Aftershocks of an M = 4.2 earthquake in Hawaii and comparison with long-term studies of the same volume

1985 ◽  
Vol 75 (3) ◽  
pp. 759-777
Author(s):  
Martha Kane Savage ◽  
Robert P. Meyer
Keyword(s):  
Main Shock ◽  
Rift Zone ◽  
Fault Plane ◽  
Linear Region ◽  
Fault Plane Solutions ◽  
One Dimensional ◽  
Delay Times ◽  
The Relationship ◽  
Long Term Studies

Abstract Study of the aftershocks recorded in a 3-hr period after a 4.2 magnitude event on the East Rift Zone of Kilauea volcano, Hawaii, on 12 April 1982 shows that the aftershocks occurred on different planes than the main shock, probably as a result of stress redistribution; the aftershock locations are probably controlled by preexisting structures. This study also suggests that these relatively small aftershocks occurred in the same seismicity patterns as larger events recorded in the same volume over a period of 10 yr. Slips on most of the aftershocks and the main shock are in the same direction, perpendicular to the East Rift Zone, as has been found in studies of other, larger earthquakes. However, fault-plane solutions varied more, as did the tensional axes, and several of the smaller events showed movement in the opposite direction from the main shock and the rest of the aftershocks, suggesting some rebound was occurring near the edges of the aftershock zone. Because ten times as much energy was released in the aftershocks in a narrow linear region as elsewhere, and since the main shock epicenter was oceanward of all the aftershocks, we suggest that rupture began at the main shock hypocenter and propagated landward, implying an almost “one-dimensional” fault. For the aftershocks, the relationship between moment and magnitude was: log M0 = (1.18 ± 0.17) ML + (17.3 ± 0.17). Differences in amplification lead to site differences of up to 0.8 units in local magnitude and 1.5 orders of magnitude in energy release. These correlated somewhat with station time corrections in that the stations with the longest delay times also had greatest amplification.

Aftershocks of the February 21, 1973 Point Mugu, California earthquake

1976 ◽  
Vol 66 (6) ◽  
pp. 1931-1952
Author(s):  
Donald J. Stierman ◽  
William L. Ellsworth
Keyword(s):  
Fault Zone ◽  
Main Shock ◽  
Fault Plane ◽  
Body Wave ◽  
P Wave ◽  
Fault System ◽  
Wave Radiation ◽  
Fault Plane Solutions ◽  
Complex Deformation ◽  
Transverse Ranges

abstract The ML 6.0 Point Mugu, California earthquake of February 21, 1973 and its aftershocks occurred within the complex fault system that bounds the southern front of the Transverse Ranges province of southern California. P-wave fault plane solutions for 51 events include reverse, strike slip and normal faulting mechanisms, indicating complex deformation within the 10-km broad fault zone. Hypocenters of 141 aftershocks fail to delineate any single fault plane clearly associated with the main shock rupture. Most aftershocks cluster in a region 5 km in diameter centered 5 km from the main shock hypocenter and well beyond the extent of fault rupture estimated from analysis of body-wave radiation. Strain release within the imbricate fault zone was controlled by slip on preexisting planes of weakness under the influence of a NE-SW compressive stress.

Rampart seismic zone of central Alaska

1983 ◽  
Vol 73 (3) ◽  
pp. 813-829
Author(s):  
P. Yi-Fa Huang ◽  
N. N. Biswas
Keyword(s):  
Main Shock ◽  
Fault Plane ◽  
B Value ◽  
Aftershock Sequence ◽  
Strike Slip ◽  
Lithospheric Plate ◽  
Normal Faults ◽  
Seismic Zone ◽  
The West ◽  
Fault Plane Solutions

