scholarly journals Determination of the Long-Term Ground Surface Displacements Using a PSI Technique—Case Study on Wrocław (Poland)

2020 ◽  
Vol 10 (10) ◽  
pp. 3343
Author(s):  
Piotr Grzempowski ◽  
Janusz Badura ◽  
Wojciech Milczarek ◽  
Jan Blachowski ◽  
Tadeusz Głowacki ◽  
...  
Keyword(s):  
Ground Surface ◽  
Surface Displacement ◽  
Temporal Analysis ◽  
Recent Measurement ◽  
Entire Area ◽  
Surface Displacements ◽  
Spatio Temporal ◽  
Potential Factors ◽  
The City

Wrocław is a major city located in the southwestern part of Poland in an aseismic tectonic fault zone. Slow, long-term, vertical displacements have been observed there from the 1930s based on the levelling network measurements with the use of a precise levelling method. Due to the high cost of classic surveys, these were performed at intervals of several decades and the most recent measurement of ground surface displacement was performed in 1999. The main aim of this study is to determine the ground surface displacements on the area of Wrocław in the 1995–2019 period, the spatio-temporal analysis of deformations and the identification of the potential factors causing these deformations. To determine the ground movements, an advanced PSI technique and data from ERS-2, Envisat, and Sentinel-1 sensors were used. Application of SAR technology for the first time in this area, provided new knowledge about the process of deformation in short time intervals over the entire area of the city. The results verify the hypothesis on the linearity of displacements obtained from historical geodetic observations. The obtained results show that the displacements, which continue to occur in the area of Wrocław have a cyclic character with 4–5 year long period of subsidence and 2–3 year long periods of stabilization or uplift. The displacement trends indicate that the area of the city gradually subsides in relation to the reference area located on the Fore-Sudetic Block.

Analysis of methodological and physical bias on borehole temperature reconstructions from a pseudo-proxy approach.

2020 ◽  
Author(s):  
Camilo Melo Aguilar ◽  
Fidel González Rouco ◽  
Elena García Bustamante ◽  
Norman Steinert ◽  
Jorge Navarro ◽  
...  
Keyword(s):  
Grid Point ◽  
Ground Surface ◽  
Temporal Distribution ◽  
Surface Air Temperature ◽  
Internal Variability ◽  
Last Millennium ◽  
Subsurface Temperature ◽  
Borehole Logs ◽  
Spatio Temporal

<p>The analysis of subsurface temperature measurements from boreholes is a well established approach for reconstructing last millennium (LM) surface air temperature (SAT). It is based on the assumption that SAT variations are strongly coupled to ground surface temperature (GST) variations and transferred to the subsurface by thermal conduction. We have evaluated the long-term SAT-GST coupling over the LM using an ensemble of both full- and single-forcing simulations form the Community Earth System Model-Last Millennium Ensemble (CESM-LME). Such a premise is explored by investigating the evolution of the long-term SAT–GST relationship. The results indicate that SAT–GST coupling is strong at global and above multi-decadal timescales in CESM-LME. However, at local to regional scales this relationship experiences considerable long-term changes mostly after the end of the 19th century. Land use land cover (LULC) changes stand as the main driver for locally and regionally decoupling SAT and GST, due to the changes in the energy fluxes at the surface. Snow cover feedbacks due to the influence of GHG forcing are also important for corrupting the long-term SAT–GST coupling. These processes may represent a source of bias for SAT reconstructions from GST borehole profiles. In light of these findings, we subsequently assessed the potential effects on SAT reconstructions from the borehole method in pseudo-proxy experiments that make use of the same set of simulations from the CESM-LME. First, a heat-conduction forward model has been used to estimate subsurface temperature-anomaly profiles using simulated GST as boundary conditions. Subsequently, singular value decomposition inversion (SVD) has been applied to reconstruct LM GST variations from the simulated profiles. We implemented and ideal scenario in which it is assumed the existence of borehole logs at every model grid point. Further, this scenario considers that all boreholes are logged homogenously at the same time. In addition, we implemented a more realistic approach in which the real-world spatio-temporal distribution of the global borehole network is considered. Results show that the SVD inversion is able to retrieve the long-term GST variations over the LM when an appropriated coverture of borehole logs is available. However, due to the limited spatio-temporal distribution of the actual borehole network, there is a lost in the accuracy to retrieve the simulated GST 20th century trends, with the temporal logging of the BTPs as the main sampling issue. Furthermore, in the surrogate reality of the CESM-LME the SAT-GST decoupling, due to the influence of LULC and GHG forcings, leads to a slightly underestimation of SAT warming during the industrial period across the CESM-LME. The level of impact is, however, highly depended on the realization of internal variability.</p>

