Modeling focal parameters for the magnitude 5.3 earthquake of the Xinfengjiang Reservoir area, People's Republic of China

1982 ◽  
Vol 72 (4) ◽  
pp. 1085-1092
Author(s):  
Chengnan Zhu ◽  
Yuquan Liu ◽  
Chunyong Wang ◽  
Ruxi Lu ◽  
Jiande Chen
Keyword(s):  
Stress Field ◽  
Lower Boundary ◽  
Normal Fault ◽  
Hydraulic Pressure ◽  
Republic Of China ◽  
Slip Dislocation ◽  
Focal Parameters ◽  
Reservoir Earthquake ◽  
Earthquake Area ◽  
Upper Boundary

abstract In this paper, the “random test-motion adjustment” method was used for the adjustment of the triangulation net of the Xinfengjiang Reservoir earthquake area, China, and for the inversion of the focal parameters of the earthquake of magnitude 5.3. Retriangulation and leveling data of the earthquake area were thus processed. The estimated focal parameters of the earthquake are: strike, NE 62°; dip, SE at 59°; length of the fault, 4.7 km; depth of the upper boundary, 0.45 km; depth of the lower boundary, 4.5 km; dip-slip dislocation, 73.4 mm; strike-slip dislocation, 25.5 mm; seismic moment, Mo, 2.2 × 1024 dyne-cm; stress drop (Δσ), 12 bars; and the lower limit of the strain energy released (E) 1.2 × 1019 ergs. It was predominantly a normal fault. This paper concludes that the regional stress field provided the main force of the shock, whereas the stress field due to hydraulic pressure contributed the inducing force.

scholarly journals ON DIVERSITY OF CONFIGURATIONS GENERATED BY EXCITABLE CELLULAR AUTOMATA WITH DYNAMICAL EXCITATION INTERVALS

2012 ◽  
Vol 23 (12) ◽  
pp. 1250085 ◽  
Author(s):  
ANDREW ADAMATZKY
Keyword(s):  
Cellular Automata ◽  
Lower Boundary ◽  
Morphological Diversity ◽  
Excitable Media ◽  
Stationary Waves ◽  
Future Studies ◽  
Time Dynamics ◽  
Wide Range ◽  
Localized Excitations ◽  
Upper Boundary

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

scholarly journals A 3-D RBF-FD solver for modeling the atmospheric global electric circuit with topography (GEC-RBFFD v1.0)

2015 ◽  
Vol 8 (10) ◽  
pp. 3007-3020 ◽  
Author(s):  
V. Bayona ◽  
N. Flyer ◽  
G. M. Lucas ◽  
A. J. G. Baumgaertner
Keyword(s):  
Numerical Model ◽  
Differential Operators ◽  
Lower Boundary ◽  
Elliptic Partial Differential Equation ◽  
Electric Circuit ◽  
Global Electric Circuit ◽  
Mesh Free ◽  
Conductivity Profile ◽  
The Right ◽  
Upper Boundary

Abstract. A numerical model based on radial basis function-generated finite differences (RBF-FD) is developed for simulating the global electric circuit (GEC) within the Earth's atmosphere, represented by a 3-D variable coefficient linear elliptic partial differential equation (PDE) in a spherically shaped volume with the lower boundary being the Earth's topography and the upper boundary a sphere at 60 km. To our knowledge, this is (1) the first numerical model of the GEC to combine the Earth's topography with directly approximating the differential operators in 3-D space and, related to this, (2) the first RBF-FD method to use irregular 3-D stencils for discretization to handle the topography. It benefits from the mesh-free nature of RBF-FD, which is especially suitable for modeling high-dimensional problems with irregular boundaries. The RBF-FD elliptic solver proposed here makes no limiting assumptions on the spatial variability of the coefficients in the PDE (i.e., the conductivity profile), the right hand side forcing term of the PDE (i.e., distribution of current sources) or the geometry of the lower boundary.

scholarly journals Theoretical Gravity Anomalies of Glaciers Having Parabolic Cross-Sections

1964 ◽  
Vol 5 (38) ◽  
pp. 255-257 ◽  
Author(s):  
Charles E. Corbató
Keyword(s):  
Cross Sections ◽  
Lower Boundary ◽  
Gravity Anomalies ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Axis Of Symmetry ◽  
Upper Boundary

