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Sample records for coseismic stress change

  1. Estimation of co-seismic stress change of the 2008 Wenchuan Ms8.0 earthquake

    SciTech Connect

    Sun Dongsheng; Wang Hongcai; Ma Yinsheng; Zhou Chunjing

    2012-09-26

    In-situ stress change near the fault before and after a great earthquake is a key issue in the geosciences field. In this work, based on the 2008 Great Wenchuan earthquake fault slip dislocation model, the co-seismic stress tensor change due to the Wenchuan earthquake and the distribution functions around the Longmen Shan fault are given. Our calculated results are almost consistent with the before and after great Wenchuan earthquake in-situ measuring results. The quantitative assessment results provide a reference for the study of the mechanism of earthquakes.

  2. Evolution of stress in Southern California for the past 200 years from coseismic, postseismic and interseismic stress changes

    NASA Astrophysics Data System (ADS)

    Freed, Andrew M.; Ali, Syed Tabrez; Bürgmann, Roland

    2007-06-01

    The seismicity of southern California results from stresses that arise from the relative motion of the Pacific and North American Plates being accommodated along the San Andreas Fault (SAF) system and the Eastern California Shear Zone (ECSZ). Here we calculate how the stress field in southern California has evolved over the past two centuries due to interseismic loading, as inferred from current GPS observations of surface velocities, from redistributions of static stress induced by large (Mw >= 6.5) earthquakes since the 1812 Wrightwood quake, and postseismic viscoelastic relaxation associated with these events that serves to transfer coseismic stresses from the deep, warm, lower crust and upper mantle to the overlying seismogenic upper crust. We calculate Coulomb stress changes on vertical strike-slip faults striking parallel to the SAF and at the hypocenters on the rupture planes of all Mw >= 6 events over the past two centuries. Our results suggest that the 1857 Mw = 8.2 Fort Tejon earthquake, by far the largest event to have occurred in the region over the past two centuries, had a profound influence on the state of stress in Southern California during the 19th century, inducing significant stress increases to the north (Parkfield region and adjoining creeping SAF) and south (southern SAF and San Jacinto fault), and stress relief across the southern ECSZ. These stress changes were then greatly magnified by postseismic relaxation through the early part of the 20th century. Slow interseismic build-up of stress further loads all major strike-slip faults and works to reload the areas of the ECSZ where stress was relieved by the 1857 quake. Our calculations suggest that only 56% of hypocenters were pushed closer to failure by preceding coseismic stress changes, suggesting that the occurrence of large earthquakes is not strongly determined by coseismic Coulomb stress changes. This percentage rises to 70% when postseismic stress changes are also considered. Our

  3. Coseismic temporal changes of slip direction: the effect of absolute stress on dynamic rupture

    USGS Publications Warehouse

    Guatteri, Mariagiovanna; Spudich, P.

    1998-01-01

    We investigate the dynamics of rupture at low-stress level. We show that one main difference between the dynamics of high- and low-stress events is the amount of coseismic temporal rake rotation occurring at given points on the fault. Curved stations on exposed fault surfaces and earthquake dislocation models derived from ground-motion inversion indicate that the slip direction may change with time at a pointon the fault during dynamic rupture. We use a 3D boundary integral method to model temporal rake variations during dynamic rupture propagation assuming a slip-weakening friction law and isotropic friction. The points at which the slip rotates most are characterized by an initial shear stress direction substantially different from the average stress direction over the fault plane. We show that for a given value of stress drop, the level of initial shear stress (i.e., the fractional stress drop) determines the amount of rotation in slip direction. We infer that seismic events that show evidence of temporal rake rorations are characterized by a low initial shear-stress level with spatially variable direction on the fault (possibly due to changes in fault surface geometry) and an almost complete stress drop. Our models motivate a new interpretation of curved and cross-cutting striations and put new constraints on their analysis. The initial rake is in general collinear with the initial stress at the hypocenter zone, supporting the assumptions made in stress-tensor inversion from first-motion analysis. At other points on the fualt, especially away from the hypocenter, the initial slip rake may not be collinear with the initial shear stress, contradicting a common assumption of structural geology. On the other hand, the later part of slip in our models is systematically more aligned withi the average stress direction than the early slip. Our modeling suggests that the length of the straight part of curved striations is usually an upper bound of the slip

  4. Coseismic temporal changes of slip direction: the effect of absolute stress on dynamic rupture

    USGS Publications Warehouse

    Guatteri, Mariagiovanna; Spudich, P.

    1998-01-01

    We investigate the dynamics of rupture at low-stress level. We show that one main difference between the dynamics of high- and low-stress events is the amount of coseismic temporal rake rotation occurring at given points on the fault. Curved striations on exposed fault surfaces and earthquake dislocation models derived from ground-motion inversion indicate that the slip direction may change with time at a point on the fault during dynamic rupture. We use a 3D boundary integral method to model temporal rake variations during dynamic rupture propagation assuming a slip-weakening friction law and isotropic friction. The points at which the slip rotates most are characterized by an initial shear stress direction substantially different from the average stress direction over the fault plane. We show that for a given value of stress drop, the level of initial shear stress (i.e., the fractional stress drop) determines the amount of rotation in slip direction. We infer that seismic events that show evidence of temporal rake rotations are characterized by a low initial shear-stress level with spatially variable direction on the fault (possibly due to changes in fault surface geometry) and an almost complete stress drop.Our models motivate a new interpretation of curved and cross-cutting striations and put new constraints on their analysis. The initial rake is in general collinear with the initial stress at the hypocentral zone, supporting the assumptions made in stress-tensor inversion from first-motion analysis. At other points on the fault, especially away from the hypocenter, the initial slip rake may not be collinear with the initial shear stress, contradicting a common assumption of structural geology. On the other hand, the later part of slip in our models is systematically more aligned with the average stress direction than the early slip. Our modeling suggests that the length of the straight part of curved striations is usually an upper bound of the slip

  5. Investigating untypical seismicity distribution in Upper Silesia hard coal mine - insight into natural, human-induced and coseismic stress changes.

    NASA Astrophysics Data System (ADS)

    Kozłowska, Maria; Orlecka-Sikora, Beata; Rudziński, Łukasz; Cielesta, Szymon; Mutke, Grzegorz

    2016-04-01

    The Upper Silesia Coal Basin (USCB) in southern Poland is the place of intense seismicity accompanying coal mining. The exploitation of three longwall panels in one of USCB coal mines held between 2005 and 2010 was accompanied by seismicity characterized by very unusual time-space distribution. The earthquakes did not follow the depth of mining but exhibited changing depths from great below to close to mined seam. What is more, most of the strongest seismic events with ML>2.2 recorded during exploitation of these longwall panels occurred when exploitation had approached the axis of Bytom syncline, local tectonic structure intersecting several mines in Upper Silesia. Strong event's hypocenters were thus at close epicentral distance to both Bytom syncline axis and active mining front but at the great depth below mined seam. Such rather unusual seismicity pattern provided the unique opportunity to study the possible coupling of natural, human-induced and coseismic stresses in longwall coal mining environment. In present study we focused on distribution of seismicity of one of the longwall panels and in particular on the strongest event which occurred during its exploitation, ML3.7 event. The full moment tensor solution of the event showed that it occurred as almost vertical reverse faulting on a northeast-striking plane consistent with approximate strike of Bytom syncline. To evaluate inducing factor of ongoing and past exploitation we performed geomechanical modelling of its influence on strain and stress in the rock mass at the target depth of ML3.7 event. The estimated mining stress changes exhibited changing vertical stress regime which might have promoted failure on preexisting, almost vertical planes of weakness. Also, the amplitude of vertical displacement along the profile at the earthquake's depth was of similar order as the estimated slip on the fault. The earthquakes' rate variation in time showed no increase in activity right after the occurrence of ML3

  6. 3D-Finite-Element Modelling of Coseismic and Postseismic Coulomb Stress Changes on Intra-Continental Dip-Slip Faults

    NASA Astrophysics Data System (ADS)

    Bagge, M.; Hampel, A.

    2015-12-01

    Investigating the interaction of faults plays a crucial role for assessing seismic hazard. The calculation of Coulomb stress changes allows quantifying stress changes on so-called receiver faults in the surrounding of a source fault that was ruptured during an earthquake. Positive Coulomb stress changes bring receiver faults closer to failure, while a negative value indicates a delay of the next earthquake. Besides the coseismic ('static') stress changes, postseismic ('transient') stress changes induced by postseismic relaxation occur. Here we use 3D finite-element models with arrays of normal or thrust faults to study the coseismic stress changes and the stress changes arising from postseismic relaxation in the lower crust. The results show that synthetic receiver faults in the hanging wall and footwall of the source fault exhibit a symmetric distribution of the coseismic Coulomb stress changes on each fault, with large areas of negative stress changes but also some smaller areas of positive values. In contrast, faults positioned in along-strike prolongation of the source fault and outside of its hanging wall and footwall undergo mostly positive stress changes. Postseismic stress changes caused by viscous flow modify the static stress changes in a way that the net Coulomb stress changes on the receiver faults change significantly through space and time. Our models also allow deciphering the combined effect of stress changes caused by the ongoing extension or shortening (leading to an interseismic stress increase) and by the postseismic relaxation (leading to stress increase or decrease). Depending on the viscosity and the dip and position of the receiver fault, stress changes induced by postseismic relaxation can outweigh the interseismic stress increase such that negative Coulomb stress changes can persist for decades. On other faults, the interseismic stress increase is further increased by postseismic relaxation.

  7. 3D-Finite-Element Modelling of Coseismic and Postseismic Coulomb Stress Changes on Intra-Continental Dip-Slip Faults

    NASA Astrophysics Data System (ADS)

    Bagge, M.; Hampel, A.

    2014-12-01

    Investigating the interaction of faults plays a crucial role for assessing seismic hazard. The calculation of Coulomb stress changes allows quantifying stress changes on so-called receiver faults in the surrounding of a source fault that was ruptured during an earthquake. Positive Coulomb stress changes bring receiver faults closer to failure, while a negative value indicates a delay of the next earthquake. Besides the coseismic ('static') stress changes, postseismic ('transient') stress changes induced by postseismic relaxation occur. Here we use 3D finite-element models with arrays of normal or thrust faults to study the coseismic stress changes and the stress changes arising from postseismic relaxation in the lower crust. The results show that synthetic receiver faults in the hanging wall and footwall of the source fault exhibit a symmetric distribution of the coseismic Coulomb stress changes on each fault, with large areas of negative stress changes but also some smaller areas of positive values. In contrast, faults positioned in along-strike prolongation of the source fault and outside of its hanging wall and footwall undergo mostly positive stress changes. Postseismic stress changes caused by viscous flow modify the static stress changes in a way that the net Coulomb stress changes on the receiver faults change significantly through space and time. Our models also allow deciphering the combined effect of stress changes caused by the ongoing extension or shortening (leading to an interseismic stress increase) and by the postseismic relaxation (leading to stress increase or decrease). Depending on the viscosity and the dip and position of the receiver fault, stress changes induced by postseismic relaxation can outweigh the interseismic stress increase such that negative Coulomb stress changes can persist for decades. On other faults, the interseismic stress increase is further increased by postseismic relaxation.

  8. Influence of pore pressure change on coseismic volumetric strain

    NASA Astrophysics Data System (ADS)

    Wang, Chi-Yuen; Barbour, Andrew J.

    2017-10-01

    Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

  9. Coseismic and postseismic Coulomb stress changes on intra-continental dip-slip faults and the role of viscoelastic relaxation in the lower crust: insights from 3D finite-element models

    NASA Astrophysics Data System (ADS)

    Bagge, Meike; Hampel, Andrea

    2016-04-01

    Investigating the stress interaction of faults plays a crucial role for assessing seismic hazard of a region. The calculation of Coulomb stress changes allows quantifying stress changes on so-called receiver faults in the surrounding of a source fault that was ruptured during an earthquake. Positive Coulomb stress changes bring receiver faults closer to failure, while a negative value indicates a delay of the next earthquake. Besides the coseismic ('static') stress changes, postseismic ('transient') stress changes induced by postseismic viscoelastic relaxation occur. Here we use 3D finite-element models with arrays of normal or thrust faults to study the coseismic stress changes and the stress changes arising from postseismic relaxation in the lower crust. The lithosphere is divided into an elastic upper crust, a viscoelastic lower crust and a viscoelastic lithospheric mantle. Gravity is included in the models. Driven by extension or shortening of the model, slip on the fault planes develops in a self-consistent way. We modelled an earthquake on a 40-km-long source fault with a coseismic slip of 2 m and calculated the displacement fields and Coulomb stress changes during the coseismic and postseismic phases. The results for the coseismic phase (Bagge and Hampel, Tectonophysics in press) show that synthetic receiver faults in the hanging wall and footwall of the source fault exhibit a symmetric distribution of the coseismic Coulomb stress changes on each fault, with large areas of negative stress changes but also some smaller areas of positive values. In contrast, faults positioned in along-strike prolongation of the source fault and outside of its hanging wall and footwall undergo mostly positive stress changes. Postseismic stress changes caused by viscous flow modify the static stress changes in a way that the net Coulomb stress changes on the receiver faults change significantly through space and time. Our models allow deciphering the combined effect of stress

  10. Coseismic and Early Post-Seismic Slip Distributions of the 2012 Emilia (Northern Italy) Seismic Sequence: New Insights in the Faults Activation and Resulting Stress Changes on Adjacent Faults

    NASA Astrophysics Data System (ADS)

    Cheloni, D.; Giuliani, R.; D'Agostino, N.; Mattone, M.; Bonano, M.; Fornaro, G.; Lanari, R.; Reale, D.

    2015-12-01

    The 2012 Emilia sequence (main shocks Mw 6.1 May 20 and Mw 5.9 May 29) ruptured two thrust segments of a ~E-W trending fault system of the buried Ferrara Arc, along a portion of the compressional system of the Apennines that had remained silent during past centuries. Here we use the rupture geometry constrained by the aftershocks and new geodetic data (levelling, InSAR and GPS measurements) to estimate an improved coseismic slip distribution of the two main events. In addition, we use post-seismic displacements, described and analyzed here for the first time, to infer a brand new post-seismic slip distribution of the May 29 event in terms of afterslip on the same coseismic plane. In particular, in this study we use a catalog of precisely relocated aftershocks to explore the different proposed geometries of the proposed thrust segments that have been published so far and estimate the coseismic and post-seismic slip distributions of the ruptured planes responsible for the two main seismic events from a joint inversion of the geodetic data.Joint inversion results revealed that the two earthquakes ruptured two distinct planar thrust faults, characterized by single main coseismic patches located around the centre of the rupture planes, in agreement with the seismological and geological information pointing out the Ferrara and the Mirandola thrust faults, as the causative structures of the May 20 and May 29 main shocks respectively.The preferred post-seismic slip distribution related to the 29 May event, yielded to a main patch of afterslip (equivalent to a Mw 5.6 event) located westward and up-dip of the main coseismic patch, suggesting that afterslip was triggered at the edges of the coseismic asperity. We then use these co- and post-seismic slip distribution models to calculate the stress changes on adjacent fault.

  11. Stress Evolution in Southern California for the Past 200 Years From Coseismic, Postseismic, and Interseismic Processes

    NASA Astrophysics Data System (ADS)

    Freed, A. M.; Ali, T.; Burgmann, R.

    2006-05-01

    Having experienced at least 36 M>6.0 earthquakes since 1812, southern California is one of the most seismically active regions in the conterminous United States. Numerical studies of the evolution of stress have sought to understand patterns and timing of earthquakes in this region for use in earthquake forecasting. Most of these studies have considered the role of coseismic slip associated with past earthquakes and interseismic strain accumulation associated with continuous slip at depth to understand the evolution of stress. We consider a third mechanism of stress change, that of viscoelastic relaxation following earthquakes, which serves to transfer coseismic stresses from the deep, warm, lower crust and upper mantle to the overlying seismogenic upper crust. We address three specific questions: Does postseismic relaxation associated with past earthquakes influence the currently observed surface velocity field? What is the relative role of coseismic, postseismic, and interseismic stress changes in the triggering of historic earthquakes in southern California over the past two centuries? And what faults/regions of southern California currently have the highest unrelieved levels of stress since 1812? Over the range of viscosities of the lower crust and upper mantle permitted by well characterized postseismic deformation studies, results suggest that postseismic relaxation following earthquakes from 1812 to 1990 do not significantly contribute to current surface velocities as compiled for the SCEC 3 crustal motion map, primarily because most of the relaxation processes are near completion. We calculate that postseismic relaxation from historic earthquakes contribute up to 1 mm/yr to currently observed surface velocities. Contributions from the 1992 Landers and 1999 Hector Mine earthquakes do contribute more significantly, but these transients have been avoided (for the most part) in the assembly of the SCEC 3 crustal motion map. Model results suggest that 69% of

  12. Open Fissure Folds record coseismic loading and postseismic stress relaxation

    NASA Astrophysics Data System (ADS)

    Nüchter, Jens-Alexander

    2015-03-01

    Open Fissure Folds hosted by high pressure/low temperature metamorphic rocks of south Evia (Greece) are introduced, their structural and microstructural record is analysed, and a mechanical model is proposed. Open Fissure Folds are preserved as at least two parallel folded quartz-feldspar veins separated by narrow buckled rock columns. The veins originated as tensile cracks that propagated in the middle crust driven by high differential stress. Features diagnostic for Open Fissure Folds indicate that the rock columns represented the layers of high viscosity, and not the veins as consistently reported in many previous studies on folded veins. This record is taken to indicate that buckling of the rock columns initiated after arrest of the fractures and terminated prior to complete vein sealing. Accordingly, mechanical decoupling by open fissures allowed for buckling of the rock columns in response to episodic creep of the host rocks according to stress relaxation, as expected for postseismic deformation in the earthquake cycle. I propose that the parental fractures propagated in response to quasi-instantaneous coseismic loading of the middle crust. Buckling was attributed to transient postseismic creep and stress relaxation. Complete sealing of the veins occurred when stresses were largely relaxed. Each Open Fissure Fold records the stress and strain history of a single earthquake.

  13. Coseismic, Postseismic and Interseismic Coulomb Stress Evolution Along the Himalayan Main Frontal Thrust Since 1803

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Tan, Kai; Qiao, Xuejun; Liu, Gang; Nie, Zhaosheng; Yang, Shaomin

    2017-05-01

    The Himalayan Main Frontal Thrust is the most active fault in the Himalayan subduction zone, with a high degree of locking and a large thrust rate. Gaps on the Himalayan Main Frontal Thrust have been free of strong earthquakes for hundreds of years and the surrounding areas are densely populated, so it is significant to study the evolution law and the current status of stress along the Himalayan Main Frontal Thrust. Based on a lithospheric viscoelastic layered medium model, we analyzed the interseismic stress accumulation along the Himalayan Main Frontal Thrust and the coseismic and postseismic stress disturbance on the fault surface caused by nine Mw ≥ 7.5 earthquakes since 1803. The results showed that the stress disturbance along the Himalayan Main Frontal Thrust caused by historical earthquakes have promoted most of the subsequent earthquakes, but the coseismic and postseismic stress changes caused by the historical earthquakes on the faulty surface of subsequent earthquakes are not significant, because of the long distance between strong earthquakes. Interseismic stress enhanced the stress level of the majority of fault planes in the study area and played a dominant role in the stress evolution and strong earthquake preparation along the Himalayan Main Frontal Thrust. The recurrence interval of Mw 7.5-7.9 earthquakes on the Himalayan Main Frontal Thrust is 70-250 years and the recurrence interval of Mw > 8 earthquakes which rupture the whole seismogenic layer may be longer than 500 years. This agrees with historical seismic records. The elapsed time of strong earthquakes in the four seismic gaps is between 460 and 915 years and the possibilities of Mw 8 earthquakes in the future 10 years always exist, including a probability of higher than 50% in three seismic gaps. The peak of cumulative Coulomb stress in the seismic gaps is more than 1 MPa, and the seismic hazard on the Himalayan Main Frontal Thrust needs further attention.

  14. Laboratory observations of transient frictional slip in rock-analog materials at co-seismic slip rates and rapid changes in normal stress

    NASA Astrophysics Data System (ADS)

    Yuan, Fuping; Prakash, Vikas

    2012-08-01

    Knowledge of frictional (shear) resistance and its dependency on slip distance, slip velocity, normal stress, and surface roughness is fundamental information for understanding earthquake physics and the energy released during such events. In view of this, in the present study, plate-impact pressure-shear friction experiments are conducted to investigate the frictional resistance in a rock analog material, i.e. soda-lime glass, under interfacial conditions of relevance to fault rupture. The results of the experiments indicate that a wide range of frictional slip conditions exist at the slip interface ranging from initial no-slip and followed by slip weakening, slip strengthening (healing), and seizure all during a single slip event. The slip-weakening phase is understood to be most likely due to thermal-induced flash heating and incipient melting at asperity junctions, while the slip strengthening (slip-healing) phase is understood to be a result of coalescence and solidification of local melt patches on the slip interface. In addition, plate impact pressure-shear normal-stress change (drop) experiments are employed to probe the response of the slip interface due to sudden alterations in normal stress. In particular, the location (timing) of the stress drop is varied so as to investigate the behavior of the slip interface in its slip-weakening, slip-strengthening (healing) phase, or the seized phase, in response to sudden drop in normal stress. These experimental results provide a rich set of data to better understand the range of possible friction slip states that can be achieved and/or critically examine existing dynamic friction models for fault slip behavior.

  15. The stresses that led to the 2008 Mw 7.9 Wenchuan, China, earthquake: Constraints from coseismic slip, aftershocks, and topography

    NASA Astrophysics Data System (ADS)

    Medina Luna, L.; Styron, R. H.; Hetland, E. A.; Zhang, G.; McConeghy, J. D.

    2013-12-01

    The 2008 Mw 7.9 Wenchuan, China earthquake occurred along the western margin of the Sichuan basin, an area characterized by extremely high topographic relief, and ruptured both the Beichuan and Pengguan faults of the Longmenshan fault zone (Lfz). Coseismic slip models derived from seismic and/or geodetic data indicate a complicated pattern of slip on fault segments with variable geometry. Roughly, all these models indicate that coseismic slip transitioned from predominantly thrust slip on moderately dipping fault segments in the southwest to dextral strike-slip along more steeply dipping fault segments in the northeast. Additionally, to the east of the southern segments of the Beichuan fault, the shallowly dipping Pengguan fault slipped mostly in thrust motion. Focal mechanisms of aftershocks are largely thrust in the southwest and strike-slip in the northeast, roughly consistent with the variation of coseismic slip rake in the mainshock. Finally, the topographic gradient across the Lfz generally decreases from the southwest to the northeast, although it is not clear how this relates to the coseismic slip in the Wenchuan earthquake. Using a probabilistic framework, we find that these coseismic slip models are consistent with a homogenous state of stress along the Lfz prior to the mainshock, where the changes in fault geometry were responsible for the change in slip rake during the earthquake. This is in contrast to the estimations of a heterogeneous state of stress inferred from aftershocks by Cai et al., (2011). However, if the coseismic stress changes are comparable to the magnitudes of background stress, the heterogeneity in the aftershock focal mechanisms may simply reflect the localized heterogeneous coseismic stress changes (CSC) due to the complex coseismic slip in the mainshock. We test this hypothesis by determining the state of stress prior to the mainshock using coseismic slip models as well as precisely determined aftershock focal mechanisms from Cai et

  16. Coseismic water level changes induced by two distant earthquakes in multiple wells of the Chinese mainland

    NASA Astrophysics Data System (ADS)

    Ma, Yuchuan; Huang, Fuqiong

    2017-01-01

    Coseismic water level oscillations, or step-like rises and step-like drops were recorded in 159 wells throughout the Chinese mainland due to the 2015 Nepal Mw 7.8 earthquake, and 184 wells for the 2011 Japan Mw 9.0 earthquake. The earthquake magnitude, and the associated dynamic stresses, has positive roles in both the sensitivity of water level to earthquake induced change, and the amplitude and duration of resulting coseismic water level changes. Wells whose water levels are sensitive to Earth tides have high potential to response to earthquakes. Polarities of step-like changes (rises or drops) are locally controlled and spatially variable, with artesian wells generally recording water-level rises. Permeability enhancement was assessed as a mechanism responsible for step-like changes by analyzing the tidal phase responses. Permeability variations are inferred for 17 out of 95 wells with step-like changes during the Nepal earthquake and for 32 out of 105 wells following the Japan earthquake; however, only 6 wells have permeability variations after both earthquakes.

  17. Coseismic radiation and stress drop during the 2015 Mw 8.3 Illapel, Chile megathrust earthquake

    NASA Astrophysics Data System (ADS)

    Yin, Jiuxun; Yang, Hongfeng; Yao, Huajian; Weng, Huihui

    2016-02-01

    On 16 September 2015, an Mw 8.3 earthquake struck middle Chile due to the subduction of the Nazca plate beneath the South America plate. This earthquake is the consequence of 72 years of strain accumulation in the region since the 1943 M 8.3 event. In this study, we apply the compressive sensing method (CS) to invert for the spatiotemporal distribution of the coseismic radiation at different frequencies of this event. The results show clear frequency-dependent feature of earthquake rupture with low-frequency (LF) radiation located in the updip region while high-frequency (HF) radiation concentrated in the downdip region of the megathrust. We also compare the CS results with three coseismic slip models as well as the stress drop distributions inferred from these slip models. The comparison confirms our understanding of coseismic radiation that energy sources are mostly located in the margin of large coseismic slip regions. Furthermore, we find that the LF radiation sources are mainly within the stress-decreasing (releasing) regions while the HF radiation sources are mainly located in the stress-increasing (loading) regions due to rupturing of relatively large asperities nearby (stress decreasing and releasing). These results help to better understand the physics of the rupture process during megathrust earthquakes. Moreover, our results do not show radiation sources south of the epicenter, suggesting that the subducting Juan Fernandez Ridge probably stopped the rupture of this earthquake toward the south.

  18. Coseismic and postseismic stress rotations due to great subduction zone earthquakes

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2012-01-01

    The three largest recent great subduction zone earthquakes (2011 M9.0 Tohoku, Japan; 2010 M8.8 Maule, Chile; and 2004 M9.2 Sumatra-Andaman) exhibit similar coseismic rotations of the principal stress axes. Prior to each mainshock, the maximum compressive stress axis was shallowly plunging, while immediately after the mainshock, both the maximum and minimum compressive stress axes plunge at ~45°. Dipping faults can be oriented for either reverse or normal faulting in this post-mainshock stress field, depending on their dip, explaining the observed normal-faulting aftershocks without requiring a complete reversal of the stress field. The significant stress rotations imply near-complete stress drop in the mainshocks, with >80% of the pre-mainshock stress relieved in the Tohoku and Maule earthquakes and in the northern part of the Sumatra-Andaman rupture. The southern part of the Sumatra-Andaman rupture relieved ~60% of the pre-mainshock stress. The stress axes rotated back rapidly in the months following the Tohoku and Maule mainshocks, and similarly in the southern part of the Sumatra-Andaman rupture. A rapid postseismic rotation is possible because the near-complete stress drop leaves very little “background” stress at the beginning of the postseismic reloading. In contrast, there has been little or no postseismic rotation in the northern part of the Sumatra-Andaman rupture over the 7 years since the mainshock. All M ≥8.0 subduction earthquakes since 1990 with an adequate number of pre- and post-mainshock events were evaluated, and not all show similar coseismic stress rotations. Deeper earthquakes exhibit smaller coseismic stress rotations, likely due to increasing deviatoric stress with depth.

  19. Co-seismic multilayer water temperature and water level changes associated with Wenchuan and Tohoku-Oki earthquakes in the Chuan no. 03 well, China

    NASA Astrophysics Data System (ADS)

    He, Anhua; Zhao, Gang; Sun, Zhaohua; Singh, Ramesh P.

    2016-12-01

    The present paper shows analysis of water level (the distance from the land surface to the water in the well under static condition) and water temperature observed at three different levels of Chuan no. 03 well to study the changes associated with the Wenchuan earthquake of 2008 and the 2011 Tohoku-Oki earthquake. Our analysis shows co-seismic changes in water level and water temperature associated with the increase in compressive stress associated with the Wenchuan earthquake. The water level shows an increase, whereas there was drop in water temperature at the shallow depth (395 m) and enhancement of water temperature at the middle (595 m) and the bottom (765 m) layers. However, no step change in water level or temperature of Chuan no. 03 well is observed associated with the Tohoku-Oki earthquake, only seismic wave propagation-induced water level oscillation and led to co-seismic response of water temperature. The analysis of the co-seismic responses and post-earthquake adjustment processes combined with the borehole histogram and the borehole temperature gradient data clearly show co-seismic changes in water temperature that could be closely associated with the changes in the regional stress and strain state and the distribution of the aquifer and the characteristics of the aquifer. The observed temperature variation of different layers in the borehole is likely to be controlled by the flow of water in the horizontal direction.

  20. Co-seismic multilayer water temperature and water level changes associated with Wenchuan and Tohoku-Oki earthquakes in the Chuan no. 03 well, China

    NASA Astrophysics Data System (ADS)

    He, Anhua; Zhao, Gang; Sun, Zhaohua; Singh, Ramesh P.