abstract This paper describes the characteristics of the Rampart seismic zone by means of the aftershock sequence of the Rampart earthquake (ML = 6.8) which occurred in central Alaska on 29 October 1968. The magnitudes of the aftershocks ranged from about 1.6 to 4.4 which yielded a b value of 0.96 ± 0.09. The locations of the aftershocks outline a NNE-SSW trending aftershock zone about 50 km long which coincides with the offset of the Kaltag fault from the Victoria Creek fault. The rupture zone dips steeply (≈80°) to the west and extends from the surface to a depth of about 10 km. Fault plane solutions for a group of selected aftershocks, which occurred over a period of 22 days after the main shock, show simultaneous occurrences of strike-slip and normal faults. A comparison of the trends in seismicity between the neighboring areas shows that the Rampart seismic zone lies outside the area of underthrusting of the lithospheric plate in southcentral and central Alaska. The seismic zone outlined by the aftershock sequence appears to represent the formation of an intraplate fracture caused by regional northwest compression.

scholarly journals Land subsidence and hydrodynamic compaction of sedimentary basins

1998 ◽  
Vol 2 (2/3) ◽  
pp. 159-171 ◽  
Author(s):  
H. Kooi ◽  
J. J. de Vries
Keyword(s):  
Response Time ◽  
Land Subsidence ◽  
Sedimentary Basins ◽  
Sediment Loading ◽  
Dimensional Model ◽  
One Dimensional ◽  
Model Equations ◽  
Sediment Layers ◽  
The Relationship

Abstract. A one-dimensional model is used to investigate the relationship between land subsidence and compaction of basin sediments in response to sediment loading. Analysis of the model equations and numerical experiments demonstrate quasi-linear systems behaviour and show that rates of land subsidence due to compaction: (i) can attain a significant fraction (>40%) of the long-term sedimentation rate; (ii) are hydrodynamically delayed with respect to sediment loading. The delay is controlled by a compaction response time τc that can reach values of 10-5-107 yr for thick shale sequences. Both the behaviour of single sediment layers and multiple-layer systems are analysed. Subsequently the model is applied to the coastal area of the Netherlands to illustrate that lateral variability in compaction-derived land subsidence in sedimentary basins largely reflects the spatial variability in both sediment loading and compaction response time. Typical rates of compaction-derived subsidence predicted by the model are of the order of 0.1 mm/yr but may reach values in excess of 1 mm/yr under favourable conditions.

scholarly journals Systematic Literature Review and Meta-Analysis of the Relationship Between Polyunsaturated and Trans Fatty Acids During Pregnancy and Offspring Weight Development

2021 ◽  
Vol 8 ◽  
Author(s):  
Xuan Ren ◽  
Birgitta Lind Vilhjálmsdóttir ◽  
Jeanett Friis Rohde ◽  
Karen Christina Walker ◽  
Suzanne Elizabeth Runstedt ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Birth Weight ◽  
Observational Studies ◽  
Trans Fatty Acids ◽  
Meta Analysis ◽  
Randomized Controlled ◽  
Neonatal Blood ◽  
The Relationship ◽  
Long Term Studies

Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and trans fatty acids (TFAs) may have an impact on offspring weight development. We conducted a systematic review and meta-analysis according to PRISMA guidelines to evaluate whether levels of these fatty acids during pregnancy influenced offspring weight development. Randomized controlled trials (RCTs) with DHA and/or EPA supplementation or cohort studies, which examined levels of DHA, EPA, or TFAs in maternal or neonatal blood samples and recorded offspring weight, were included. Overall, 27 RCTs and 14 observational studies were identified. The results showed that DHA and/or EPA supplementation doses >650 mg/day resulted in slightly higher birth weight (MD 87.5 g, 95% CI 52.3–122.6, n = 3,831) and combined BMI and BMI z score at 5–10 years (SMD 0.11, 95% CI 0.04–0.18, n = 3,220). These results were rated as moderate quality. Results from the observational studies were generally inconsistent. High TFA levels during pregnancy seemed to be associated with lower birth weight. Finally, this review and meta-analysis supports a relationship between high maternal or neonatal DHA and/or EPA levels and higher offspring birth weight and weight in childhood. More high-quality long-term studies are still needed.

