Seismic strain rate and deep slab deformation in Tonga

1991 ◽  
Vol 96 (B9) ◽  
pp. 14429-14444 ◽  
Author(s):  
Karen M. Fischer ◽  
Thomas H. Jordan
Keyword(s):  
Strain Rate ◽  
Seismic Strain Rate ◽  
Seismic Strain

Experimental Study on Dynamic Mechanical Properties of Galvanized Iron Wire under Seismic Strain Rate

2014 ◽  
Vol 580-583 ◽  
pp. 1435-1438
Author(s):  
Hao Zhang ◽  
Jia He Zhang ◽  
De Bin Wang ◽  
Xu Li
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Mechanical Properties ◽  
Constitutive Relationship ◽  
Iron Wire ◽  
Seismic Strain Rate ◽  
Seismic Strain ◽  
Hydraulic Servo ◽  
Dynamic Tensile Test ◽  
Relationship Of

This paper focuses on the mechanical properties of galvanized iron wire under various conditions of earthquake-type strain rate. The dynamic tensile test of galvanized iron wire was conducted on MTS New 810 electro-hydraulic servo-controlled testing system. The dynamic tensile constitutive relationship of galvanized iron wire was proposed under seismic strain rate. The accuracy of the proposed constitutive relationship of galvanized iron wire was verified by comparing with reinforcing steel.

Regional bias in estimates of earthquake MS due to surface-wave path effects

1994 ◽  
Vol 84 (2) ◽  
pp. 377-382
Author(s):  
Rachel E. Abercrombie
Keyword(s):  
Surface Wave ◽  
Tectonic Setting ◽  
High Surface ◽  
Earthquake Source ◽  
Plate Boundaries ◽  
Source Type ◽  
Shallow Earthquakes ◽  
Seismic Strain Rate ◽  
Seismic Strain ◽  
Wave Path

Abstract Continental earthquakes have long been known to have anomalously high surface-wave magnitudes relative to their seismic moments. A recent global study of shallow earthquakes by Ekström and Dziewonski (1988) confirmed this and found other regional, systematic anomalies in the MS-M0 relationship. It is important to determine the source of these anomalies in order to understand the controls on earthquake-source radiation and to obtain accurate estimates of historical seismic strain rates. In this study the magnitudes of 82 earthquakes from eight different tectonic regions are recalculated using a simple surface-wave path correction to determine whether path effects are responsible for the observed anomalies. The magnitudes of continental earthquakes are reduced by an average of 0.2 magnitude units, an improvement in fit to the global average significant at the 98% level. Surface-wave path effects are clearly responsible for the high MS observed in continental areas. There is a small decrease in scatter in the other areas, but lateral refraction of the surface waves at plate boundaries prevents the simple correction from having a significant effect. There is no evidence in the observed anomalies, however, for any dependence of earthquake-source type on tectonic setting. It is clear that to obtain reliable, unbiased estimates of regional seismic strain rate and hazard, a local moment-magnitude relationship should be preferred to a global one.

scholarly journals SEISMIC STRAIN MAP IN MALAYSIA DERIVED FROM LONG-TERM GLOBAL POSITIONING SYSTEM DATA

2019 ◽  
Vol XLII-4/W16 ◽  
pp. 399-408
Author(s):  
M. S. Mohamad ◽  
W. A. W. Aris ◽  
N. J. Jaffar ◽  
R. Othman
Keyword(s):  
Strain Rate ◽  
Global Positioning System ◽  
Crustal Deformation ◽  
Peninsular Malaysia ◽  
Positioning System ◽  
North Borneo ◽  
Global Positioning ◽  
The Status ◽  
Seismic Strain

Abstract. Series of major earthquakes struck the Sundaland plate as a result of convergence with neighboring plates such as Indian, Australian and Philippine plates. Since then, the Sundaland is experiencing significant crustal deformation that implicate reactivation of local fault and embark question on the status of geohazard and seismic risk. In Malaysia, crustal deformation study by using Global Positioning System (GPS) has been conducted for many years. However, the information of crustal deformation was reported separately and difficult to be archived. In addition, continuous estimation of crustal deformation derived from GPS has to be carried out in order to provide present day seismic status. This study aims at generating a seismic catalog map in Malaysia derived from approximately nine (9) years of GPS data. In this study, derived long-term crustal deformation in the form of coordinate time series (CTS) were converted into yearly strain map. The changes of strain with respect to location of old and active fault line in Malaysia were properly analysed. From the result, the highest changes of strain rate for Peninsular Malaysia happened in 2004 until 2005 and 2012 until 2013 prior to 2004 Acheh earthquake event with the moment magnitude (Mw) and 2012 two strike-slip events in Northern Sumatera with the magnitude of 8.2Mw and 8.6Mw. In North Borneo region, the most significant changes of strain rate happened from 2007 to 2009 and 2011 to 2013. It can be expected that the results will be beneficial in augmenting geohazard mitigation in Malaysia.