    2017-07-01

    The present paper shows analysis of water level (the distance from the land surface to the water in the well under static condition) and water temperature observed at three different levels of Chuan no. 03 well to study the changes associated with the Wenchuan earthquake of 2008 and the 2011 Tohoku-Oki earthquake. Our analysis shows co-seismic changes in water level and water temperature associated with the increase in compressive stress associated with the Wenchuan earthquake. The water level shows an increase, whereas there was drop in water temperature at the shallow depth (395 m) and enhancement of water temperature at the middle (595 m) and the bottom (765 m) layers. However, no step change in water level or temperature of Chuan no. 03 well is observed associated with the Tohoku-Oki earthquake, only seismic wave propagation-induced water level oscillation and led to co-seismic response of water temperature. The analysis of the co-seismic responses and post-earthquake adjustment processes combined with the borehole histogram and the borehole temperature gradient data clearly show co-seismic changes in water temperature that could be closely associated with the changes in the regional stress and strain state and the distribution of the aquifer and the characteristics of the aquifer. The observed temperature variation of different layers in the borehole is likely to be controlled by the flow of water in the horizontal direction.

  1. Low coseismic shear stress on the Tohoku-Oki megathrust determined from laboratory experiments.

    PubMed

    Ujiie, Kohtaro; Tanaka, Hanae; Saito, Tsubasa; Tsutsumi, Akito; Mori, James J; Kameda, Jun; Brodsky, Emily E; Chester, Frederick M; Eguchi, Nobuhisa; Toczko, Sean

    2013-12-06

    Large coseismic slip was thought to be unlikely to occur on the shallow portions of plate-boundary thrusts, but the 11 March 2011 Tohoku-Oki earthquake [moment magnitude (Mw) = 9.0] produced huge displacements of ~50 meters near the Japan Trench with a resultant devastating tsunami. To investigate the mechanisms of the very large fault movements, we conducted high-velocity (1.3 meters per second) friction experiments on samples retrieved from the plate-boundary thrust associated with the earthquake. The results show a small stress drop with very low peak and steady-state shear stress. The very low shear stress can be attributed to the abundance of weak clay (smectite) and thermal pressurization effects, which can facilitate fault slip. This behavior provides an explanation for the huge shallow slip that occurred during the earthquake.

  2. Asymptotic expressions for changes in the surface co-seismic strain on a homogeneous sphere

    NASA Astrophysics Data System (ADS)

    Tang, He; Sun, Wenke

    2017-04-01

    In the dislocation theory for a spherical Earth model, the computation of surface co-seismic deformations using straightforward numerical methods is time consuming and may encounter a series of convergence problems, especially for the near-field deformations due to shallow earthquakes. This study proposes an asymptotic method to approximate changes in the co-seismic surface strain that are caused by an arbitrary point dislocation in a homogeneous sphere. The corresponding expressions are in analytical form and can overcome these difficulties without the numerical integration of differential equations and summations of infinite associated Legendre series in practical applications. Importantly, in contrast with the classical solution for a half-space Earth model, the asymptotic solution can reflect the effect of the Earth's curvature.

  3. Coseismic changes of gravitational potential energy induced by global earthquakes based on spherical-Earth elastic dislocation theory

    NASA Astrophysics Data System (ADS)

    Xu, Changyi; Chao, B. Fong

    2017-05-01

    We compute the coseismic gravitational potential energy Eg change using the spherical-Earth elastic dislocation theory and either the fault model treated as a point source or the finite fault model. The rate of the accumulative Eg loss produced by historical earthquakes from 1976 to 2016 (about 42,000 events) using the Global Centroid Moment Tensor Solution catalogue is estimated to be on the order of -2.1 × 1020 J/a, or -6.7 TW (1 TW = 1012 W), amounting to 15% in the total terrestrial heat flow. The energy loss is dominated by the thrust faulting, especially the megathrust earthquakes such as the 2004 Sumatra earthquake (Mw 9.0) and the 2011 Tohoku-Oki earthquake (Mw 9.1). It is notable that the very deep focus events, the 1994 Bolivia earthquake (Mw 8.2) and the 2013 Okhotsk earthquake (Mw 8.3), produced significant overall coseismic Eg gain according to our calculation. The accumulative coseismic Eg is mainly lost in the mantle of the Earth and also lost in the core of the Earth but with a relatively smaller magnitude. By contrast, the crust of the Earth gains gravitational potential energy cumulatively because of the coseismic deformations. We further investigate the tectonic signature in the coseismic crustal Eg changes in some complex tectonic zone, such as Taiwan region and the northeastern margin of the Tibetan Plateau. We found that the coseismic Eg change is consistent with the regional tectonic character.

  4. Monthly GRACE detection of coseismic gravity change associated with 2011 Tohoku-Oki earthquake using northern gradient approach

    NASA Astrophysics Data System (ADS)

    Li, Jin; Shen, Wen-Bin

    2015-02-01

    We demonstrate that the coseismic gravitational changes due to the 2011 M w = 9.0 Tohoku-Oki earthquake are detectable by GRACE with only 1-month data after the earthquake, which is also supported by a simulation test using the seismic-signal-contained observations synthesized with the signals of a dislocation model prediction. The commonly used destriping to filter correlated errors in GRACE coefficients tends to distort the true coseismic signals in both amplitude and spatial pattern. In order to better retrieve coseismic gravitational signals, we apply a northern gravity gradient approach with the filter of spatial averaging and without destriping. The coseismic northern gravity gradient changes of Tohoku-Oki earthquake are extracted from the monthly data of April 2011, which reveal a positive-negative-positive spatial pattern and agree with the model prediction. The northern gradient approach provides an efficient means to detect coseismic signals and potentially constrain fault slip models with large-scale gravitational changes using limited time span of monthly GRACE solutions.

  5. Coseismic and postseismic velocity changes caused by the 2016 Mw 6.5 Meinong, Taiwan earthquake using ambient seismic noise

    NASA Astrophysics Data System (ADS)

    Tseng, Po-Chin; Rau, Ruey-Juin; Huang, Tzu-Ying; Gung, Yuan-Cheng

    2017-04-01

    The 6 February 2016 MW 6.5 Meinong earthquake with a focal depth of 14.6 km produced widespread strong shaking in the 30-km-away Tainan city and caused about 10 buildings collapsed and 117 death. We collected seismic waveforms from 11 broadband stations within 40 km epicentral distances and reconstruct the Green's functions from cross-correlation function of ambient seismic noise between two stations. We first analyzed seismic data for six different frequency ranges from 0.01 to 2 Hz, which yielded time series for different station pairs from January 2014 to August 2016. Then we used an exponential model to fit the time series of velocity variation consisting of a coseismic velocity drop followed by seasonal changes and postseismic recovery. We found coseismic velocity drops of about 0.20% mostly in 0.5 to 1 Hz at the Hsinhua fault area and the region 20 km SW of the epicenter, however postseismic velocity variation differs between these two regions. The time series of velocity change presented a non-recovery trend in the Hsinhua fault area, however the SW region is indicated by a recovering trend three months after the Meinong earthquake. For the surface wave tomography results in southwestern Taiwan, the regional geological structures are recognizable in the estimated phase-velocity dispersion maps. The dispersion map in the 7.0s Rayleigh wave displays low velocity in the alluvial plain, but indicates high velocity in the north of the Hsinhua fault. The anisotropy direction changes from SSW in the south to SW in the north, which followed the strike of regional geological structure. During the three months of the postseismic period, based on the GPS observations in the Hsinhua fault area, the block south of the fault continuously moved 15 - 20 mm along the southwest direction while the north of the fault remained stationary. The Hsinhua fault is located near the boundary between the Tainan basin and the muddy continental shelf, and where the block south of the

  6. Coulomb stress evolution in the Shanxi rift system, North China, since 1303 associated with coseismic, post-seismic and interseismic deformation

    NASA Astrophysics Data System (ADS)

    Li, Bin; Sørensen, Mathilde Bøttger; Atakan, Kuvvet

    2015-12-01

    The Shanxi rift system is one of the most active intraplate tectonic zones in the North China Block, resulting in devastating seismicity. Since 1303, the rift has experienced fifteen Ms ≥ 6.5 earthquakes. Aiming at a better understanding of Coulomb stress evolution and its relationship with the seismicity in the rift system, we investigated the Coulomb stress changes due to coseismic slip and post-seismic relaxation processes following strong earthquakes as well as the interseismic tectonic loading since the 1303 Hongdong Ms = 8.0 earthquake. Our calculation applies a specified regional medium model, takes the gravity effect into account and uses the fault geometry of the next event as the receiver fault in a given calculation. Our results show that nine out of 12 Ms ≥ 6.5 earthquakes since the 1303 Hongdong earthquake and more than 82 per cent of small-medium instrumental events after the 1989 Datong-Yanggao Ms = 6.1 earthquake fall into the total stress increased areas. Our results also reveal the different roles of the coseismic, post-seismic and interseismic Coulomb stress changes in the earthquake triggering process in the Shanxi rift system. In a short period after a strong event, the stress field changes are dominated by coseismic Coulomb stress due to sudden slip of the ruptured fault, while in the long term, the stress field is mainly dominated by the accumulation of interseismic tectonic loading. Post-seismic stress changes play an important role by further modifying the distribution of stress and therefore cannot be ignored. Based on the current stress status in the Shanxi rift system, the Linfen basin, southern and northern Taiyuan basin, Xinding basin and the north part of the rift system are identified as the most likely locations of large events in the future. The results of this study can provide important clues for the further understanding of seismic hazard in the Shanxi rift system and thus help guiding earthquake risk mitigation efforts in

  7. Coseismic gravity changes of the 2010 earthquake in Central Chile from satellite gravimetry

    NASA Astrophysics Data System (ADS)

    Heki, K.; Matsuo, K.

    2010-12-01

    Fault dislocations modify gravity fields by deforming layer boundaries with density contrasts (e.g. surface uplift and subsidence) and by changing density of rocks due to volume strain (coseismic dilatation and compression). Coseismic changes in gravity have been first mapped using the data from GRACE satellite for the 2004 Sumatra-Andaman (SA) Earthquake (Han et al., 2006). No earthquakes after that event left gravity signatures detectable with GRACE including the 2005 Nias Earthquake, Indonesia. The 2010 February 27 Chile Earthquake (Mw=8.8), the largest event after the 2004 SA Earthquake, ruptured the boundary between the Nazca and the South American Plates known as the Constitución-Concepción seismic gap. Here we present the coseismic gravity changes of the 2010 Chile Earthquake. A monthly GRACE data set (Level-2, RL04, Center for Space Research, Univ. Texas) consists of the coefficients of spherical harmonics with degree and order complete to 60. We replaced the Earth’s oblateness values with those from SLR, and applied a fan filter with averaging radius of 300 km to reduce short wavelength noises. We also reduced longitudinal stripes by using polynomials of degree 3 for coefficients with orders 15 or higher. In order to correct for changes in soil moisture, snow and canopy water, we used the GLDAS hydrological models. After expanding the equivalent water depth data to spherical harmonics, we applied the same fan filter and converted them to gravity changes. They showed negative jump at the back-arc side of the faults with the largest drop of ~5 microgal 200-300 km to the east of the epicenter. In order to calculate predicted gravity changes, we assumed fault parameters composed of two rectangular faults inferred from coseismic displacements of GPS stations. We used Sun et al. (2009) to calculate gravity changes caused by their slips in a spherical, layered earth. Because the original program assumed dry earth (i.e. surface uplift anywhere is interpreted

  8. Exploring the uncertainty range of coseismic stress drop estimations of large earthquakes using finite fault inversions

    NASA Astrophysics Data System (ADS)

    Adams, Mareike; Twardzik, Cedric; Ji, Chen

    2017-01-01

    A new finite fault inversion strategy is developed to explore the uncertainty range for the energy based average coseismic stress drop (overline {{{Δ }}{τ_E}}) of large earthquakes. For a given earthquake, we conduct a modified finite fault inversion to find a solution that not only matches seismic and geodetic data but also has a overline {{{Δ }}{τ_E}} matching a specified value. We do the inversions for a wide range of stress drops. These results produce a trade-off curve between the misfit to the observations and overline {{{Δ }}{τ_E}} , which allows one to define the range of overline {{{Δ }}{τ_E}} that will produce an acceptable misfit. The study of the 2014 Rat Islands Mw 7.9 earthquake reveals an unexpected result: when using only teleseismic waveforms as data, the lower bound of overline {{{Δ }}{τ_E}} (5-10 MPa) for this earthquake is successfully constrained. However, the same data set exhibits no sensitivity to its upper bound of overline {{{Δ }}{τ_E}} because there is limited resolution to the fine scale roughness of fault slip. Given that the spatial resolution of all seismic or geodetic data is limited, we can speculate that the upper bound of overline {{{Δ }}{τ_E}} cannot be constrained with them. This has consequences for the earthquake energy budget. Failing to constrain the upper bound of overline {{{Δ }}{τ_E}} leads to the conclusions that (1) the seismic radiation efficiency determined from the inverted model might be significantly overestimated and (2) the upper bound of the average fracture energy EG cannot be constrained by seismic or geodetic data. Thus, caution must be taken when investigating the characteristics of large earthquakes using the energy budget approach. Finally, searching for the lower bound of overline {{{Δ }}{τ_E}} can be used as an energy-based smoothing scheme during finite fault inversions.

  9. Co-seismic water level changes in response to multiple large earthquakes at the LGH well in Sichuan, China

    NASA Astrophysics Data System (ADS)

    Lai, Guijuan; Jiang, Changsheng; Han, Libo; Sheng, Shuzhong; Ma, Yuchuan

    2016-06-01

    We examined the water level data at the LGH well in Sichuan, China, from December 2007 to July 2015 and their responses to multiple large earthquakes with seismic energy densities greater than 10- 4 J/m3. Co-seismic water level declines were observed in response to eleven earthquakes out of twelve in the farfield, and co-seismic water level increase was observed in one nearfield case. The water level declines in the farfield showed a linear relation with the common logarithm of the seismic energy densities, whereas the water level increase in the nearfield fell away from this relation, indicating that the farfield responses and the nearfield response were produced by distinct mechanisms. We used the phase shift of tidal responses as a proxy for permeability and found that permeability enhancements were observed both in the farfield and nearfield. The co-seismic water level declines in response to the distant earthquakes could be explained by permeability enhancements caused by the passage of seismic waves through the mobilization of colloidal particles; the co-seismic water level increase in response to the nearfield case could be caused both by the compression of the static stress and by the seismic waves.

  10. Co-Seismic Energy Changes Induced by Earthquakes on a Rotating, Gravitating Earth

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.; Gross, Richard S.

    2003-01-01

    Besides operating its own energy budget, an earthquake acts as an agent transferring a much greater amount of energy among the Earth's rotation, elastic field, gravitational field and internal heat. We compute the co-seismic, globally integrated gravitational and rotation changes induced by some 20,000 large earthquakes that occurred in the last quarter century, according to Chao et al. (1995, GJI, 122,776- 783,784-789) and using the Harvard CMT catalog. The result confirms an extremely strong tendency for the earthquakes to decrease the global gravitational energy and to increase the spin energy. It is found that energy is being extracted from the Earth's gravitational field by the action of earthquakes at an average rate of about approx. 2 TeraW during the studied period, larger by far than the approx. 7 GigaW for the average rate of the earthquake-induced rotational energy increase and the approx. 5 GigaW for the seismic energy release. Based on energetics considerations and assuming the inability of the Earth to build up elastic energy continuously over time, it is argued that earthquakes, by converting gravitational energy, may make a significant contribution to the global hedflow.

  11. Determining the Uncertainty Range of Coseismic Stress Drop of Large Earthquakes Using Finite Fault Inversion

    NASA Astrophysics Data System (ADS)

    Adams, M.; Ji, C.; Twardzik, C.; Archuleta, R. J.

    2015-12-01

    A key component in understanding the physics of earthquakes is the resolution of the state of stress on the fault before, during and after the earthquake. A large earthquake's average stress drop is the first order parameter for this task but is still poorly constrained, especially for intermediate and deep events. Classically, the average stress drop is estimated using the corner frequency of observed seismic data. However a simple slip distribution is implicitly assumed; this assumed distribution is often not appropriate for large earthquakes. The average stress drop can be calculated using the inverted finite fault slip model. However, conventional finite fault inversion methods do not directly invert for on-fault stress change; thus it is unclear whether models with significantly different stress drops can match the observations equally well. We developed a new nonlinear inversion to address this concern. The algorithm searches for the solution matching the observed seismic and geodetic data under the condition that the average stress drop is close to a pre-assigned value. We perform inversions with different pre-assigned stress drops to obtain the relationship between the average stress drop of the inverted slip model and the minimum waveform misfit. As an example, we use P and SH displacement waveforms recorded at teleseismic distances from the 2014 Mw 7.9 Rat Island intermediate depth earthquake to determine its average stress drop. Earth responses up to 2 Hz are calculated using an FK algorithm and the PREM velocity structure. Our preliminary analysis illustrates that with this new approach, we are able to define the lower bound of the average stress drop but fail to constrain its upper bound. The waveform misfit associated with the inverted model increases quickly as pre-assigned stress drop decreases from 3 MPa to 0.5 MPa. But the misfit varies negligibly when the pre-assigned stress drop increases from 4.0 MPa to 50 MPa. We notice that the fine

  12. Coseismic Water-Level Changes in the Same Well Induced By Teleseismic Waves of Three Huge Earthquakes

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Fu, L. Y.; Huang, F.; Chen, X.

    2014-12-01

    Three huge earthquakes (the 2007 Mw 8.4 Sumatra, the 2008 Mw 7.9 Wenchuan, and the 2011 Mw 9.0 Tohoku earthquakes) happened in recent years induce obvious coseismic water-level increases at far fields (epicentral distances >1000 km) in the Fuxin well located in the Fuxin city of Liaoning province, northeastern China (the well with the observation of both water levels and volume strains). We compare water levels and volume strains for these earthquakes. A comprehensive analysis for the mechanism of far-field coseismic water-level changes is performed by analyzing the in-situ permeability, Skempton's coefficient B, and together with the broadband seismograms from a nearby station. We find that an undrained consolidation with a decreasing permeability induced by the shaking of teleseismic waves is observed in the far field. By the in-situ observation for different earthquakes, shaking of teleseismic waves can induce consolidation or dilatation in the aquifer of Fuxin well, both of them being able to enhance permeability and thus to build a new pore-pressure equilibrium system between the Fuxin well and the nearby Sihe reservoir (150 m away from the Fuxin well). The resulting interstitial fluid flow across the region increases coseismic water levels in the aquifer of Fuxin well.

  13. Coseismic deformation of the 2011 M9 Tohoku-Oki Earthquake inverted from geodetic data using finite element models: Implications for tsunami genesis and poroelastic stress-coupling

    NASA Astrophysics Data System (ADS)

    Masterlark, T.; Grilli, S. T.; Harris, J.; Kyriakopoulos, C.; Tao, W.

    2011-12-01

    The 2011 M9 Tohoku-Oki Earthquake ruptured the boundary separating the subducting Pacific Plate from the overriding Eurasian Plate, offshore from northern Honshu, Japan. We construct three-dimensional finite element models that simulate the stiff subducting Pacific Plate and compliant forearc and moderately stiff volcanic arc of the overriding Eurasian plate, separated by an interface that follows the curvature of the Japan Trench. We estimate the coseismic slip distribution from both onshore and offshore observed displacements using linear inverse methods and Green's Functions calculated with finite element models. Preliminary results indicate the presence of significant slip (several tens of meters) along the up-dip portion of the rupture near the Japan Trench. From the standpoint of geodetic inversion, the location of this relatively shallow slip appears to be controlled by the compliant forearc materials. In contrast, corresponding slip distributions from models simulating layered or homogeneous material properties are relatively deeper along the rupture zone. Preliminary results suggest that the shallow concentrations of slip agree with tsunami wave data. Alternatively, the deeper slip of the homogeneous model under-predicts the amplitude of the tsunami and lags the wave in time. We use the coseismic slip to generate stress and pore pressure fields that serve as the initial conditions for models of postseismic poroelastic stress coupling of aftershocks within the oceanic crust of the Pacific plate and seaward from the Japan Trench. Coseismic Coulomb stress in this region increases, although the coseismic pore pressure decreases. The pore pressure then recovers via pore-fluid flow, resulting in increasing Coulomb stress during the early postseismic period. Thus, the combination of coseismic stress and postseismic relaxation is consistent with aftershock occurrence in both space and time for aftershocks seaward of the Japan Trench.

  14. Acoustic monitoring of co-seismic changes in gas bubble rupture rate in a hydrothermal reservoir: field evaluation of a possible precursor and mechanism for remote seismic triggering

    NASA Astrophysics Data System (ADS)

    Crews, J. B.

    2015-12-01

    Remotely triggered seismicity is a phenomenon in which an earthquake at one location triggers others over distances up to thousands of kilometers. The mechanism by which low-amplitude dynamic oscillations of the confining stress can produce such an effect, often after a time delay of minutes-to-days, is unclear, but a concentration of remotely triggered seismic events in carbon-dioxide-rich volcanic and geothermal regions suggests that an increase in pore fluid pressure associated with the nucleation and growth of carbon-dioxide gas bubbles may reduce the effective stress in critically loaded geologic faults. While this hypothesis has been tested in bench-scale laboratory experiments, field detection of seismically initiated gas bubble growth in groundwater may provide further evidence for this remote triggering mechanism. In the present study, a hydrophone continuously records the acoustic power spectrum in CH-10B, a hydrothermal well located in Long Valley Caldera, California - a site that is susceptible to remotely seismic triggering. This well exhibits co-seismic changes in water level in response to near and distant earthquakes, including every magnitude-six or greater at any location on Earth. Exploiting the inverse relationship between gas bubble radius and the peak acoustic frequency emitted when a gas bubble ruptures, this investigation seeks to detect changes in the acoustic power spectrum arising from a shift in the size-distribution or count rate of rupturing gas bubbles, coincident with a distant earthquake. By resolving the timing and intensity of the onset of a change in gas bubble rupture rate after the passage of seismic wave from a distant source, it may be possible to establish the extent to which seismically initiated gas bubble growth contributes to co-seismic borehole water level response, pore fluid pressure perturbations, and the onset of remotely triggered seismicity.

  15. Estimating Stresses, Fault Friction and Fluid Pressure from Topography and Coseismic Slip Models

    NASA Astrophysics Data System (ADS)

    Styron, R. H.; Hetland, E. A.

    2014-12-01

    Stress is a first-order control on the deformation state of the earth. However, stress is notoriously hard to measure, and researchers typically only estimate the directions and relative magnitudes of principal stresses, with little quantification of the uncertainties or absolute magnitude. To improve upon this, we have developed methods to constrain the full stress tensor field in a region surrounding a fault, including tectonic, topographic, and lithostatic components, as well as static friction and pore fluid pressure on the fault. Our methods are based on elastic halfspace techniques for estimating topographic stresses from a DEM, and we use a Bayesian approach to estimate accumulated tectonic stress, fluid pressure, and friction from fault geometry and slip rake, assuming Mohr-Coulomb fault mechanics. The nature of the tectonic stress inversion is such that either the stress maximum or minimum is better constrained, depending on the topography and fault deformation style. Our results from the 2008 Wenchuan event yield shear stresses from topography up to 20 MPa (normal-sinistral shear sense) and topographic normal stresses up to 80 MPa on the faults; tectonic stress had to be large enough to overcome topography to produce the observed reverse-dextral slip. Maximum tectonic stress is constrained to be >0.3 * lithostatic stress (depth-increasing), with a most likely value around 0.8, trending 90-110°E. Minimum tectonic stress is about half of maximum. Static fault friction is constrained at 0.1-0.4, and fluid pressure at 0-0.6 * total pressure on the fault. Additionally, the patterns of topographic stress and slip suggest that topographic normal stress may limit fault slip once failure has occurred. Preliminary results from the 2013 Balochistan earthquake are similar, but yield stronger constraints on the upper limits of maximum tectonic stress, as well as tight constraints on the magnitude of minimum tectonic stress and stress orientation. Work in progress on

  16. Exploring the uncertainty range of co-seismic stress drop estimations of large earthquakes using finite fault inversions

    NASA Astrophysics Data System (ADS)

    Adams, Mareike; Twardzik, Cedric; Ji, Chen

    2016-10-01

    A new finite fault inversion strategy is developed to explore the uncertainty range for the energy based average co-seismic stress drop (overline {{{Δ }}{τ_E}}) of large earthquakes. For a given earthquake, we conduct a modified finite fault inversion to find a solution that not only matches seismic and geodetic data but also has a overline {{{Δ }}{τ_E}} matching a specified value. We do the inversions for a wide range of stress drops. These results produce a trade-off curve between the misfit to the observations and overline {{{Δ }}{τ_E}} , which allows one to define the range of overline {{{Δ }}{τ_E}} that will produce an acceptable misfit. The study of the 2014 Rat Islands Mw 7.9 earthquake reveals an unexpected result: when using only teleseismic waveforms as data, the lower bound of overline {{{Δ }}{τ_E}} (5-10 MPa) for this earthquake is successfully constrained. However, the same dataset exhibits no sensitivity to its upper bound of overline {{{Δ }}{τ_E}} because there is limited resolution to the fine scale roughness of fault slip. Given that the spatial resolution of all seismic or geodetic data is limited, we can speculate that the upper bound of overline {{{Δ }}{τ_E}} cannot be constrained with them. This has consequences for the earthquake energy budget. Failing to constrain the upper bound of overline {{{Δ }}{τ_E}} leads to the conclusions that 1) the seismic radiation efficiency determined from the inverted model might be significantly overestimated; 2) the upper bound of the average fracture energy EG cannot be constrained by seismic or geodetic data. Thus, caution must be taken when investigating the characteristics of large earthquakes using the energy budget approach. Finally, searching for the lower bound of overline {{{Δ }}{τ_E}} can be used as an energy-based smoothing scheme during finite fault inversions.

  17. Aftershock triggering by complete Coulomb stress changes

    USGS Publications Warehouse

    Kilb, Debi; Gomberg, J.; Bodin, P.

    2002-01-01

    We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (??CFS(t)) that this earthquake generated. At close distances the time-varying "dynamic" portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent "static" portion (??CFS) depends only on the final coseismic displacement. ??CFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ??CFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ??CFS(t) can alter the failure rate only by the latter means. We calculate both ??CFS and the maximum positive value of ??CFS(t) (peak ??CFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ??CFS and peak ??CFS(t) and find agreement for both models. However, rupture directivity, which does not affect ??CFS, creates larger peak ??CFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ??CFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.

  18. Coseismic Ground level Changes Associated with the Great Andaman-Sumatra Earthquake: A Tour from Nicobar to North Andaman

    NASA Astrophysics Data System (ADS)

    Rajendran, K.; Rajendran, C.; Earnest, A.; Freymueller, J.

    2005-12-01

    The 26 December 2004 in the Andaman-Sumatra subduction zone led to significant ground level changes, uplift as well as subsidence of land, along the Andaman and Nicobar Islands. Falling nearly 400 km north of the epicenter of the main shock, and extending northwards, the second phase of the rupture observed in these islands account for more about two thirds of the total rupture. Ground level changes were observed along both the eastern and western margins of the islands. The western margins were generally characterized by uplift of about 1m, while the eastern margins subsided by nearly 1 m, permanently submerging many parts of these islands. Elevated beaches, uplifted coral colonies and biological markers such as mangroves, lines of barnacles on rock exposures and man-made structures provide spectacular visual effects of ground uplift. Along the western margin of the Interview Island, in the middle Andamans, we observed at least two older terraces, probably formed by the predecessors of the 2004 earthquake. In the Diglipur region, north Andaman, we observed elevation change of about 1 m, and in this part of the arc, both the western and eastern margins are characterized by uplift. Coseismic vertical offset observed from GPS data suggest a change of +0.6m at Diglipur, a region that also marks the termination of rupture in the north. Field observations conform to nearly +1m change in this region. Maximum subsidence of nearly 1.5 m was documented in Campbell Bay, Great Nicobar, and a GPS site there shows a change in elevation of -1.05m. This paper gives a short tour of the sites of ground level changes from Car Nicobar in the south to Diglipur in the North Andaman.

  19. Coseismic slip and afterslip of the 2015 Mw 8.3 Illapel (Chile) earthquake determined from continuous GPS data

    NASA Astrophysics Data System (ADS)

    Shrivastava, Mahesh N.; González, Gabriel; Moreno, Marcos; Chlieh, Mohamed; Salazar, Pablo; Reddy, C. D.; Báez, Juan Carlos; Yáñez, Gonzalo; González, Juan; Llera, Juan Carlos

    2016-10-01

    We analyzed the coseismic and early postseismic deformation of the 2015, Mw 8.3 Illapel earthquake by inverting 13 continuous GPS time series. The seismic rupture concentrated in a shallow (<20 km depth) and 100 km long asperity, which slipped up to 8 m, releasing a seismic moment of 3.6 × 1021 Nm (Mw = 8.3). After 43 days, postseismic afterslip encompassed the coseismic rupture. Afterslip concentrated in two main patches of 0.50 m between 20 and 40 km depth along the northern and southern ends of the rupture, partially overlapping the coseismic slip. Afterslip and aftershocks confined to region of positive Coulomb stress change, promoted by the coseismic slip. The early postseismic afterslip was accommodated 53% aseismically and 47% seismically by aftershocks. The Illapel earthquake rupture is confined by two low interseismic coupling zones, which coincide with two major features of the subducting Nazca Plate, the Challenger Fault Zone and Juan Fernandez Ridge.

