Data collected from optical remote sensing systems can be used to effectively measure ground horizontal displacements related for example to earthquake ruptures, glacier flows, dune migrations, and slow landslides. However, displacement of interest is often corrupted with and even hidden under a considerable amount of unwanted noise. Most traditional methods can eliminate such noise but may change unexpectedly our concerned displacement pattern. If the clean displacement can be recovered, with unwanted noise removed, we can more accurately interpret how tectonic process contributes to surface displacement. With the recently successful application in geodetic deformation denoising, deep learning is also expected to be able to address the problem associated with optical displacement. Here, we trained a deep-learning-based autoencoder on a real noise dataset generated from a large amount of Sentinel-2 images. We applied the autoencoder to synthetic and real test datasets to successfully eliminate the unwanted noises in given MPICs, accurately revealing noise-free displacement signals. Interestingly, we even discovered detailed surface migrating information about a dune near the Maduo earthquake in the Tibet Plateau. The finding highlights the autoencoder is a robust method that can also improve horizontal displacement caused by those tectonic processes other than just earthquakes.

Ionospheric response to sudden stratospheric warming (SSW) are not well understood. During the 2013 SSW, ionospheric disturbances were observed in eighteen stations on three meridional chains of 100°E, 110°E and 120°E ranging from 19.03°N to 49.21°N at latitudes over East Asia region. The TEC response showed evident semi-diurnal disturbance that enhancement in the morning and depletion in the afternoon. The maximum TEC increased by more than 220% on the chain 120°E. In addition, the semi-diurnal disturbance of TEC were enhanced and indicated evident latitudinal and longitudinal dependence. The wavelet spectra of semi-diurnal disturbance in TEC presented quasi-16 day planetary wave-like oscillations at middle latitudes and quasi-10 day planetary wave-like oscillations at low latitudes. Meanwhile, the zonal winds and meridional winds at altitudes of 92-100 km showed quasi-16 day planetary wave at Mohe located middle latitude and quasi-10 day planetary wave at Sanya located low latitude, which are agree with semi-diurnal disturbance of TEC. Especially, the 12-hour component of TEC showed a quasi-16 day periodic component at middle latitude and a quasi-10 day periodic component at low latitude, indicating that the modulated semi-diurnal tides may transmit these 10 day and 16 day planetary wave-like oscillations to the ionosphere. The coupling between the atmosphere and ionosphere may be strengthened by the quasi-16 day waves at middle latitude and quasi-10 day waves at low latitude. This can further confirm the PW-tide interaction theory during the 2013 SSW and it is of significance in the middle and low latitude ionospheric response to SSW.

Long-term fault growth involves the dynamic evolution of fault zone architecture, structural maturity, and physical properties. Accurate characterization of these features is essential for improved understanding of fault mechanics, rupture dynamics and earthquake hazard. Fault structural maturity has traditionally been quantified via analysis of geological features. Nonetheless, the manifestations of an incipient fault are still poorly known, partly due to a lack of fault outcrops and limited diagnostic characteristics of this type of fault. In this study, we integrate coseismic and postseismic geodetic (InSAR/GPS) observations, relocated aftershocks, optical satellite imagery, and field measurements to characterize the fault kinematics of the May 21 2001 Mw7.4 Maduo earthquake, which occurred on an immature fault. Using relocated aftershocks, we determine the fault damage zone thickness and damage density decay at a comparable resolution with field geological investigations. We analyze surface inelastic strain along the rupture using both InSAR and optical images. We construct a buried slip model and refine the coseismic slip distribution to determine a shallow slip deficit, which we attribute to off-fault deformation. We also examine the afterslip distribution and moment release following the earthquake to probe its relationship with coseismic rupture. All pieces of evidence point to the dominant role of immaturity of the fault hosting the Maduo earthquake. Our study demonstrates that the combined analysis of seismological data, geodetic observations and field measurements helps to comprehensively characterize fault structural maturity and to better understand the role of single earthquakes in the long-term fault zone evolution.