scholarly journals Sensitivity Analysis for Seafloor Geodetic Constraints on Coseismic Slip and Interseismic Slip-Deficit Distributions

2021 ◽  
Vol 9 ◽  
Author(s):  
Sota Murakami ◽  
Tsuyoshi Ichimura ◽  
Kohei Fujita ◽  
Takane Hori ◽  
Yusaku Ohta
Keyword(s):  
Finite Element ◽  
Quantitative Evaluation ◽  
Crustal Structure ◽  
Crustal Deformation ◽  
High Accuracy ◽  
Slip Distribution ◽  
Estimation Accuracy ◽  
Coseismic Slip ◽  
Slip Deficit ◽  
Observation Methods

Estimating the coseismic slip distribution and interseismic slip-deficit distribution play an important role in understanding the mechanism of massive earthquakes and predicting the resulting damage. It is useful to observe the crustal deformation not only in the land area, but also directly above the seismogenic zone. Therefore, improvements in terms of measurement precision and increase in the number of observation points have been proposed in various forms of seafloor observation. However, there is lack of research on the quantitative evaluation of the estimation accuracy in cases where new crustal deformation observation points are available or when the precision of the observation methods have been improved. On the other hand, the crustal structure models are improving and finite element analysis using these highly detailed crustal structure models is becoming possible. As such, there is the real possibility of performing an inverted slip estimation with high accuracy via numerical experiments. In view of this, in this study, we proposed a method for quantitatively evaluating the improvement in the estimation accuracy of the coseismic slip distribution and the interseismic slip-deficit distribution in cases where new crustal deformation observation points are available or where the precision of the observation methods have been improved. As a demonstration, a quantitative evaluation was performed using an actual crustal structure model and observation point arrangement. For the target area, we selected the Kuril Trench off Tokachi and Nemuro, where M9-class earthquakes have been known to occur in the past and where the next imminent earthquake is anticipated. To appropriately handle the effects of the topography and plate boundary geometry, a highly detailed three-dimensional finite element model was constructed and Green’s functions of crustal deformation were calculated with high accuracy. By performing many inversions via optimization using Green’s functions, we statistically evaluated the effect of increase in the number of observation points of the seafloor crustal deformation measurement and the influence of measurement error, taking into consideration the diversity of measurement errors. As a result, it was demonstrated that the observation of seafloor crustal deformation near the trench axis plays an extremely important role in the estimation performance.

scholarly journals Tsunami Analysis Method with High-Fidelity Crustal Structure and Geometry Model

2017 ◽  
Vol 11 (05) ◽  
pp. 1750018
Author(s):  
Tsuyoshi Ichimura ◽  
Ryoichiro Agata ◽  
Takane Hori ◽  
Kenji Satake ◽  
Kazuto Ando ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crustal Structure ◽  
Crustal Deformation ◽  
Computation Method ◽  
High Fidelity ◽  
Analysis Method ◽  
Element Analysis ◽  
Geometry Model ◽  
Finite Element Analysis Method

Higher fidelity seafloor topography and crustal structure models have become available with accumulation of observation data. Previous studies have shown that the consideration of such high-fidelity models produces significant effects, in some cases, on crustal deformation results that are used as inputs for tsunami analysis. However, it is difficult to apply high-fidelity model of crustal deformation computations to tsunami computations because of large computational costs. In this paper, we propose a new crustal deformation computation method for estimating inputs for tsunami computations, which is based on a finite element analysis method with remarkable reduction of computation costs by efficient use of the arithmetic space and the solution space. This finite element analysis method enables us to conduct [Formula: see text]-times crustal deformation computations using high-fidelity models with a degree of freedom on the order of [Formula: see text] for the 2011 Tohoku earthquake example. Tsunami computations with typical settings are conducted as an application example to present the advantages and characteristics of the proposed method. Comparisons between results of the proposed and the conventional method reveal that large shallow fault slip around the trench axis may lead to significant differences in tsunami waveforms and inundation height distributions in some cases.