Seismotectonic Analysis of the 2017 Moiyabana Earthquake (MW 6.5; Botswana), Insights from field investigations, aftershock and InSAR studies 

2021 ◽  
Author(s):  
Thifhelimbilu Mulabisana ◽  
Mustapha Meghraoui ◽  
Vunganai Midzi ◽  
Mohamed Saleh ◽  
Onkgopotse Ntibinyane ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Aftershock Sequence ◽  
Earthquake Rupture ◽  
Normal Faulting ◽  
Coseismic Slip ◽  
African Plate ◽  
Focal Mechanism Solutions ◽  
Seismic Strain Rate ◽  
Seismic Strain ◽  
Largest Aftershock

<p>The 3 April 2017 M<sub>W</sub> 6.5, Moiyabana (Botswana) earthquake occurred in the continental interior of the African plate and in a seismogenic region previously considered as stable. We analyse the mainshock and aftershock sequence based on a local seismic network and local seismotectonic characteristics. The earthquake rupture geometry is constrained with more than 1,000 aftershocks recorded over a period of three months and from the InSAR analysis of Sentinel-1 images (ascending orbit). The mainshock (25.134 E, 22.565 S; depth 22 ± 3 km) was followed by more than 500 events of magnitude M ≥ 0.8 recorded in April 2017 including the largest aftershock (M<sub>W</sub> 4.6 on the 5 April 2017). Focal mechanism solutions of the mainshock and aftershocks display predominance of NW-SE trending and NE dipping normal faulting. Stress inversion of focal mechanisms obtained from the mainshock and aftershock database are compatible with a NE-SW extension under normal faulting regime. The InSAR study shows fringes with two lobes with 4 to 6 cm coseismic slip on a NW-SE elongated and 30-km-long surface deformation consistent with the mainshock location and normal faulting mechanism. The modelling of surface deformation provides the earthquake rupture dimension at depth with ~ 1 m maximum slip on a fault plane striking 315°, dipping 45°, -80° rake and with M<sub>o</sub> 7.12 10<sup>18</sup> Nm Although the seismic strain rate is of low level, the occurrence of the 2017 Moiyabana earthquake, followed by an aftershock sequence in the central Limpopo belt classifies the intraplate region as an active plate interior. </p>

Study on Strain Rate Effect on Dynamic Strain Aging and Safety Margin of Pipe Elbow at Seismic Event

2009 ◽  
Author(s):  
Hiro Kobayashi ◽  
Yoshio Urabe
Keyword(s):  
Elevated Temperature ◽  
Strain Rate ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Carbon Steels ◽  
Task Group ◽  
Dynamic Strain ◽  
Team Working ◽  
Stress Levels ◽  
Seismic Strain

This paper presents the technical reasoning and justification for using the B2′ = (2/3)*B2 in Paragraphs NB-3656(b) and NC/ND-3655(b) of Section III. ASME revised the rules for piping subjected to seismic and other building filtered loads in the 1994 addenda to the 1992 Code to provide an alternative to the existing rules. The purpose of the revision was to recognize the results of significant testing and experience that supported a decrease in the multiplier (B index) of the moment term, among other changes. The use of a B2′ index set equal to 2/3 of the current B2 index effectively raised the Level D allowable 50%. As part of its review in 10CFR50.55a, the NRC noted that use of the new rules was not permitted, due to disagreements in the approach. Since the 1994 addenda were published, the NRC and ASME have worked together to revise the changes. At this time, it is ASME’s understanding that the rules proposed for inclusion in the 2007 Code will be accepted by the NRC, with the exception of the use of a B2′ index equal to 2/3 of B2 for bends and tees. For those items, the NRC believes a multiplier of 3/4 is more appropriate for ferritic steels at temperatures above 300°F, due to dynamic strain aging. Concern has been expressed that since the tests that form part of the basis for setting B2′ = (2/3)*B2 were conducted at ambient temperature, the effect of dynamic strain aging of carbon steels could reduce the seismic margins at temperatures in excess of 300°F (150°C). In response to this concern, the authors prepared this paper as a team working under the Piping Seismic Task Group, ASME Code Committee. This paper demonstrates that: 1) In order to investigate this possibility, authors collected test data at room temperature, and then benchmarked its analytical work against both its tests and data from the EPRI test program since dynamic testing of components at elevated temperature and high stress levels can be quite difficult. From its analytical and test work on components, plus elevated temperature and strain rate work on small specimens, it was concluded that strain rate effects at typical seismic strain rates and amplitudes are not a concern. 2) For typical carbon steel under seismic strain rate loading, at elevated temperature [(above 300°F (150°C)] and at stress levels permitted by the alternative Code equation [NB-3556(b)(2) and NB-3556(b)(3)], the margin to failure is at least 1.5, as recommended by Dr. R.P. Kennedy(1). Thus, the use of B2′ = (2/3)*B2 results in a component with acceptable margin. This is a part of the paper prepared as a team working under the Piping Seismic Task Group under ASME Sec. III, Subgroup Design.