  20. Co-seismic stress transfer and magnitude-frequency distribution due to the 2012 Varzaqan-Ahar earthquake doublets (Mw 6.5 and 6.4), NW Iran

    NASA Astrophysics Data System (ADS)

    Ansari, Shoja

    2016-12-01

    The Coulomb stress changes imparted by the 2012 Varzaqan-Ahar earthquake doublets to the surrounding area have been examined and correlated with the spatial distribution of the aftershocks. The stress changes due to the first main shock show that the western half of the South Ahar Fault, the southeastern half of the magnetic lineament ML1, the northeastern end of the ML2, the entire length of the ML3, a large part of the ML4 and the northeastern half of the ML5 were brought closer to failure. Whereas the entire length of the Khajeh Fault, a part of the North Tabriz Fault, the western half of the ML1, a large part of the ML2, the northwestern end of the ML4 and the southwestern half of the ML5 were moved away from failure. Along the length of the ML1, some aftershocks were clustered in the southeastern and central sections, while around the western section there is no earthquake clustering. The epicentral distributions of the aftershocks exhibit that most of the events were concentrated in the increased Coulomb stress zones. The b-value distributions in the map view and in the cross-sectional view have been investigated. The map view shows that the low b-value regions (e.g., the north-northwest, east-northeast and southeast of the main shock) are in good agreement with the positive Coulomb stress change zones. The cross-sectional view indicates that the high b-value regions correlate with the areas of high co-seismic slip release. Therefore, surrounding the hypocenter and the western end of the first main shock fault have high b-values, more slip and positive stress drop, while the central sections of the fault have low b-values, less slip and negative stress drop.

  1. Coseismic and postseismic velocity changes detected by Passive Image Interferometry: Comparison of five strong earthquakes (magnitudes 6.6 - 6.9) and one great earthquake (magnitude 9.0) in Japan

    NASA Astrophysics Data System (ADS)

    Hobiger, Manuel; Wegler, Ulrich; Shiomi, Katsuhiko; Nakahara, Hisashi

    2015-04-01

    We analyzed ambient seismic noise near five strong onshore crustal earthquakes in Japan as well as for the great Tohoku offshore earthquake. Green's functions were computed for station pairs (cross-correlations) as well as for different components of a single station (single-station cross-correlations) using a filter bank of five different bandpass filters between 0.125 Hz and 4 Hz. Noise correlations for different time periods were treated as repeated measurements and coda wave interferometry was applied to estimate coseismic as well as postseismic velocity changes. We used all possible component combinations and analyzed periods from a minimum of 3.5 years (Iwate region) up to 8.25 years (Niigata region). Generally, the single-station cross-correlation and station pair cross-correlation show similar results, but the single station method is more reliable for higher frequencies (f > 0.5 Hz), whereas the station pair method is more reliable for lower frequencies (f < 0.5 Hz). For all six earthquakes we found a similar behavior of the velocity change curve as a function of time. We observe coseismic velocity drops at the times of the respective earthquakes followed by postseismic recovery for all earthquakes. Additionally, most stations show a seasonal velocity variation. This seasonal variation was removed by a curve fitting and velocity changes of tectonic origin only were analyzed in our study. The postseismic velocity changes can be described by an exponential recovery model, where for all areas about half of the coseismic velocity drops recover on a time scale of the order of half a year. The other half of the coseismic velocity drops remain as a permanent change. The coseismic velocity drops are stronger at larger frequencies for all earthquakes. We assume that these changes are concentrated in the superficial layers but for some stations can also reach a few kilometers of depth. The coseismic velocity drops for the strong earthquakes (magnitudes 6.6 - 6

  2. Correlation of Coseismic Velocity and Static Volumetric Strain Changes Induced by the 2010 Mw6.3 Jiasian Earthquake under the Southern Taiwan Orogenic Belt

    NASA Astrophysics Data System (ADS)

    Wu, S. M.; Hung, S. H.

    2015-12-01

    Earthquake-induced temporal changes in seismic velocity of the earth's crust have been demonstrated to be monitored effectively by the time-lapse shifts of coda waves recently. Velocity drop during the coseismic rupture has been explicitly observed in proximity to the epicenters of large earthquakes with different styles of faulting. The origin of such sudden perturbation in crustal properties is closely related to the damage and/or volumetric strain change influenced by seismic slip distribution. In this study, we apply a coda wave interferometry method to investigate potential velocity change in both space and time related to the moderate-sized (Mw6.3) 2010 Jiasian earthquake, which nucleated deeply in the crust (~23 km), ruptured and terminated around the depth of 10 km along a previously unidentified blind thrust fault near the lithotectonic boundary of the southern Taiwan orogenic belt. To decipher the surface and crustal response to this relatively deep rupture, we first measure relative time-lapse changes of coda between different short-term time frames spanning one year covering the pre- and post-seismic stages by using the Moving Window Cross Spectral Method. Rather than determining temporal velocity variations based on a long-term reference stack, we conduct a Bayesian least-squares inversion to obtain the optimal estimates by minimizing the inconsistency between the relative time-lapse shifts of individual short-term stacks. The results show the statistically significant velocity reduction immediately after the mainshock, which is most pronounced at the pairs with the interstation paths traversing through the hanging-wall block of the ruptured fault. The sensitivity of surface wave coda arrivals mainly in the periods of 3-5 s to shear wave speed perturbation is confined within the depth of 10 km, where the crust mostly experienced extensional strain changes induced by the slip distribution from the finite-fault model. Compared with coseismic slip

  3. The Relationship Between Coseismic and Postseismic Deformation Associated with the 2010 Mw 8.8 Maule, Chile Earthquake

    NASA Astrophysics Data System (ADS)

    Lin, Y. N.; Simons, M.; Sladen, A.; Ortega Culaciati, F. H.; Avouac, J.; Brooks, B. A.; Fielding, E. J.; Minson, S. E.; Bevis, M. G.

    2011-12-01

    Observations of coseismic and postseismic deformation associated with large megathrust earthquakes probe the frictional properties and states of stress along a subduction interface. The 2010 Mw 8.8 Maule earthquake in south-central Chile, together with the 1835 Concepción earthquake and the 1960 Valdivia earthquake, provide key constraints on the distribution of seismogenic asperities and apparent barriers. The Arauco Peninsula appears to be a barrier between the 1835 and 2010 event in the north and the 1960 event in the south. To explore the relationship between coseismic and postseismic deformation from the Maule earthquake, we carry out forward and inverse models constrained using GPS and InSAR data to estimate the spatial and temporal evolution of afterslip. We find two major regions of post-seismic slip down-dip of the regions that slipped during the earthquake. The northern patch near Constitución, extends along strike and encircles the coseismic slip patch along the northern and downdip edges. Most of the postseismic slip in this section occurs from 45 km to 65 km depth. A southern region of afterslip extends downdip of the coseismic slip patch beneath the Arauco Peninsula to as deep as 90 km. Aftershocks are distributed along the borders between the patches that slip coseismically and postseismically. These two patches show different temporal behavior, reflecting along-strike changes of frictional properties on the megathrust. Our models for the Arauco Peninsula find ~3 m coseismic uplift, followed by 0.1 m gradual postseismic subsidence within the first six months. By correlating the deformation and uplift of the peninsula with coseismic and postseismic slip distribution, we explore the linkage between the seismic cycles and peninsula building as well as determine the long-term spatial stability of the seismic barrier under Arauco.

  4. SAR Interferometry and Optical Image Changes of Kachchh, India: Applications to the 26 January 2001 Earthquake Geomorphology and Co-seismic Strain*

    NASA Astrophysics Data System (ADS)

    Fielding, E. J.; Bilham, R.; Rogez, F.; Hensley, S.; Rosen, P. A.; Mueller, K.

    2001-05-01

    Digital topographic data, usually called a digital elevation model or DEM, is valuable both for quantifying the tectonic geomorphology of active faults and for processing co-seismic interferograms. A preliminary DEM has been produced from data acquired by the Shuttle Radar Topography Mission (SRTM) in February 2000. The simultaneous interferometry of the SRTM avoids the atmospheric changes that bedevil uses of repeat-pass interferometry for DEM production. A mosaic of four SRTM swaths was used to better cover the Kachchh area at a grid spacing of 30 meters. The system is not fully calibrated yet, but the DEM allows the identification and measurement of extended elevation features with heights less than 10 m, although individual spot heights have greater variation. One early result is the identification of the Allah Bund, the low ridge uplifted by the 1819 M=7.7 earthquake in the northwest Rann of Kachchh, despite the substantial erosion that has occurred in the last 182 years. The remaining Allah Bund has a height of 3-6 meters. Other small topographic features may be related to other faults, possibly the fault activated in 2001. Optical images of the Kachchh area taken before and after the earthquake also provide valuable information on changes resulting from the event. The most dramatic changes are the numerous areas of liquefaction in the salt flats of the Rann where water, mud and sand were forced to the surface. Many, but not all, of the liquefaction features appeared along former river channels that were buried beneath the salt flats. These features are visible on Landsat 7, SPOT, and MISR imagery. Satellite image offsets at the sub-pixel level can also be used to measure co-seismic deformation of the surface, but the effects of topography must be removed. Differential SAR interferometry, if it becomes available for this earthquake, is also sensitive to topography. The SRTM DEM will be valuable for removing topographic signals from these data. * Portions of

  5. Slip to Trench: Coseismic, Postseismic, or Interseismic?

    NASA Astrophysics Data System (ADS)

    Sun, T.; Wang, K.; Davis, E. E.; Fujiwara, T.; Kodaira, S.; He, J.

    2015-12-01

    It is poorly known whether the shallow parts of subduction megathrust faults commonly weaken in great earthquakes to cause coseismic slip to trench, or strengthen to resist coseismic slip but slip to trench afterwards. The 2011 M 9.0 Tohoku-oki earthquake offers an example of coseismic slip to trench. Comparison of high-resolution bathymetry data collected over the Japan Trench before and after the earthquake shows an overall seafloor uplift of ~ 10-20 m landward of the trench. By modeling the bathymetry change, we determine a coseismic fault slip up to ~ 60 m at the trench. In comparison, GPS displacements recorded on the near-trench (~ 60 km) islands after the 2005 M 8.7 Nias, Sumatra, earthquake suggest large shallow afterslip, although coseismic slip at the trench cannot be resolved. The 2012 M 7.6 Nicoya, Costa Rica, earthquake provides an unambiguous example for slip to trench only after the earthquake. The difference in seafloor pressures observed at sites < 1 km apart on the seaward and landward sides of the thrust outcrop did not show any change during the earthquake, indicating no coseismic slip to trench; only afterwards did pressure differences indicate gradual uplift of the prism toe relative to the incoming plate, suggesting afterslip reaching the trench. Finally, at Nankai, occurrences of very-low-frequency earthquakes at shallow depths (< 10 km below seafloor) and concurrent borehole pressure transients near the trench suggest that episodic slip to trench occurs well into the interseismic interval there. These observations showing distinctly different shallow fault behaviour raise several questions: What factors control the behaviour of the shallow fault? Is the shallow fault behaviour margin-dependent? Can the same shallow fault behave differently in different earthquakes? We speculate that earthquake size and the amount of slip play dominant roles. The shallow megathrust tends to exhibit rate-strengthening at low slip rates and resists seismic

  6. Is the co-seismic slip distribution fractal?

    NASA Astrophysics Data System (ADS)

    Milliner, Christopher; Sammis, Charles; Allam, Amir; Dolan, James

    2015-04-01

    Co-seismic along-strike slip heterogeneity is widely observed for many surface-rupturing earthquakes as revealed by field and high-resolution geodetic methods. However, this co-seismic slip variability is currently a poorly understood phenomenon. Key unanswered questions include: What are the characteristics and underlying causes of along-strike slip variability? Do the properties of slip variability change from fault-to-fault, along-strike or at different scales? We cross-correlate optical, pre- and post-event air photos using the program COSI-Corr to measure the near-field, surface deformation pattern of the 1992 Mw 7.3 Landers and 1999 Mw 7.1 Hector Mine earthquakes in high-resolution. We produce the co-seismic slip profiles of both events from over 1,000 displacement measurements and observe consistent along-strike slip variability. Although the observed slip heterogeneity seems apparently complex and disordered, a spectral analysis reveals that the slip distributions are indeed self-affine fractal i.e., slip exhibits a consistent degree of irregularity at all observable length scales, with a 'short-memory' and is not random. We find a fractal dimension of 1.58 and 1.75 for the Landers and Hector Mine earthquakes, respectively, indicating that slip is more heterogeneous for the Hector Mine event. Fractal slip is consistent with both dynamic and quasi-static numerical simulations that use non-planar faults, which in turn causes heterogeneous along-strike stress, and we attribute the observed fractal slip to fault surfaces of fractal roughness. As fault surfaces are known to smooth over geologic time due to abrasional wear and fracturing, we also test whether the fractal properties of slip distributions alters between earthquakes from immature to mature fault systems. We will present results that test this hypothesis by using the optical image correlation technique to measure historic, co-seismic slip distributions of earthquakes from structurally mature, large

  7. The spatial distribution of earthquake stress rotations following large subduction zone earthquakes

    NASA Astrophysics Data System (ADS)

    Hardebeck, Jeanne L.

    2017-05-01

    Rotations of the principal stress axes due to great subduction zone earthquakes have been used to infer low differential stress and near-complete stress drop. The spatial distribution of coseismic and postseismic stress rotation as a function of depth and along-strike distance is explored for three recent M ≥ 8.8 subduction megathrust earthquakes. In the down-dip direction, the largest coseismic stress rotations are found just above the Moho depth of the overriding plate. This zone has been identified as hosting large patches of large slip in great earthquakes, based on the lack of high-frequency radiated energy. The large continuous slip patches may facilitate near-complete stress drop. There is seismological evidence for high fluid pressures in the subducted slab around the Moho depth of the overriding plate, suggesting low differential stress levels in this zone due to high fluid pressure, also facilitating stress rotations. The coseismic stress rotations have similar along-strike extent as the mainshock rupture. Postseismic stress rotations tend to occur in the same locations as the coseismic stress rotations, probably due to the very low remaining differential stress following the near-complete coseismic stress drop. The spatial complexity of the observed stress changes suggests that an analytical solution for finding the differential stress from the coseismic stress rotation may be overly simplistic, and that modeling of the full spatial distribution of the mainshock static stress changes is necessary.[Figure not available: see fulltext.

  8. The spatial distribution of earthquake stress rotations following large subduction zone earthquakes

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2017-01-01

    Rotations of the principal stress axes due to great subduction zone earthquakes have been used to infer low differential stress and near-complete stress drop. The spatial distribution of coseismic and postseismic stress rotation as a function of depth and along-strike distance is explored for three recent M ≥ 8.8 subduction megathrust earthquakes. In the down-dip direction, the largest coseismic stress rotations are found just above the Moho depth of the overriding plate. This zone has been identified as hosting large patches of large slip in great earthquakes, based on the lack of high-frequency radiated energy. The large continuous slip patches may facilitate near-complete stress drop. There is seismological evidence for high fluid pressures in the subducted slab around the Moho depth of the overriding plate, suggesting low differential stress levels in this zone due to high fluid pressure, also facilitating stress rotations. The coseismic stress rotations have similar along-strike extent as the mainshock rupture. Postseismic stress rotations tend to occur in the same locations as the coseismic stress rotations, probably due to the very low remaining differential stress following the near-complete coseismic stress drop. The spatial complexity of the observed stress changes suggests that an analytical solution for finding the differential stress from the coseismic stress rotation may be overly simplistic, and that modeling of the full spatial distribution of the mainshock static stress changes is necessary.

  9. Necessity of using heterogeneous ellipsoidal Earth model with terrain to calculate co-seismic effect

    NASA Astrophysics Data System (ADS)

    Cheng, Huihong; Zhang, Bei; Zhang, Huai; Huang, Luyuan; Qu, Wulin; Shi, Yaolin

    2016-04-01

    Co-seismic deformation and stress changes, which reflect the elasticity of the earth, are very important in the earthquake dynamics, and also to other issues, such as the evaluation of the seismic risk, fracture process and triggering of earthquake. Lots of scholars have researched the dislocation theory and co-seismic deformation and obtained the half-space homogeneous model, half-space stratified model, spherical stratified model, and so on. Especially, models of Okada (1992) and Wang (2003, 2006) are widely applied in the research of calculating co-seismic and post-seismic effects. However, since both semi-infinite space model and layered model do not take the role of the earth curvature or heterogeneity or topography into consideration, there are large errors in calculating the co-seismic displacement of a great earthquake in its impacted area. Meanwhile, the computational methods of calculating the co-seismic strain and stress are different between spherical model and plane model. Here, we adopted the finite element method which could well deal with the complex characteristics (such as anisotropy, discontinuities) of rock and different conditions. We use the mash adaptive technique to automatically encrypt the mesh at the fault and adopt the equivalent volume force replace the dislocation source, which can avoid the difficulty in handling discontinuity surface with conventional (Zhang et al., 2015). We constructed an earth model that included earth's layered structure and curvature, the upper boundary was set as a free surface and the core-mantle boundary was set under buoyancy forces. Firstly, based on the precision requirement, we take a testing model - - a strike-slip fault (the length of fault is 500km and the width is 50km, and the slippage is 10m) for example. Because of the curvature of the Earth, some errors certainly occur in plane coordinates just as previous studies (Dong et al., 2014; Sun et al., 2012). However, we also found that: 1) the co-seismic

  10. Thermo-Chemical Pressurization of Fault Gouges During Coseismic Slip

    NASA Astrophysics Data System (ADS)

    Brantut, N.; Schubnel, A.; Corvisier, J.

    2008-12-01

    This work deals with thermo-hydro-mechanical couplings within fault gouges during coseismic slip, including effects of possible thermal dehydration of hydrous minerals. The framework of thermal pressurization of pore fluid is extend to include the dehydration effect as a source term for pore pressure and a sink for temperature. The dehydration kinetics is modelled by a first order reaction rate which is bounded by the ratio between heating rate and the reaction enthalpy variation. We first solve analytically the equations in the case of no fluid and heat transport and with a constant reaction rate. It shows that the dehydration reaction, if the rate constant is of the order of 1~s-1, induces a pore pressure increase that can grow beyond the normal stress apllied on the fault. At the same time, the temperature slightly decreases as the reaction progresses. If the kinetics is calculated from the ratio between frictional heating and enthalpy variation, the temperature is kept constant during the reaction, and the pore pressure increases asymptotically to the normal stress. This corresponds to a transient equilibrium where the pressurization is maintained by the mineral reaction. Then we model the phenomenon more precisely by taking into account transport of fluid and heat and we use an Arrhenius law to calculate the rate constant as function of temperature. The overall behaviour of the system is characterized by a sudden increase of pore pressure and an almost constant temperature as the reaction starts. The parameters values are then discussed, showing that overpressures can occur for low reaction temperatures, low enthalpy change, deep faults and/or thick slipping zones. It shows that dehydration is an effective mechanism for delaying or preventing melting during coseismic slip, if the mass fraction of released water is larger than ~ 1%.

  11. A World That Includes Both Dynamic and Static Stress Changes

    NASA Astrophysics Data System (ADS)

    Harris, R.

    2009-12-01

    Earthquake scientists have been calculating static stress changes due to earthquakes and fault interaction for at least 40 years. Dynamic stress change calculations have a shorter history, but have still been computed for at least the past 24 years, although the original contributions to this literature are often forgotten. The early promoters of dynamic stress changes viewed a seamless transition from dynamic to static fields as time progresses. However, new studies sometimes propose a disconnect from this holistic view. Distant, far-field triggering of earthquakes appears proven to have occurred for a number of large earthquakes (e.g., Hill et al., 1993; Gomberg et al., 2004). Remote triggering can only occur dynamically, since the static far-field effect is too small. In contrast, near-field triggering has a range of options, from coseismic to postseismic processes. One risk that we take if we eliminate the near-field static effects (e.g., Simpson and Reasenberg, 1992, Stein et al., 1992, King et al., 1994) is that we also eliminate stress relaxation, and thereby, stress shadows (Harris and Simpson, 1993; 1996; 1998). A world without stress shadows leads to a revamping of our hypotheses about earthquake recurrence probabilities at the very least (e.g., Parsons, 2008), in addition to a complete rewrite of our understanding about how faults and large earthquakes operate in tectonically active areas, starting with Reid's (1910) elastic rebound hypothesis. Similarly, eliminating the hypothesis of near-field dynamic triggering has ramifications. A world without near-field dynamic triggering implies that large earthquakes are not dynamic cascade events, but are instead a random collection of slip in space and time, the latter of which is not the view presented by seismic inversion results to date. Dynamic and static stress changes both act, not separately, but instead as a seamless transition from one to the other. It is through this holistic view that we can learn

  12. Postseismic Coulomb stress changes on intra-continental dip-slip faults due to viscoelastic relaxation in the lower crust and lithospheric mantle: insights from 3D finite-element modelling

    NASA Astrophysics Data System (ADS)

    Bagge, Meike; Hampel, Andrea

    2017-03-01

    Earthquakes in the brittle upper crust induce viscoelastic flow in the lower crust and lithospheric mantle, which can persist for decades and lead to significant Coulomb stress changes on receiver faults located in the surrounding of the source fault. As most previous studies calculated the Coulomb stress changes for a specific earthquake in nature, a general investigation of postseismic Coulomb stress changes independent of local geological conditions is still lacking for intra-continental dip-slip faults. Here we use finite-element models with normal and thrust fault arrays, respectively, to show that postseismic viscoelastic flow considerably modifies the original coseismic Coulomb stress patterns through space and time. Depending on the position of the receiver fault relative to the source fault, areas with negative coseismic stress changes may exhibit positive postseismic stress changes and vice versa. The lower the viscosity of the lower crust or lithospheric mantle, the more pronounced are the transient stress changes in the 1st years, with the lowest viscosity having the largest effect on the stress changes. The evolution of postseismic Coulomb stress changes is further controlled by the superposition of transient stress changes caused by viscoelastic relaxation (leading to stress increase or decrease) and the interseismic strain accumulation (leading to a stress increase). Stress changes induced by viscoelastic relaxation can outweigh the interseismic stress increase such that negative Coulomb stress changes can persist for decades. On some faults, postseismic relaxation and interseismic strain accumulation can act in concert to enhance already positive Coulomb stress changes.

  13. Stress changes from the 2008 Wenchuan earthquake and increased hazard in the Sichuan basin.

    PubMed

    Parsons, Tom; Ji, Chen; Kirby, Eric

    2008-07-24

    On 12 May 2008, the devastating magnitude 7.9 (Wenchuan) earthquake struck the eastern edge of the Tibetan plateau, collapsing buildings and killing thousands in major cities aligned along the western Sichuan basin in China. After such a large-magnitude earthquake, rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. The mainshock of the 12 May earthquake ruptured with as much as 9 m of slip along the boundary between the Longmen Shan and Sichuan basin, and demonstrated the complex strike-slip and thrust motion that characterizes the region. The Sichuan basin and surroundings are also crossed by other active strike-slip and thrust faults. Here we present calculations of the coseismic stress changes that resulted from the 12 May event using models of those faults, and show that many indicate significant stress increases. Rapid mapping of such stress changes can help to locate fault sections with relatively higher odds of producing large aftershocks.

  14. Recordings of the 2004 Parkfield Earthquake on the General Earthquake Observation System Array: Implications for Earthquake Precursors, Fault Rupture, and Coseismic Strain Changes

    USGS Publications Warehouse

    Borcherdt, R.D.; Johnston, M.J.S.; Glassmoyer, G.; Dietel, C.

    2006-01-01

    The 2004 Parkfield earthquake generated a unique set of near-field, high-resolution colocated measurements of acceleration, volumetric strain, and velocity at 11 stations in the General Earthquake Observation System (GEOS) array. The recordings indicate no precursory strain or displacement was discernable at sensitivities of 10-11 strain and 5 ?? 10 -8 m 25 sec prior to the earthquake at distances of 0.5 to 12 km of fault rupture. Coherent fault-parallel and fault-normal displacement pulses, observed along the fault north of the epicenter, are consistent with model predictions for "fling," directivity, and displacement for right-lateral, strike-slip fault rupture. The fault-parallel and fault-normal pulses imply apparent rupture velocities of 2.86 ?? 0.15 and 3.03 ?? 0.24 km/sec, respectively. Unprecedented high-resolution volumetric-strain recordings on opposite sides of the fault show that dynamic strains radiated from ruptured segments of the fault are more than an order of magnitude larger than final coseismic strain offsets associated with fault slip, suggesting that dynamic radiated strain may have contributed to the triggering of failure on unruptured segments. High-resolution recordings show that coseismic strain offsets occur abruptly over time intervals of less than 10 sec near the time of arrival of the dominant radiated fault-parallel and fault-normal displacements. Subsequent measurements show that the strain offsets continue to increase by as much as 69% in 5 min and 300% in 24 hr over that measured during initial fault slip at depth. Estimates of local material parameters from simultaneous measurements of volumetric strain and acceleration confirm seismic calibration factors previously measurable in situ only at tidal periods.

  15. Smectite-illite transition during coseismic slip

    NASA Astrophysics Data System (ADS)

    Takahashi, M.; Kitajima, H.

    2013-12-01

    Few evidences for coseismic slip events are preserved in natural fault rocks except pseudotachylytes showing a clear evidence of melting caused by frictional shear at high slip rates [e.g., Spray, 1987; Tsutsumi and Shimamoto, 1997; Hirose and Shimamoto, 2005]. Higher maturity of vitrinite of coal fragments is observed in the fault cores recovered from the Nankai accretionary prism [Sakaguchi eta al., 2011], and also in the friction experiments sheared at seismic slip rates [Kitamura et al., 2012], implying that local heating is caused by frictional shear during earthquakes. Another possible evidence for coseismic slip is illitization of smectite clay along faults observed in the present and ancient accretionary prisms [Yamaguchi et al., 2011; Kameda et al., 2013]. Kameda et al. [2013] have estimated the fault activity using the kinetics of smectite-illite transition, which is determined in the studies on long-term diagenetic processes of smectite-illite transition and may not be appropriate for the short-tem reaction caused by frictional heating associated with coseismic slip. Here we report on high-speed friction experiments on synthetic smectite-quartz mixtures. The goals of our experiments are: (1) to reproduce the illitization of smectite clay (Na-montmorillonite) during coseismic shear and (2) to obtain better kinetic parameters to estimate the fault activity of coseismic slip. The friction experiments were conducted on the rotary-shear apparatus at AIST. One gram of the synthetic gouge of smectite-quartz (70:30 wt.%) mixture was sheared at slip velocity of 1.3 m/s, normal stress of 1 MPa, and up to displacement of 55 m. Because cation exchange between sodium ion in smectite and potassium ion in fluid is required for the illitization, we used gouge samples dampened with two different pore fluid media: (1) 1 mol/L aqueous solution of potassium chloride (KCl) and (2) pure water. Friction coefficient of the gouge sheared with potassium rich fluid is 0.45 at peak

  16. Stress changes along the Sunda trench following the 26 December 2004 Sumatra-Andaman and 28 March 2005 Nias earthquakes

    USGS Publications Warehouse

    Pollitz, F.F.; Banerjee, P.; Burgmann, R.; Hashimoto, M.; Choosakul, N.

    2006-01-01

    The 26 December 2004 Mw = 9.2 and 28 March 2005 Mw = 8.7 earthquakes on the Sumatra megathrust altered the state of stress over a large region surrounding the earthquakes. We evaluate the stress changes associated with coseismic and postseismic deformation following these two large events, focusing on postseismic deformation that is driven by viscoelastic relaxation of a low-viscosity asthenosphere. Under Coulomb failure stress (CFS) theory, the December 2004 event increased CFS on the future hypocentral zone of the March 2005 event by about 0.25 bar, with little or no contribution from viscous relaxation. Coseismic stresses around the rupture zones of the 1797 and 1833 Sunda trench events are negligible, but postseismic stress perturbations since December 2004 are predicted to result in CFS increases of 0.1 to 0.2 bar around these rupture zones between 2 and 8 years after the December 2004 event. These are considerable stress perturbations given that the 1797 and 1833 rupture zones are likely approaching the end of a complete seismic cycle. Copyright 2006 by the American Geophysical Union.

  17. Geomorphic Evidence of Coseismic Coastline Changes in Southern Miura Peninsula Associated with the Recent Kanto Earthquakes: Analysis of the LIDAR Data, air Photos and Topo Maps

    NASA Astrophysics Data System (ADS)

    Kim, H.; Kumaki, Y.; Satake, K.