scholarly journals Estimate of a spatially variable reservoir compressibility by assimilation of ground surface displacement data

2015 ◽  
Vol 372 ◽  
pp. 351-356 ◽  
Author(s):  
C. Zoccarato ◽  
D. Baù ◽  
F. Bottazzi ◽  
M. Ferronato ◽  
G. Gambolati ◽  
...  
Keyword(s):  
Land Surface ◽  
Ground Surface ◽  
Surface Displacement ◽  
Test Case ◽  
Geomechanical Model ◽  
Gas Field ◽  
Surface Displacements ◽  
Model Response ◽  
Synthetic Test ◽  
Gas Fields

Abstract. Fluid extraction from producing hydrocarbon reservoirs can cause anthropogenic land subsidence. In this work, a 3-D finite-element (FE) geomechanical model is used to predict the land surface displacements above a gas field where displacement observations are available. An ensemble-based data assimilation (DA) algorithm is implemented that incorporates these observations into the response of the FE geomechanical model, thus reducing the uncertainty on the geomechanical parameters of the sedimentary basin embedding the reservoir. The calibration focuses on the uniaxial vertical compressibility cM, which is often the geomechanical parameter to which the model response is most sensitive. The partition of the reservoir into blocks delimited by faults motivates the assumption of a heterogeneous spatial distribution of cM within the reservoir. A preliminary synthetic test case is here used to evaluate the effectiveness of the DA algorithm in reducing the parameter uncertainty associated with a heterogeneous cM distribution. A significant improvement in matching the observed data is obtained with respect to the case in which a homogeneous cM is hypothesized. These preliminary results are quite encouraging and call for the application of the procedure to real gas fields.

scholarly journals Evaluating Temporal Approximation Methods Using Burglary Data

2020 ◽  
Vol 9 (6) ◽  
pp. 386
Author(s):  
Lukas Oswald ◽  
Michael Leitner
Keyword(s):  
Temporal Analysis ◽  
Approximation Methods ◽  
The Novel ◽  
Occurrence Time ◽  
Criminal Intelligence ◽  
Time Stamps ◽  
Spatio Temporal ◽  
Crime Types ◽  
The City ◽  
Intelligence Service

Law enforcement is very interested in knowing when a crime has happened. Unfortunately, the occurrence time of a crime is often not exactly known. In such circumstances, estimating the most likely time that a crime has happened is crucial for spatio-temporal analysis. The main purpose of this research is to introduce two novel temporal approximation methods, termed retrospective temporal analysis (RTA) and extended retrospective temporal analysis (RTAext). Both methods are compared to six existing temporal approximation methods and subsequently evaluated in order to identify the method that can most accurately estimate the occurrence time of crimes. This research is conducted with 100,000+ burglary crimes from the city of Vienna, Austria provided by the Criminal Intelligence Service Austria, from 2009–2015. The RTA method assumes that crimes in the immediate past occur at very similar times as in the present and in the future. Historical crimes with accurately known time stamps can therefore be applied to estimate when crimes occur in the present/future. The RTAext method enhances one existing temporal approximation method, aoristicext, with probability values derived from historical crime data with accurately known time stamps. The results show that the RTA method performs superiorly to all other temporal approximation methods, including the novel RTAext method, in two out of the three crime types analyzed. Additionally, the RTAext method shows very good results that are similar to the best performing existing approximation methods.