AbstractEquations and a graph are presented for calculating gravity anomalies on a two-dimensional glacier model having a horizontal upper boundary and a lower boundary which is a parabola with a vertical axis of symmetry.

scholarly journals Transnasal Humidified Rapid Insufflation Ventilatory Exchange With Nasopharyngeal Airway Facilitates Apneic Oxygenation: A Randomized Clinical Noninferiority Trial

2020 ◽  
Vol 7 ◽  
Author(s):  
Lingke Chen ◽  
Liu Yang ◽  
Weitian Tian ◽  
Xiao Zhang ◽  
Yanhua Zhao ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Lower Boundary ◽  
Clinical Trial Registration ◽  
Apneic Oxygenation ◽  
Nasopharyngeal Airway ◽  
Airway Opening ◽  
The Difference ◽  
To Receive ◽  
Noninferiority Margin ◽  
Upper Boundary

Background: Transnasal humidified rapid insufflation ventilatory exchange (THRIVE) was used to extend the safe apnea time. However, THRIVE is only effective in patients with airway opening. Nasopharyngeal airway (NPA) is a simple device that can help to keep airway opening. This study aimed to investigate the noninferiority of NPA to jaw thrust for airway opening during anesthesia-induced apnea.Methods: This was a prospective randomized single-blinded noninferiority clinical trial on the use of THRIVE in patients with anesthesia-induced apnea. The participants were randomly allocated to receive NPA or jaw thrust. The primary outcomes were PaO2 and PaCO2 at 20 min after apnea, with noninferiority margin criteria of −6.67 and 0.67 kPa, respectively.Results: A total of 123 patients completed the trial: 61 in the NPA group and 62 in the jaw thrust group. PaO2 at 20 min after apnea was 42.9 ± 14.0 kPa in the NPA group and 42.7 ± 13.6 kPa in the jaw thrust group. The difference between these two means was 0.25 kPa (95% CI, −3.87 to 4.37 kPa). Since the lower boundary of the 95% CI was > −6.67 kPa, noninferiority was established because higher PO2 is better. PaCO2 at 20 min after apnea was 10.74 ± 1.09 kPa in the NPA group and 10.54 ± 1.18 kPa in the jaw thrust group. The difference between the two means was 0.19 kPa (95% CI, −0.14 to 0.53 kPa). Since the upper boundary of the 95% CI was <0.67 kPa, noninferiority was established because lower PCO2 is better. No patient had a SpO2 < 90% during apnea.Conclusion: When THRIVE was applied during anesthesia-induced apnea, NPA placement kept airway opening and was noninferior to jaw thrust in terms of its effects on PaO2 and PaCO2 at 20 min after apnea.Clinical Trial Registration:ClinicalTrials.gov (NCT03741998).

The effects of thermal conditions on the cell sizes of two-dimensional convection

1994 ◽  
Vol 281 ◽  
pp. 33-50 ◽  
Author(s):  
Masaki Ishiwatari ◽  
Shin-Ichi Takehiro ◽  
Yoshi-Yuki Hayashi
Keyword(s):  
Heat Flux ◽  
Lower Boundary ◽  
Thermal Conditions ◽  
Heat Fluxes ◽  
Internal Cooling ◽  
Two Dimensional ◽  
Numerical Integrations ◽  
The Difference ◽  
Convective Cells ◽  
Upper Boundary

The effects of thermal conditions on the patterns of two-dimensional Boussinesq convection are studied by numerical integration. The adopted thermal conditions are (i) the heat fluxes through both upper and lower boundaries are fixed, (ii) the same as (i) but with internal cooling, (iii) the temperature on the lower boundary and the heat flux through the upper boundary are fixed, (iv) the same as (iii) but with internal cooling, and (v) the temperatures on both upper and lower boundaries are fixed. The numerical integrations are performed with Ra = 104 and Pr = 1 over the region whose horizontal and vertical lengths are 8 and 1, respectively.The results confirm that convective cells with the larger horizontal sizes tend to form under the conditions where the temperature is not fixed on any boundaries. Regardless of the existence of internal cooling, one pair of cells spreading all over the region forms in the equilibrium states. On the other hand, three pairs of cells form and remain when the temperature on at least one boundary is fixed. The formation of single pairs of cells appearing under the fixed heat flux conditions shows different features with and without internal cooling. The difference emerges as the appearance of a phase change, whose existence can be suggested by the weak nonlinear equation derived by Chapman & Proctor (1980).