    2011-12-01

    In order to study geomorphic evidence related to the past Kanto earthquakes, we analyzed LIDAR data, air photos and topographical maps, and traced uplifted marine terraces during the recent earthquakes including the 1923 and 1703 earthquakes. Tokyo Metropolitan Area's well-documented earthquake history is dominated by the 1703 and 1923 great Kanto earthquakes, that were resulted from the subducting Philippine Sea plate. Around the source region of the past Kanto earthquakes, Miura and Boso Peninsulas are located facing the Sagami Bay. The average recurrence interval of Kanto earthquake has been estimated on basis of the seismological, geodetic, geological and gemorophological data. The Earthquake Research Committee [2004] proposed that there are types of earthquakes with the recurrence intervals of 200-400 years, and about 2300 years. They produced different amounts of uplift at Boso Peninsula, but the uplifts of Miura Peninsula are similar. The uplift amounts of Miura Peninsula have been estimated about 1.5 m in 1923 and 1703, from the wave-cut-benches, -notches and the distribution of fossil remains along the coast [Matsuda et al. (1978), Shishikura et al. (2007)]. The coastline just before the 1923 earthquakes can be restored from the old topographical map. By using it, the coseismic uplifts associated with the 1923 and 1703 earthquakes may be more accurately estimated. The air photos we used are by 1946 U.S. forces photography and 1963/1966 Geographical Survey Institute photography; the topographical maps are 1:25,000 topographical maps measured in 1921 and 1:20,000 topographical maps of the Meiji period. In addition, we made a high-density (50 cm mesh) digital elevations map by aerial measurements of the Light Detection and Ranging (LIDAR). In Miura Peninsula, three additional steps of marine terrace surface are formed at 7 to 20 m above MSL, at ~5200,~3300 and ~1500 cal. BC, and these are called Nobi 1, 2 and 3 in order from top [Kumaki, 1985; 14C Age was

  18. Dependence of b-value on Depth, Co-Seismic Slip, and Time for Large Magnitude Earthquakes

    NASA Astrophysics Data System (ADS)

    Aiken, J. M.; Uchide, T.; Schorlemmer, D.

    2016-12-01

    Spatial and temporal variations in parameters of earthquake sources and seismicity will be a key to understand the status of faults such as applied stress and fault strength and hence the potential of earthquake occurrence. Recent studies have shown that the b-value of the Gutenberg-Richter relationship decreases before large magnitude events for timescales of five years or more. In addition, large co-seismic slip values have been found to occur in extremely low b-value regions, e.g., the 2011 Tohoku-oki earthquake [Nanjo, et. al. 2012]. A comprehensive understanding requires us to explore the relationship between depth, co-seismic slip of a large earthquake, time, and b-value for large magnitude events occurring in different tectonic environments (oceanic and in-land). Here we present the relationship between co-seismic slip and b-values prior to several large magnitude events in Japan, e.g., the 2003 M8.3 Tokachi-oki earthquake near Hokkaido, using the Japan Meteorological Agency (JMA) earthquake catalog. We calculated the b-values at three-dimensionally distributed grids using the maximum likelihood estimation method and the reported JMA magnitude of completeness. We examined the cross section of depth, co-seismic slip, and time with the calculated b-values to investigate whether a common behavior exists prior to large events by comparing our results to the case of the 2011 Tohoku-oki earthquake, and consequently study what causes the change in b-value.

  19. The Uncertainty Range of Co-Seismic Stress Drop of Large Earthquakes and an Energy-Based Smoothing Constraint during Finite Fault Inversions

    NASA Astrophysics Data System (ADS)

    Adams, M.; Hao, J.; Twardzik, C.; Ji, C.

    2016-12-01

    The large uncertainties of some basic earthquake source parameters, such as average stress drop (Cotton et al., 2013), are largely caused by over-simplifications of the source (e.g., Madariaga, 1979). In contrast, the results of finite fault source inversions suffer from the uncertainties caused by over-parameterization. Hundreds of free parameters are often used to represent spatiotemporal rupture history, despite the fact that not all of them are well constrained by the available observations. The uncertainties of individual sub-fault parameters are often difficult to access because they are not only caused by the limited data but also the regularizations applied to stabilize the inversions. We develop a new finite fault inversion strategy to explore the uncertainty range for the energy based average stress drop (ΔτE) of large earthquakes. For a given earthquake, a series of modified finite fault inversions are conducted to search for the solution that not only best fits seismic and geodetic data but also has a ΔτE matching a given value. It results in a trade-off curve between the misfit to the observations and ΔτE, allowing the range of ΔτE constrained by the given geophysical dataset to be robustly defined. Our initial study of the 2014 Mw7.9 Rat Islands earthquake using teleseismic data revealed that only the lower bound of ΔτE could be constrained with far field seismic data (Adams et al., 2016). To investigate whether such a conclusion also holds for near field data, the slip distribution and ΔτE of the 2015 Mw7.9 Gorkha, Nepal earthquake is studied using near-source geodetic data. Our result reveals a similar pattern that the misfit gradually improves when the target ΔτE increases from 0.5 to 8 MPa; but becomes nearly constant from 10 MPa to 50 MPa. Hence, only the lower bound ( 8-10 MPa) of ΔτE can be constrained, even with such a comprehensive geodetic dataset. As ΔτE is proportional to the available seismic energy, our results imply

  20. Coseismic and postseismic slip of the 2006 Kiholo Bay earthquake in Hawaii from GPS data

    NASA Astrophysics Data System (ADS)

    Aryal, A.; Smith-Konter, B. R.; Foster, J. H.

    2014-12-01

    On October 15th 2006, two large earthquakes (Kiholo Bay, M­­w = 6.7 and Mahukona, M­­w = 6.0) occurred below the northwest coast of the Big Island of Hawaii in a region that has not been typically associated with large earthquakes. While the 2006 earthquakes occurred only ~28 km and six minutes apart in space and time, their distinct focal mechanisms and source depths (~40 km and 20 km, respectively) suggest an interesting main shock-aftershock association. These two mantle (non-volcanic) earthquakes in Hawaii provide a rare opportunity to investigate lithospheric stresses associated with long-term flexural loading. Here, we use GPS observations and a semi-analytic dislocation model to estimate the co-seismic and post-seismic slip of these two events. For the Kiholo Bay event, we find that 0.5 m of net slip, occurring between 39 - 51 km depth on a nearly 30 km east-west striking fault that dips south at 45°, fits the data well with an RMS residual of 0.87 mm (~10 % of the observed maximum surface displacement). This geodetically estimated fault attitude matches with one of the nodal planes in the Global CMT catalog. Furthermore, positive Coulomb stress changes are predicted in the Mahukona source region due to the Kiholo Bay mainshock, suggesting an elastic stress triggering relationship. GPS time-series data will be used to investigate possible postseismic viscoelastic relaxation by mantle flow in response to these coseismic stress changes.

  1. Factors that affect coseismic folds in an overburden layer

    NASA Astrophysics Data System (ADS)

    Zeng, Shaogang; Cai, Yongen

    2016-12-01

    Coseismic folds induced by blind thrust faults have been observed in many earthquake zones, and they have received widespread attention from geologists and geophysicists. Numerous studies have been conducted regarding fold kinematics; however, few have studied fold dynamics quantitatively. In this paper, we establish a conceptual model with a thrust fault zone and tectonic stress load to study the factors that affect coseismic folds and their formation mechanisms using the finite element method. The numerical results show that the fault dip angle is a key factor that controls folding. The greater the dip angle is, the steeper the fold slope. The second most important factor is the overburden thickness. The thicker the overburden is, the more gradual the fold. In this case, folds are difficult to identify in field surveys. Therefore, if a fold can be easily identified with the naked eye, the overburden is likely shallow. The least important factors are the mechanical parameters of the overburden. The larger the Young's modulus of the overburden is, the smaller the displacement of the fold and the fold slope. Strong horizontal compression and vertical extension in the overburden near the fault zone are the main mechanisms that form coseismic folds.

  2. Coulomb stress change for the normal-fault aftershocks triggered near the Japan Trench by the 2011 M w 9.0 Tohoku-Oki earthquake

    NASA Astrophysics Data System (ADS)

    Sato, Tamao; Hiratsuka, Shinya; Mori, Jim

    2012-12-01

    Coulomb stress triggering is examined using well-determined aftershock focal mechanisms and source models of the 2011 M w 9.0 off the Pacific coast of Tohoku Earthquake. We tested several slip distributions obtained by inverting onshore GPS-derived coseismic displacements under different a priori constraints on the initial fault parameters. The aftershock focal mechanisms are most consistent with the Coulomb stress change calculated for a slip distribution having a center of slip close to the trench. This demonstrates the capability of the Coulomb stress change to help constrain the slip distribution that is otherwise difficult to determine. Coulomb stress changes for normal-fault aftershocks near the Japan Trench are found to be strongly dependent on the slip on the shallow portion of the fault. This fact suggests the possibility that the slip on the shallow portion of the fault can be better constrained by combining information of the Coulomb stress change with other available data. The case of normal-fault aftershocks near some trench segment which are calculated to be negatively stressed shows such an example, suggesting that the actual slip on the shallow portion of the fault is larger than that inverted from GPS-derived coseismic displacements.

  3. [Stress in a changing society].

    PubMed

    Artazcoz, Lucía; Escribà-Agüir, Vicenta; Cortès, Imma

    2006-03-01

    The objective of this study is to describe the job stress models and non-work stressors, their influence on health and magnitude in Spain. Data come from scientific publications, reports and official statistics, primarily of the last decade. Moreover, original data are provided from the analysis of the 5th Spanish Working Conditions Survey. Job stress analysis is based on two complementary models, that based on psychological demands, control and social support (Karaseks model) and another based on the effort-reward unbalance (Siegrists model). In Spain 15% of men and 22% of women have had an excessive workload that have made them feel tired in the last three months. A quarter of workers have low autonomy and 48% of men and 32% of women work in occupations that do not require special abilities, just experience. Moreover, Spain has the highest unemployment and temporary contracts rates in the 15-European Union. The entrance of women into the labour market implies difficulties in reconciling job and family life. Moreover, paid work provides women with power and economic autonomy, therefore making possible the divorce that has significantly increased in Spain as well as the lonely parents families, these being difficult and stressing situations. Additionally the higher economic autonomy and power among women is considered as one of the causes of the gender violence as well. Response to stress-related problems derived from the globalisation, the increasing importance of the tertiary sector and other social changes is insufficient either because health professionals ignore the causes of the problem and treat pharmacologically the consequences or because health consequences of these new social and economic tendencies are not taken into account in other sectors.

  4. Stress state in the largest displacement area of the 2011 Tohoku-Oki earthquake.

    PubMed

    Lin, Weiren; Conin, Marianne; Moore, J Casey; Chester, Frederick M; Nakamura, Yasuyuki; Mori, James J; Anderson, Louise; Brodsky, Emily E; Eguchi, Nobuhisa

    2013-02-08

    The 2011 moment magnitude 9.0 Tohoku-Oki earthquake produced a maximum coseismic slip of more than 50 meters near the Japan trench, which could result in a completely reduced stress state in the region. We tested this hypothesis by determining the in situ stress state of the frontal prism from boreholes drilled by the Integrated Ocean Drilling Program approximately 1 year after the earthquake and by inferring the pre-earthquake stress state. On the basis of the horizontal stress orientations and magnitudes estimated from borehole breakouts and the increase in coseismic displacement during propagation of the rupture to the trench axis, in situ horizontal stress decreased during the earthquake. The stress change suggests an active slip of the frontal plate interface, which is consistent with coseismic fault weakening and a nearly total stress drop.

  5. Rapid ductile afterslip from coseismic heating

    NASA Astrophysics Data System (ADS)

    Platt, J. D.; Meade, B. J.; Savage, H. M.; Rowe, C. D.

    2015-12-01

    Earthquakes are typically followed by months of afterslip, the total of which is generally an order of magnitude smaller than the seismic slip. The classic model for afterslip envisions seismic slip transferring stress to adjacent regions, driving accelerated stable sliding that expands the rupture area. However, a small proportion of earthquakes exhibit unusually large and rapid afterslip in the hours immediately following rupture. Here we present a new model that bridges the transition from seismic to postseismic deformation and may explain these observations of rapid afterslip. Seismic slip produces a significant temperature rise that slowly diffuses into the surrounding material following the cessation of seismic slip. Any process with strong temperature dependence is more sensitive to this heat transient than to the ambient temperatures present during the interseismic period. Coupling the temperature evolution of a fault to a ductile flow law we model postseismic deformation during the heat transient. Our idea of coseismic heating enhancing ductile flow is supported by field observations of micro-shear zones adjacent to psuedotachylyte veins. Enhanced ductility is largely confined to the zone that deformed seismically, making our model equivalent to rapid afterslip. Combining analytic and numerical methods we solve for the total afterslip in terms of the slip rate and fault strength during seismic slip and the ductile flow parameters. Our results are sensitive to the assumed rheology and deforming zone thickness, and while total afterslip is generally small some plausible parameter ranges predict afterslip comparable to or greater than the seismic slip developing over timescales shorter than an hour. We demonstrate that rapid afterslip can drive significant frictional heating, leading to a thermal runaway instability that produces a near total postseismic stress drop. To conclude we investigate the tsunami magnitude that rapid afterslip could produce.

  6. Lithospheric Structure and Active Deformation in the Salton Trough from Coseismic and Postseismic Models of the 2010 Mw 7.2 El Mayor-Cucapah Earthquake

    NASA Astrophysics Data System (ADS)

    Fielding, E. J.; Huang, M. H.; Dickinson, H.; Freed, A. M.; Burgmann, R.; Gonzalez-Ortega, J. A.; Andronicos, C.

    2016-12-01

    The 4 April 2010 Mw 7.2 El Mayor-Cucapah (EMC) Earthquake ruptured about 120 km along several NW-striking faults to the west of the Cerro Prieto Fault in the Salton Trough of Baja California, Mexico. We analyzed interferometric synthetic aperture radar (SAR), SAR and optical pixel offsets, and continuous and campaign GPS data to optimize an EMC coseismic rupture model with 9 fault segments, which fits the complex structure of the faults. Coseismic slip inversion with a layered elastic model shows that largely right-lateral slip is confined to upper 10 km with strong variations along strike. Near-field GPS measures slip on a north-striking normal fault that ruptured at the beginning of the earthquake, previously inferred from seismic waveforms. EMC Earthquake postseismic deformation shows the Earth's response to the large coseismic stress changes. InSAR shows rapid shallow afterslip at the north and south ends of the main ruptures. Continuous GPS from the Plate Boundary Observatory operated by UNAVCO measures the first six years of postseismic deformation, extremely rapid near the rupture. Afterslip on faults beneath the coseismic rupture cannot explain far-field displacements that are best explained by viscoelastic relaxation of the lower crust and upper mantle. We built a viscoelastic 3D finite element model of the lithosphere and asthenosphere based on available data for the region with the EMC coseismic faults embedded inside. Coseismic slip was imposed on the model, allowed to relax for 5 years, and then compared to the observed surface deformation. Systematic exploration of the viscoelastic parameters shows that horizontal and vertical heterogeneity is required to fit the postseismic deformation. Our preferred viscoelastic model has weaker viscosity layers beneath the Salton Trough than adjacent blocks that are consistent with the inferred differences in the geotherms. Defining mechanical lithosphere as rocks that have viscosities greater than 10^19 Pa s (able

  7. Coseismic Slip Variation and the Intimate Link with Fault Structure

    NASA Astrophysics Data System (ADS)

    Milliner, C. W. D.; Sammis, C. G.; Allam, A. A.; Dolan, J. F.; Hollingsworth, J.; Leprince, S.; Ayoub, F.

    2015-12-01

    Co-seismic along-strike slip heterogeneity is widely observed for many surface-rupturing earthquakes as revealed by field and high-resolution geodetic methods. However, this co-seismic slip variability is currently a poorly understood phenomenon. Key unanswered questions include: What are the characteristics and underlying causes of along-strike slip variability? Do the properties of slip variability change from fault-to-fault, along-strike or at different scales? We cross-correlate optical, pre- and post-event air photos using the program COSI-Corr to measure the near-field, surface deformation pattern of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes in high-resolution. We produce the co-seismic slip profiles of both events from over 1,500 displacement measurements and observe consistent along-strike slip variability. Although the observed slip heterogeneity seems apparently complex and disordered, a spectral analysis reveals that the slip distributions are self-affine fractal and variations of slip are not random. We find a fractal dimension of 1.68 + 0.25 and 1.58 + 0.30 for the Landers and Hector Mine earthquakes, respectively, indicating the slip distribution is rougher for the former. We show deterministically that the wavelength and amplitude of slip fluctuations of both earthquakes can be directly correlated to points of geometrical fault complexities (such as stepovers, kinks or bends) of similar size. We find the correlation of the wavelength of slip fluctuations to the size of geometrical fault complexities at all observable length scales, can explain why the complex surface rupture of the Landers earthquake has a rougher slip distribution than the geometrically simpler surface rupture of the Hector Mine event. Our results address longstanding questions concerning co-seismic slip variability, resulting in a more complete understanding of the relationship between slip distributions and fault structure.

  8. Salt Marsh Response and Recovery to Coseismic Subsidence

    NASA Astrophysics Data System (ADS)

    Aranda, A. N.; Carlin, J. A.; Rhodes, B. P.; Kirby, M.; Leeper, R. J.; Smith, R. W.

    2016-12-01

    Salt marshes worldwide are under increasing stress from eustatic sea level rise. Along the tectonically active west coast of North America, some salt marshes are also vulnerable to abrupt increases in relative sea level rise (RSLR) resulting from coseismic subsidence. Elevation zonation of sub-environments within a marsh provides the opportunity to interpret the sedimentary record in marshes to infer past earthquakes, which may improve understanding of regional seismic hazards and ecosystem response to increases in sea level. Our study area is the Seal Beach Wetlands (SBW), an 3 km2 salt marsh straddling the seismically active Newport-Inglewood fault zone in southern California. A previous study of the SBW identified sedimentary evidence of three coseismic subsidence events. Here, our goals were to identify coseismic subsidence events preserved in SBW stratigraphy and to quantify marsh recovery following an earthquake to assess marsh resiliency to rapid RSLR. To do this, we focused on one core collected near the fringe of the SBW and applied a suite of sedimentary and geochemical analyses. Our results indicated that the SBW may preserve sedimentary evidence of four potential coseismic subsidence events. Events were distinguished in the stratigraphy by a sharp upper contact interpreted as an abrupt shift in marsh depositional sub-environments, from a vegetated marsh, to an intertidal mudflat or a subtidal environment. This stratigraphy suggests that the marsh rapidly subsided, preserving the evidence of the vegetated marsh as a peat deposit overlain by a low-organic mud or muddy-sand layer. A typical marsh accretion facies succession occurred above each earthquake event in the core, suggesting full marsh recovery. From the core data, we also observed that the net average rate of marsh recovery, i.e., marsh accretion, was consistent. Estimated recovery rates between 0.6 and 1.1 mm/yr were comparable to the overall accretion rate and regional late Holocene RSLR rate

  9. Stress Field Variation after the 2001 Skyros Earthquake, Greece, Derived from Seismicity Rate Changes

    NASA Astrophysics Data System (ADS)

    Leptokaropoulos, K.; Papadimitriou, E.; Orlecka-Sikora, B.; Karakostas, V.

    2012-04-01

    The spatial variation of the stress field (ΔCFF) after the 2001 strong (Mw=6.4) Skyros earthquake in North Aegean Sea, Greece, is investigated in association with the changes of earthquake production rates. A detailed slip model is considered in which the causative fault is consisted of several sub-faults with different coseismic slip onto each one of them. First the spatial distribution of aftershock productivity is compared with the static stress changes due to the coseismic slip. Calculations of ΔCFF are performed at different depths inside the seismogenic layer, defined from the vertical distribution of the aftershocks. Seismicity rates of the smaller magnitude events with M≥Mc for different time increments before and after the main shock are then derived from the application of a Probability Density Function (PDF). These rates are computed by spatially smoothing the seismicity and for this purpose a normal grid of rectangular cells is superimposed onto the area and the PDF determines seismicity rate values at the center of each cell. The differences between the earthquake occurrence rates before and after the main shock are compared and used as input data in a stress inversion algorithm based upon the Rate/State dependent friction concept in order to provide an independent estimation of stress changes. This model incorporates the physical properties of the fault zones (characteristic relaxation time, fault constitutive parameters, effective friction coefficient) with a probabilistic estimation of the spatial distribution of seismicity rates, derived from the application of the PDF. The stress patterns derived from the previously mentioned approaches are compared and the quantitative correlation between the respective results is accomplished by the evaluation of Pearson linear correlation coefficient and its confidence intervals to quantify their significance. Different assumptions and combinations of the physical and statistical parameters are tested for

  10. Coseismic deformation due to the 2011 Tohoku earthquake: influence of 3-D plate structure around Japan

    NASA Astrophysics Data System (ADS)

    Hashima, A.; Freed, A. M.; Becker, T. W.; Sato, H.; Okaya, D. A.; Suito, H.; Hatanaka, Y.; Matsubara, M.; Takeda, T.; Ishiyama, T.; Iwasaki, T.

    2013-12-01

    Beneath the Japan islands, the Pacific plate descends from the east and the Philippine sea plate descends from the south, causing interaction of two slabs at depth. The 2011 M9 Tohoku earthquake in northern Japan had a source region with a length of ~500 km and a width of ~200 km and forced broad lithospheric and mantle regions in the region to deform. Here, we investigate the effects of slab geometry and 3D heterogeneity on the inversion of inferred coseismic slip and the resulting broad coseismic deformation throughout the region. We construct a 3-D finite element model (FEM) to generate Green's functions for use in a coseismic inversion study that allows considering the influence of complex slab geometry as well as heterogeneities in elastic structure on inferred slip. We utilize the large, land-based Japan GPS array as well as seafloor geodetic constraints in the inversion. We are particularly interested in how coseismic seafloor constraints influence inversion results. Our FEM considers a region of 4500 km x 4900 km x 670 km, incorporating the Pacific and the Philippine sea slabs by interpolating models for the Tohoku region and the Nankai trough, as well as the Kuril, Ryukyu and Izu-Bonin arcs. The model region is divided into about 500,000 tetrahedral elements with average dimension ranging from 20-100 km. We also test the role of gravity on coseismic results, with initial results suggesting that gravitational loading is not an important factor because of the shallow dip of the upper Pacific slab.Our long-term objective is to study the influence of the Tohoku earthquake on evolution of stresses throughout Japan due to both coseismic and postseismic processes, the latter including afterslip and viscoelastic relaxation. An accurate accounting of coseismic slip is very important to such an endeavor.

  11. Coseismic deformation of the 2001 El Salvador and 2002 Denali fault earthquakes from GPS geodetic measurements

    NASA Astrophysics Data System (ADS)

    Hreinsdottir, Sigrun

    2005-07-01

    GPS geodetic measurements are used to study two major earthquakes, the 2001 MW 7.7 El Salvador and 2002 MW 7.9 Denali Fault earthquakes. The 2001 MW 7.7 earthquake was a normal fault event in the subducting Cocos plate offshore El Salvador. Coseismic displacements of up to 15 mm were measured at permanent GPS stations in Central America. The GPS data were used to constrain the location of and slip on the normal fault. One month later a MW 6.6 strike-slip earthquake occurred in the overriding Caribbean plate. Coulomb stress changes estimated from the M W 7.7 earthquake suggest that it triggered the MW 6.6 earthquake. Coseismic displacement from the MW 6.6 earthquake, about 40 mm at a GPS station in El Salvador, indicates that the earthquake triggered additional slip on a fault close to the GPS station. The MW 6.6 earthquake further changed the stress field in the overriding Caribbean plate, with triggered seismic activity occurring west and possibly also to the east of the rupture in the days to months following the earthquake. The MW 7.9 Denali Fault earthquake ruptured three faults in the interior of Alaska. It initiated with a thrust motion on the Susitna Glacier fault but then ruptured the Denali and Totschunda faults with predominantly right-lateral strike-slip motion unilaterally from west to east. GPS data measured in the two weeks following the earthquake suggest a complex coseismic rupture along the faults with two main regions of moment release along the Denali fault. A large amount of additional data were collected in the year following the earthquake which greatly improved the resolution on the fault, revealing more details of the slip distribution. We estimate a total moment release of 6.81 x 1020 Nm in the earthquake with a M W 7.2 thrust subevent on Susitna Glacier fault. The slip on the Denali fault is highly variable, with 4 main pulses of moment release. The largest moment pulse corresponds to a MW 7.5 subevent, about 40 km west of the Denali

  12. Coseismic Deformations Associated with the M=7.2, April 04, 2010, El Mayor-Cucapah Earthquake, Observed from Leveling Survey, Geotechnical Instruments and Water Level Changes in the Mexicali Valley

    NASA Astrophysics Data System (ADS)

    Glowacka, E.; Robles, B.; Vázquez, R.; Sarychikhina, O.; Suárez-Vidal, F.; Ramirez, J.; Nava Pichardo, F. A.; Farfan, F.; Diaz de Cossio, G.

    2010-12-01

    A first order, second class leveling survey in the Mexicali Valley had been just finished in February 2010, for a project carried out by CICESE (Center for Scientific Research and Higher Education of Ensenada), IMTA (Mexican Institute of Water Technology) and CONAGUA (National Water Comission). Immediately after the M=7.2 earthquake the survey was repeated along 240 km of the profiles in the area of the Cerro Prieto pull-apart basin. The leveling started at the LN00 GPS monument in La Puerta. Overall, an uplift of about 30 cm towards the NE, along the 38 km line, in direction SW-NE is observed with larger gradient to the South of the area. Three subsidence bowls differ from this general pattern. One, south from Ejido Saltillo, with the relative subsidence of 19 cm (considering the displacement at LN00 as zero subsidence), probably reflects subsidence of the Saltillo-Guerrero graben; the second, with a subsidence of 23 cm, is situated south from Ejido Nuevo Leon and can be related to the subsidence triggered by the earthquake in the production area of Cerro Prieto IV. For the third one, with relative depth of 36 cm, situated close to Zacamoto, the southeastern limit cannot be determined, so only a comparison with other methods can explain the origin of this anomaly. All the subsidence bowls are associated with liquefaction observed in the area, with more liquefaction observed close to Zacamoto. Since 1996, CICESE has been operating a network of geotechnical instruments (REDECVAM) for continuous recording of deformation related to tectonic (seismic and interseismic) phenomena, as well as anthropogenic deformation caused by the deep fluid extraction at the Cerro Prieto Geothermal Field. The instruments are installed along the faults which limit the Cerro Prieto pull-apart basin at a distance from 8 to 15 km from the epicenter. Coseismic step-like groundwater level changes ranging from 0.4 to 5.0 meters were recorded at 4 wells in the Cerro Prieto Pull apart

  13. Coseismic Deformation Field and Fault Slip Distribution of the 2015 Chile Mw8.3 Earthquake

    NASA Astrophysics Data System (ADS)

    Qu, Chunyan; Zuo, Ronghu; Shan, Xin Jian; Zhang, Guohong; Zhang, Yingfeng; Song, Xiaogang

    2016-06-01

    On September 16, 2015, a magnitude 8.3 earthquake struck west of Illapel, Chile. We analyzed Sentinel-1A/IW InSAR data on the descending track acquired before and after the Chile Mw8.3 earthquake of 16 September 2015. We found that the coseismic deformation field of this event consists of many semi circular fringes protruding to east in an approximately 300km long and 190km wide region. The maximum coseismic displacement is about 1.33m in LOS direction corresponding to subsidence or westward shift of the ground. We inverted the coseismic fault slip based on a small-dip single plane fault model in a homogeneous elastic half space. The inverted coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The rupture length along strike is about 340 km with maximum slip of about 8.16m near the trench. The estimated moment is 3.126×1021 N.m (Mw8.27) the maximum depth of coseismic slip near zero appears to 50km. We also analyzed the postseismic deformation fields using four interferograms with different time intervals. The results show that postseismic deformation occurred in a narrow area of approximately 65km wide with maximum slip 11cm, and its predominant motion changes from uplift to subsidence with time. that is to say, at first, the postseismic deformation direction is opposite to that of coseismic deformation, then it tends to be consistent with coseismic deformation.It maybe indicates the differences and changes in the velocity between the Nazca oceanic plate and the South American continental plate.

  14. Stress changes from the 2008 Wenchuan earthquake and increased hazard in the Sichuan basin

    USGS Publications Warehouse

    Parsons, T.; Ji, C.; Kirby, E.

    2008-01-01

    On 12 May 2008, the devastating magnitude 7.9 (Wenchuan) earthquake struck the eastern edge of the Tibetan plateau, collapsing buildings and killing thousands in major cities aligned along the western Sichuan basin in China. After such a large-magnitude earthquake, rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. The mainshock of the 12 May earthquake ruptured with as much as 9 m of slip along the boundary between the Longmen Shan and Sichuan basin, and demonstrated the complex strike-slip and thrust motion that characterizes the region. The Sichuan basin and surroundings are also crossed by other active strike-slip and thrust faults. Here we present calculations of the coseismic stress changes that resulted from the 12 May event using models of those faults, and show that many indicate significant stress increases. Rapid mapping of such stress changes can help to locate fault sections with relatively higher odds of producing large aftershocks. ??2008 Macmillan Publishers Limited. All rights reserved.