Estimating surface displacement in the Hanshin area, Japan, by PS-InSAR analysis using satellite Sentinel-1 data

2021 ◽  
Author(s):  
Yutaro Shigemitsu ◽  
Kazuya Ishitsuka ◽  
Weiren Lin
Keyword(s):  
Fault Zone ◽  
Groundwater Level ◽  
Active Faults ◽  
Surface Displacement ◽  
Sar Interferometry ◽  
Surface Displacements ◽  
Active Segment ◽  
2018 Northern Osaka Earthquake ◽  
Groundwater Level Changes

<p>The 2018 northern Osaka earthquake with a magnitude 6.1 earthquake struck on June 18, 2018 in northern Osaka, causing enormous damage. SAR interferometry using satellite synthetic aperture radar (SAR) data can detect surface displacement distribution over a wide area and is effective for observing surface displacement during an earthquake. On the other hand, it is also important to observe the tendency of long-term surface displacement around active faults on a yearly basis in order to monitor the deformation at and around active faults. In this study, we used persistent scatter SAR interferometry (PS-InSAR) to clarify the recent surface displacement including before and after the 2018 northern Osaka earthquake near the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment, near the epicenter of the earthquake. PS-InSAR analysis is a method that analyzes coherent pixels only, and can extract surface displacements with less noise than the conventional two-pass SAR interferometry. By using Sentinel-1 data, we expect to understand a long-term surface displacement and temporal changes in displacement pattern by comparing with the results using other satellites in previous studies. As a result of our analysis, we found that (i) ground subsidence occurred near the Mt. Rokko active segment, (ii) subsidence or eastward displacement occurred in the eastern part of the Takarazuka GNSS station, (iii) surface displacement in the wedge-shaped area located between the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment is suggested to be caused by groundwater level changes, (iv) groundwater level changes may have caused surface displacement considered to be uplift in the wide area between the Ikoma Fault Zone and Uemachi Fault Zone, and (v) slip of the source fault may have caused surface displacement around the epicenter of the 2018 northern Osaka earthquake. Furthermore, we validated the estimated surface displacements by comparison with GNSS measurements and previous studies. These results suggest that surface displacement near the Arima-Takatsuki fault zone was caused by the 2018 northern Osaka earthquake. In order to reveal the mechanism of surface displacement in the vicinity of the fault, it is necessary to continue to monitor the surface displacement in this area using time-series SAR interferometry.</p><p> </p><p> </p><p>We acknowledge Sentinel-1 data provided from the European Space Agency (ESA) based on the open data policy.</p>

scholarly journals Seasonal and Interannual Ground-Surface Displacement in Intact and Disturbed Tundra along the Dalton Highway on the North Slope, Alaska

Land ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 22
Author(s):  
Go Iwahana ◽  
Robert C. Busey ◽  
Kazuyuki Saito
Keyword(s):  
Ground Surface ◽  
Surface Displacement ◽  
Satellite System ◽  
The North ◽  
Surface Displacements ◽  
Standard Deviation Range ◽  
Thaw Depth ◽  
Ice Wedge ◽  
Global Navigation Satellite ◽  
Northern Alaska

Spatiotemporal variation in ground-surface displacement caused by ground freeze–thaw and thermokarst is critical information to understand changes in the permafrost ecosystem. Measurement of ground displacement, especially in the disturbed ground underlain by ice-rich permafrost, is important to estimate the rate of permafrost and carbon loss. We conducted high-precision global navigation satellite system (GNSS) positioning surveys to measure the surface displacements of tundra in northern Alaska, together with maximum thaw depth (TD) and surface moisture measurements from 2017 to 2019. The measurements were performed along two to three 60–200 m transects per site with 1–5 m intervals at the three areas. The average seasonal thaw settlement (STS) at intact tundra sites ranged 5.8–14.3 cm with a standard deviation range of 2.1–3.3 cm. At the disturbed locations, averages and variations in STS and the maximum thaw depth were largest in all observed years and among all sites. The largest seasonal and interannual subsidence (44 and 56 cm/year, respectively) were recorded at points near troughs of degraded ice-wedge polygons or thermokarst lakes. Weak or moderate correlation between STS and TD found at the intact sites became obscure as the thermokarst disturbance progressed, leading to higher uncertainty in the prediction of TD from STS.

