many of the marsquakes located in Cerberus Fossae (Giardini et al., 2020;Stähler et al., 2022). Centroid moment tensor inversion was applied to some of these marsquakes (Brinkman et al., 2021;Jacob et al., 2022; Sita & van der Lee, 2022). However, the tectonic setting, such as fault movement, magmatic activity, or mass wasting, in most regions of Mars remains to be discovered, which relies on the analyses of marsquakes in the regions of interest.The source characteristics of a marsquake are described by its source spectrum, such as the classical ω 2 model in terrestrial seismology (Aki & Richards, 2002), in which the seismic spectra decay with frequency by the power of 2. Spectral analysis is a classical technique to constrain the source spectrum of a quake, and to estimate the seismic spectra as a key parameter. Corner frequency estimation is commonly applied to investigate the source features of a quake (e.g., Boatwright, 1984;Brune, 1970;Madariaga, 1976). On Earth, corner frequency estimation has been conducted for different regions to estimate the stress drops at source regions (e.g., Allmann &

The Pacific and Philippine Sea Plate subductions have resulted in and controlled the development of a typical trench‐arc‐back‐arc system in NE Asia since the Cenozoic. The formation of widely distributed intraplate volcanoes and the dynamic pattern of the entire region are still debated. Here we constructed a three‐dimensional anisotropic S‐wave velocity model of NE Asia by inverting Rayleigh wave dispersion using a modified reversible‐jump Markov Chain Monte Carlo (rj‐MCMC) algorithm. The resulting model revealed a localized mantle upwelling beneath intraplate volcanoes in NE Asia and an ongoing lithospheric downwelling beneath the central Korean Peninsula. This suggests vigorous asthenosphere and lithosphere interactions, which is likely to control the spatial distribution of Cenozoic volcanoes. The fast directions show clockwise rotation beneath NE Asia, which eventually points to the Nankai Trough. This observation is broadly consistent with shear wave splitting and suggests the presence of mantle flow from East China to the Philippine Sea Plate. The slab window beneath the Nankai Trough within the Philippine Sea Plate subduction system may accommodate the mantle flow from East China. Our study indicates that the interaction of the Philippine, Pacific Sea Plates, and Eurasian Plates plays an essential role in controlling the mantle flow and intraplate volcanism of NE Asia.