  15. Energy Partitioning during Frictional Sliding at Coseismic Slip Rates

    NASA Astrophysics Data System (ADS)

    Hirose, T.; Mizoguchi, K.

    2008-12-01

    Determination of the energy partitioning during an earthquake is key to understanding the physics of earthquakes (e.g., Kanamori and Rivera, 2006). Observations made on natural faults that have experienced earthquakes suggest that part of the energy dissipates into a volume of rock surrounding the fault though grain crushing processes, forming fault gouge (e.g., Wilson et al., 2005). Thus we performed high-velocity wear experiments using a rotary-shear apparatus, in order to estimate the partitioning of the frictional work into heat and surface energy during frictional sliding at nearly coseismic slip rates. In particular, we attempted to test whether the ratio of the energy partitioning varies as a function of slip rate. The ratio of dissipated energy as heat to the total frictional work was estimated from the difference between measured temperature around the sliding surfaces and calculated temperature by 2D-FEM on the assumption that all frictional work converts into heat. The surface energy was estimated based on the particle size distribution of the wear materials, which was determined by FE-SEM image analysis. The particles size ranged between 0.03 and 10 μm in average diameter. In the experiments, hollow cylindrical specimens of gabbro were slid at slip rates of 0.004 to 0.3 m/s and normal stresses of 0.2 to 5.6 MPa under unconfined and dry conditions. Rock powder (gouge) was continuously produced by abrasive wear of initially bare fault surfaces during sliding. Because the sliding surfaces were not confined in the experiments, the gouge was extruded from the fault surfaces, resulting in shortening of axial length of specimen. In this study, we defined the dimensionless wear rate, given by that an axial shortening rate of the specimen was divided by slip rate. Then, we examined how the wear rate and temperature changed as a function of the rate of frictional work per a unit fault area, Ef, determined by shear stress multiplied by slip rate. Hereafter, Q and

  16. Stress changes ahead of an advancing tunnel

    USGS Publications Warehouse

    Abel, J.F.; Lee, F.T.

    1973-01-01

    Instrumentation placed ahead of three model tunnels in the laboratory and ahead of a crosscut driven in a metamorphic rock mass detected stress changes several tunnel diameters ahead of the tunnel face. Stress changes were detected 4 diameters ahead of a model tunnel drilled into nearly elastic acrylic, 2??50 diameters ahead of a model tunnel drilled into concrete, and 2 diameters ahead of a model tunnel drilled into Silver Plume Granite. Stress changes were detected 7??50 diameters ahead of a crosscut driven in jointed, closely foliated gneisses and gneissic granites in an experimental mine at Idaho Springs, Colorado. These results contrast markedly with a theoretical elastic estimate of the onset of detectable stress changes at 1 tunnel diameter ahead of the tunnel face. A small compressive stress concentration was detected 2 diameters ahead of the model tunnel in acrylic, 1.25 diameters ahead of the model tunnel in concrete, and 1 diameter ahead of the model tunnel in granite. A similar stress peak was detected about 6 diameters ahead of the crosscut. No such stress peak is predicted from elastic theory. The 3-dimensional in situ stress determined in the field demonstrate that geologic structure controls stress orientations in the metamorphic rock mass. Two of the computed principal stresses are parallel to the foliation and the other principal stress is normal to it. The principal stress orientations vary approximately as the foliation attitude varies. The average horizontal stress components and the average vertical stress component are three times and twice as large, respectively, as those predicted from the overburden load. An understanding of the measured stress field appears to require the application of either tectonic or residual stress components, or both. Laboratory studies indicate the presence of proportionately large residual stresses. Mining may have triggered the release of strain energy, which is controlled by geologic structure. ?? 1973.

  17. Co-Seismic Displacement of 24-March-2011 Mw=6.8 Mong Hpayak (Tarlay) Earthquake, Myanmar

    NASA Astrophysics Data System (ADS)

    Trisirisatayawong, Itthi; Hopper, Andy; Aobpaet, Anuphao

    2012-01-01

    The 2011 Mw=6.8 Mong Hpayak earthquake occurred on the western segment of the Nam Ma fault, one of many left-lateral faults in the borderregion of Myanmar, Laos and Thailand. SAR images are probably the only available geodetic data for studying the co-seismic motion of this earthquake. Two-pass DInSAR processing of both ascending and descending ALOS PALSAR images reveals surface displacement pattern of nearly pure strike-slip fault. These InSAR results are modelled as elastic repsonse to slip on a planar fault and then downsampled for the inversion to solve for fault parameters. The co-seismic displacements predicted by the resulted fault model agrees well with InSAR observations. We then calculate the distribution of Coulomb stress change in nearby active faults and it is revealed that sections of nearby faults in northern Thailand have increasing stress. This information would help re-evaluate the likelihood of future earthquake in this fault zone.

  18. Ruptured Pebbles - a coseismic and paleoseismic indicator?

    NASA Astrophysics Data System (ADS)

    Weismüller, Christopher; Reicherter, Klaus

    2017-04-01

    fostered the assumption that these pebbles must have been fractured in-situ in the matrix. During slow deformation in combination with the contrast in competence between pebble and matrix, the pebbles would rotate and realign along a shear plane within the matrix. We explain the observed shearing of pebbles in the debris flow to be the product of a temporary tensile stress induced by the propagation of a seismic wave through the sediment body. The quick deformation causes the pebbles and matrix to engage in a state of similar competence, enabling the shearing of the clasts in the matrix. Under the given circumstances, we conclude the near-fault presence of ruptured pebbles in a soft sediment body to indicate paleoseismic activity and coseismic deformation. In contrast to that we regard aligned pebbles as a slow deformation, probably caused by afterslip and post-seismic deformation.

  19. Calibrating coseismic coastal land-level changes during the 2014 Iquique (Mw=8.2) earthquake (northern Chile) with leveling, GPS and intertidal biota.

    PubMed

    Jaramillo, Eduardo; Melnick, Daniel; Baez, Juan Carlos; Montecino, Henry; Lagos, Nelson A; Acuña, Emilio; Manzano, Mario; Camus, Patricio A

    2017-01-01

    The April 1st 2014 Iquique earthquake (MW 8.1) occurred along the northern Chile margin where the Nazca plate is subducted below the South American continent. The last great megathrust earthquake here, in 1877 of Mw ~8.8 opened a seismic gap, which was only partly closed by the 2014 earthquake. Prior to the earthquake in 2013, and shortly after it we compared data from leveled benchmarks, deployed campaign GPS instruments, continuous GPS stations and estimated sea levels using the upper vertical level of rocky shore benthic organisms including algae, barnacles, and mussels. Land-level changes estimated from mean elevations of benchmarks indicate subsidence along a ~100-km stretch of coast, ranging from 3 to 9 cm at Corazones (18°30'S) to between 30 and 50 cm at Pisagua (19°30'S). About 15 cm of uplift was measured along the southern part of the rupture at Chanabaya (20°50'S). Land-level changes obtained from benchmarks and campaign GPS were similar at most sites (mean difference 3.7±3.2 cm). Higher differences however, were found between benchmarks and continuous GPS (mean difference 8.5±3.6 cm), possibly because sites were not collocated and separated by several kilometers. Subsidence estimated from the upper limits of intertidal fauna at Pisagua ranged between 40 to 60 cm, in general agreement with benchmarks and GPS. At Chanavaya, the magnitude and sense of displacement of the upper marine limit was variable across species, possibly due to species-dependent differences in ecology. Among the studied species, measurements on lithothamnioid calcareous algae most closely matched those made with benchmarks and GPS. When properly calibrated, rocky shore benthic species may be used to accurately measure land-level changes along coasts affected by subduction earthquakes. Our calibration of those methods will improve their accuracy when applied to coasts lacking pre-earthquake data and in estimating deformation during pre-instrumental earthquakes.

  20. An Evaluation of Coulomb Stress Changes from Earthquake Productivity Variations in the Western Gulf of Corinth, Greece

    NASA Astrophysics Data System (ADS)

    Leptokaropoulos, K. M.; Papadimitriou, E. E.; Orlecka-Sikora, B.; Karakostas, V. G.

    2016-01-01

    Spatial and temporal evolution of the stress field in the seismically active and well-monitored area of the western Gulf of Corinth, Greece, is investigated. The highly accurate and vast regional catalogues were used for inverting seismicity rate changes into stress variation using a rate/state-dependent friction model. After explicitly determining the physical quantities incorporated in the model (characteristic relaxation time, fault constitutive parameters, and reference seismicity rates), we looked for stress changes across space and over time and their possible association with earthquake clustering and fault interactions. We focused our attention on the Efpalio doublet of January 2010 ( M = 5.5 and M = 5.4), with a high aftershock productivity, and attempted to reproduce and interpret stress changes prior to and after the initiation of this seismicity burst. The spatial distribution of stress changes was evaluated after smoothing the seismological data by means of a probability density function (PDF). The inverted stress calculations were compared with the calculations derived from an independent approach (elastic dislocation model) and this comparison was quantified. The results of the two methods are in good agreement (up to 80 %) in the far field, with the inversion technique providing more robust results in the near field, where they are more sensitive to the uncertainties of coseismic slip distribution. It is worth mentioning that the stress inversion model proved to be a very sensitive stress meter, able to detect even small stress changes correlated with spatio-temporal earthquake clustering. Data analysis was attempted from 1975 onwards to simulate the stress changes associated with stronger earthquakes over a longer time span. This approach revealed that only M > 5.5 events induce considerable stress variations, although in some cases there was no evidence for such stress changes even after an M > 5.5 earthquake.

  1. Calibrating coseismic coastal land-level changes during the 2014 Iquique (Mw=8.2) earthquake (northern Chile) with leveling, GPS and intertidal biota

    PubMed Central

    Melnick, Daniel; Baez, Juan Carlos; Montecino, Henry; Lagos, Nelson A.; Acuña, Emilio; Manzano, Mario; Camus, Patricio A.

    2017-01-01

    The April 1st 2014 Iquique earthquake (MW 8.1) occurred along the northern Chile margin where the Nazca plate is subducted below the South American continent. The last great megathrust earthquake here, in 1877 of Mw ~8.8 opened a seismic gap, which was only partly closed by the 2014 earthquake. Prior to the earthquake in 2013, and shortly after it we compared data from leveled benchmarks, deployed campaign GPS instruments, continuous GPS stations and estimated sea levels using the upper vertical level of rocky shore benthic organisms including algae, barnacles, and mussels. Land-level changes estimated from mean elevations of benchmarks indicate subsidence along a ~100-km stretch of coast, ranging from 3 to 9 cm at Corazones (18°30’S) to between 30 and 50 cm at Pisagua (19°30’S). About 15 cm of uplift was measured along the southern part of the rupture at Chanabaya (20°50’S). Land-level changes obtained from benchmarks and campaign GPS were similar at most sites (mean difference 3.7±3.2 cm). Higher differences however, were found between benchmarks and continuous GPS (mean difference 8.5±3.6 cm), possibly because sites were not collocated and separated by several kilometers. Subsidence estimated from the upper limits of intertidal fauna at Pisagua ranged between 40 to 60 cm, in general agreement with benchmarks and GPS. At Chanavaya, the magnitude and sense of displacement of the upper marine limit was variable across species, possibly due to species—dependent differences in ecology. Among the studied species, measurements on lithothamnioid calcareous algae most closely matched those made with benchmarks and GPS. When properly calibrated, rocky shore benthic species may be used to accurately measure land-level changes along coasts affected by subduction earthquakes. Our calibration of those methods will improve their accuracy when applied to coasts lacking pre-earthquake data and in estimating deformation during pre–instrumental earthquakes. PMID

  2. Calculation of the Co-seismic Effect of Ms8.1 Earthquake, Apirl 25, 2015, Nepal

    NASA Astrophysics Data System (ADS)

    Cheng, H.

    2015-12-01

    On April 25, 2015, an Ms8.1earthquake occurred in Nepal, which caused a rupture zone of over 100 kilometers developing southeast and the epicenter was only 70 kilometers away from Kathmandu, the capital of Nepal, causing heavy casualties in Nepal. Based on the elastic dislocation theory and global finite element method, an equivalent volume force of layered co-seismic crustal computation model is set up. And based on the USGS and CEA fault slip models, we calculate the co-seismic displacement, stress field and ΔCFS caused by Nepal Ms8.1 earthquake. The calculation result shows that: (1) Nepal Ms8.1 earthquake is a typical low-angle thrust earthquake and co-seismic displacement caused by the earthquake is mainly concentrated in the horizontal plane and centered in the surrounding area of Katmandu, the capital of Nepal. The maximum co-seismic horizontal slippage under USGS slip model and CEA slip model is about 4m and 2m respectively; compared with the east-west and vertical displacement caused by the earthquake, the horizontal displacement in south-north direction is larger, which is reflected as the handing wall diving southward; the computed result based on CEA model and USGS models show that the maximum displacement of southward hanging wall is 1.2m and 3.47m respectively; (2) Nepal is located in the collision and compression fault zone of Eurasian Plate and Indian Plate, with well-developed tectonic fault. The seismogenic fault of Ms8.1 earthquake may belongs to the MHT fault zone. The ΔCFS induced by the earthquake is positive in the seismic source area and the maximum of ΔCFS can reach 0.1MPa, showing there still more dangerous; (3) Nepal Ms8.1 earthquake has a certain impact on the Tibet region of China. According to the seismogenic fault of Ms8.1 earthquake, the stress change of 1kPa in Yaruzampbo region and Lhasa block can be calculated, which may even reach 10kPa; Shigatse and Lhasa are located in the area in where the ΔCFS increases. Close attention

  3. Fault pseudotachylyte: a coseismic lightning rod

    NASA Astrophysics Data System (ADS)

    Ferre, E. C.; Conder, J. A.; MathanaSekaran, N.; Geissman, J. W.

    2013-12-01

    The electrical conductivity of fault rocks varies considerably during an earthquake due to catastrophic physical changes, such as cataclastic deformation and frictional melting. We model independently the role of each parameter affecting electrical conductivity for a rock of granitic composition with an initial electrical conductivity s = 6.25 x 10^-7 S/m at 300 K and a density d = 2.64 x 10^3 kg/m3. In dry, unfractured rock, the electrical conductivity increases with temperature by one order of magnitude between 300 and 1300 K. Above 1300 K, partial melting generally takes place and the electrical conductivity drastically increases because metallic conduction prevails in a melt. Complex phase transitions, involving hematite, maghemite and magnetite, are responsible for discrete changes in electrical conductivity as a function of temperature. As the number and width of fractures increases towards the fault core and during slip, due to high strain rates (10^-2 m/s), the porosity also increases. The electrical conductivity can be modeled using a variation of Archie's Law. Our model assumes an increase in porosity from 0.2 to 2.0 %, similar to that observed for both the Nojima and the Soultz fault, which cut granites, and a fluid conductivity of Sw = 0.5 S/m, consistent with conductivity of fluids commonly present at depths of 2000 m. An increase in electrical conductivity by two orders of magnitude is predicted. Finally, the electrical conductivity of a mixture of solid rock and silicate melt is a composite of the electrical properties of both components. The electrical conductivity of the silicate melt results from metallic conduction and varies considerably with melt temperature. During seismic slip, the solid rock temperature is considered constant due to the low thermal conductivity of granitic rocks. Our model, a variant of the brick layer model of Partzsch et al. (2000), reveals another cause for the rise in electrical conductivity due to increasing abundance

  4. Rupture Propagation of the 2013 Mw7.7 Balochistan, Pakistan, Earthquake Affected by Poroelastic Stress Changes

    NASA Astrophysics Data System (ADS)

    He, J.; Wang, W.; Xiao, J.

    2015-12-01

    The 2013 Mw7.7 Balochistan, Pakistan, earthquake occurred on the curved Hoshab fault. This fault connects with the north-south trending Chaman strike-slip fault to northeast, and with the west-east trending Makran thrust fault system to southwest. Teleseismic waveform inversion, incorporated with coseismic ground surface deformation data, show that the rupture of this earthquake nucleated around northeast segment of the fault, and then propagated southwestward along the northwest dipping Hoshab fault about 200 km, with the maximum coseismic displacement, featured mainly by purely left-lateral strike-slip motion, about 10 meters. In context of the India-Asia collision frame, associating with the fault geometry around this region, the rupture propagation of this earthquake seems to not follow an optimal path along the fault segment, because after nucleation of this event the Hoshab fault on the southwest of hypocenter of this earthquake is clamped by elastic stress change. Here, we build a three-dimensional finite-element model to explore the evolution of both stress and pore-pressure during the rupturing process of this earthquake. In the model, the crustal deformation is treated as undrained poroelastic media as described by Biot's theory, and the instantaneous rupture process is specified with split-node technique. By testing a reasonable range of parameters, including the coefficient of friction, the undrained Poisson's ratio, the permeability of the fault zone and the bulk crust, numerical results have shown that after the nucleation of rupture of this earthquake around the northeast of the Hoshab fault, the positive change of normal stress (clamping the fault) on the fault plane is greatly reduced by the instantaneous increase of pore pressure (unclamping the fault). This process could result in the change of Coulomb failure stress resolved on the Hoshab fault to be hastened, explaining the possible mechanism for southwestward propagation of rupture of the Mw7

  5. Stress Changes Induced by Earthquakes and Secular Stress Accumulation in the Buller Region, South Island, New Zealand (1929 2002)

    NASA Astrophysics Data System (ADS)

    Hincapie, Jaime O.; Doser, Diane I.; Robinson, Russell

    2005-02-01

    Between 1929 and 1968 the Buller region, located west of the strike-slip Alpine fault system, experienced two Mw > 7.1 earthquakes along high-angle reverse faults. We have modeled induced changes in Coulomb failure stress (ΔCFS) to determine whether stress triggering could have occurred during the 1929 and 1968 sequences and to determine how these earthquakes have affected stress along the Alpine fault and neighboring strike-slip faults located to the east of the Alpine fault. We have included the effects of secular stress accumulation on the five most rapidly slipping fault systems in the region (Alpine, Wairau, Awatere, Clarence, and Hope), but have neglected the effects of viscoelastic relaxation. Our results suggest that larger aftershocks of the 1929 Buller mainshock and moderate (Mw < 6.0) events following the 1968 Inangahua mainshock may have been triggered or hastened by the mainshocks. The 1929 mainshock does not appear to have been significantly hastened by previous Mw > 7.0 events in 1848 and 1888 along strike-slip faults to the east of the Buller region or by secular stress accumulation since 1848. The 1929 Buller earthquake may have delayed the 1968 Inangahua mainshock. Present values of ΔCFS along segments of the major strike-slip faults located east of the Buller region indicate that every fault segment except the North Westlands North segment of the Alpine fault contains regions of negative ΔCFS that are related to the coseismic effects of Mw > 7.0 earthquakes occurring between 1848 and 1968. The complex variation in ΔCFS along most major strike-slip faults in the region highlights the difficulty in evaluating which faults may presently be the closest to failure.

  6. Dynamic stress changes during earthquake rupture

    USGS Publications Warehouse

    Day, S.M.; Yu, G.; Wald, D.J.

    1998-01-01

    We assess two competing dynamic interpretations that have been proposed for the short slip durations characteristic of kinematic earthquake models derived by inversion of earthquake waveform and geodetic data. The first interpretation would require a fault constitutive relationship in which rapid dynamic restrengthening of the fault surface occurs after passage of the rupture front, a hypothesized mechanical behavior that has been referred to as "self-healing." The second interpretation would require sufficient spatial heterogeneity of stress drop to permit rapid equilibration of elastic stresses with the residual dynamic friction level, a condition we refer to as "geometrical constraint." These interpretations imply contrasting predictions for the time dependence of the fault-plane shear stresses. We compare these predictions with dynamic shear stress changes for the 1992 Landers (M 7.3), 1994 Northridge (M 6.7), and 1995 Kobe (M 6.9) earthquakes. Stress changes are computed from kinematic slip models of these earthquakes, using a finite-difference method. For each event, static stress drop is highly variable spatially, with high stress-drop patches embedded in a background of low, and largely negative, stress drop. The time histories of stress change show predominantly monotonic stress change after passage of the rupture front, settling to a residual level, without significant evidence for dynamic restrengthening. The stress change at the rupture front is usually gradual rather than abrupt, probably reflecting the limited resolution inherent in the underlying kinematic inversions. On the basis of this analysis, as well as recent similar results obtained independently for the Kobe and Morgan Hill earthquakes, we conclude that, at the present time, the self-healing hypothesis is unnecessary to explain earthquake kinematics.

  7. Low-Stress Upper Plate Near Subduction Zones and Implications for Temporal Changes in Loading Forces

    NASA Astrophysics Data System (ADS)

    Wang, K.; Hu, Y.; Yoshida, K.

    2016-12-01

    Subduction megathrusts are weak, often with effective friction coefficients as low as 0.03. Consequently, differential stress (S1 - S3) in the nearby upper plate is low. Compression due to plate coupling and tension due to gravity are in a subtle balance that can be tipped by small perturbations. For example, the 2011 M=9 Tohoku-oki earthquake, which has a rupture-zone-average stress drop of only a few MPa, switched offshore margin-normal stress from compression to tension and affected seismicity pattern and stress directions of various parts of the land area. The low differential stress is also reflected in spatial variations of stresses, such as with changes in topography. In the Andes, crustal earthquake focal mechanisms change from thrust-faulting in low-elevation areas to normal-faulting in high-elevation areas. Given the lack of evidence for a pervasively weak crust, the low differential stress may indicate that in general the crust near subduction zones is not critically stressed. If so, crustal earthquakes do not represent pervasive failure but only local failure due to stress, material, and fluid pressure heterogeneity. If distributed permanent deformation that creates topography is not the norm, it either happens in brief episodes or took place in the past. The outer wedge may enter a compressively or extensionally critical state due to coseismic strengthening or weakening, respectively, of the shallow megathrust in largest interplate earthquakes. Temporal changes in loading forces must occur also at much larger temporal and spatial scales in response to changes in the nature of the subducting plate and other tectonic conditions. We propose that submarine wedges and high topography in the upper plate attain their geometry in geologically brief episodes of high differential stress. They normally stay in a low-stress stable state, but their geometry often reflects high-stress episodes of critical states in the past. In other words, rocks have a sustained

  8. Seismic cycle stress change in western Taiwan over the last 270 years

    NASA Astrophysics Data System (ADS)

    Mouyen, M.; Cattin, R.; Masson, F.

    2010-02-01

    The island of Taiwan is affected by intense seismic activity, which includes large events as the disastrous 1999 Chi-Chi earthquake. To improve seismic hazard assessment in this area, we estimate the effect of both interseismic loading and major events since 1736 on the state of stress of major active faults. We focus our approach on western Taiwan, which is the most densely populated part of Taiwan. We pay a specific attention to faults geometry and to both interseismic and coseismic slip distributions. Our results suggest that both earthquakes and interseismic loading before 1999 increase the Coulomb stress in the north-western part of the Chelungpu fault, a region which experienced the highest coseismic slip during the Chi-Chi earthquake. More importantly our results reveal a Coulomb stress increase in the southern part of the Changhua thrust fault, below a densely populated area.

  9. Coseismic slip resolution along a plate boundary megathrust: the Nankai Trough, southwest Japan

    USGS Publications Warehouse

    Sagiya, Takeshi; Thatcher, Wayne

    1999-01-01

    Geodetic survey measurements are used to estimate the coseismic slip distribution in the 1944 Tonankai (Mw=8.1) and 1946 Nankaido (Mw=8.3) earthquakes and to assess quantitatively the degree to which this slip is resolved on the plate boundary megathrust. Data used include 798 angle changes from triangulation surveys, 328 leveling section differences, and 5 coseismic tidal gage offsets. Many of the nominally coseismic triangulation data span ∼50 years, nearly half the earthquake cycle, and correction for interseismic deformation using post-1950 observations is applied. Microseismicity is used to define the configuration of the plate boundary interface and approximate it with a continuous, multisegment fault model. Because the onshore geodetic data have very limited resolving power for offshore fault segments, offshore coseismic slip was constrained by Satctke's [1993] estimation based on tsunami data. The majority of the coseismic slip occurs between 15 and 25 km depth. Although resolution declines toward the trench axis, it is sufficiently good to define two distinct high-slip regions, one off southeastern Shikoku Island (11 m maximum) and the other offshore of Kii Peninsula (3 m maximum). The slip magnitude off southeastern Shikoku, coupled with the plate convergence rate, would imply an recurrence interval of about 270 years, much-longer than the average repeat time of ∼120 years for historical great earthquakes on the Nankai Trough. However, the maximum coseismic slip is sensitive to the assumed fault geometry, and slippage on trough-parallel splay faults could significantly decrease the maximum slip to about 6 m.

  10. Modeling frictional melt injection to constrain coseismic physical conditions

    NASA Astrophysics Data System (ADS)

    Sawyer, William J.; Resor, Phillip G.

    2017-07-01

    Pseudotachylyte, a fault rock formed through coseismic frictional melting, provides an important record of coseismic mechanics. In particular, injection veins formed at a high angle to the fault surface have been used to estimate rupture directivity, velocity, pulse length, stress drop, as well as slip weakening distance and wall rock stiffness. These studies have generally treated injection vein formation as a purely elastic process and have assumed that processes of melt generation, transport, and solidification have little influence on the final vein geometry. Using a pressurized crack model, an analytical approximation of injection vein formation based on dike intrusion, we find that the timescales of quenching and flow propagation may be similar for a subset of injection veins compiled from the Asbestos Mountain Fault, USA, Gole Larghe Fault Zone, Italy, and the Fort Foster Brittle Zone, USA under minimum melt temperature conditions. 34% of the veins are found to be flow limited, with a final geometry that may reflect cooling of the vein before it reaches an elastic equilibrium with the wall rock. Formation of these veins is a dynamic process whose behavior is not fully captured by the analytical approach. To assess the applicability of simplifying assumptions of the pressurized crack we employ a time-dependent finite-element model of injection vein formation that couples elastic deformation of the wall rock with the fluid dynamics and heat transfer of the frictional melt. This finite element model reveals that two basic assumptions of the pressurized crack model, self-similar growth and a uniform pressure gradient, are false. The pressurized crack model thus underestimates flow propagation time by 2-3 orders of magnitude. Flow limiting may therefore occur under a wider range of conditions than previously thought. Flow-limited veins may be recognizable in the field where veins have tapered profiles or smaller aspect ratios than expected. The occurrence and

  11. Stress change and fault interaction from a two century-long earthquake sequence in the central Tell Atlas (Algeria)

    NASA Astrophysics Data System (ADS)

    Kariche, Jughurta; Meghraoui, Mustapha; Ayadi, Abdelhakim; Salah Boughacha, Mohamed

    2017-04-01

    We study the role and distribution of stress transfer that may trigger destructive earthquakes in the Central Tell Atlas (Algeria). A sequence of historical events reaching Ms 7.3 and related stress tensors with thrust faulting mechanisms allows the modeling of the Coulomb Failure Function (deltaCFF). We explore here the physical parameters for a stress transfer along the Tell thrust-and-fold belt taking into account an eastward trending earthquake migration from 1891 to 2003. The Computation integrated the seismicity rate in the deltaCFF computation, which is in good agreement with the migration seismicity. The stress transfer progression and increase of 0.1 to 0.8 bar are obtained on fault planes at 7-km-depth with a friction coefficient µ' 0.4 showing stress loading lobes on targeted coseismic fault zone and location of stress shadow across other thrust-and-fold regions. The Coulomb modeling suggests a distinction in earthquake triggering between zones with moderate-sized and large earthquake ruptures. Recent InSAR and levelling studies and aftershocks that document postseismic deformation of major earthquakes are integrated into the static stress change calculations. The presence of fluid and related poroelastic deformation can be considered as an open question with regards to their contribution to major earthquakes and their implications in the seismic hazard assessment of northern Algeria.

  12. Stress change and fault interaction from a two century-long earthquake sequence in the central Tell Atlas (Algeria)

    NASA Astrophysics Data System (ADS)

    Kariche, Jugurtha; Meghraoui, Mustapha; Ayadi, Abdelhakim; Cakir, Ziyadin; Boughacha, Med-Salah

    2016-04-01

    We study the rôle and distribution of stress transfer that may trigger destructive earthquakes in the Central Tell Atlas (Algeria). A sequence of historical events reaching Ms 7.3 and related stress tensor with thrust faulting mechanism illustrates the Coulomb Failure Function (CFF) modeling. We explore here the physical pattern for a stress transfer along the Tell thrust-and-fold belt taking into account an eastward trending earthquake migration from 1891 to 2003. The Computation integrated the seismicity rate in the CFF computation, which is in good agreement with the migration seismicity. The stress transfer progression and increase of 0.1 to 0.8 bar are obtained on fault planes at 7-km-depth with a friction coefficient μ' 0.4 showing stress loading lobes on targeted coseismic fault zone and location of stress shadow across other thrust-and-fold regions. The Coulomb modelling suggest a distinction in earthquake triggering between zones with moderate-sized and large earthquake ruptures. Recent geodetic (InSAR and levelling) studies and aftershocks that document postseismic deformation of major earthquakes are integrated into the static stress change calculations. The presence of fluid and related poroelastic deformation can be considered as open questions on the occurrence of majors earthquakes in the north-central Algeria.