Slowly migrating tectonic microearthquake swarms in the Icelandic Rift Zone: driven by pore-pressure or aseismic slip transients?

2021 ◽  
Author(s):  
Tom Winder ◽  
Robert S White
Keyword(s):  
High Resolution ◽  
Rift Zone ◽  
Fault Plane ◽  
Plate Boundary ◽  
Double Difference ◽  
Aseismic Slip ◽  
Tectonic Earthquake ◽  
Fault Plane Solutions ◽  
Scaling Properties ◽  
Waveform Cross Correlation

<p>Intense swarms of microearthquakes have been detected in the rift zone of Central Iceland since the 1970s, but the cause of their clear swarm-like nature remains enigmatic. We use the QuakeMigrate earthquake detection and location software<sup>1</sup> to produce a highly complete catalogue of microseismicity from 2007-2020, using data from a dense local seismic network. Automatic hypocentre locations have been refined using waveform cross-correlation and double-difference relocation, and tightly constrained focal mechanisms have been obtained by manual analysis of a subset of events.</p><p>The resulting high-resolution earthquake catalogue reveals a network of conjugate strike-slip faults, oriented to accommodate plate-boundary extension. Sharply defined fault planes imaged by the microearthquake hypocentres range from 1-10 km in length, and are found between 1 and 8 km b.s.l., with their orientations closely matching the fault plane geometry inferred from the fault plane solutions. Seismicity within individual swarms displays a systematic migration of hypocentres at velocities of ~ 1 km/day. In the majority of swarms we also observe clusters of identical repeating events, providing evidence for re-loading of brittle asperities.</p><p>For a selection of swarms our high resolution seismic observations are complemented by GPS and InSAR measurements, allowing us to place constraints on the amount of fault slip. Comparing this, and the area of the fault plane activated in the swarm, to the seismic moment release reveals a significant contribution of aseismic slip, or very low effective stress drop. Analysis of swarms within this fault network triggered by the 2014 Bárðarbunga-Holuhraun dike intrusion provides further constraint on the amplitude of the stress cycle.</p><p>We combine our observations with comparisons to numerical & laboratory modelling studies, observed swarm scaling properties and knowledge of the geological and permeability structure of the Icelandic crust to determine the nature of the transient forcing driving these exceptionally well-recorded tectonic earthquake swarms.</p><p> </p><p>1: https://github.com/QuakeMigrate/QuakeMigrate Tom Winder, Conor Bacon, Jonathan D. Smith, Thomas S. Hudson, Julian Drew, & Robert S. White. (2021, January 15). QuakeMigrate v1.0.0 (Version v1.0.0). Zenodo. http://doi.org/10.5281/zenodo.4442749</p>

Persistent homeothermy in large domestic mammals maintained under standard farming conditions

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Giuseppe Piccione ◽  
Claudia Giannetto ◽  
Elisabetta Giudice ◽  
Roberto Refinetti
Keyword(s):  
Rectal Temperature ◽  
Quantitative Measure ◽  
Circadian Oscillation ◽  
Unrestricted Access ◽  
The Stability ◽  
Access To Food ◽  
The Relationship ◽  
Long Term Studies ◽  
Daily Oscillation

AbstractBackgroundMammals, particularly large domestic ones, are considered to be year-round homeotherms. Surprisingly, however, very few long-term studies of the stability of core temperature of large domestic mammals have been conducted.MethodsWe monitored the auricular temperature and rectal temperature of goats, sheep, cows, and donkeys monthly for 2 years and compared their annual variation with their daily and day-to-day variations.ResultsAlthough ambient temperature varied from 8 °C in the winter to 30 °C in the summer, auricular temperature varied less than 0.5 °C, and rectal temperature varied less than 0.3 °C. We found that the daily oscillation in body temperature was up to three times as large as the day-to-day and month-to-month variations and that month-to-month variation was negligibly larger than day-to-day variation.ConclusionOur results confirm persistent homeothermy in large domestic mammals with unrestricted access to food and water and provide a quantitative measure of the relationship between long-term homeothermy and the wider range of daily/circadian oscillation.

