scholarly journals A Multiphysics approach to constrain the dynamics of the Altiplano-Puna magmatic system

2021 ◽  
Author(s):  
Arne Spang ◽  
Tobias Baumann ◽  
Boris Kaus
Keyword(s):  
Surface Deformation ◽  
Scaling Law ◽  
Gravity Anomalies ◽  
Density Contrast ◽  
Deformation Pattern ◽  
Interferometric Synthetic Aperture Radar ◽  
Thermomechanical Model ◽  
Magma Body ◽  
3D Geometry ◽  
Joint Interpretation

Continuous Interferometric Synthetic Aperture Radar (InSAR) monitoring (> 25 years) has revealed a concentric surface deformation pattern above the Altiplano-Puna magma body (APMB) in the central Andes. Here, we use a joint interpretation of seismic imaging, gravity anomalies and InSAR data to constrain location, 3D geometry and density of the magma body. By combining gravity modelling, thermomechanical modelling, scaling law analysis and Bayesian inference, we are able to create a relationship between the geometry of a mid-crustal magma body and surface observations. Furthermore, we can estimate the uncertainties associated with the geometry of the APMB and identify the most important parameters that control the dynamics of the system. We constrain the density contrast between the APMB and the surrounding host rock to 90 - 130 kg m−3 (2σ) and the associated melt fraction to 15 - 22 %. Our visco-elasto-plastic 3D thermomechanical model reproduces the observed surface deformation self-consistently by buoyancy driven magma transport without the need for additional pressure sources. The flow pattern is controlled by a central rise at the top of the APMB whose geometry can be constrained with the help of InSAR observations while Bouguer anomalies constrain the deeper parts of the APMB. Automated scaling law analysis shows that the rheology of the upper crust and the magma mush as well as the density contrast between the two are the most important parameters in the system and need to be constrained for a better understanding of the subsurface processes.

3D Geodynamic Models of the Present-Day Altiplano-Puna Magmatic System

2020 ◽  
Author(s):  
Arne Spang ◽  
Tobias Baumann ◽  
Boris Kaus
Keyword(s):  
Surface Deformation ◽  
Gravity Anomalies ◽  
Deformation Pattern ◽  
Interferometric Synthetic Aperture Radar ◽  
Magmatic System ◽  
Magma Body ◽  
Rate Dependent ◽  
Numerical Studies ◽  
Joint Interpretation ◽  
Geodynamic Models

<p>For the past decades, several numerical studies have successfully reproduced the concentric uplift pattern observed above the Altiplano-Puna Magma Body (APMB) in the central Andes. However, the temperature- and strain rate-dependent viscoelastoplastic rheology of rocks, the buoyancy of magma, the effects of modelling in 3D as well as the shape of the magma body have often been simplified or neglected.</p><p>Here, we use a joint interpretation of seismic imaging and gravity anomalies to constrain location, 3D shape and density of the magma body. With the help of the thermo-mechanical finite difference code LaMEM, we then model the surface deformation and test our results against observations made by Interferometric Synthetic-Aperture Radar (InSAR) missions. This way, we gain insights into the dynamics and rheology of the present-day magmatic system and can test how a change to the current conditions (e.g., magma influx) could impact it.</p><p>We find that only an APMB with a maximum thickness of 14 to 18 km and a corresponding density contrast to the surrounding host rock of 100 to 175 kg/m<sup>3</sup> satisfies both tomography and Bouguer data. Based on that and the chemistry of eruption products, we estimate the melt content of the APMB to be on the order of 20 - 25%. We also find that the observed uplift can be reproduced by magma-induced buoyancy forces without the need for an additional pressure source or magma injection within the mush, and that the geometry of the top of the magma body exerts a major control on the deformation pattern at the surface.</p>

scholarly journals INVESTIGATION OF LITHOSPHERIC STRUCTURE IN MONGOLIA: INSIGHTS FROM INSAR OBSERVATIONS AND MODELLING

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 609-616
Author(s):  
Z. Jing ◽  
F. Bihong ◽  
S. Pilong ◽  
G. Qiang
Keyword(s):  
Fault Zone ◽  
Surface Deformation ◽  
Line Of Sight ◽  
Tectonic Deformation ◽  
Deformation Pattern ◽  
Interferometric Synthetic Aperture Radar ◽  
Crust And Upper Mantle ◽  
Western Mongolia ◽  
Deformation Velocity ◽  
The Relationship