  13. The impact of static stress change, dynamic stress change, and the background stress on aftershock focal mechanisms

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2014-01-01

    The focal mechanisms of earthquakes in Southern California before and after four M ≥ 6.7 main shocks provide insight into how fault systems respond to stress and changes in stress. The main shock static stress changes have two observed impacts on the seismicity: changing the focal mechanisms in a given location to favor those aligned with the static stress change and changing the spatial distribution of seismicity to favor locations where the static stress change aligns with the background stress. The aftershock focal mechanisms are significantly aligned with the static stress changes for absolute stress changes of ≥ 0.02 MPa, for up to ~20 years following the main shock. The dynamic stress changes have similar, although smaller, effects on the local focal mechanisms and the spatial seismicity distribution. Dynamic stress effects are best observed at long periods (30–60 s) and for metrics based on repeated stress cycling in the same direction. This implies that dynamic triggering operates, at least in part, through cyclic shear stress loading in the direction of fault slip. The background stress also strongly controls both the preshock and aftershock mechanisms. While most aftershock mechanisms are well oriented in the background stress field, 10% of aftershocks are identified as poorly oriented outliers, which may indicate limited heterogeneity in the postmain shock stress field. The fault plane orientations of the outliers are well oriented in the background stress, while their slip directions are not, implying that the background stress restricts the distribution of available fault planes.

  14. GPS and seismic constraints on the M = 7.3 2009 Swan Islands earthquake: implications for stress changes along the Motagua fault and other nearby faults

    NASA Astrophysics Data System (ADS)

    Graham, Shannon E.; DeMets, Charles; DeShon, Heather R.; Rogers, Robert; Maradiaga, Manuel Rodriguez; Strauch, Wilfried; Wiese, Klaus; Hernandez, Douglas

    2012-09-01

    We use measurements at 35 GPS stations in northern Central America and 25 seismometers at teleseismic distances to estimate the distribution of slip, source time function and Coulomb stress changes of the Mw = 7.3 2009 May 28, Swan Islands fault earthquake. This event, the largest in the region for several decades, ruptured the offshore continuation of the seismically hazardous Motagua fault of Guatemala, the site of the destructive Ms = 7.5 earthquake in 1976. Measured GPS offsets range from 308 millimetres at a campaign site in northern Honduras to 6 millimetres at five continuous sites in El Salvador. Separate inversions of geodetic and seismic data both indicate that up to ˜1 m of coseismic slip occurred along a ˜250-km-long rupture zone between the island of Roatan and the eastern limit of the 1976 M = 7.5 Motagua fault earthquake in Guatemala. Evidence for slip ˜250 km west of the epicentre is corroborated independently by aftershocks recorded by a local seismic network and by the high concentration of damage to structures in areas of northern Honduras adjacent to the western limit of the rupture zone. Coulomb stresses determined from the coseismic slip distribution resolve a maximum of 1 bar of stress transferred to the seismically hazardous Motagua fault and further indicate unclamping of normal faults along the northern shore of Honduras, where two M > 5 normal-faulting earthquakes and numerous small earthquakes were triggered by the main shock.

  15. Holocene coseismic and aseismic uplift of Isla Mocha, south-central Chile

    USGS Publications Warehouse

    Nelson, A.R.; Manley, W.F.

    1992-01-01

    During the past 6000 years Isla Mocha, a 12 km-long island 30 km off the coast of south-central Chile, experienced a 38 m fall of relative sea level caused primarily by rapid tectonic uplift of the island. As many as 18 raised shorelines (strandlines) record this uplift. Historic accounts of uplift during the great earthquakes (M > 8) of 1835 and 1960 suggest some of the more prominent prehistoric strandlines also emerged during great earthquakes on the interface between the Nazca and South America plates. But the close elevational spacing of strandlines, subdued morphology of strandline beaches, scarcity of exposed bedrock wave-cut platforms, and the extremely high rates of aseismic uplift (ca. 70 mm/yr) of the island since the last great earthquake suggest that many strandlines were raised by aseismic rather than coseismic uplift. Strandline heights and 14 new radiocarbon ages on marine shells show that the present-day uplift rate is more than three times the net rate (ca. 20 mm/yr) of the past 1000 years. The recent high rate probably reflects increased aseismic slip on an inferred thrust fault in the overriding South America plate. Isla Mocha overlies an area of high stress concentration between two major segments of the Chilean subduction zone. The inferred high rate of slip on the thrust fault may be a response to stress changes on the plate interface near the boundary between the segments. ?? 1992.

  16. Managing stress and change during service reviews.

    PubMed

    Sweeney, Corinne

    2009-01-01

    Service reviews occur throughout the National Health Service from time to time, and changes in commissioning policies have recently led many Primary Care Trusts to hold reviews of the community health services. Although reviews can provide opportunities for fresh thinking, the process can be a time of considerable stress and apprehension for many staff as current systems and ways of working are challenged and possibly changed. If this stress is not managed appropriately, staff may suffer ill health leading to possible staff absences and pressure on services. Leaders and managers are ideally placed to manage this time of stress, if they have the necessary skills and qualities. Self-help measures are also beneficial and recommended as part of a healthy lifestyle. This article discusses how change can affect people in different stages of their life and how it can be managed more positively in the workplace.

  17. Investigation of Coulomb stress changes in south Tibet (central Himalayas) due to the 25th April 2015 M W 7.8 Nepal earthquake using a Coulomb stress transfer model

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Meng, Guojie

    2016-10-01

    After M W 7.8 Nepal earthquake occurred, the rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. We present the calculations of the coseismic stress changes that resulted from the 25th April event using models of regional faults designed according to south Tibet-Nepal structure, and show that some indicative significant stress increases. We calculate static stress changes caused by the displacement of a fault on which dislocations happen and an earthquake occurs. A M W 7.3 earthquake broke on 12 May at a distance of 130 km SEE of the M W 7.8 earthquake, whose focus roughly located on high Coulomb stress change (CSC) site. Aftershocks (first 15 days after the mainshock) are associated with stress increase zone caused by the main rupture. We set receiver faults with specified strikes, dips, and rakes, on which the stresses imparted by the source fault are resolved. Four group normal faults to the north of the Nepal earthquake seismogenic fault were set as receiver faults and variant results followed. We provide a discussion on Coulomb stress transfer for the seismogenic fault, which is useful to identify potential future rupture zones.

  18. Effects of Variable Finite Fault Slip Models in Static Stress Changes and Implications for Seismic Hazard and Seismic Risk in Japan

    NASA Astrophysics Data System (ADS)

    Apel, E. V.; Nyst, M.; Williams, C. R.

    2012-12-01

    We calculate regional static stress changes following the M 9.0 Tohoku Japan earthquake using fourteen published models and eight synthetic models of co-seismic slip for the March 11, 2011 megathrust event. The published slip models all solve for the distribution of slip along the ruptured megathrust interface using various data sets, seismic, GPS, and tsunami, or some combination thereof. Considered synthetic models have consistent moment but concentrated patches of slip in differenet areas. We model stress changes on the subduction zones and crustal faults in northern Honshu to estimate regional seismicity rate changes, fault slip rate changes, and the consequent impact on earthquake hazard and risk in the area. We explore the sensitivity of the areas of high slip on fault stress changes and the range of stress changes predicted by these slip models on individual faults and subduction zones, the so-called receiver faults. Generally, the published slip models have consistent rupture area geometry and contain patches of high slip in similar areas, although the maximum amount of slip per model varies between 20 and 60 meters. Patterns of stress change predicted by the 14 slip models are similar; the range of the magnitude of stress changes on receiver faults is significant in general and can be as high as 30 bars. Variability in stress changes due to the various slip models appear to be most dependent on the proximity of the receiver fault to the highest slip patches. Predicted stress changes are also sensitive to changes in elastic parameters (i.e., the coefficient of friction). We apply the different calculated stress change models to our hazard model seismic rates using both the clock reset and the recurrence rate methodology (Parsons, 2005). We then compare a suite of metrics between the original model and the models with updated rates to assess 1) the impact on hazard and risk from static stress changes and 2) the uncertainty associated with this implementation.

  19. Stress induced changes in testis function.

    PubMed

    López-Calderón, A; Ariznavarreta, C; González-Quijano, M I; Tresguerres, J A; Calderón, M D

    1991-01-01

    The mechanism through which chronic stress inhibits the hypothalamic-pituitary-testicular axis has been investigated. Chronic restraint stress decreases testosterone secretion, an effect that is associated with a decrease in plasma gonadotropin levels. In chronically stressed rats there was a decrease in hypothalamic luteinizing hormone-releasing hormone (LHRH) content and the response on plasma gonadotropins to LHRH administration was enhanced. Thus the inhibitory effect of chronic stress on plasma LH and FSH levels seems not to be due to a reduction in pituitary responsiveness to LHRH, but rather to a modification in LHRH secretion. It has been suggested that beta-endorphin might interfere with hypothalamic LHRH secretion during stress. Chronic immobilization did not modify hypothalamic beta-endorphin, while an increase in pituitary beta-endorphin secretion was observed. Since we cannot exclude that changes in beta-endorphin secreted by the pituitary or other opioids may play some role in the stress-induced decrease in LHRH secretion, the effect of naltrexone administration on plasma gonadotropin was studied in chronically stressed rats. Naltrexone treatment did not modify the decrease in plasma concentrations of LH or FSH. These findings suggest that the inhibitory effect of restraint on the testicular axis is exerted at hypothalamic level by some mechanism other than opioids.

  20. Earthquake source localization from the analysis of coseismic landslide catalogues

    NASA Astrophysics Data System (ADS)

    Meunier, Patrick; Marc, Odin; Uchida, Taro; Gorum, Tolga; Robert, Alexandra; Hovius, Niels

    2014-05-01

    In the epicentral area of large continental earthquakes, the density of seismically induced landslides is controlled by the intensity of the ground shaking, the local gradient and lithology. Once corrected for the latter parameters, the decrease of the landslide density with distance to the seismic source in depth is adequately described by a wave attenuation law. This relationship allows to localize the earthquake source using coseismic landslide catalogues and a fault plane geometry [1]. We summarize the results of the inversions of the seismic sources of the 1999 Chichi, the 2004 Niigata, the 2008 Iwate and the 2008 Sichuan earthquakes and discuss the changes in the values of the parameters, namely the source term and the quality factor, with the local geology. [1] Meunier, P., Uchida, T., & Hovius, N. (2013). Landslide patterns reveal the sources of large earthquakes. Earth and Planetary Science Letters, 363, 27-33.

  1. Earthquake cycle deformation in Mexico and Central America constrained by GPS: Implications for coseismic, postseismic, and slow slip

    NASA Astrophysics Data System (ADS)

    Graham, Shannon E.

    Using surface deformation measured by GPS stations within Mexico and Central America, I model coseismic slip, Coulomb stress changes, postseismic afterslip, and slow slip events in order to increase our knowledge of the earthquake deformation cycle in seismically hazardous regions. In Chapter 1, I use GPS data to estimate coseismic slip due to the May 28, 2009 Swan Islands fault earthquake off the coast of Honduras and then use the slip distribution to calculate Coulomb stress changes for the earthquake. Coulomb stress change calculations resolve stress transfer to the seismically hazardous Motagua fault and further show an unclamping of normal faults in northern Honduras. In Chapter 2, the focus shifts to southern Mexico, where continuous GPS measurements since the mid-1990s are revolutionizing our understanding of the flatly subducting Cocos plate. I perform a time-dependent inversion of continuous GPS observations of the 2011-2012 slow slip event (SSE) to estimate the location and magnitude of slow slip preceding the March 20, 2012 Ometepec earthquake. Coulomb stress changes as a result of slip during the SSE are consistent with the hypothesis that the SSE triggered the Ometepec earthquake. Chapter 3 describes inversions for slip both during and after the Ometepec earthquake. Time-dependent modeling of the first six months of postseismic deformation reveals that fault afterslip extended ˜250 km inland to depths of ˜50 km along the Cocos plate subduction. The postseismic afterslip and previous SSEs in southern Mexico occur at similar depths down-dip from the seismogenic zone, indicating that transitional areas of the subduction interface underlie much of southern Mexico. Finally, I perform the first time-dependent modeling of SSEs below Mexico and the first to exploit all available continuous GPS stations in southern and central Mexico. The results provide a more complete and consistent catalog of modeled SSE for the Mexico subduction zone (MSZ) than is

  2. Coseismic ionospheric and geomagnetic disturbances caused by great earthquakes

    NASA Astrophysics Data System (ADS)

    Hao, Yongqiang; Zhang, Donghe; Xiao, Zuo

    2016-04-01

    Despite primary energy disturbances from the Sun, oscillations of the Earth surface due to a large earthquake will couple with the atmosphere and therefore the ionosphere, then the so-called coseismic ionospheric disturbances (CIDs) can be detected in the ionosphere. Using a combination of techniques, total electron content, HF Doppler, and ground magnetometer, a new time-sequence of such effects propagation were developed on observational basis and ideas on explanation provided. In the cases of 2008 Wenchuan and 2011 Tohoku earthquakes, infrasonic waves accompanying the propagation of seismic Rayleigh waves were observed in the ionosphere by all the three kinds of techniques. This is the very first report to present CIDs recorded by different techniques at co-located sites and profiled with regard to changes of both ionospheric plasma and current (geomagnetic field) simultaneously. Comparison between the oceanic (2011 Tohoku) and inland (2008 Wenchuan) earthquakes revealed that the main directional lobe of latter case is more distinct which is perpendicular to the direction of the fault rupture. We argue that the different fault slip (inland or submarine) may affect the way of couplings of lithosphere with atmosphere. References Zhao, B., and Y. Hao (2015), Ionospheric and geomagnetic disturbances caused by the 2008 Wenchuan earthquake: A revisit, J. Geophys. Res. Space Physics, 120, doi:10.1002/2015JA021035. Hao, Y. Q., Z. Xiao, and D. H. Zhang (2013), Teleseismic magnetic effects (TMDs) of 2011 Tohoku earthquake, J. Geophys. Res. Space Physics, 118, 3914-3923, doi:10.1002/jgra.50326. Hao, Y. Q., Z. Xiao, and D. H. Zhang (2012), Multi-instrument observation on co-seismic ionospheric effects after great Tohoku earthquake, J. Geophys. Res., 117, A02305, doi:10.1029/2011JA017036.

  3. Coupling between coseismic deformation of Wenchuan earthquake and the deep tectonics

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Xie, F.; Huang, Z.; Ren, J.

    2009-12-01

    crust along the east margin of Songpan-Ganzi block favor the hypothesis of lower crust channel flow. The deformations of upper crust shortening and lower crust uplifting is absorbed by the up-bending of the east margin of the Tibetan plateau and the detachment and folding in the west part of Sichuan basin (Fig. 1). When the stress accumulation overpasses the ultimate strength the Longmenshan faults turn to thrust and the locked area relaxs through coseismic deformation. Fig.1 Lithosphere tectonic model of Wenchuan earthquake

  4. The 2010 Maule, Chile Co-Seismic Gap and its Relationship to the Mw 7.1 March 25, 2012 Earthquake

    NASA Astrophysics Data System (ADS)

    Kiser, E.; Ishii, M.

    2012-12-01

    occur within the aftershock area of the 2010 mainshock since that event. Back-projection results from the 2012 event show that the rupture initiates near the terminus of the first 2010 sub-event and ends near the origin of the second 2010 sub-event, thus completely filling the 2010 co-seismic gap. This behavior, which is well documented with regular seismic gaps along subduction zones, suggests that the seismic potential within the co-seismic gap is increased by stress changes due to the 2010 mainshock even though the gap is within the general mainshock area. A similar feature to the 2010 Chile co-seismic gap can be seen in the back-projection results from the 2011 Mw 9.0 Tohoku-oki earthquake. For this event, a rupture jump is imaged near the coast of Miyagi and Fukushima where interseismic coupling abruptly changes. This jump leaves a co-seismic gap near the downdip edge of the seismogenic zone that may be the site of a future large earthquake.

  5. Coseismic Gravity and Displacement Signatures Induced by the 2013 Okhotsk Mw8.3 Earthquake.

    PubMed

    Zhang, Guoqing; Shen, Wenbin; Xu, Changyi; Zhu, Yiqing

    2016-09-01

    In this study, Gravity Recovery and Climate Experiment (GRACE) RL05 data from January 2003 to October 2014 were used to extract the coseismic gravity changes induced by the 24 May 2013 Okhotsk Mw8.3 deep-focus earthquake using the difference and least square fitting methods. The gravity changes obtained from GRACE data agreed well with those from dislocation theory in both magnitude and spatial pattern. Positive and negative gravity changes appeared on both sides of the epicenter. The positive signature appeared on the western side, and the peak value was approximately 0.4 microgal (1 microgal = 10(-8) m/s²), whereas on the eastern side, the gravity signature was negative, and the peak value was approximately -1.1 microgal. It demonstrates that deep-focus earthquakes Mw ≤ 8.5 are detectable by GRACE observations. Moreover, the coseismic displacements of 20 Global Positioning System (GPS) stations on the Earth's surface were simulated using an elastic dislocation theory in a spherical earth model, and the results are consistent with the GPS results, especially the near-field results. We also estimated the gravity contributions from the coseismic vertical displacements and density changes, analyzed the proportion of these two gravity change factors (based on an elastic dislocation theory in a spherical earth model) in this deep-focus earthquake. The gravity effect from vertical displacement is four times larger than that caused by density redistribution.

  6. Coseismic Gravity and Displacement Signatures Induced by the 2013 Okhotsk Mw8.3 Earthquake

    PubMed Central

    Zhang, Guoqing; Shen, Wenbin; Xu, Changyi; Zhu, Yiqing

    2016-01-01

    In this study, Gravity Recovery and Climate Experiment (GRACE) RL05 data from January 2003 to October 2014 were used to extract the coseismic gravity changes induced by the 24 May 2013 Okhotsk Mw8.3 deep-focus earthquake using the difference and least square fitting methods. The gravity changes obtained from GRACE data agreed well with those from dislocation theory in both magnitude and spatial pattern. Positive and negative gravity changes appeared on both sides of the epicenter. The positive signature appeared on the western side, and the peak value was approximately 0.4 microgal (1 microgal = 10−8 m/s2), whereas on the eastern side, the gravity signature was negative, and the peak value was approximately −1.1 microgal. It demonstrates that deep-focus earthquakes Mw ≤ 8.5 are detectable by GRACE observations. Moreover, the coseismic displacements of 20 Global Positioning System (GPS) stations on the Earth’s surface were simulated using an elastic dislocation theory in a spherical earth model, and the results are consistent with the GPS results, especially the near-field results. We also estimated the gravity contributions from the coseismic vertical displacements and density changes, analyzed the proportion of these two gravity change factors (based on an elastic dislocation theory in a spherical earth model) in this deep-focus earthquake. The gravity effect from vertical displacement is four times larger than that caused by density redistribution. PMID:27598158

  7. Coseismic Deformation Detection and Quantification for Great Earthquakes Using Spaceborne Gravimetry

    NASA Astrophysics Data System (ADS)

    Wang, Lei

    Because of Earth's elasticity and its viscoelasticity, earthquakes induce mass redistributions in the crust and upper mantle, and consequently change Earth's external gravitational field. Data from Gravity Recovery And Climate Experiment (GRACE) spaceborne gravimetry mission is able to detect the permanent gravitational and its gradient changes caused by great earthquakes, and provides an independent and thus valuable data type for earthquake studies. This study uses a spatiospectral localization analysis employing the Slepian basis functions and shows that the method is novel and efficient to represent and analyze regional signals, and particularly suitable for extracting coseismic deformation signals from GRACE. For the first time, this study uses the Monte Carlo optimization method (Simulated Annealing) for geophysical inversion to quantify earthquake faulting parameters using GRACE detected gravitational changes. GRACE monthly gravity field solutions have been analyzed for recent great earthquakes. For the 2004 Mw 9.2 Sumatra-Andaman and 2005 Nias earthquakes (Mw 8.6), it is shown for the first time that refined deformation signals are detectable by processing the GRACE data in terms of the full gravitational gradient tensor. The GRACE-inferred gravitational gradients agree well with coseismic model predictions. Due to the characteristics of gradient measurements, which have enhanced high-frequency contents, the GRACE observations provide a more clear delineation of the fault lines, locate significant slips, and better define the extent of the coseismic deformation; For the 2010 Mw 8.8 Maule (Chile) earthquake and the 2011 Mw 9.0 Tohoku-Oki earthquake, by inverting the GRACE detected gravity change signals, it is demonstrated that, complimentary to classic teleseismic records and geodetic measurements, the coseismic gravitational change observed by spaceborne gravimetry can be used to quantify large scale deformations induced by great earthquakes.

  8. Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure

    PubMed Central

    Milliner, C. W. D.; Sammis, C.; Allam, A. A.; Dolan, J. F.; Hollingsworth, J.; Leprince, S.; Ayoub, F.

    2016-01-01

    Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies. PMID:27256901

  9. Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure

    NASA Astrophysics Data System (ADS)

    Milliner, C. W. D.; Sammis, C.; Allam, A. A.; Dolan, J. F.; Hollingsworth, J.; Leprince, S.; Ayoub, F.

    2016-06-01

    Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies.

  10. Resolving Fine-Scale Heterogeneity of Co-seismic Slip and the Relation to Fault Structure.

    PubMed

    Milliner, C W D; Sammis, C; Allam, A A; Dolan, J F; Hollingsworth, J; Leprince, S; Ayoub, F

    2016-06-03

    Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies.

  11. Coseismic deformation due to the 2011 Tohoku, Japan, earthquake: influence of 3-D elastic heterogeneity

    NASA Astrophysics Data System (ADS)

    Hashima, A.; Becker, T. W.; Freed, A. M.; Sato, H.; Okaya, D. A.; Suito, H.; Hatanaka, Y.; Matsubara, M.; Takeda, T.; Ishiyama, T.; Iwasaki, T.

    2014-12-01

    The 2011 M9 Tohoku earthquake ruptured a fault area with length and width of ~500 km and ~200 km, respectively, and elastically deformed broad lithospheric and mantle regions. In order to evaluate the influence of the Tohoku earthquake on lithospheric stresses throughout Japan, an accurate accounting of coseismic slip is very important as the initial condition. We investigate the effects of heterogeneous elastic moduli under Japan on the inversion for coseismic slip, utilizing the land-based Japan GPS network as well as seafloor geodetic constraints near the trench. For this purpose, we construct a 3-D finite element model (FEM) to generate Green's functions that allows considering the influence of complex slab geometry as well as heterogeneities in elastic structure. Our FEM incorporates the Pacific and Philippine sea slabs by interpolating seismicity for the Tohoku region and the Nankai trough, as well as the Kuril, Ryukyu and Izu-Bonin arcs. As fault source geometry, we consider not only the Pacific but also the Phillipine sea slab, with initial results suggesting that slip occurring beyond the triple junction is ~1 m. As for elastic heterogeneity, we investigated the effect of the crust-mantle stratification, the contrast of oceanic and continental crust, and the effects of slabs. Results indicate that crust-mantle stratification has to be considered to obtain an appropriate coseismic slip distribution; heterogeneous models show smaller maximum slip and a wider distribution compared to homogeneous structure. This confirms some earlier work, but is in contrast to some recent suggestions. The effect of the ocean-continent contrast and deep slab heterogeneity appear negligible for co-seismic inversions.

  12. The effect of stress changes on time-dependent earthquake probability: an example from the Wasatch Fault Zone, Utah, USA.

    NASA Astrophysics Data System (ADS)

    Verdecchia, Alessandro; Carena, Sara; Pace, Bruno; DuRoss, Christopher

    2016-04-01

    Static and quasi-static Coulomb stress changes produced by large earthquakes can modify the probability of occurrence of subsequent events on neighbouring faults. In order to better understand and minimize the uncertainties in this kind of approach based on physical (Coulomb stress changes) and statistical (probability calculations) models, we focused our study on the Wasatch fault zone (WFZ), a well-studied active normal fault system having abundant geologic and paleoseismic data. Paleoseismic trench investigations of the WFZ indicate that at least 24 large, surface-faulting earthquakes have ruptured the fault's five central, 35-59-km long segments since ~7 ka. Our goal is to determine if the stress changes due to selected paleoevents have significantly modified the present-day probability of occurrence of large earthquakes on each of the segments. For each segment, we modeled the cumulative (coseismic + postseismic) Coulomb stress changes (∆CFScum) due to earthquakes younger than the most recent event and applied the resulting values to the time-dependent probability calculations. Results from the probability calculations predict high percentages of occurrence for the Brigham City and Salt Lake City segments, due to their long elapsed times (>1-2 kyr) when compared to the Weber, Provo, and Nephi segments (< 1 kyr). We also found that the Brigham City, Salt Lake City, and Provo segments have accumulated ∆CFScum larger than 10 bar, whereas the Weber segment has experienced a stress drop of 5 bar. Our results indicate that the ∆CFScum resulting from earthquakes postdating the youngest events on the segments significantly affect the probability calculations only for the Brigham City, Salt Lake City, and Provo segments. In particular, the probability of occurrence of a large earthquake in the next 50 years on these three segments may be underestimated if a time-independent approach, or a time-dependent approach that does not consider ∆CFS, is adopted.

  13. Regression models for estimating coseismic landslide displacement

    USGS Publications Warehouse

    Jibson, R.W.

    2007-01-01

    Newmark's sliding-block model is widely used to estimate coseismic slope performance. Early efforts to develop simple regression models to estimate Newmark displacement were based on analysis of the small number of strong-motion records then available. The current availability of a much larger set of strong-motion records dictates that these regression equations be updated. Regression equations were generated using data derived from a collection of 2270 strong-motion records from 30 worldwide earthquakes. The regression equations predict Newmark displacement in terms of (1) critical acceleration ratio, (2) critical acceleration ratio and earthquake magnitude, (3) Arias intensity and critical acceleration, and (4) Arias intensity and critical acceleration ratio. These equations are well constrained and fit the data well (71% < R2 < 88%), but they have standard deviations of about 0.5 log units, such that the range defined by the mean ?? one standard deviation spans about an order of magnitude. These regression models, therefore, are not recommended for use in site-specific design, but rather for regional-scale seismic landslide hazard mapping or for rapid preliminary screening of sites. ?? 2007 Elsevier B.V. All rights reserved.

  14. Postseismic viscoelastic stress changes following the 1960 M9.5 Chile earthquake: Implications for its relationship with the 2010 M8.8 Chile earthquake

    NASA Astrophysics Data System (ADS)

    Ding, M.; Lin, J.

    2010-12-01

    We investigate viscoelastic deformation and the associated Coulomb stress changes following the 22 May 1960 M9.5 Chile earthquake with particular focus on its relationship to the 27 Feb. 2010 M8.8 earthquake offshore Maule, Chile. The hypocenter of the 2010 quake is found to be located within a zone of coseismic Coulomb stress increases caused by the 1960 mainshock according to models of Lin & Stein (JGR, 2004). We use a stratified viscoelastic rheology model and calculate the 3D viscoelastic flow and stress changes using the spherical VISCO1D code of Politz (BSSA, 1992). Viscoelastic deformation is assumed to be dominant in an asthenospheric mantle layer of relatively low viscosity at the depths between about 100 to 670 km. This low-viscosity asthenospheric layer is sandwiched between an elastic lithospheric lid, within which the earthquake rupture zone lies, and deeper mantle of relatively high viscosity. We find that following the 1960 quake, creep processes within the low-viscosity asthenospheric layer causes a transfer of stresses to the lithospheric lid. As a result, the Coulomb failure stress at the future hypocenter of the 2010 earthquake is calculated to have increased with time for all models examined, approaching a steady-state level. The time period required to reach the steady-state stress level is less for lower values of the assumed viscosity of the asthenospheric layer.

  15. Coseismic slip and early afterslip of the 2015 Illapel, Chile, earthquake: Implications for frictional heterogeneity and coastal uplift

    USGS Publications Warehouse

    Barnhart, William D.; Murray, Jessica R.; Briggs, Richard W.; Gomez, Francisco; Miles, Charles P. J.; Svarc, Jerry L.; Riquelme, Sebástian; Stressler, Bryan J.

    2016-01-01

    Great subduction earthquakes are thought to rupture portions of the megathrust, where interseismic coupling is high and velocity-weakening frictional behavior is dominant, releasing elastic deformation accrued over a seismic cycle. Conversely, postseismic afterslip is assumed to occur primarily in regions of velocity-strengthening frictional characteristics that may correlate with lower interseismic coupling. However, it remains unclear if fixed frictional properties of the subduction interface, coseismic or aftershock-induced stress redistribution, or other factors control the spatial distribution of afterslip. Here we use interferometric synthetic aperture radar and Global Position System observations to map the distribution of coseismic slip of the 2015 Mw 8.3 Illapel, Chile, earthquake and afterslip within the first 38 days following the earthquake. We find that afterslip overlaps the coseismic slip area and propagates along-strike into regions of both high and moderate interseismic coupling. The significance of these observations, however, is tempered by the limited resolution of geodetic inversions for both slip and coupling. Additional afterslip imaged deeper on the fault surface bounds a discrete region of deep coseismic slip, and both contribute to net uplift of the Chilean Coastal Cordillera. A simple partitioning of the subduction interface into regions of fixed frictional properties cannot reconcile our geodetic observations. Instead, stress heterogeneities, either preexisting or induced by the earthquake, likely provide the primary control on the afterslip distribution for this subduction zone earthquake. We also explore the occurrence of coseismic and postseismic coastal uplift in this sequence and its implications for recent hypotheses concerning the source of permanent coastal uplift along subduction zones.