Job Insecurity

2021 ◽  
Author(s):  
Nele De Cuyper ◽  
Hans De Witte
Keyword(s):  
Cultural Values ◽  
Job Insecurity ◽  
Well Being ◽  
Structural Features ◽  
And Behavior ◽  
The Relationship ◽  
Health And Well Being ◽  
Scarring Effects ◽  
Long Term Studies

Job insecurity has been high on the policy and research agenda since the 1980s: there has always been cause for concern about job loss, though those causes may vary across context and time. Job insecurity is particularly prevalent among employees with a more precarious profile, in particular employees in blue-collar positions or on temporary contracts, and among employees in jobs of lower quality. Job insecurity has typically been advanced as a stressor and a cause for imbalance in the employment relationship, which has led to the hypothesis that job insecurity induces strain (e.g., poorer health and well-being), poorer attitudes vis-à-vis the job and the organization (e.g., poorer organizational commitment), and poorer performance. This hypothesis has found overall support. In addition, job insecurity also threatens one’s identity, and this has been related to more conservative social attitudes and behaviors, for example, in terms of voting intentions and behavior. Finally, job insecurity affects outcomes beyond the current job and the organization: it affects other stakeholders, for example, labor unions and families, and it has scarring effects in the long term. Studies have also attempted to identify moderators that could buffer the relationship between job insecurity and outcomes; these mostly concern personal, job, and organizational resources. Other studies have sought to explain differences between countries in terms of both structural features and cultural values.

scholarly journals Seismicity and seismotectonics of the Albstadt Shear Zone in the northern Alpine foreland

2020 ◽  
Author(s):  
Sarah Mader ◽  
Joachim R. R. Ritter ◽  
Klaus Reicherter ◽  
Keyword(s):  
Shear Zone ◽  
Fault Plane ◽  
Seismic Velocity ◽  
Driving Forces ◽  
Horizontal Stress ◽  
Fault Plane Solutions ◽  
Velocity Models ◽  
Delay Times ◽  
Seismic Networks ◽  
Maximum Horizontal Stress

Abstract. The region around the town Albstadt, SW Germany, was struck by four damaging earthquakes with magnitudes greater than five during the last century. Those earthquakes occurred along the Albstadt Shear Zone (ASZ) which is characterized by more or less continuous microseismicity. As there are no surface ruptures visible which may be connected to the fault zone, its characteristics can only be studied by its seismicity. We use the earthquake data of the state earthquake service of Baden-Württemberg from 2011 to 2018 and complement it with additional phase picks beginning 2016 at the AlpArray and StressTransfer seismic networks in the vicinity of the ASZ. This extended dataset is used to determine new minimum 1-D seismic vp and vs velocity models and corresponding station delay times for earthquake relocation. Fault plane solutions are determined for selected events and the direction of the maximum horizontal stress is derived. The minimum 1-D seismic velocity models have a simple and stable layering with increasing velocity with depth in the upper crust. The corresponding station delay times can be well explained by the lateral depth variation of the crystalline basement. The relocated events align north-south with most of the seismic activity between the towns of Tübingen and Albstadt east of the 9° E meridian. The events can be separated into several subclusters which indicate a segmentation of the ASZ. The majority of the 36 determined fault plane solutions features a NNE-SSW strike, but also NNW-SSE striking fault planes are observed. The main fault plane associated with the ASZ is dipping steeply and the rake indicates mainly sinistral strike-slip, but we also find minor components of normal and reverse faulting. The determined direction of the maximum horizontal stress of 147° is in good agreement with prior studies. This result indicates that the stress field in the area of the ASZ is mainly generated by the regional plate driving forces as well as the Alpine topography.