scholarly journals Spatial distribution of horizontal seismic strain in the Apennines from historical earthquakes

1998 ◽  
Vol 41 (2) ◽  
Author(s):  
G. Selvaggi
Keyword(s):  
Seismic Moment ◽  
Recent Literature ◽  
Moment Tensor ◽  
Historical Earthquakes ◽  
Time Interval ◽  
Seismic Moment Tensor ◽  
Southern Apennines ◽  
Seismic Strain Rate ◽  
Seismic Strain ◽  
Main Deformation

Horizontal principal seismic strain rate axes have been calculated within a regular mesh of triangles covering the Italian peninsula in a time interval of 700 years. I have used both the method of Kostrov (1974), that requires knowledge of the seismic moment tensor of earthquakes, and the modified version provided by England and Molnar (1997) that makes use of length and kinematics of the activated faults. Seismic moment tensor of historical earthquakes can be inferred from recent literature, while length of faults has been obtained from the observation that strain drop is almost constant for large Apenninic earthquakes. Spatial strain distribution from historical earthquakes shows that the Apennines can be divided into three homogeneous structural arcs (Northern Apenninic, Southern Apenninic and Calabrian arcs) within which strain is roughly constant. Although NE-SW extension is the main deformation process along the two Apenninic arcs it involves a velocity more than five times greater in the Southern Apennines. Along the Calabrian arc, I tested the effect on the strain field of the contemporaneous ~WNW-ESE and ~NNE-SSW extension due to the longitudinal dilatation of the arc during its still ESE migration.

Dislocation Substructures Produced During Tensile, Creep, and Fatigue Deformation of Ti3Al at 700°C

1977 ◽  
Vol 35 ◽  
pp. 272-273
Author(s):  
S. M. L. Sastry
Keyword(s):  
Intermetallic Compound ◽  
Strain Rate ◽  
Tensile Creep ◽  
Slip Systems ◽  
Slip Vector ◽  
Superlattice Structure ◽  
Slip Activity ◽  
Dislocation Arrangement ◽  
Ordered Intermetallic ◽  
Tangled Dislocation

Ti3Al is an ordered intermetallic compound having the DO19-type superlattice structure. The compound exhibits very limited ductility in tension below 700°C because of a pronounced planarity of slip and the absence of a sufficient number of independent slip systems. Significant differences in slip behavior in the compound as a result of differences in strain rate and mode of deformation are reported here.Figure 1 is a comparison of dislocation substructures in polycrystalline Ti3Al specimens deformed in tension, creep, and fatigue. Slip activity on both the basal and prism planes is observed for each mode of deformation. The dominant slip vector in unidirectional deformation is the a-type (b) = <1120>) (Fig. la). The dislocations are straight, occur for the most part in a screw orientation, and are arranged in planar bands. In contrast, the dislocation distribution in specimens crept at 700°C (Fig. lb) is characterized by a much reduced planarity of slip, a tangled dislocation arrangement instead of planar bands, and an increased incidence of nonbasal slip vectors.

Quantitative analysis of in situ straining experiments in the case of strong frictional forces

1978 ◽  
Vol 36 (1) ◽  
pp. 570-571
Author(s):  
F. Louchet ◽  
L.P. Kubin
Keyword(s):  
Strain Rate ◽  
Radiation Effects ◽  
Dislocation Line ◽  
Critical Length ◽  
Local Strain ◽  
Local Flow ◽  
Double Kink ◽  
Dislocation Densities ◽  
Frictional Forces ◽  
Local Strain Rate

Investigation of frictional forces -Experimental techniques and working conditions in the high voltage electron microscope have already been described (1). Care has been taken in order to minimize both surface and radiation effects under deformation conditions.Dislocation densities and velocities are measured on the records of the deformation. It can be noticed that mobile dislocation densities can be far below the total dislocation density in the operative system. The local strain-rate can be deduced from these measurements. The local flow stresses are deduced from the curvature radii of the dislocations when the local strain-rate reaches the values of ∿ 10-4 s-1.For a straight screw segment of length L moving by double-kink nucleation between two pinning points, the velocity is :where ΔG(τ) is the activation energy and lc the critical length for double-kink nucleation. The term L/lc takes into account the number of simultaneous attempts for double-kink nucleation on the dislocation line.

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