  16. Coseismic slip and early afterslip of the 2015 Illapel, Chile, earthquake: Implications for frictional heterogeneity and coastal uplift

    NASA Astrophysics Data System (ADS)

    Barnhart, William D.; Murray, Jessica R.; Briggs, Richard W.; Gomez, Francisco; Miles, Charles P. J.; Svarc, Jerry; Riquelme, Sebastian; Stressler, Bryan J.

    2016-08-01

    Great subduction earthquakes are thought to rupture portions of the megathrust, where interseismic coupling is high and velocity-weakening frictional behavior is dominant, releasing elastic deformation accrued over a seismic cycle. Conversely, postseismic afterslip is assumed to occur primarily in regions of velocity-strengthening frictional characteristics that may correlate with lower interseismic coupling. However, it remains unclear if fixed frictional properties of the subduction interface, coseismic or aftershock-induced stress redistribution, or other factors control the spatial distribution of afterslip. Here we use interferometric synthetic aperture radar and Global Position System observations to map the distribution of coseismic slip of the 2015 Mw 8.3 Illapel, Chile, earthquake and afterslip within the first 38 days following the earthquake. We find that afterslip overlaps the coseismic slip area and propagates along-strike into regions of both high and moderate interseismic coupling. The significance of these observations, however, is tempered by the limited resolution of geodetic inversions for both slip and coupling. Additional afterslip imaged deeper on the fault surface bounds a discrete region of deep coseismic slip, and both contribute to net uplift of the Chilean Coastal Cordillera. A simple partitioning of the subduction interface into regions of fixed frictional properties cannot reconcile our geodetic observations. Instead, stress heterogeneities, either preexisting or induced by the earthquake, likely provide the primary control on the afterslip distribution for this subduction zone earthquake. We also explore the occurrence of coseismic and postseismic coastal uplift in this sequence and its implications for recent hypotheses concerning the source of permanent coastal uplift along subduction zones.

  17. Stress Matters Revisited: A Boundary Change Experiment

    PubMed Central

    Breen, Mara; Clifton, Charles

    2013-01-01

    Breen and Clifton (2011) argued that readers’ eye movements during silent reading are influenced by the stress patterns of words. This claim was supported by the observation that syntactic reanalysis that required concurrent metrical reanalysis (e.g., a change from the noun form of abstract to the verb form) resulted in longer reading times than syntactic reanalysis that did not require metrical reanalysis (e.g., a change from the noun form of report to the verb form). However, the data contained a puzzle: the disruption appeared on the critical word (abstract, report) itself, although the material that forced the part of speech change did not appear until the next region. Breen and Clifton argued that parafoveal preview of the disambiguating material triggered the revision, and that the eyes did not move on until a fully-specified lexical representation of the critical word was achieved. The present experiment used a boundary change paradigm (Rayner, 1975) in which parafoveal preview of the disambiguating region was prevented. Once again, an interaction was observed: syntactic reanalysis resulted in particularly long reading times when it also required metrical reanalysis. However, now the interaction did not appear on the critical word, but only following the disambiguating region. This pattern of results supports Breen and Clifton's claim that readers form an implicit metrical representation of text during silent reading. PMID:23425386

  18. Identification of Stress Change Within a Rock Mass Through Apparent Stress of Local Seismic Events

    NASA Astrophysics Data System (ADS)

    Brown, Laura; Hudyma, Martin

    2017-01-01

    Mine blasting produces excavation geometry changes which induce stress change that can be observed in the seismic source parameter apparent stress calculated for local seismic events. Using high apparent stress as a proxy for increasing stress within a rock mass, areas experiencing increases in the local stress conditions can be determined. This paper presents the use of apparent stress of seismic events to identify areas within a rock mass experiencing local stress change. Examples from a deep Canadian mine, operating in excess of 2900 m below surface, are provided.

  19. Classification of climate-change-induced stresses on biological diversity.

    PubMed

    Geyer, Juliane; Kiefer, Iris; Kreft, Stefan; Chavez, Veronica; Salafsky, Nick; Jeltsch, Florian; Ibisch, Pierre L

    2011-08-01

    Conservation actions need to account for and be adapted to address changes that will occur under global climate change. The identification of stresses on biological diversity (as defined in the Convention on Biological Diversity) is key in the process of adaptive conservation management. We considered any impact of climate change on biological diversity a stress because such an effect represents a change (negative or positive) in key ecological attributes of an ecosystem or parts of it. We applied a systemic approach and a hierarchical framework in a comprehensive classification of stresses to biological diversity that are caused directly by global climate change. Through analyses of 20 conservation sites in 7 countries and a review of the literature, we identified climate-change-induced stresses. We grouped the identified stresses according to 3 levels of biological diversity: stresses that affect individuals and populations, stresses that affect biological communities, and stresses that affect ecosystem structure and function. For each stress category, we differentiated 3 hierarchical levels of stress: stress class (thematic grouping with the coarsest resolution, 8); general stresses (thematic groups of specific stresses, 21); and specific stresses (most detailed definition of stresses, 90). We also compiled an overview of effects of climate change on ecosystem services using the categories of the Millennium Ecosystem Assessment and 2 additional categories. Our classification may be used to identify key climate-change-related stresses to biological diversity and may assist in the development of appropriate conservation strategies. The classification is in list format, but it accounts for relations among climate-change-induced stresses. © 2011 Society for Conservation Biology.

  20. Passive monitoring of temporal, coseismic, velocity variations at the ocean floor

    NASA Astrophysics Data System (ADS)

    Gouedard, P.; Collins, J. A.; McGuire, J. J.; van der Hilst, R. D.

    2010-12-01

    Passive techniques are now widely used for seismic imaging, for example ambient noise tomography. A recent development of passive techniques, namely the Passive Image Interferometry, allows the monitoring of temporal variations of seismic velocities from the continuous recording of ambient noise. The sensitivity of the method is as high as 0.01% in relative velocity changes. Such a high sensitivity is reached by using the (multiply-) scattered waves reconstructed in the noise cross-correlation functions in the surface-wave coda. In our study we utilized passive image interferometry to detect changes in velocity before/after a Mw 6.0 earthquake at the Gofar transform fault at the East Pacific Rise. The data set consists of a year of continuous recording at 15 ocean bottom seismometers (OBS) located in the vicinity of the fault. A velocity drop of 0.1% is measured at the time of the earthquake. Preliminary results suggest that the temporal variation is localized within the fault zone. Coseismic variations are usually interpreted as a consequence of the stress release on the fault. Multi-component analysis (3 components seismometers plus accelerometers) allows to make independent measurements of the velocity variations, and further improve the resolution. We note that the method is insensitive to clock errors, which is of particular interest when working with OBS, and can also be used to measure and correct for clock errors, if any. The sensitivity of the method, along with its low cost and its continuous and real time nature, make it a promising tool for monitoring geological structures at different scales.

  1. Coseismic-initiated calving at a freshwater-terminating glacier: Tasman Glacier, New Zealand

    NASA Astrophysics Data System (ADS)

    Dykes, R. C.; Lube, G.; Brook, M. S.

    2012-04-01

    Glacier retreat resulting from iceberg calving represents one of the major controls on ice loss from water-terminating glaciers (ice sheets, tidewater and freshwater glaciers) globally. However, the impact that calving has on the transfer of mass between the cryosphere and hydrosphere is still heavily debated, and the physical mechanisms behind calving remain poorly understood. Hitherto, the initiation of calving events has largely been attributed to underlying glaciological mechanisms (including fracturing of ice due to high longitudinal stress gradients) and changes in the proglacial water-body characteristics. We present evidence for a large-magnitude calving event following high magnitude (>Mw 6) earthquakes as a potentially important triggering mechanism of calving in tectonically-active areas. We describe the response of Tasman Glacier, New Zealand, a freshwater-terminating glacier undergoing accelerated calving retreat, to the Mw 6.3, 5.7 and 4.5 Christchurch 22 February 2011 earthquakes and the subsequent calving event. Time-series analysis of timed video and photographic records of the glacier terminus immediately pre-, co- and post- the 22 February earthquakes demonstrates that the large calving event on the 22 February 2011 occurred in direct response to a resonance effect caused by shear (S-) waves oscillating the terminus at the ice-water interface. We suggest that, in this instance, the magnitude of calving was amplified because Tasman Glacier had reached a critical threshold for buoyancy-induced calving in relation to perturbations in lake level. Prior to this event, small- to intermediate magnitude calving, leading to terminus retreat, had been dominated by thermo-erosional notching at the waterline, destabilising the subaerial ice cliff. Indeed, recent (post-2006) large calving events have primarily been driven by torque-induced, buoyancy-driven calving. Hence, in tectonically-active areas, coseismic-initiated calving can have an episodic, but

  2. Coseismic Deformation and Landslides Assosiated with Cinchona Earthquake, Mw 6.1, Costa Rica, Detected by ALOS/PALSAR

    NASA Astrophysics Data System (ADS)

    Umemura, S.; Furuya, M.

    2014-12-01

    A shallow earthquake with magnitude 6.1 (Mw) occurred in Costa Rica, Central America, on 8 January 2009. This earthquake, called Cinchona earthquake, caused many landslides and around 20 fatalities. Alvarado (2009) reported that the area of landslides was concentrated in the northwestern part of the epicenter. To simulate the relationships between the location of landslides and acceleration, we detected landslides and coseismic deformation by using the ALOS/PALSAR radar image analyses. We first detected the coseismic deformation for ascending and descending tracks by InSAR analysis. The maximum coseismic Line of Sight (LOS) changes were around 20cm for both tracks. We derived the fault source model to explain the LOS changes, using elastic dislocation sources; the optimum geometry was inferred by trial-and-errors. The location of the fault model indicated that the source fault of this earthquake was the northern part of the Angel fault. We also detected the signal of landslides by pixel-offset techniques. The signal had larger amplitude in narrower area than coseismic deformation. The signal was placed on the same area reported by Alvarado (2009). As following the attenuation relationships for peak ground acceleration (Si and Midorikawa, 1999), we calculated the horizontal peak ground acceleration. The signal of landslides was concentrated in the area where the value of peak ground acceleration had larger than 450 gal.

  3. Correlation of Static and Peak Dynamic Coulomb Failure Stress with Aftershocks, Seismicity Rate Change, and Triggered Slip in the Salton Trough

    NASA Astrophysics Data System (ADS)

    Eddo, J.; Olsen, K.

    2007-12-01

    Numerous studies have found significant correlation of static Coulomb Failure Stress (sCFS, co-seismic earthquake induced stresses) with the occurrence of mainshocks, aftershocks, and triggered slip (e.g. Stein, 1999; Kilb, 2003; King et al., 1994, Arnadottir, 2003; Du et al., 2003; Freed, 2005). Static CFS estimates are primarily dependent on the final co-seismic slip distribution and fault geometry. Recently, complete or dynamic Coulomb Failure Stress, parameterized by its largest positive value (peak dCFS), has been proposed as an alternative triggering mechanism (Kilb, 2002). Peak dCFS estimates, in addition to the final slip dependence, have been shown to be strongly dependent on co-seismic source effects, such as rupture directivity (Kilb, 2002). However, most studies of stress transfer and earthquake triggering only incorporate sCFS and only a few studies have attempted to correlate seismicity rate change and triggered slip on surrounding faults. In this study we have modeled the distributions of sCFS and peak dCFS for four recent historical earthquakes (1968 M6.7 Borrego Mountain, 1979 M6.6 Imperial Valley, 1987 M6.6 Elmore Ranch, and M6.5 Superstition Hills) using a fourth-order staggered-grid finite-difference method, which incorporates anelastic attenuation, a 3-D velocity model, and heterogeneous slip distributions derived from strong ground-motion and geodetic inversions. The study area is 150 by 150 km located in the Salton Trough of the Imperial Valley, California. A cross-correlation is calculated between the modeled stresses and seismicity rate change in terms of the Z-value (Habermann, 1983) with a background seismicity rate removed. Modeling results show that peak dCFS provides significantly better correlation with aftershock distributions, seismicity rate change, and triggered slip than sCFS for all four events. Both sCFS and peak dCFS provide significant goodness of fit (>55%) with seismicity rate change up to a month after the mainshocks, with

  4. Enhanced stress and changes to regional seismicity due to the 2015 Mw 7.8 Gorkha, Nepal, earthquake on the neighbouring segments of the Main Himalayan Thrust

    NASA Astrophysics Data System (ADS)

    Chan, Chung-Han; Wang, Yu; Almeida, Rafael; Yadav, R. B. S.

    2017-01-01

    In this study we evaluate stress evolution and change in seismic hazard after the 2015 Gorkha earthquake sequence. We take a methodology usually used in areas with well-established seismic monitoring and apply it to an area with a sparse dataset and a limited time observation window. Our goal is to validate this approach as a rapid response tool for seismic forecasting after large earthquakes. We propose a long-term seismic forecasting model of the Main Himalayan Thrust using the historical earthquake catalogue and regional paleo-seismicity. Through application of the rate-and-state friction model, we evaluate short-term rate evolution after the Gorkha earthquake. The long elapsed time since the last megathrust event and the mainshock coseismic stress increase on the Main Himalayan Thrust suggest high seismic potential in the Lalitpur and Lamjung areas along the fault system. We also calculate the stress change on optimally oriented planes in the region and model the regional seismicity rate using a smoothing kernel method and seismicity since 1921. The location of the consequent earthquakes coincides with areas of high background seismicity rate and areas where stress was enhanced by the Mw 7.8 mainshock and Mw 7.3 aftershock. We model the change of seismic rate over time and project a fast decrease, due to the short aftershock duration assumption we use.

  5. Constraints on the coseismic properties of faults dynamically weakened due to silica gel lubrication

    NASA Astrophysics Data System (ADS)

    Tullis, T. E.; Beeler, N. M.; Goldsby, D. L.; Spagnuolo, E.; Smith, S. A.; Di Toro, G.; Nielsen, S. B.

    2012-12-01

    At normal stresses between a few MPa and 110 MPa, silica-rich bare rock surfaces weaken from typical Byerlee friction coefficients of ~0.7 to 0.2 when sheared at sliding speeds of mm/s over meters of slip. Restrengthening of the fault is approximately exponential with a characteristic time of hundreds of seconds. The weakening has been attributed to the formation of finely comminuted, amorphous, wet material on the sliding surface ('silica gel') [Goldsby and Tullis, 2002; DiToro et al, 2004] or to unknown properties of the highly sheared granular wear material [Reches and Lockner, 2010]. Because strength recovery for this weakening mechanism is slow relative to earthquake rise times, for large natural earthquakes this mechanism implies large dynamic strength losses and no coseismic self-healing. We have conducted new friction experiments on bare rock surfaces of Arkansas novaculite at the INGV in Rome to further constrain the implied coseismic and post-seismic response. Our experiments, and in retrospect some of the original experiments of Goldsby and Tullis [2002], reveal that the fault undergoes stick-slip sliding at low slip rates even in its most weakened state and continues to stick-slip during time-dependent restrengthening. Thus, there are two weakening distances, one on the order of meters, which specifies the first-order weakening, and one much shorter, on the order of tens of microns, which determines the stability of sliding in the weakened state. If this weakening mechanism were operating in the Earth, aftershocks could occur on the coseismic fault plane for some period following the mainshock. Using the stick-slip stress drop and machine stiffness we constrain the weakening distance and the approximate rate dependence.

  6. Stress-related changes in personality: A longitudinal study of perceived stress and trait pessimism.

    PubMed

    Shields, Grant S; Toussaint, Loren L; Slavich, George M

    2016-10-01

    Although research has shown that certain aspects of personality can change over time, the determinants of such change remain unclear. Stress alters neural dynamics and precipitates disorders that shape personality traits involving negative affectivity. In this study, therefore, we assessed the perceived stress and pessimism levels of 332 young, middle-aged, and older adults for five weeks to examine how levels of stress and pessimism change and interrelate over time. The best fitting longitudinal model was a bivariate latent growth curve model, which indicated that stress and pessimism both changed and exhibited significant variability in change over time. Moreover, changes in stress were associated with changes in pessimism. Pessimism thus changes over time, with alterations in stress potentially structuring these changes.

  7. Postseismic Gravity Change After the 2006-2007 Great Earthquake Doublet and Constraints on the Asthenosphere Structure in the Central Kuril Islands

    NASA Technical Reports Server (NTRS)

    Shin-Chan, Han; Sauber, Jeanne; Pollitz, Fred

    2016-01-01

    Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in GRACE but without a discernible coseismic gravity change. The gravity increase of approximately 4 micro-Gal, observed consistently from various GRACE solutions around the epicentral area during 2007-2015, is interpreted as resulting from gradual seafloor uplift by (is) approximately 6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25-35 km for the elastic thickness and approximately 10(exp 18) Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault-locking scenarios in the Kuril subduction zone.

  8. Postseismic gravity change after the 2006-2007 great earthquake doublet and constraints on the asthenosphere structure in the central Kuril Islands.

    PubMed

    Han, Shin-Chan; Sauber, Jeanne; Pollitz, Fred

    2016-04-16

    Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in GRACE but without a discernible coseismic gravity change. The gravity increase of ~4 µGal, observed consistently from various GRACE solutions around the epicentral area during 2007-2015, is interpreted as resulting from gradual seafloor uplift by ~6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25-35 km for the elastic thickness and ~10(18) Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault-locking scenarios in the Kuril subduction zone.

  9. Coseismic density redistribution of the Earth interior based on the spherical dislocation theory and comparison to GRACE data

    NASA Astrophysics Data System (ADS)

    Xu, Changyi; Sun, Wenke; Fu, Guangyu; Dong, Jie

    2015-04-01

    Coseismic deformation produces sudden changes in the Earth's layered density structure due to the volume and internal topography changes, which can disturb global gravitational field. Such gravitational perturbations have been detected by the gravity space mission data (Han et al., 2006; Heki and Matsuo, 2010; Zhou et al., 2011). Han et al. (2006) discussed the gravity changes produced by the density changes related to the crustal dilatation produce by the 2004 Sumatra earthquake (Mw 9.0). But he neglected the gravity changes due to the internal topography changes, and the adopted Earth model is the simple half space media. Cambiotti et al. (2011) also discussed the gravity changes due to coseismic volume changes based on the normal mode summation, in which he took the point source as the fault model. However, the maximum coseismic changes occur in the vicinity of the fault, if the point source is adopted to conduct the near-field computation, there are many errors in the results. In this work, we present a method to compute the coseismic density changes in term of volumetric dilatation and internal topography changes based on the elastic dislocation theory. Using this computing scheme, the modelling density changes can be compared directly with the GRACE-observed ones. Combined with the finite fault model, we conduct the case study of the 2004 Sumatra earthquake (Mw 9.3) and the 2011 Tohoku-Oki earthquake (Mw 9.0). Then we compare the modelling results to the GRACE-derived surface density changes given as the equivalent water height (EWH). The comparison reveals some interesting details about the pattern and behavior of the internal density redistribution due to earthquakes at the subduction zone.

  10. Laboratory Experiments of Silica Powder Lubrication Between Rock Faces at Coseismic Velocities

    NASA Astrophysics Data System (ADS)

    Lu, K.; Kavehpour, P.; Brodsky, E.

    2004-12-01

    One of the unresolved problems in earthquake mechanics is the physical process controlling friction on faults during the rupture of large earthquakes. Many studies suggest that coseismic friction is low even at great depths and several mechanisms have been introduced to explain these observations. In these experiments, we attempt to investigate the physics of mechanical lubrication between rock surfaces by using dry powder. To simulate rock friction, we utilize a tribo-rheometer where two novaculite disks, with 1-inch diameter and 5-micron surface roughness, are compressed together with a thin layer of 5-micron silica powder applied in between. The tribo-rheometer is a highly sensitive instrument that measures torque and normal force when a test substance is placed between the rotating plates. The measurements can be used to directly calculate the viscosity and the friction coefficient. These experiments investigate the velocity dependence of friction by rotating the top disk through velocities from 10-3 to 102 rad/sec while the normal stress is kept constant on the order of 104 Pa. The preliminary experiments show frictional regimes of boundary, mixed, and hydrodynamic lubrication; together known as the Stribeck curve. At high shear rates of >10 rad/sec, hydrodynamic lubrication occurs when fluid-like behavior of granular flow are responsible for the shear stress between the surfaces. In contrast, boundary lubrication has full asperity contact between the top and bottom surfaces during low shear rates of <0.01 rad/sec and shear stress arises from physical interactions. Between the two regimes above, the mixed lubrication is where there is a combination of surface asperity and powder lubricant interactions. From the data, we find the friction coefficient drops from a boundary lubrication value of ˜0.3 -- 0.4 to a mixed regime minimum of ˜0.2 -- 0.3 while transitioning to the hydrodynamic lubrication. The transition corresponds to a change from solid

  11. Co-seismic landslide topographic analysis based on multi-temporal DEM-A case study of the Wenchuan earthquake.

    PubMed

    Ren, Zhikun; Zhang, Zhuqi; Dai, Fuchu; Yin, Jinhui; Zhang, Huiping

    2013-01-01

    Hillslope instability has been thought to be one of the most important factors for landslide susceptibility. In this study, we apply geomorphic analysis using multi-temporal DEM data and shake intensity analysis to evaluate the topographic characteristics of the landslide areas. There are many geomorphologic analysis methods such as roughness, slope aspect, which are also as useful as slope analysis. The analyses indicate that most of the co-seismic landslides occurred in regions with roughness, hillslope and slope aspect of >1.2, >30, and between 90 and 270, respectively. However, the intersection regions from the above three methods are more accurate than that derived by applying single topographic analysis method. The ground motion data indicates that the co-seismic landslides mainly occurred on the hanging wall side of Longmen Shan Thrust Belt within the up-down and horizontal peak ground acceleration (PGA) contour of 150 PGA and 200 gal, respectively. The comparisons of pre- and post-earthquake DEM data indicate that the medium roughness and slope increased, the roughest and steepest regions decreased after the Wenchuan earthquake. However, slope aspects did not even change. Our results indicate that co-seismic landslides mainly occurred at specific regions of high roughness, southward and steep sloping areas under strong ground motion. Co-seismic landslides significantly modified the local topography, especially the hillslope and roughness. The roughest relief and steepest slope are significantly smoothed; however, the medium relief and slope become rougher and steeper, respectively.

  12. Sensitivity analysis of earthquake-induced static stress changes on volcanoes: the 2010 Mw 8.8 Chile earthquake

    NASA Astrophysics Data System (ADS)

    Bonali, F. L.; Tibaldi, A.; Corazzato, C.

    2015-06-01

    In this work, we analyse in detail how a large earthquake could cause stress changes on volcano plumbing systems and produce possible positive feedbacks in promoting new eruptions. We develop a sensitivity analysis that considers several possible parameters, providing also new constraints on the methodological approach. The work is focus on the Mw 8.8 2010 earthquake that occurred along the Chile subduction zone near 24 historic/Holocene volcanoes, located in the Southern Volcanic Zone. We use six different finite fault-slip models to calculate the static stress change, induced by the coseismic slip, in a direction normal to several theoretical feeder dykes with various orientations. Results indicate different magnitudes of stress change due to the heterogeneity of magma pathway geometry and orientation. In particular, the N-S and NE-SW-striking magma pathways suffer a decrease in stress normal to the feeder dyke (unclamping, up to 0.85 MPa) in comparison to those striking NW-SE and E-W, and in some cases there is even a clamping effect depending on the magma path strike. The diverse fault-slip models have also an effect (up to 0.4 MPa) on the results. As a consequence, we reconstruct the geometry and orientation of the most reliable magma pathways below the 24 volcanoes by studying structural and morphometric data, and we resolve the stress changes on each of them. Results indicate that: (i) volcanoes where post-earthquake eruptions took place experienced earthquake-induced unclamping or very small clamping effects, (ii) several volcanoes that did not erupt yet are more prone to experience future unrest, from the point of view of the host rock stress state, because of earthquake-induced unclamping. Our findings also suggest that pathway orientation plays a more relevant role in inducing stress changes, whereas the depth of calculation (e.g. 2, 5 or 10 km) used in the analysis, is not key a parameter. Earthquake-induced magma-pathway unclamping might contribute to

  13. Running Therapy: Change Agent in Anxiety and Stress Management.

    ERIC Educational Resources Information Center

    Sachs, Michael L.

    1982-01-01

    Running can be used effectively to produce positive physiological and psychological changes, including cardiovascular and physical fitness, reduction of anxiety, and more effective management of stress. (CJ)

  14. Stressing out: Handling Change in a Digital World

    ERIC Educational Resources Information Center

    Fiehn, Barbara

    2010-01-01

    Living in a world of rapid change and increased use of technologies can lead to an increase in personal levels of stress. Each person needs to find their own stress management systems. This article makes a few suggestions about recognizing stress sources and potential coping strategies.

  15. Stressing out: Handling Change in a Digital World

    ERIC Educational Resources Information Center

    Fiehn, Barbara

    2010-01-01

    Living in a world of rapid change and increased use of technologies can lead to an increase in personal levels of stress. Each person needs to find their own stress management systems. This article makes a few suggestions about recognizing stress sources and potential coping strategies.

  16. Stress reduction correlates with structural changes in the amygdala.

    PubMed

    Hölzel, Britta K; Carmody, James; Evans, Karleyton C; Hoge, Elizabeth A; Dusek, Jeffery A; Morgan, Lucas; Pitman, Roger K; Lazar, Sara W

    2010-03-01

    Stress has significant adverse effects on health and is a risk factor for many illnesses. Neurobiological studies have implicated the amygdala as a brain structure crucial in stress responses. Whereas hyperactive amygdala function is often observed during stress conditions, cross-sectional reports of differences in gray matter structure have been less consistent. We conducted a longitudinal MRI study to investigate the relationship between changes in perceived stress with changes in amygdala gray matter density following a stress-reduction intervention. Stressed but otherwise healthy individuals (N = 26) participated in an 8-week mindfulness-based stress reduction intervention. Perceived stress was rated on the perceived stress scale (PSS) and anatomical MR images were acquired pre- and post-intervention. PSS change was used as the predictive regressor for changes in gray matter density within the bilateral amygdalae. Following the intervention, participants reported significantly reduced perceived stress. Reductions in perceived stress correlated positively with decreases in right basolateral amygdala gray matter density. Whereas prior studies found gray matter modifications resulting from acquisition of abstract information, motor and language skills, this study demonstrates that neuroplastic changes are associated with improvements in a psychological state variable.

  17. Estimating fluid-induced stress change from observed deformation

    DOE PAGES

    Vasco, D. W.; Harness, Paul; Pride, Steve; ...

    2016-12-19

    Observed deformation is sensitive to a changing stress field within the Earth. There are, however, several impediments to a direct inversion of geodetic measurements for changes in stress. Estimating six independent components of stress change from a smaller number of displacement or strain components is inherently non-unique. The reliance upon surface measurements leads to a loss of resolution, due to the attenuation of higher spatial frequencies in the displacement field with distance from a source. Here, we adopt a technique suited to the estimation of stress changes due to the injection and/or withdrawal of fluids at depth. In this approachmore » the surface displacement data provides an estimate of the volume change responsible for the deformation, rather than stress changes themselves. The inversion for volume change is constrained by the fluid fluxes into and out of the reservoir. The distribution of volume change is used to calculate the displacements in the region above the reservoir. Estimates of stress change follow from differentiating the displacement field in conjunction with a geomechanical model of the o verburden. We also apply the technique to Interferometric Synthetic Aperture Radar (InSAR) observations gathered over a petroleum reservoir in the San Joaquin Valley of California. An analysis of the InSAR range changes reveals that the stress field in the overburden varies rapidly both in space and in time. The inferred stress variations are found to be compatible with the documented failure of a well in the field.« less

  18. Estimating fluid-induced stress change from observed deformation

    SciTech Connect

    Vasco, D. W.; Harness, Paul; Pride, Steve; Hoversten, Mike

    2016-12-19

    Observed deformation is sensitive to a changing stress field within the Earth. There are, however, several impediments to a direct inversion of geodetic measurements for changes in stress. Estimating six independent components of stress change from a smaller number of displacement or strain components is inherently non-unique. The reliance upon surface measurements leads to a loss of resolution, due to the attenuation of higher spatial frequencies in the displacement field with distance from a source. Here, we adopt a technique suited to the estimation of stress changes due to the injection and/or withdrawal of fluids at depth. In this approach the surface displacement data provides an estimate of the volume change responsible for the deformation, rather than stress changes themselves. The inversion for volume change is constrained by the fluid fluxes into and out of the reservoir. The distribution of volume change is used to calculate the displacements in the region above the reservoir. Estimates of stress change follow from differentiating the displacement field in conjunction with a geomechanical model of the o verburden. We also apply the technique to Interferometric Synthetic Aperture Radar (InSAR) observations gathered over a petroleum reservoir in the San Joaquin Valley of California. An analysis of the InSAR range changes reveals that the stress field in the overburden varies rapidly both in space and in time. The inferred stress variations are found to be compatible with the documented failure of a well in the field.