scholarly journals Statistical analysis of recent fault-plane solutions of earthquakes

1959 ◽  
Vol 49 (4) ◽  
pp. 337-347
Author(s):  
A. E. Scheidegger
Keyword(s):  
Statistical Analysis ◽  
Fault Plane ◽  
Strike Slip ◽  
Slip Angle ◽  
Fault Plane Solutions ◽  
Deep Earthquakes ◽  
Central Asian ◽  
Normal Character ◽  
The Relationship

Abstract The large number of fault-plane solutions at present available in the literature permit one to calculate several statistical averages that have an important bearing upon geotectonics. The present paper represents a continuation of earlier work in this direction: 101 new fault-plane solutions are listed and the ratio of pressure to tension, strike slip to dip slip, and the average slip angle have been calculated for nine earthquake areas. Some of the older results are thereby corroborated, viz., that the “normal” character of earthquakes is to represent strike-slip faulting, and that the central Asian regions constitute an exception to this rule. In addition, it is now possible to make a breakdown with regard to depth. In this, a peculiar situation is found at 0.03 R depth, where the slip angle reaches a maximum. If the relationship between shallow and deep earthquakes be considered for any one area, however, it turns out that they are on the whole of the same character. Thus, whatever it is that causes earthquakes, acts in a similar fashion at all depths in any one area, but differs from one area to another.

scholarly journals Seismicity and seismotectonics of the Albstadt Shear Zone in the northern Alpine foreland

Solid Earth ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 1389-1409
Author(s):  
Sarah Mader ◽  
Joachim R. R. Ritter ◽  
Klaus Reicherter ◽  
Keyword(s):  
Shear Zone ◽  
Fault Plane ◽  
Seismic Velocity ◽  
Driving Forces ◽  
Stress Component ◽  
Horizontal Stress ◽  
Fault Plane Solutions ◽  
Data Set ◽  
Velocity Models ◽  
Delay Times

Abstract. The region around the town Albstadt, SW Germany, was struck by four damaging earthquakes with magnitudes greater than 5 during the last century. These earthquakes occurred along the Albstadt Shear Zone (ASZ), which is characterized by more or less continuous microseismicity. As there are no visible surface ruptures that may be connected to the fault zone, we study its characteristics by its seismicity distribution and faulting pattern. We use the earthquake data of the state earthquake service of Baden-Württemberg from 2011 to 2018 and complement it with additional phase picks beginning in 2016 at the AlpArray and StressTransfer seismic networks in the vicinity of the ASZ. This extended data set is used to determine new minimum 1-D seismic vp and vs velocity models and corresponding station delay times for earthquake relocation. Fault plane solutions are determined for selected events, and the principal stress directions are derived. The minimum 1-D seismic velocity models have a simple and stable layering with increasing velocity with depth in the upper crust. The corresponding station delay times can be explained well by the lateral depth variation of the crystalline basement. The relocated events align about north–south with most of the seismic activity between the towns of Tübingen and Albstadt, east of the 9∘ E meridian. The events can be separated into several subclusters that indicate a segmentation of the ASZ. The majority of the 25 determined fault plane solutions feature an NNE–SSW strike but NNW–SSE-striking fault planes are also observed. The main fault plane associated with the ASZ dips steeply, and the rake indicates mainly sinistral strike-slip, but we also find minor components of normal and reverse faulting. The determined direction of the maximum horizontal stress of 140–149∘ is in good agreement with prior studies. Down to ca. 7–8 km depth SHmax is bigger than SV; below this depth, SV is the main stress component. The direction of SHmax indicates that the stress field in the area of the ASZ is mainly generated by the regional plate driving forces and the Alpine topography.

Sign in / Sign up

Export Citation Format

Share Document