Source parameters of the Ensenada Bay earthquake swarm, Baja California, Mexico

1985 ◽  
Vol 22 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Cecilio J. Rebollar
Keyword(s):  
Seismic Data ◽  
Strain Energy ◽  
High Strain ◽  
Source Parameters ◽  
Earthquake Swarm ◽  
Ground Displacement ◽  
Source Dimensions ◽  
Fault Type ◽  
Stress Drops ◽  
High Strain Energy

Seismic data collected from the Ensenada Bay earthquake swarm of late 1981 were used to calculate the spectra of ground displacement. Data from the stations of Ensenada (ENX) and Cerro Bola (CBX), at epicentral distances of 14 and 57 km, respectively, were used to evaluate source parameters. The focal depths determined for these events were less than 10 km. The focal mechanism was a strike-slip fault type, with the plane of motion striking N52°W, parallel to the Agua Blanca Fault. Seismic moments ranging from 3.44 × 1019 to 5.99 × 1020 dyn∙cm (3.44 × 1014 to 5.99 × 1015 N∙cm) were estimated for events with local magnitudes in the range 1.7–2.3. The source dimensions were found to be 186 ± 36 m and the stress drops between 3 and 66 bar (0.3 and 6.6 MPa), comparable to results obtained in previous studies of shallow events (depths <10 km). The Ensenada swarm could be attributed to a localized zone of high-strain energy at the intersection of two faults. Ratios of P to S corner frequencies were evident for only five events; they were 1.39 ± 0.38. Magnitude and seismic moment from other studies were compared with the Ensenada data in the range of magnitudes 0–3. All the data can be accommodated by log M0 = 1.5 ML + (16.9 ± 1.1). The Ensenada earthquake swarm and the Victoria earthquake swarm, which occurred in the Mexicali valley in 1978, have similar source radii and corner frequencies for the same range of seismic moments.

Source parameters and scaling relationships of small earthquakes in the northeastern Caribbean

1981 ◽  
Vol 71 (4) ◽  
pp. 1173-1190
Author(s):  
Arthur Frankel
Keyword(s):  
Seismic Moment ◽  
Dynamic Stress ◽  
Source Parameters ◽  
Earthquake Swarm ◽  
Fold Increase ◽  
Virgin Islands ◽  
Scaling Relationships ◽  
Short Period ◽  
Relative Stress ◽  
Stress Drops

abstract The seismic moments and stress drops of 23 earthquakes (1.1 ≦ M ≦ 2.4) that occurred during an earthquake swarm in the Virgin Islands were determined from the analysis of their P waveforms. The data consist of digitally recorded seismograms collected by a short-period seismic network operating in the northeastern Caribbean. The events of the swarm are particularly useful for comparing the relative stress drops of small earthquakes, because their source to receiver paths and focal mechanisms are very similar. The static stress drops calculated for these earthquakes varied from about 0.2 to 2 bars. The data clearly illustrate that the static and dynamic stress drops of these earthquakes generally increased with the size (moment) of the events. The fault radii for these shocks increased with seismic moment, but only by a factor of 2 for a 100-fold increase in seismic moment. The velocity waveforms of the larger events were systematically more impulsive than those of the smaller earthquakes. These observations imply that, for this set of earthquakes, the final fault radius is a function of the stress drop that occurs during the rupture process.

Azetidinium-based Hypergolic Ionic Liquids with High Strain Energy

2018 ◽  
Vol 3 (1) ◽  
pp. 284-288
Author(s):  
Bingxiao Zheng ◽  
Yanqiang Zhang ◽  
Zejun Zhang ◽  
Long Liu ◽  
Shengli Chen ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Strain Energy ◽  
High Strain ◽  
High Strain Energy

Focal depths and source parameters of the Rocky Mountain House earthquake swarm from digital data at Edmonton

1984 ◽  
Vol 21 (10) ◽  
pp. 1105-1113 ◽  
Author(s):  
C. J. Rebollar ◽  
E. R. Kanasewich ◽  
E. Nyland
Keyword(s):  
Epicentral Distance ◽  
Source Parameters ◽  
Earthquake Swarm ◽  
Focal Depth ◽  
Rocky Mountain ◽  
Small Variation ◽  
B Value ◽  
Digital Data ◽  
The Difference ◽  
Stress Drops