scholarly journals Spatio-temporal Analysis of Urban Growth and Its Effects on Wetlands in Rwanda: The Case of Rwampara Wetland in the City of Kigali

2020 ◽  
Vol 24 (9) ◽  
pp. 1495-1501
Author(s):  
G. Rwanyiziri ◽  
C. Kayitesi ◽  
M. Mugabowindekwe ◽  
R.V. Byizigiro ◽  
E. Muyombano ◽  
...  
Keyword(s):  
Urban Growth ◽  
Wetland Management ◽  
Temporal Analysis ◽  
High Population ◽  
Central Administration ◽  
Structured Interviews ◽  
Landsat Images ◽  
Spatio Temporal ◽  
Wetland Resources ◽  
The City

This study aimed at analyzing the spatio-temporal patterns of urban growth and its effects on Rwampara wetland, located in the City of Kigali,  Rwanda. First, the study was based on the application of remote sensing technology, where 4 Landsat images (1987, 1999, 2009 & 2018) were  classified using maximum likelihood classification algorithm. This helped in analyzing the Land Use and Land Cover (LULC) trends in the study area. Secondly, it used the existing LULC data for the years 1990, 2000, 2010 and 2018 in order to investigate the overall changes in LULC in Kigali City. Finally, semi-structured interviews were used to collect data from local people and decision-makers about their past and future management strategies of Rwampara wetland. In this regard, 30 local communities (mainly natives from the study area), 15 local government authorities at sector and district levels as well as 4 senior government authorities in the central administration were interviewed. The findings revealed that over the past 4 decades, urban growth in Kigali City has rapidly increased at the expense of resource degradation in Rwampara wetland. Specifically, there has been an increase of about 77% of the built-up area over the last 31 years (1987-2018) which has led to the decrease of the wetland surface area from 24 ha in 1987 to only 7.7 ha in 2018. The results also revealed that demographic factors (i.e. a high population growth rate and high population  densities) were mainly responsible for urban growth and degradation of wetland resources in the area under investigation. Keywords: urban growth, wetland, wetland resources, wetland degradation, wetland management

scholarly journals Short-term temperature variability in a tropical Andean city Manizales, Colombia

2020 ◽  
Vol 17 (2) ◽  
pp. 129-139
Author(s):  
Jeannette Zambrano Nájera ◽  
Victor Delgado ◽  
Jorge Julian Vélez Upegui
Keyword(s):  
Urban Areas ◽  
Climatic Variability ◽  
Temporal Analysis ◽  
Temperature Structure ◽  
Tropical Andes ◽  
Temporal Complexity ◽  
Short And Long Term ◽  
Available Information ◽  
The City

The climatic variability in the Tropical Andes area is high, both spatially and temporally, and its analysis must be carried out both in the short and long term depending on the available information. This type of spatial-temporal analysis provides tools for planning and environmental management in urban areas, given its high complexity. This investigation focuses on a diagnosis of the diurnal cycle and the analysis of the monthly temperature structure in 13 stations located in the city of Manizales, Caldas (Colombia). This applied research aims to understand the behavior of the temperature in a tropical Andes city in Colombia, where the spatial-temporal complexity of this variable improve the urban and hydrological planning strategies. Results correspond to what has been previously defined by other authors for the Andean zone: city temperature shows very stable patrons, yet important variations in temperature range across the city are appreciated during the day.

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