Assessment of 2D ultrasound fluid volume estimation accuracy in different shaped objects: an in vitro study

2019 ◽  
Vol 61 (2) ◽  
pp. 253-259
Author(s):  
Iroshani Kodikara ◽  
Iroshini Abeysekara ◽  
Dhanusha Gamage ◽  
Isurani Ilayperuma
Keyword(s):  
Estimation Error ◽  
In Vitro Study ◽  
High Accuracy ◽  
Volume Estimation ◽  
Estimation Accuracy ◽  
Rater Agreement ◽  
Actual Volume ◽  
2D Ultrasound ◽  
One Way Anova

Background Volume estimation of organs using two-dimensional (2D) ultrasonography is frequently warranted. Considering the influence of estimated volume on patient management, maintenance of its high accuracy is empirical. However, data are scarce regarding the accuracy of estimated volume of non-globular shaped objects of different volumes. Purpose To evaluate the volume estimation accuracy of different shaped and sized objects using high-end 2D ultrasound scanners. Material and Methods Globular (n=5); non-globular elongated (n=5), and non-globular near-spherical shaped (n=4) hollow plastic objects were scanned to estimate the volumes; actual volumes were compared with estimated volumes. T-test and one-way ANOVA were used to compare means; P<0.05 was considered significant. Results The actual volumes of the objects were in the range of 10–445 mL; estimated volumes ranged from 6.4–425 mL ( P=0.067). The estimated volume was lower than the actual volume; such volume underestimation was marked for non-globular elongated objects. Regardless of the scanner, the highest volume estimation error was for non-globular elongated objects (<40%) followed by non-globular near-spherical shaped objects (<23.88%); the lowest was for globular objects (<3.6%). Irrespective of the shape or the volume of the object, volume estimation difference among the scanners was not significant: globular (F=0.430, P=0.66); non-globular elongated (F=3.69, P=0.064); and non-globular near-spherical (F=4.00, P=0.06). A good inter-rater agreement (R=0.99, P<0.001) and a good correlation between actual versus estimated volumes (R=0.98, P<0.001) were noted. Conclusion The 2D ultrasonography can be recommended for volume estimation purposes of different shaped and different sized objects, regardless the type of the high-end scanner used.

Complex Slip Distribution of the 2021 Mw 7.4 Maduo, China, Earthquake: An Event Occurring on the Slowly Slipping Fault

2021 ◽  
Author(s):  
Rumeng Guo ◽  
Hongfeng Yang ◽  
Yu Li ◽  
Yong Zheng ◽  
Lupeng Zhang
Keyword(s):  
Slip Rate ◽  
Slip Distribution ◽  
Seismic Gap ◽  
Seismogenic Fault ◽  
Coseismic Slip ◽  
Slip Rates ◽  
Kunlun Mountain ◽  
Coulomb Failure ◽  
Main Fault ◽  
Large Earthquakes

Abstract The 21 May 2021 Maduo earthquake occurred on the Kunlun Mountain Pass–Jiangcuo fault (KMPJF), a seismogenic fault with no documented large earthquakes. To probe its kinematics, we first estimate the slip rates of the KMPJF and Tuosuo Lake segment (TLS, ∼75 km north of the KMPJF) of the East Kunlun fault (EKLF) based on the secular Global Positioning System (GPS) data using the Markov chain Monte Carlo method. Our model reveals that the slip rates of the KMPJF and TLS are 1.7 ± 0.8 and 7.1 ± 0.3 mm/yr, respectively. Then, we invert high-resolution GPS and Interferometric Synthetic Aperture Radar observations to decipher the fault geometry and detailed coseismic slip distribution associated with the Maduo earthquake. The geometry of the KMPFJ significantly varies along strike, composed of five fault subsegments. The most slip is accommodated by two steeply dipping fault segments, with the patch of large sinistral slip concentrated in the shallow depth on a simple straight structure. The released seismic moment is ∼1.5×1020  N·m, equivalent to an Mw 7.39 event, with a peak slip of ∼9.3 m. Combining the average coseismic slip and slip rate of the main fault, an earthquake recurrence period of ∼1250−400+1120  yr is estimated. The Maduo earthquake reminds us to reevaluate the potential of seismic gaps where slip rates are low. Based on our calculated Coulomb failure stress, the Maduo earthquake imposes positive stress on the Maqin–Maqu segment of the EKLF, a long-recognized seismic gap, implying that it may accelerate the occurrence of the next major event in this region.