Seismic records at Edmonton (EDM) and Suffield (SES) between January 1976 and February 1980 show 220 events with magnitudes less than 4 originating near Rocky Mountain House. Many of these events show well defined Sn, Sg, and Pg phases and a small variation in the difference of Sg − Sn and Sg − Pg. Analysis of the theoretical travel times using a structure determined for central Alberta yields an average focal depth of 20 ± 5 km and an average epicentral distance of 175 ± 5 km southwest of Edmonton for 40 of these events. Because Sn was not clear on the remainder, it was not possible to get focal depths for all the events.Seismic moments of 80 events with local magnitudes from 1.6 to 3.5 were found to be in the range of 6.6 ± 2 × 1018 to 7.9 ± 2 × 1020 dyn∙cm (6.6 ± 2 × 1013 to 7.9 ± 2 × 1015 N∙cm). A relationship between local magnitude and seismic moment was log (M0) = 1.3ML + 16.6. This is similar to that determined for California. Source radii, where they could be determined, were 500 ± 50 m and stress drops were 0.75 ± 0.75 bar (75 ± 75 kPa).The energy release of 263 events recorded at EDM from the Rocky Mountain House area was 5.6 × 1017 erg (5.6 × 1010 J). The b value for this earthquake swarm was 0.8, similar to that observed in other parts of western Canada.The depths of focus, the low stress drops, and the statistical similarity to other natural earthquake sequences suggest that at least part of the swarm is of a natural origin.

Spiro fused β-lactam cyclopropenes

1992 ◽  
Vol 70 (12) ◽  
pp. 2967-2971 ◽  
Author(s):  
Michel Zoghbi ◽  
John Warkentin
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Strain Energy ◽  
High Strain ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray Diffraction ◽  
Cyclopropene Ring ◽  
X Ray ◽  
Lactam Ring ◽  
High Strain Energy

Δ3-1,3,4-Oxadiazolines (1) that share their C2 with C4 of a β-lactam ring in a spiro fusion were prepared. The structures were established through single crystal X-ray diffraction of 1a and by infrared, 1H, and 13C nuclear magnetic resonance spectroscopies. Thermolysis of 1 at 100 °C, in benzene containing dimethyl acetylenedicarboxylate, afforded spiro-fused β-lactam cyclopropene 12 in 33% yield. Similar thermolysis of 1b in the presence of ethyl phenylpropiolate gave spiro-fused β-lactam cyclopropene 13 (32%). The molecular structure of 12, determined by single crystal X-ray diffraction, has the two ester carbonyl carbons out of the plane of the cyclopropene ring by about 0.17 Ǻ, indicating substantial nonbonded steric interactions and suggesting unusually high strain energy. At 154.5 °C, 12 underwent isomerization to 19, presumably through a vinyl carbene intermediate.

Localized Damage in Vertebral Bone Is Most Detrimental in Regions of High Strain Energy Density

1999 ◽  
Vol 121 (6) ◽  
pp. 622-628 ◽  
Author(s):  
D. L. Kopperdahl ◽  
A. D. Roberts ◽  
T. M. Keaveny
Keyword(s):  
Finite Element ◽  
Energy Density ◽  
Apparent Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
High Strain ◽  
Stiffness Reduction ◽  
Anatomic Location ◽  
High Strain Energy ◽  
Localized Damage

It was hypothesized that damage to bone tissue would be most detrimental to the structural integrity of the vertebral body if it occurred in regions with high strain energy density, and not necessarily in regions of high or low trabecular bone apparent density, or in a particular anatomic location. The reduction in stiffness due to localized damage was computed in 16 finite element models of 10-mm-thick human vertebral sections. Statistical analyses were performed to determine which characteristic at the damage location — strain energy density, apparent density, or anatomic location — best predicted the corresponding stiffness reduction. There was a strong positive correlation between regional strain energy density and structural stiffness reduction in all 16 vertebral sections for damage in the trabecular centrum (p < 0.05, r2 = 0.43–0.93). By contrast, regional apparent density showed a significant negative correlation to stiffness reduction in only four of the sixteen bones (p < 0.05, r2 = 0.47 – 0.58). While damage in different anatomic locations did lead to different reductions in stiffness (p < 0.0001, ANOVA), no single location was consistently the most critical location for damage. Thus, knowledge of the characteristics of bone that determine strain energy density distributions can provide an understanding of how damage reduces whole bone mechanical properties. A patient-specific finite element model displaying a map of strain energy density can help optimize surgical planning and reinforcement of bone in individuals with high fracture risk.