The hydraulics problem in slope stability analysis

1991 ◽  
Vol 28 (6) ◽  
pp. 903-909 ◽  
Author(s):  
Étienne J. Windisch
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Key Words ◽  
Normal Stress ◽  
Soil Mechanics ◽  
Lower Boundary ◽  
Slope Stability Analysis ◽  
Hydraulic Pressure ◽  
Effective Normal Stress ◽  
Hydraulic Force

Hydraulic pressures and forces are obtained on a typical slice, as used in current methods of slope stability analysis, under hydrostatic and flowing groundwater conditions. It is shown that current methods do not satisfy some basic hydraulics and soil mechanics principles. The effective normal stress on the lower boundary of a slice is shown to be underestimated, and the resultant hydraulic force is not accounted for adequately. Key words: effective stress, hydraulic pressure, hydraulic gradient, hydraulic force, slope stability.

The effect of viscous dissipation on the onset of convection in an inclined porous layer

2011 ◽  
Vol 679 ◽  
pp. 544-558 ◽  
Author(s):  
D. A. NIELD ◽  
A. BARLETTA ◽  
M. CELLI
Keyword(s):  
Viscous Dissipation ◽  
Lower Boundary ◽  
Boussinesq Approximation ◽  
Darcy Law ◽  
Convection Flow ◽  
Free Convection Flow ◽  
Onset Of Convection ◽  
Temperature Distributions ◽  
Residual Solution ◽  
Upper Boundary

The linear stability of a basic forced and free convection flow in an inclined porous channel is analysed by using the Darcy law and the Oberbeck–Boussinesq approximation. The basic velocity and temperature distributions are influenced by the effect of viscous dissipation, as well as by the boundary conditions. The boundary planes are assumed to be impermeable and isothermal, with a temperature of the lower boundary higher than that of the upper boundary. The instability against longitudinal rolls is studied by employing a second-order weighted residual solution and an accurate sixth-order Runge–Kutta solution of the disturbance equations. The instability against transverse rolls is also investigated. It is shown that these disturbances are in every case less unstable than the longitudinal rolls.

THE OTWAY BASIN: EARLY CRETACEOUS RIFTING TO NEOGENE INVERSION

1995 ◽  
Vol 35 (1) ◽  
pp. 494 ◽  
Author(s):  
A.J. Buffin ◽  
A.J. Sutherland ◽  
J.A. Gorski
Keyword(s):  
Stress Field ◽  
Normal Fault ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
Natural Fracture ◽  
Water Flooding ◽  
Hydraulic Fractures ◽  
Vertical Wells ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress

Borehole breakouts and hydraulic fractures in­ferred from dipmeter and formation microscanner logs indicate that the minimum horizontal stress (σh) is oriented 035°N in the South Australian sector of the Otway Basin. Density and sonic check-shot log data indicate that vertical stress (σv) increases from approximately 20 MPa at a depth of one km to 44 MPa at two km and 68 MPa at three km. Assum­ing a normal fault condition (i.e. σy > σH > σh), the magnitude of σh is 75 per cent of the magnitude of the maximum horizontal stress (σH), and the magni­tude of σH is close to that of av. Sonic velocity compaction trends for shales suggest that pore pressure is generally near hydrostatic in the Otway Basin.Knowledge of the contemporary stress field has a number of implications for hydrocarbon produc­tion and exploration in the basin. Wellbore quality in vertical wells may be improved (breakouts sup­pressed) by increasing the mud weight to a level below that which induces hydraulic fracture, or other drilling problems related to excessive mud weight. Horizontal wells drilled in the σh direction (035°N/215°N) should be more stable than those drilled in the σH direction, and indeed than vertical wells. In any EOR operations where water flooding promotes hydraulic fracturing, injectors should be aligned in the aH (125°N/305°N) direction, and off­set from producers in the orthogonal σh direction. Any deviated/horizontal wells targeting the frac­tured basement play should be oriented in the σh (035°N/215°N) direction to maximise intersection with this open, natural fracture trend. Hydrocar­bon recovery in wells deviated towards 035°N/215°N may also be enhanced by inducing multiple hydrau­lic fractures along the wellbore.Considering exploration-related issues, faults following the dominant structural trend, sub-paral­lel to σH orientation, are the most prone to be non-sealing during any episodic build-up of pore pres­sure. Pre-existing vertical faults striking 080-095°N and 155-170°N are the most prone to at least a component of strike-slip reactivation within the contemporary stress field.