The Influence of the Interstand Tension of the Band on Roll Wear during the Continuous Groove-Rolling Process

2015 ◽  
Vol 220-221 ◽  
pp. 898-904 ◽  
Author(s):  
Piotr Szota ◽  
Sebastian Mróz ◽  
Andrzej Stefanik ◽  
Henryk Dyja
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Quantitative Evaluation ◽  
Theoretical Study ◽  
Rolling Process ◽  
Wear Model ◽  
Bar Rolling ◽  
Groove Rolling ◽  
Roll Wear ◽  
Round Bar

Numerical modelling of the round bar rolling process, while considering the wear of passes depending on their shape, was carried out within the present work. The analysis of the rolling process was conducted thus analysing the influence of interstand tension on roll wear. For the theoretical study of the rolling process, Forge2011® was employed, which is finite element method-relying software that enables the thermo-mechanical simulation of rolling processes in a triaxial state of strain. The wear model implemented in Forge2011® permits no quantitative evaluation, but only a comparative analysis of the wear of rolls. In order to use the results of simulation employing the simplified Archard model for the quantitative evaluation of roll wear, it is necessary to define the factor of wear and the hardness of the tool as a function of temperature.

scholarly journals Quantitative Evaluation of Work Efficiency and Eye Strain for Remote Control Construction Equipment Using 2D/3D Displays

2020 ◽  
Vol 14 (1) ◽  
pp. 133-138
Author(s):  
Yoshihiro Sato ◽  
Shohei Yamaguchi ◽  
Shota Funaki ◽  
Atsutoshi Kurihara ◽  
Yuki Kumagai ◽  
...  
Keyword(s):  
Remote Control ◽  
Quantitative Evaluation ◽  
High Accuracy ◽  
Construction Equipment ◽  
Work Efficiency ◽  
Display System ◽  
3D Display ◽  
Physical Conditions ◽  
Before And After ◽  
Operator Workload

Remotely operated construction machines are used in cases where the operators are in danger, such as on steep slopes or contaminated sites. However, remote operation differs from what operators perceive during hands-on machine operation. Various studies have focused on improving work efficiency by employing remote control operation to reduce operator workload. In these studies, questionnaires were generally employed to evaluate the operator workload. However, the results obtained from the questionnaires varied depending on the physical conditions and the mood of the person on that day. It was therefore concluded that an accurate evaluation cannot be performed based on this method. Hence, in this study, the eye strain of machine operators was measured using an Auto Refractor/Keratometer. In particular, the ciliary muscle activities were measured before and after operating three display systems used for remote control of construction equipment. A quantitative evaluation was then conducted based on the eye strain data. The 2D display system exhibited low work accuracy and efficiency and resulted in significant eye strain. Although the 3D display system that required glasses exhibited high accuracy and efficiency, it resulted in significant eye strain. The 3D display system that did not require glasses demonstrated high accuracy and lower eye strain. From the results presented above, it was confirmed that the autostereoscopic 3D system is suitable for operators.

scholarly journals The 2009 L’Aquila earthquake coseismic rupture: open issues and new insights from 3D finite element inversion of GPS, InSAR and strong motion data

2015 ◽  
Vol 58 (2) ◽  
Author(s):  
Manuela Volpe ◽  
Simone Atzori ◽  
Antonio Piersanti ◽  
Daniele Melini
Keyword(s):  
Finite Element ◽  
Fault Plane ◽  
Numerical Models ◽  
Tectonic Setting ◽  
Strong Motion ◽  
Slip Distribution ◽  
Coseismic Deformation ◽  
L’Aquila Earthquake ◽  
Local Tomography ◽  
2009 L’Aquila Earthquake

<p>We present a Finite Element inverse analysis of the static deformation field for the M<sub>w</sub>= 6.3, 2009 L’Aquila earthquake, in order to infer the rupture slip distribution on the fault plane. An univocal solution for the rupture slip distribution has not been reached yet with negative impact for reliable hazard scenarios in a densely populated area. In this study, Finite Element computed Green’s functions were implemented in a linear joint inversion scheme of geodetic (GPS and InSAR) and seismological (strong motion) coseismic deformation data. In order to fully exploit the informative power of our dense dataset and to honor the complexities of the real Earth, we implemented an optimized source model, represented by a fault plane subdivided in variable size patches, embedded in a high-resolution realistic three-dimensional model of the Apenninic seismo-tectonic setting, accounting for topographic reliefs and rheological heterogeneities deduced from local tomography. We infer that the investigated inversion domain contains two minima configurations in the solution space, i.e. a single- and a double-patch slip distribution, which are almost equivalent, so that the available datasets and numerical models are not able to univocally discriminate between them. Nevertheless our findings suggest that a two high-slip patch pattern is slightly favoured.</p>

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