The western Mongolia is a seismically active intracontinental region, with ongoing tectonic deformation and widespread seismicity related to the far-field effects of India-Eurasia collision. During the 20th century, four earthquakes with the magnitude larger than 8 occurred in the western Mongolia and its surrounding regions, providing a unique opportunity to study the geodynamics of intracontinental tectonic deformations. The 1957 magnitude 8.3 Gobi-Altai earthquake is one of the largest seismic events. The deformation pattern of rupture zone associated with this earthquake is complex, involving left-lateral strike-slip and reverse dip-slip faulting on several distinct geological structures in a 264&amp;thinsp;×&amp;thinsp;40&amp;thinsp;km wide zone. To understand the relationship between the observed postseismic surface deformation and the rheological structure of the upper lithosphere, Interferometric Synthetic Aperture Radar (InSAR) data are used to study the 1957 earthquake. Then we developed a postseismic model in a spherical, radially layered elastic-viscoelastic Earth based on InSAR results, and further analysed the dominant contribution to the surface deformation. This work is important for understanding not only the regional tectonics, but also the structure and dynamics of the lithosphere. <br><br> SAR data were acquired from the ERS1/2 and Envisat from 1996 to 2010. Using the Repeat Orbit Interferometry Package (ROI_PAC), 124 postseismic interferograms are produced on four adjacent tracks. By stacking these interferograms, the maximum InSAR line-of-sight deformation rate along the Gobi-Altai fault zone is obtained. The main results are as follows: (1) The maximum InSAR line-of-sight deformation velocity along this large fault zone is about 6&amp;thinsp;mm/yr; (2) The modelled surface deformation suggests that the viscoelastic relaxation is the most reasonable mechanism to explain the observed surface motion; (3) The optimal model cover the Gobi-Altai seismogenic thickness is 10&amp;thinsp;km; (4) The lower bound of Maxwell viscosity of lower crust and upper mantle is approximately 9&amp;thinsp;×&amp;thinsp;10<sup>19</sup>&amp;thinsp;Pa&amp;thinsp;s, and the Maxwell relaxation time corresponding to this viscosity is 95.13 years.

The ambiguous fault geometry derived from InSAR measurements of buried thrust earthquakes: a synthetic data based study

2021 ◽  
Vol 225 (3) ◽  
pp. 1799-1811
Author(s):  
Yingfeng Zhang ◽  
Xinjian Shan ◽  
Wenyu Gong ◽  
Guohong Zhang
Keyword(s):  
Surface Deformation ◽  
Fault Plane ◽  
Synthetic Data ◽  
Deformation Pattern ◽  
Interferometric Synthetic Aperture Radar ◽  
Fault Geometry ◽  
Noise Levels ◽  
Data Set ◽  
Mountain Belts ◽  
Deformation Patterns

SUMMARY The challenge of ruling out potential rupture nodal planes with opposite dip orientations during interferometric synthetic aperture radar (InSAR)-based kinematic inversions has been widely reported. Typically, slip on two or more different fault planes can match the surface deformation measurements equally well. The ambiguous choice of the nodal plane for the InSAR-based models was thought to be caused by InSAR's 1-D measurement and polar orbiting direction, leading to its poor sensitivity to north–south crustal motion. Through synthetic experiments and simulations, this paper quantitatively demonstrates the main reason of the ambiguous InSAR-based models, which confuse researchers in the small-to-moderate thrust earthquake cases investigation. We propose the inherent 1-D measurement is not the principle cause of the fault plane ambiguity, since models derived from the same InSAR data predict similar, but not identical, 3-D deformation patterns. They key to differentiating between these different models is to be able to resolve the small asymmetry in the surface deformation pattern, which may be smaller in amplitude than the typical noise levels in InSAR measurements. We investigate the fault geometry resolvability when using InSAR data with different noise levels through ‘R’ value. We find that the resolvability does not only rely on the InSAR noise, but also on the fault geometry itself (i.e. depth, dips angle and strike). Our result shows that it is impossible to uniquely determine the dip orientation of thrust earthquakes with Mw &lt; 6.0 and depth &gt; 5.0 km with InSAR data at a noise level that is typical for mountain belts. This inference is independent from the specific data set (i.e. interferogram or time-series) and allows one to assess if one can expect to be able to resolve the correct fault plane at all.