On: “Magnetic anomalies of two‐dimensional bodies in a magnetic half‐space” by E. E. S. Sampaio (GEOPHYSICS, v. 47, p. 1229–1234, August, 1982).

Geophysics ◽  
1984 ◽  
Vol 49 (10) ◽  
pp. 1800-1800
Author(s):  
L. Eskola
Keyword(s):  
Magnetic Field ◽  
Half Space ◽  
Analytic Solution ◽  
Lower Boundary ◽  
Magnetic Anomalies ◽  
Additional Source ◽  
Field Problem ◽  
Susceptibility Contrast ◽  
The Magnetic Field ◽  
Upper Boundary

In a recent paper Sampaio presented an analytic solution of the magnetic field problem for a circular magnetized cylinder embedded in a homogeneous magnetized half‐space. In his paper, Sampaio also stated that the numerical method for solving magnetostatic problems by Eskola and Tervo (1980) doesn’t take into consideration the susceptibility contrast between the half‐space and the air. The model treated by Sampaio doesn’t actually exist, however. For a magnetized environment, in addition to the upper boundary, there is also a lower boundary, i.e., where the rock loses its magnetization (at least at the Curie point). This boundary holds an additional source of magnetic field that is of the same order of strength as the field caused by the upper boundary, if the horizontal dimensions of the magnetized environment are large. If the horizontal dimensions are not large, the effect of the vertical boundaries of the environment must also be taken into consideration. Eskola and Tervo (1980) find no difficulty in taking into consideration all the boundaries by means of their method.

Characteristics of Seismicity in the Eagle Ford Shale Play, Southern Texas, Constrained by Earthquake Relocation and Centroid Moment Tensor Inversion

2021 ◽  
Author(s):  
Peng Li ◽  
Guo-Chin D. Huang ◽  
Alexandros Savvaidis ◽  
Florentia Kavoura ◽  
Robert W. Porritt
Keyword(s):  
Stress Field ◽  
Energy Release ◽  
Fault Plane ◽  
Anthropogenic Activities ◽  
Moment Tensor ◽  
Normal Fault ◽  
Strike Slip ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Earthquake Energy

Abstract Analysis of earthquake locations and centroid moment tensors (CMTs) is critical in assessing seismogenic structures and connecting earthquakes to anthropogenic activities. The objective of this study was to gain insights into the seismotectonics of the Eagle Ford Shale play (EF), southern Texas, through relative relocation of earthquakes, assessment of CMT solutions, and investigation of the background stress field. Using Texas Seismological Network (TexNet) data from 2017 through 2019, we were able to relocate 326 earthquakes and obtain CMT solutions for 37 ML≥2.0 earthquakes. These earthquakes are located in the sedimentary basin and uppermost crust, with depths ranging from 2 to 10 km. The earthquake groups in the northeastern EF are linearly distributed along the Karnes fault zone, whereas the southern and western groups are spatially scattered around mapped or unmapped faults. CMT solutions identified 32 normal fault earthquakes and five strike-slip earthquakes. The orientation of the fault plane of most normal fault earthquakes is southwest–northeast, whereas the possible fault plane of the strike-slip fault is from north-northwest to south-southeast, which is roughly perpendicular to the normal faults. Normal and strike-slip faults in the EF are of high dip angles, with the dip angles of the most faults ranging from 60° to 80°. Stress inversion results show that the major orientation of maximum horizontal stress (SHmax) is southwest–northeast, with minor local stress-field rotations. We further estimated earthquake energy release in the EF region using moment magnitude from the CMT solutions, and the cumulative earthquake energy release curve reveals three notable increases in cumulative seismic moment, which occurred in January–July 2018 and January–March 2019, and May–August 2019. Whether these energy releases were caused by anthropogenic activities is a matter for further investigation.

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