scholarly journals Specialization of tendon mechanical properties results from interfascicular differences

2012 ◽  
Vol 9 (76) ◽  
pp. 3108-3117 ◽  
Author(s):  
Chavaunne T. Thorpe ◽  
Chineye P. Udeze ◽  
Helen L. Birch ◽  
Peter D. Clegg ◽  
Hazel R. C. Screen
Keyword(s):  
Mechanical Properties ◽  
Strain Energy ◽  
High Strain ◽  
Failure Strain ◽  
Extensor Tendon ◽  
Superficial Digital Flexor Tendon ◽  
Matrix Organization ◽  
The Common ◽  
High Strain Energy

Tendons transfer force from muscle to bone. Specific tendons, including the equine superficial digital flexor tendon (SDFT), also store and return energy. For efficient function, energy-storing tendons need to be more extensible than positional tendons such as the common digital extensor tendon (CDET), and when tested in vitro have a lower modulus and failure stress, but a higher failure strain. It is not known how differences in matrix organization contribute to distinct mechanical properties in functionally different tendons. We investigated the properties of whole tendons, tendon fascicles and the fascicular interface in the high-strain energy-storing SDFT and low-strain positional CDET. Fascicles failed at lower stresses and strains than tendons. The SDFT was more extensible than the CDET, but SDFT fascicles failed at lower strains than CDET fascicles, resulting in large differences between tendon and fascicle failure strain in the SDFT. At physiological loads, the stiffness at the fascicular interface was lower in the SDFT samples, enabling a greater fascicle sliding that could account for differences in tendon and fascicle failure strain. Sliding between fascicles prior to fascicle extension in the SDFT may allow the large extensions required in energy-storing tendons while protecting fascicles from damage.

Design of O-Rings as an Example of Passive Adaptive Structures

2008 ◽  
Author(s):  
Barney E. Klamecki ◽  
Ryan B. Sefkow ◽  
Nicholas J. Maciejewski
Keyword(s):  
Strain Energy ◽  
High Strain ◽  
Material Design ◽  
Finite Element Models ◽  
Energy Density Distribution ◽  
Strain Behavior ◽  
Numerical Studies ◽  
Softening Material ◽  
Elastomeric Seals ◽  
High Strain Energy

The use of material design to overcome time-dependent material deformation resulting in loss of sealing effectiveness of elastomeric seals was considered. O-ring sections with different stress-strain behavior in different regions of the section were studied. Experimentally validated finite element models were used to characterize the strain energy density distribution and seal-housing contact pressure for various section designs. The design rules extracted from experimental and numerical studies indicate that o-ring sections with lower elastic modulus, softening material located at regions of high strain energy will result in slower growth of permanent seal deformation and so improved seal performance over time. O-ring sections based on this material design were evaluated numerically and improved seal life predicted.

High stress drops of short-period subevents from the 1968 Tokachi-Oki earthquake as observed on strong-motion records

1984 ◽  
Vol 74 (5) ◽  
pp. 1529-1544
Author(s):  
Jim Mori ◽  
Kunihiko Shimazaki
Keyword(s):  
Source Parameters ◽  
High Stress ◽  
Strong Motion ◽  
P Waves ◽  
Strong Motion Records ◽  
Source Dimensions ◽  
Short Period ◽  
High Dynamic ◽  
Stress Drops ◽  
Very High

Abstract Strong-motion records of the 1968 Tokachi-Oki earthquake were examined, and two very high stress drop subevents were identified. The first subevent had been previously located by Nagamune (1969), and the second subevent was located in this study using P waves recorded on short-period WWSSN records. Estimates of source parameters revealed small source dimensions (&lt;1 per cent of the aftershock area) and very high dynamic and static stress drops in the kilobar range for both of the subevents. It is suggested that these subevents are important in driving the main rupture of this earthquake. The two subevents also produced the dominant accelerations on the strong-motion records, and it is shown that high-peak accelerations (150 to 200 cm/sec2) were recorded even at relatively large distances (100 to 200 km).

Sign in / Sign up

Export Citation Format

Share Document