scholarly journals GPS measurements on pre-, co- and post-seismic surface deformation at first multi-parametric geophysical observatory, Ghuttu in Garhwal Himalaya, India

2020 ◽  
Vol 10 (1) ◽  
pp. 136-144
Author(s):  
P.K. Gautam ◽  
S. Rajesh ◽  
N. Kumar ◽  
C.P. Dabral
Keyword(s):  
Time Series ◽  
Surface Deformation ◽  
Translational Motion ◽  
Anomalous Behavior ◽  
Deformation Pattern ◽  
Local Earthquakes ◽  
Position Time Series ◽  
Continuous Gps ◽  
Gps Time Series ◽  
Gps Station

Abstract We investigate the surface deformation pattern of GPS station at MPGO Ghuttu (GHUT) to find out the cause of anomalous behavior in the continuous GPS time series. Seven years (2007-2013) of GPS data has been analyzed using GAMIT/GLOBK software and generated the daily position time series. The horizontal translational motion at GHUT is 43.7 ± 1 mm/yr at an angle of 41°± 3° towards NE, while for the IGS station at LHAZ, the motion is 49.4 ±1 mm/yr at 18 ± 2.5° towards NEE. The estimated velocity at GHUT station with respect to IISC is 12 ± 1 mm/yr towards SW. Besides, we have also examined anomalous changes in the time series of GHUT before, after and during the occurrences of local earthquakes by considering the empirical strain radius; such that, a possible relationship between the strain radius and the occurrences of earthquakes have been explored. We considered seven local earthquakes on the basis of Dobrovolsky strain radius condition having magnitude from 4.5 to 5.7, which occurred from 2007 to 2011. Results show irrespective of the station strain radius, pre-seismic surface deformational anomalies are observed roughly 70 to 80 days before the occurrence of a Moderate or higher magnitude events. This has been observed for the cases of those events originated from the Uttarakashi and the Chamoli seismic zones in the Garhwal and Kumaun Himalaya. Occurrences of short (< 100 days) and long (two years) inter-seismic events in the Garhwal region plausibly regulating and diffusing the regional strain accumulation.

Generalised Scaling Law for Soft Contact Tribology: Influence of Load and Asymmetric Surface Deformation

2021 ◽  
pp. 107192
Author(s):  
Yuan Xu ◽  
Ben Cartwright ◽  
Lian Advincula ◽  
Connor Myant ◽  
Jason R. Stokes
Keyword(s):  
Surface Deformation ◽  
Scaling Law ◽  
Soft Contact

scholarly journals Evolution of surface deformation related to salt extraction-caused sinkholes in Solotvyno (Ukraine) revealed by Sentinel-1 radar interferometry

2020 ◽  
Author(s):  
Eszter Szűcs ◽  
Sándor Gönczy ◽  
István Bozsó ◽  
László Bányai ◽  
Alexandru Szakacs ◽  
...  
Keyword(s):  
Disaster Response ◽  
Surface Deformation ◽  
Characteristic Size ◽  
Interferometric Synthetic Aperture Radar ◽  
Mining Operations ◽  
Data Set ◽  
Linear Feature ◽  
Repetition Time ◽  
Response And Recovery ◽  
Radar Measurements

Abstract. Rocksalt has remarkable mechanical properties and a high economic importance, however, this strength of salt compared to other rocks makes it a rather vulnerable material. Human activities could lead to acceleration of the dissolution of soluble rocksalt and collapse of subsurface caverns. Although sinkhole development can be considered local geological disaster regarding the characteristic size of surface depressions the deformations can result in catastrophic events. In this study we report the spatiotemporal evolution of surface deformation in Solotvyno salt mine area in Ukraine based on Sentinel-1 interferometric synthetic aperture radar measurements. Although the mining operations were finished in 2010 several sinkholes have been opened up since then. Our results show that even though the enormous risk managing efforts the sinkholes continue to expand with a maximum line-of-sight deformation rate of 5 cm/yr. The deformation time series show a rather linear feature and unfortunately no slowdown of the processes can be recognized based on the investigated 4.5 year-long data set. We utilized both ascending and descending satellite passes to discriminate the horizontal and vertical deformations and our results revealed that vertical deformation is much more dominant in the area. With the 6-day repetition time of Sentinel-1 observations the evolution of surface changes can be detected in quasi real-time which can facilitate disaster response and recovery.

