Dynamics and Transformation of Sea Surface Gravity Waves at the Shelf of Decreasing Depth

This paper reviews the results of the processing of synchronized data on hydrosphere pressure variations and the Earth’s crust deformation in the microseismic range (5–15 s), obtained over the course of numerous experiments, using a coastal laser strainmeter and laser meters of hydrosphere pressure variations installed in various points of the Sea of Japan shelf. Interpreting the results, we have discovered new regularities in the dynamics of surface progressive gravity waves, and their transformation into primary microseisms, when waves move at the shelf of decreasing depth. For example, we found non-isochronous behavior of progressive waves, which manifests itself in a decrease in the periods of gravity waves due to the transformation of a part of their energy into the energy of primary microseisms. Furthermore, when processing the synchronous fragments of the records, made by laser strainmeters and laser meters of hydrosphere pressure variations, we identified approximate zones of the most effective transformation of the energy of gravity progressive waves into the energy of primary microseisms, which start from the depth of less than a half-wavelength and stretch to the surf zone.

Test on the Reliability of the Subsurface Fault Geometry Estimated by Deformed River Terraces Along the Bailang River, North Front of the Qilian Shan (North West China)

The subsurface fault geometry is the base for understanding a process of crust deformation and mountain building. Based on kinematic models for fault-related folds, a geomorphic method is recently applied to estimate the subsurface fault geometry, while the validation on its reliability is lacking. In this study, we surveyed a suit of river terrace surfaces across an active fold at the north front of the Qilian Shan. According to the deformation geometry of the terraces, the fold deformation is interpreted by a listric fault fold model, and based on this kinematic model, the fault geometry underlying the fold is estimated. In comparison between the estimated fault geometry and a seismic reflection profile, we found that the decollement depth and the back thrust are highly consistent with each other. Although some small fault bends or internal shearing cannot be estimated solely by the terrace deformation, the overall fault geometry is successfully revealed by the terrace deformation. Using this fault geometry and the terrace dating results, the region deformation kinematics are re-evaluated, which suggest that the dip slip (in a rate of 1.8 ± 0.4 mm/a) along the decollement is mainly accommodated by two structures, one is the blind-back-thrust fault within the piggy basin in a dip-slip rate of 0.9 ± 0.3 mm/a and another is the thrust and fold at the west portion of the Yumu Shan range.

Modeling Water Droplet Freezing and Collision with a Solid Surface

Water droplets released from the sea surface represent one of the major causes of ice accretion on marine vessels. A one-dimensional model of the freezing of a spherical water droplet moving in cold air was developed. The crystallization model allows one to obtain an analytical solution if a uniform temperature distribution over the liquid’s core is assumed. The model was validated using STAR CCM+ Computational fluid dynamics (CFD) code. A collision of a partially frozen droplet with a solid wall assuming the plastic deformation of an ice crust was also considered. The ratio of the crust deformation to the crust thickness was evaluated. It was assumed that if this ratio were to exceed unity, the droplet would stick to the wall’s surface due to ice bridge formation caused by the water released from the droplet’s core.

Applying the ICA method to extract the potential signals in GNSS timeseries

<p>Spatial filtering is an effective way to identify and reduce the so-called common mode error (CME) from the regional GPS networks measurements, which could improve GPS positioning accuracy and precision for detection of subtle crustal deformation signals. In this work, we decompose GPS coordinate time series into a set of temporally varying modes with the widely used principal component analysis (PCA) on minizine the misfit calculated using a L2 norm(x2). The results show that the decomposed components from PCA are not statically independent to each other. It is difficult to reveal the original geophysical mechanisms for the related signals only on the PCA results. To work around the problems, we reanalysis the output from PCA to recovery and separate the original signals from mixed observations with the independent component analysis (ICA). Here, we firstly apply the PCA methods on the GPS position time series in Sichuan_Yunnan region of China to evaluate the ability in discerning and charactering different source of crust deformation in the space and time domains. Using the PCA decomposed first 6 PCs, we find that the spatially and temporally correlated CME can be decomposed into two independent components by ICA, the second IC shows obvious variations in the beginning of each year, the same characters are also seen in the atmosphere press variations. Then we compare the two timeseries and demonstrated that atmosphere high frequency pressure mass loading is one of the main contributors to the CME.</p>

Evaluation of the Performance of Online GPS/GNSS Data Processing Services for Monitoring the Land Deformations and Movements

In recent years, the Global Navigation Satellite Services (GNSS) technology has been frequently employed for monitoring the Earth crust deformation and movement. Such applications necessitate high positional accuracy that can be achieved through processing GPS/GNSS data with scientific software such as BERENSE, GAMIT, and GIPSY-OSIS. Nevertheless, these scientific softwares are sophisticated and have not been published as free open source software. Therefore, this study has been conducted to evaluate an alternative solution, GNSS online processing services, which may obtain this privilege freely. In this study, eight years of GNSS raw data for TEHN station, which located in Iran, have been downloaded from UNAVCO website on a daily basis. Furthermore, TEHN GNSS observations are processed with CSRS-PPP, which is based on Precise Point Positioning (PPP) algorithm, and OPUS, which is based on double difference (DD) algorithm, to compare between these two techniques in terms of station velocity estimation and Earth deformation. On the other hand, TEHN station solutions that produce via scientific software, GIPSY-OSIS, are obtained from Nevada Geodetic Laboratory (NGL) website for data validation. Eventually, the results show that both GNSS online processing services (CSRS-PPP and OPUS) are credibly efficient to estimate station velocities, while CSRS-PPP trustworthy service for monitoring the Earth deformation.

The appearance of copper-bearing mineralization in the region of Muang Xay, Laos

Geotectonic events in the Indochina Peninsula, associatted with the Indosinian orogeny between the Paleozoic and Mesozoic, has created many fold structures and fault areas oin the territory of Laos. Magmatic processes and Earth’s crust deformation enabled arising of rich Cu mineralization. A prospective area for the occurrence of Cu, Ag and Au minerals is the folded region on Muang Xay, northern Laos. The main purpose of geological research of the Muang Xay area was the recognition of chemical and mineralogical composition of rock samples and the evaluation of the area of potential geological resources. During field reconnaissance in 2018, the rock samples were taken from an abandoned mine. It was concluded that primary rocks suffered intense Na-metasomatic processes, preserving primary copper sulphides – bornite, chalcocite and covellite. The content of Cu is up to 49.64% and Ag up to 119.5 ppm. As a result of metasomatism of igneous rocks, diorite or andesite types – albitite was formed. Albitite is composed of medium-grained albite, Mg-chlorite and Cu-carbonates. The prospective research shows that the Muang Xay region has a high potential of metalliferous deposits.

Deformation-Electromagnetic Relations in Lithospheric Activity Manifestations

It has been shown that dipole radiation of accelerated charges, described by Larmor relation, is the basis of the known mechanic-electromagnetic processes of rock deformation. Comparison of crust deformation acceleration with natural electromagnetic field parameters of ELF-VLF range showed good relation. It manifests in the maxima of occurrence frequency density of synchronous deformation-electromagnetic events on two dimensional histograms. The data of a laser strain-meter and a recorder of natural electromagnetic radiation of ELF-VLF range, recorded in a zone of increased seismic activity (Kamchatka, Karymshina site), were used. The authors made an assumption on the existence of stationary regions of deformation process and mechanic-electromagnetic transformations corresponding to regions with different mechanic properties and rock petrographic composition.