Optimal Self-Propulsion of a Deformable Prolate Spheroid

1983 ◽  
Vol 27 (02) ◽  
pp. 121-130
Author(s):  
T. Miloh
Keyword(s):  
Kinetic Energy ◽  
Surface Deformation ◽  
Deformable Body ◽  
Large Degree ◽  
Prolate Spheroid ◽  
The Body ◽  
Deformation Pattern ◽  
Inviscid Fluid ◽  
Periodic Surface ◽  
Deformation Velocity

The problem of self-propulsion of an elongated deformable body moving in an infinite medium of inviscid fluid is considered in some detail. A prolate spheroid is chosen as a model shape, and a particular deformation pattern which maximizes the Froude efficiency is sought. The Froude efficiency in this context is defined by the ratio of the kinetic energy of the body to the total kinetic energy of the system comprising the body and the fluid. It is demonstrated that a body can propel itself from rest in a persistent manner even for a periodic surface deformation with zero mean which preserves both the volume and the location of its centroid. Under these constraints the induced forward velocity of the body is of 0(ε2) where ε is the amplitude of the deformation velocity. It is also demonstrated that for a persistent self-propulsion to exist the body should develop a large degree of skewness, resulting from the interaction between the two deformation components—one with fore-and-aft symmetry and one without. It is also essential that the symmetric and asymmetric deformation components should be out of phase.

scholarly journals Constraints on the location, depth and yield of the 2017 September 3 North Korean nuclear test from InSAR measurements and modelling

2019 ◽  
Vol 220 (1) ◽  
pp. 345-351 ◽  
Author(s):  
K M Sreejith ◽  
Ritesh Agrawal ◽  
A S Rajawat
Keyword(s):  
Large Scale ◽  
Surface Deformation ◽  
Nuclear Explosion ◽  
Source Parameters ◽  
Test Site ◽  
Nuclear Test ◽  
Interferometric Synthetic Aperture Radar ◽  
Surface Displacements ◽  
Detailed Surface ◽  
Scale Surface

SUMMARY The Democratic People's Republic of Korea (North Korea) conducted its sixth and largest affirmed underground nuclear test on 2017 September 3. Analysis of Interferometric Synthetic Aperture Radar (InSAR) data revealed detailed surface displacements associated with the nuclear explosion. The nuclear explosion produced large-scale surface deformation causing decorrelation of the InSAR data directly above the test site, Mt. Mantap, while the flanks of the Mountain experienced displacements up to 0.5 m along the Line-of-Sight of the Satellite. We determined source parameters of the explosion using the Bayesian inversion of the InSAR data. The explosive yield was estimated as 245–271 kiloton (kt) of TNT, while the previous yield estimations range from 70–400 kt. We determined the nuclear source at a depth of 542 ± 30 m below Mt. Mantap (129.0769°E, 41.0324°N). We demonstrated that the Bayesian modelling of the InSAR data reduces the uncertainties in the source parameters of the nuclear test, particularly the yield and source depth that are otherwise poorly resolved in seismic methods.

Gravity interpretation using Fourier transforms and simple geometrical models with exponential density contrast

Geophysics ◽  
1993 ◽  
Vol 58 (8) ◽  
pp. 1074-1083 ◽  
Author(s):  
D. Bhaskara Rao ◽  
M. J. Prakash ◽  
N. Ramesh Babu
Keyword(s):  
Los Angeles ◽  
Fourier Transforms ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
Density Contrast ◽  
Model Parameters ◽  
Exponential Density ◽  
Exponential Density Contrast ◽  
Gravity Interpretation

The decrease of density contrast in sedimentary basins can often be approximated by an exponential function. Theoretical Fourier transforms are derived for symmetric trapezoidal, vertical fault, vertical prism, syncline, and anticline models. This is desirable because there are no equivalent closed form solutions in the space domain for these models combined with an exponential density contrast. These transforms exhibit characteristic minima, maxima, and zero values, and hence graphical methods have been developed for interpretation of model parameters. After applying end corrections to improve the discrete transforms of observed gravity data, the transforms are interpreted for model parameters. This method is first tested on two synthetic models, then applied to gravity anomalies over the San Jacinto graben and Los Angeles basin.

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