  19. Stress-induced structural changes in plant chromatin.

    PubMed

    Probst, Aline V; Mittelsten Scheid, Ortrun

    2015-10-01

    Stress defense in plants is elaborated at the level of protection and adaptation. Dynamic changes in sophisticated chromatin substructures and concomitant transcriptional changes play an important role in response to stress, as illustrated by the transient rearrangement of compact heterochromatin structures or the modulation of chromatin composition and modification upon stress exposure. To connect cytological, developmental, and molecular data around stress and chromatin is currently an interesting, multifaceted, and sometimes controversial field of research. This review highlights some of the most recent findings on nuclear reorganization, histone variants, histone chaperones, DNA- and histone modifications, and somatic and meiotic heritability in connection with stress.

  20. Using stress shadows to invert for changes in local stress field

    NASA Astrophysics Data System (ADS)

    Latimer, C. D.; Tiampo, K. F.; Rundle, J.

    2009-12-01

    When a large earthquake occurs, stresses in the crust are redistributed creating regions that experience an increase in stress while others experience a stress decrease which are called stress shadows. In many studies, these stress shadows are said to contain less seismic activity than the average background rate, and so correlations are made between lack of seismicity or a decrease in seismicity rate and the stress shadow locations and magnitudes (the amount of decrease of stress). In this study the opposite procedure is applied: We use seismicity rate changes to determine information about the stress changes due to a large magnitude earthquake, as well as its effect on the stress field itself. We use the Pattern Informatics method to examine the changes in seismicity rate, as it is an objective measure of the rate changes with respect to the regional background rate. The results from this analysis are then used to invert for, with a genetic algorithm, parameters that define the stress field such as the principal stress orientations, the coefficient of friction, and the calculation depth. The modelled stress data is calculated using Coulomb stress change theory and the Coulomb 3 program, and it is trying to produce the same size and location of stress shadows as seen in the seismicity rate change data. Four different Californian earthquakes were chosen in order to determine their effect on the local stress field: (1) 1987 Superstition Hills (2) 1989 Loma Prieta (3) 1992 Landers and (4) 1994 Northridge. In order to find out the effect that each of the parameters have on the modelled results, we performed a Monte Carlo simulation to find the errors associated with each, and a sensitivity analysis to determine the magnitude of change that each one produces. We hope with this new information of the changes incurred due to a large magnitude earthquake occurrence, that modelling of earthquakes can be advanced, and our understanding of their mechanics enhanced.

  1. Spatial variations of earthquake occurrence and coseismic deformation in the Upper Rhine Graben, Central Europe

    NASA Astrophysics Data System (ADS)

    Barth, A.; Ritter, J. R. R.; Wenzel, F.

    2015-05-01

    Seismic activity in the densely populated Upper Rhine Graben (URG) is an aspect in the public, political, and industrial decision making process. The spatial analysis of magnitude-frequency distributions provides valuable information about local seismicity patterns and regional seismic hazard assessment and can be used also as a proxy for coseismic deformation to explore the seismo-tectonic setting of the URG. We combine five instrumental and one historic earthquake bulletins to obtain for the first time a consistent database for events with local magnitudes ML ≥ 2.0 in the whole URG and use it for the determination of magnitude frequencies. The data processing results in a dataset with 274 Poisson distributed instrumentally recorded earthquakes within the URG between 01/1971 and 02/2012 and 34 historic events since the year 1250. Our analysis reveals significant b-value variations along the URG that allow us to differentiate four distinct sections (I-IV) with significant differences in earthquake magnitude distributions: I: Basel region in the Swiss-France-German border region (b = 0.83), II: region between Mulhouse and Freiburg in the southern URG (b = 1.42), III: central URG (b = 0.93), and IV: northern URG (b = 1.06). High b-values and thus a relatively low amount of high magnitude events in the Freiburg section are possibly a consequence of strongly segmented, small-scale structures that are not able to accumulate high stresses. We use the obtained magnitude-frequency distributions and representative source mechanisms for each section to determine coseismic displacement rates. A maximum horizontal displacement rate of 41 μm/a around Basel is found whereas only 8 μm/a are derived for the central and northern URG. A comparison with geodetic and geological constraints implies that the coseismic displacement rates cover less than 10% of the overall displacement rates, suggesting a high amount of aseismic deformation in the URG.

  2. The spin zone: Transient mid-crust permeability caused by coseismic brecciation

    NASA Astrophysics Data System (ADS)

    Melosh, Benjamin L.; Rowe, Christie D.; Gerbi, Christopher; Bate, Charlotte E.; Shulman, Deborah

    2016-06-01

    Pore fluids migrating through the deep section of continental strike-slip fault zones have been invoked to explain such phenomena as tectonic tremor, stress transfer across the brittle-ductile transition, and short timescales of co-seismic healing. In this contribution, we describe a coseismic mechanism for forming transient vertical fluid conduits within dilational jogs in strike-slip faults. We present field observations of breccias that formed coseismically at dilational stepovers in the dextral Pofadder Shear Zone, a ∼ 1 Ga exhumed continental strike-slip fault in South Africa and Namibia. These breccias are interpreted to have formed when tensile fractures emanating from rupture tips intersected mylonitic foliation parallel to the rupture surface, which then failed, disaggregating the rock. We used quartz textures in the mylonites determined by electron backscatter diffraction to uniquely compare the orientation of each clast to the neighboring wall rock and constrain finite clast rotation within breccia bodies. Comparison of two- and three-dimensional rotation patterns show that clast trajectories are highly scattered when decoupled from wall rock, suggesting that Pofadder breccias were not formed by gradual plucking of clasts during slip. The dilational breccia bodies have sub-vertical geometries and high porosities relative to the host mylonites. We infer that the opening of these breccias may have created instantaneous, temporary vertical pathways for fluid draining through the brittle-plastic transition. These pathways healed post-seismically by cementation or ductile creep along the fault. The connection of many adjacent and overprinting breccia bodies through time provides a mechanism for fluid transport on a 10 s of km scale though the middle crust.

  3. Prenatal stress changes learning strategies in adulthood.

    PubMed

    Schwabe, Lars; Bohbot, Veronique D; Wolf, Oliver T

    2012-11-01

    It is well known that stressful experiences may shape hippocampus-dependent learning and memory processes. However, although most studies focused on the impact of stress at the time of learning or memory testing, very little is known about how stress during critical periods of brain development affects learning and memory later in life. In this study, we asked whether prenatal stress exposure may influence the engagement of hippocampus-dependent spatial learning strategies and caudate nucleus-dependent response learning strategies in later life. To this end, we tested healthy participants whose mothers had experienced major negative life events during their pregnancy in a virtual navigation task that can be solved by spatial and response strategies. We found that young adults with prenatal stress used rigid response learning strategies more often than flexible spatial learning strategies compared with participants whose mothers did not experience major negative life events during pregnancy. Individual differences in acute or chronic stress do not account for these findings. Our data suggest that the engagement of hippocampal and nonhippocampal learning strategies may be influenced by stress very early in life.

  4. Stress-induced changes in wheat grain composition and quality.

    PubMed

    Ashraf, M

    2014-01-01

    Abiotic stresses such as drought, salinity, waterlogging, and high temperature cause a myriad of changes in the metabolism of plants, and there is a lot of overlap in these changes in plants in response to different stresses such as drought and salinity. These stress-induced metabolic changes cause impaired crop growth thereby resulting in poor yield. The metabolic changes taking place in several plant species due to a particular abiotic stress have been revealed from the whole plant to the molecular level by researchers, but most studies have focused on organs such as leaf, stem, and root. Information on such stress-induced changes in seed or grains is infrequent in the literature. From the information that is available, it is now evident that abiotic stress can induce considerable changes in the composition and quality of cereal grains including those of wheat, the premier staple food crop in the world. Thus, the present review discusses how far different types of stresses, mainly salinity, drought, high temperature, and waterlogging, can alter the wheat grain composition and quality. By fully uncovering the stress-induced changes in the nutritional values of wheat grains it would be possible to establish whether balanced supplies of essential nutrients are available to the human population from the wheat crop grown on stress-affected areas.

  5. Local interpolation of coseismic displacements measured by InSAR

    NASA Astrophysics Data System (ADS)

    Yaseen, M.; Hamm, N. A. S.; Woldai, T.; Tolpekin, V. A.; Stein, A.

    2013-08-01

    Coseismic displacements play a significant role in characterizing earthquake causative faults and understanding earthquake dynamics. They are typically measured from InSAR using pre- and post-earthquake images. The displacement map produced by InSAR may contain missing coseismic values due to the decorrelation of ASAR images. This study focused on interpolating missing values in the coseismic displacement map of the 2003 Bam earthquake using geostatistics with the aim of running a slip distribution model. The gaps were grouped into 23 patches. Variograms of the patches showed that the displacement data were spatially correlated. The variogram prepared for ordinary kriging (OK) indicated the presence of a trend and thus justified the use of universal kriging (UK). Accuracy assessment was performed in 3 ways. First, 11 patches of equal size and with an equal number of missing values generated artificially, were kriged and validated. Second, the four selected patches results were validated after shifting them to new locations without missing values and comparing them with the observed values. Finally, cross validation was performed for both types of patch at the original and shifted locations. UK results were better than OK in terms of kriging variance, mean error (ME) and root mean square error (RMSE). For both OK and UK, only 4 out of 23 patches (1, 5, 11 and 21) showed ME and RMSE values that were substantially larger than for the other patches. The accuracy assessment results were found to be satisfactory with ME and RMSE values close to zero. InSAR data inversion demonstrated the usefulness of interpolation of the missing coseismic values by improving a slip distribution model. It is therefore concluded that kriging serves as an effective tool for interpolating the missing values on a coseismic displacement map.

  6. Coseismic conjugate faulting structures produced by the 2016 Mw 7.1 Kumamoto earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Lin, Aiming; Chiba, Tatsuro

    2017-06-01

    Field investigations and analyses of airborne LiDAR data reveal that the 2016 Mw7.1 Kumamoto earthquake produced a ∼40-km-long surface rupture zone with a typical conjugate Riedel shearing fault structure along the pre-existing right-lateral strike-slip Hinagu-Futagawa Fault Zone (HFFZ). The conjugate Riedel shearing structure comprises two sets of coseismic shear fault zones that are oriented to NE-SW to ENE-WSW and WNW-ESE to E-W. The NE-SW to ENE-WSW-trending shear fault zone is characterized by R Riedel shear structures with right-lateral strike-slip displacement of up to 2.5 m, including left-stepping en echelon cracks (T-shear) and mole tracks (P-shear). In contrast, the WNW-ESE to E-W-trending shear fault zone is dominated by R‧ Riedel shear structures with left-lateral displacement of up to 1.3 m, including right-stepping en echelon tension cracks (T) and mole tracks (P), which are concentrated in a zone of <10 m within individual rupture zones. Our findings demonstrate that the coseismic conjugate Riedel shear faulting is mainly controlled by the pre-existing active strike-slip faults of HFFZ under the present E-W compressive stress in the study area, associated with the ongoing penetration of the Philippine Sea Plate into the Eurasian Plate.

  7. Developmental Changes in Infants' Responses to Stress.

    ERIC Educational Resources Information Center

    Lewis, Michael; Ramsay, Douglas S.

    1995-01-01

    Observed infants' stress responses to a well-baby examination and inoculation at two, four, and six months. Found an increase in salivary cortisol level over baseline in response to the procedures and that the cortisol response decreased with age, indicating a developmental shift in adrenocortical functioning between two and six months of age. (BC)

  8. Six months later: Testing the Coulomb stress change model by examining calculations made immediately after the 12 May, 2008 Ms=8.0 Wenchuan earthquake

    NASA Astrophysics Data System (ADS)

    Parsons, T.; Ji, C.; Kirby, E.

    2008-12-01

    On the 12th of May, 2008 a devastating Ms=8.0 earthquake struck the eastern edge of the Tibetan Plateau, collapsing buildings and killing thousands in major cities aligned along the western Sichuan basin in China. After a high-magnitude earthquake like the 12 May event, rearrangement of stresses in the crust commonly causes subsequent damaging earthquakes. The Sichuan basin and surroundings are crossed by major active strike-slip and thrust faults. By 72 hours after the earthquake, coseismic stress changes were calculated on models of those faults, with many showing significant stress increases. Rapid mapping of stress changes was intended to locate fault sections with relatively higher odds of producing the largest aftershocks and to enable prospective testing of the static-stress triggering hypothesis. A recent prospective test of the method was conducted by McCloskey et al. [2005] after the great 2004 Sumatra earthquake, and was validated by a M=8.7 shock that struck three months later in a region calculated to have been stressed by the mainshock. Our test begins at the time peer review was completed, 38 days after the mainshock on 19 June, 2008. Thus aftershocks occurring between that time and the present can be used for prospective testing. As of this writing, in our test region magnitude greater than 4.0 aftershocks have been largely confined to the mainshock rupture zone, with virtually no activity on Sichuan basin faults with calculated stress increases. Examination of magnitude-frequency behavior of the aftershocks suggests either a corner magnitude at about magnitude 6, or a deficiency in the magnitude greater than 6 range. This experiment is ongoing, and time will tell if the Coulomb model is confirmed in the Sichuan region; our conclusion at present is that there has been no validation, and that use of a generalized aftershock forecast model would have been sufficient.

  9. Sensitivity of Southern Ocean circulation to wind stress changes: Role of relative wind stress

    NASA Astrophysics Data System (ADS)

    Munday, D. R.; Zhai, X.

    2015-11-01

    The influence of different wind stress bulk formulae on the response of the Southern Ocean circulation to wind stress changes is investigated using an idealised channel model. Surface/mixed layer properties are found to be sensitive to the use of the relative wind stress formulation, where the wind stress depends on the difference between the ocean and atmosphere velocities. Previous work has highlighted the surface eddy damping effect of this formulation, which we find leads to increased circumpolar transport. Nevertheless the transport due to thermal wind shear does lose sensitivity to wind stress changes at sufficiently high wind stress. In contrast, the sensitivity of the meridional overturning circulation is broadly the same regardless of the bulk formula used due to the adiabatic nature of the relative wind stress damping. This is a consequence of the steepening of isopycnals offsetting the reduction in eddy diffusivity in their contribution to the eddy bolus overturning, as predicted using a residual mean framework.

  10. [Stress fracture after changing to barefoot running].

    PubMed

    Christensen, Mikkel

    2014-12-15

    Barefoot running is increasing in popularity but little is known about the implications in respect to injuries. It has been proposed that barefoot running is associated with a decrease in running injuries as it represents a more natural way of running. A 50-year-old runner with a weekly running distance of 50 km presented suffering from a stress fracture of the second metatarsal after six weeks of intensive barefoot running.

  11. Static stress changes and the triggering of earthquakes

    USGS Publications Warehouse

    King, Geoffrey C.P.; Stein, Ross S.; Lin, Jian

    1994-01-01

    To understand whether the 1992 M = 7.4 Landers earthquake changed the proximity to failure on the San Andreas fault system, we examine the general problem of how one earthquake might trigger another. The tendency of rocks to fail in a brittle manner is thought to be a function of both shear and confining stresses, commonly formulated as the Coulomb failure criterion. Here we explore how changes in Coulomb conditions associated with one or more earthquakes may trigger subsequent events. We first consider a Coulomb criterion appropriate for the production of aftershocks, where faults most likely to slip are those optimally orientated for failure as a result of the prevailing regional stress field and the stress change caused by the mainshock. We find that the distribution of aftershocks for the Landers earthquake, as well as for several other moderate events in its vicinity, can be explained by the Coulomb criterion as follows: aftershocks are abundant where the Coulomb stress on optimally orientated faults rose by more than one-half bar, and aftershocks are sparse where the Coulomb stress dropped by a similar amount. Further, we find that several moderate shocks raised the stress at the future Landers epicenter and along much of the Landers rupture zone by about a bar, advancing the Landers shock by 1 to 3 centuries. The Landers rupture, in turn, raised the stress at site of the future M = 6.5 Big Bear aftershock site by 3 bars. The Coulomb stress change on a specified fault is independent of regional stress but depends on the fault geometry, sense of slip, and the coefficient of friction. We use this method to resolve stress changes on the San Andreas and San Jacinto faults imposed by the Landers sequence. Together the Landers and Big Bear earthquakes raised the stress along the San Bernardino segment of the southern San Andreas fault by 2 to 6 bars, hastening the next great earthquake there by about a decade.

  12. Coseismic source model of the 2003 Mw 6.8 Chengkung earthquake, Taiwan, determined from GPS measurements

    USGS Publications Warehouse

    Ching, K.-E.; Rau, R.-J.; Zeng, Y.

    2007-01-01

    A coseismic source model of the 2003 Mw 6.8 Chengkung, Taiwan, earthquake was well determined with 213 GPS stations, providing a unique opportunity to study the characteristics of coseismic displacements of a high-angle buried reverse fault. Horizontal coseismic displacements show fault-normal shortening across the fault trace. Displacements on the hanging wall reveal fault-parallel and fault-normal lengthening. The largest horizontal and vertical GPS displacements reached 153 and 302 mm, respectively, in the middle part of the network. Fault geometry and slip distribution were determined by inverting GPS data using a three-dimensional (3-D) layered-elastic dislocation model. The slip is mainly concentrated within a 44 ?? 14 km slip patch centered at 15 km depth with peak amplitude of 126.6 cm. Results from 3-D forward-elastic model tests indicate that the dome-shaped folding on the hanging wall is reproduced with fault dips greater than 40??. Compared with the rupture area and average slip from slow slip earthquakes and a compilation of finite source models of 18 earthquakes, the Chengkung earthquake generated a larger rupture area and a lower stress drop, suggesting lower than average friction. Hence the Chengkung earthquake seems to be a transitional example between regular and slow slip earthquakes. The coseismic source model of this event indicates that the Chihshang fault is divided into a creeping segment in the north and the locked segment in the south. An average recurrence interval of 50 years for a magnitude 6.8 earthquake was estimated for the southern fault segment. Copyright 2007 by the American Geophysical Union.

  13. Coseismic compression/dilatation and viscoelastic uplift/subsidence following the 2012 Indian Ocean earthquakes quantified from satellite gravity observations

    NASA Astrophysics Data System (ADS)

    Han, Shin-Chan; Sauber, Jeanne; Pollitz, Fred

    2015-05-01

    The 2012 Indian Ocean earthquake sequence (Mw 8.6, 8.2) is a rare example of great strike-slip earthquakes in an intraoceanic setting. With over a decade of Gravity Recovery and Climate Experiment (GRACE) data, we were able to measure and model the unanticipated large coseismic and postseismic gravity changes of these events. Using the approach of normal mode decomposition and spatial localization, we computed the gravity changes corresponding to five moment tensor components. Our analysis revealed that the gravity changes are produced predominantly by coseismic compression and dilatation within the oceanic crust and upper mantle and by postseismic vertical motion. Our results suggest that the postseismic positive gravity and the postseismic uplift measured with GPS within the coseismic compressional quadrant are best fit by ongoing uplift associated with viscoelastic mantle relaxation. Our study demonstrates that the GRACE data are suitable for analyzing strike-slip earthquakes as small as Mw 8.2 with the noise characteristics of this region.

  14. Coseismic uplift along the coasts of the Northern Cyprus

    NASA Astrophysics Data System (ADS)

    Yıldırım, Cengiz; Melnick, Daniel; Tüysüz, Okan; Özcan, Orkan

    2017-04-01

    Coseismic tectonic deformation along the coasts of Cyprus is important to understand seismic hazard in the Eastern Mediterranean Region. Since the island is situated at the boundary between African and Eurasian plates it may provide information about major tectonic events. The presence of uplifted wave-cut platforms at the northern and eastern coasts of the Cyprus is evidence of coseismic uplift. We focus on wave-cut platforms at six localities that preserve wave-cut platform morphology allow defining shoreline angle elevations with high-resolution (10cm) digital elevation models. We used Radiocarbon (14C) dating method to date coral fossils attached on the wave-cut platforms. Our primarily results indicate presence of wave-cut platform shoreline angles at 0.3 -0.6 m and 1.0-1.5 m above sea level. We believe that these levels are associated with coseismic events associated with plate boundary. Our radiocarbon 14C results will help us to constrain timing of these events.

  15. An analytical approach to estimate curvature effect of coseismic deformations

    NASA Astrophysics Data System (ADS)

    Dong, Jie; Sun, Wenke; Zhou, Xin; Wang, Rongjiang

    2016-08-01

    We present an analytical approach to compute the curvature effect by the new analytical solutions of coseismic deformation derived for the homogeneous sphere model. We consider two spheres with different radii: one is the same as earth and the other with a larger radius can approximate a half-space model. Then, we calculate the coseismic displacements for the two spheres and define the relative percentage of the displacements as the curvature effect. The near-field curvature effect is defined relative to the maximum coseismic displacement. The results show that the maximum curvature effect is about 4 per cent for source depths of less than 100 km, and about 30 per cent for source depths of less than 600 km. For the far-field curvature effect, we define it relative to the observing point. The curvature effect is extremely large and sometimes exceeds 100 per cent. Moreover, this new approach can be used to estimate any planet's curvature effect quantitatively. For a smaller sphere, such as the Moon, the curvature effect is much larger than that of the Earth, with an inverse ratio to the earth's radius.

  16. Coseismic fault slip associated with the 1992 M(sub w) 6.1 Joshua Tree, California, earthquake: Implications for the Joshua Tree-Landers earthquake sequence

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.; Reilinger, Robert E.; Rodi, William; Li, Yingping; Toksoz, M. Nafi; Hudnut, Ken

    1995-01-01

    Coseismic surface deformation associated with the M(sub w) 6.1, April 23, 1992, Joshua Tree earthquake is well represented by estimates of geodetic monument displacements at 20 locations independently derived from Global Positioning System and trilateration measurements. The rms signal to noise ratio for these inferred displacements is 1.8 with near-fault displacement estimates exceeding 40 mm. In order to determine the long-wavelength distribution of slip over the plane of rupture, a Tikhonov regularization operator is applied to these estimates which minimizes stress variability subject to purely right-lateral slip and zero surface slip constraints. The resulting slip distribution yields a geodetic moment estimate of 1.7 x 10(exp 18) N m with corresponding maximum slip around 0.8 m and compares well with independent and complementary information including seismic moment and source time function estimates and main shock and aftershock locations. From empirical Green's functions analyses, a rupture duration of 5 s is obtained which implies a rupture radius of 6-8 km. Most of the inferred slip lies to the north of the hypocenter, consistent with northward rupture propagation. Stress drop estimates are in the range of 2-4 MPa. In addition, predicted Coulomb stress increases correlate remarkably well with the distribution of aftershock hypocenters; most of the aftershocks occur in areas for which the mainshock rupture produced stress increases larger than about 0.1 MPa. In contrast, predicted stress changes are near zero at the hypocenter of the M(sub w) 7.3, June 28, 1992, Landers earthquake which nucleated about 20 km beyond the northernmost edge of the Joshua Tree rupture. Based on aftershock migrations and the predicted static stress field, we speculate that redistribution of Joshua Tree-induced stress perturbations played a role in the spatio-temporal development of the earth sequence culminating in the Landers event.

  17. Coseismic fault slip associated with the 1992 M(sub w) 6.1 Joshua Tree, California, earthquake: Implications for the Joshua Tree-Landers earthquake sequence

    NASA Astrophysics Data System (ADS)

    Bennett, Richard A.; Reilinger, Robert E.; Rodi, William; Li, Yingping; Toksoz, M. Nafi; Hudnut, Ken

    1995-04-01

    Coseismic surface deformation associated with the M(sub w) 6.1, April 23, 1992, Joshua Tree earthquake is well represented by estimates of geodetic monument displacements at 20 locations independently derived from Global Positioning System and trilateration measurements. The rms signal to noise ratio for these inferred displacements is 1.8 with near-fault displacement estimates exceeding 40 mm. In order to determine the long-wavelength distribution of slip over the plane of rupture, a Tikhonov regularization operator is applied to these estimates which minimizes stress variability subject to purely right-lateral slip and zero surface slip constraints. The resulting slip distribution yields a geodetic moment estimate of 1.7 x 10(exp 18) N m with corresponding maximum slip around 0.8 m and compares well with independent and complementary information including seismic moment and source time function estimates and main shock and aftershock locations. From empirical Green's functions analyses, a rupture duration of 5 s is obtained which implies a rupture radius of 6-8 km. Most of the inferred slip lies to the north of the hypocenter, consistent with northward rupture propagation. Stress drop estimates are in the range of 2-4 MPa. In addition, predicted Coulomb stress increases correlate remarkably well with the distribution of aftershock hypocenters; most of the aftershocks occur in areas for which the mainshock rupture produced stress increases larger than about 0.1 MPa. In contrast, predicted stress changes are near zero at the hypocenter of the M(sub w) 7.3, June 28, 1992, Landers earthquake which nucleated about 20 km beyond the northernmost edge of the Joshua Tree rupture. Based on aftershock migrations and the predicted static stress field, we speculate that redistribution of Joshua Tree-induced stress perturbations played a role in the spatio-temporal development of the earth sequence culminating in the Landers event.

  18. Re-evaluating Occupational Heat Stress in a Changing Climate

    PubMed Central

    Spector, June T.; Sheffield, Perry E.

    2014-01-01

    The potential consequences of occupational heat stress in a changing climate on workers, workplaces, and global economies are substantial. Occupational heat stress risk is projected to become particularly high in middle- and low-income tropical and subtropical regions, where optimal controls may not be readily available. This commentary presents occupational heat stress in the context of climate change, reviews its impacts, and reflects on implications for heat stress assessment and control. Future efforts should address limitations of existing heat stress assessment methods and generate economical, practical, and universal approaches that can incorporate data of varying levels of detail, depending on resources. Validation of these methods should be performed in a wider variety of environments, and data should be collected and analyzed centrally for both local and large-scale hazard assessments and to guide heat stress adaptation planning. Heat stress standards should take into account variability in worker acclimatization, other vulnerabilities, and workplace resources. The effectiveness of controls that are feasible and acceptable should be evaluated. Exposure scientists are needed, in collaboration with experts in other areas, to effectively prevent and control occupational heat stress in a changing climate. PMID:25261455

  19. Re-evaluating occupational heat stress in a changing climate.

    PubMed

    Spector, June T; Sheffield, Perry E

    2014-10-01

    The potential consequences of occupational heat stress in a changing climate on workers, workplaces, and global economies are substantial. Occupational heat stress risk is projected to become particularly high in middle- and low-income tropical and subtropical regions, where optimal controls may not be readily available. This commentary presents occupational heat stress in the context of climate change, reviews its impacts, and reflects on implications for heat stress assessment and control. Future efforts should address limitations of existing heat stress assessment methods and generate economical, practical, and universal approaches that can incorporate data of varying levels of detail, depending on resources. Validation of these methods should be performed in a wider variety of environments, and data should be collected and analyzed centrally for both local and large-scale hazard assessments and to guide heat stress adaptation planning. Heat stress standards should take into account variability in worker acclimatization, other vulnerabilities, and workplace resources. The effectiveness of controls that are feasible and acceptable should be evaluated. Exposure scientists are needed, in collaboration with experts in other areas, to effectively prevent and control occupational heat stress in a changing climate. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  20. Zoning of cold stress associated with climatic change in Russia

    SciTech Connect

    Vinogradova, V.V.

    1997-12-31

    The purpose of my work is to learn the connection of geographical zonality with the distribution of stress in Russia. The map {open_quotes}Geographical distribution of climate life condition ranged on the degree of discomfort in Russia{close_quotes}, made in Institute of Geography of Russian Academy of Sciences, reflects the zoning of cold stress in Russia. This zoning was used for the estimation of cold stress in Russia at various screenplays of climate change. The base of zoning was mating of boundaries of nature-climatic zonality with characteristics of cold presented by indices of cold stress (enthalpy, dry cooling, wet cooling, wind chill etc.). The paper covers geographical distribution of factors provoking cold stress: low temperatures, wind speed and air humidity. Zoning of cold stress on the territory of Russia for long standing average conditions and for the periods of cooling and warming of global climate in the XX century was performed.

  1. Evidence for coseismic subsidence events in a southern California coastal saltmarsh

    PubMed Central

    Leeper, Robert; Rhodes, Brady; Kirby, Matthew; Scharer, Katherine; Carlin, Joseph; Hemphill-Haley, Eileen; Avnaim-Katav, Simona; MacDonald, Glen; Starratt, Scott; Aranda, Angela

    2017-01-01

    Paleoenvironmental records from a southern California coastal saltmarsh reveal evidence for repeated late Holocene coseismic subsidence events. Field analysis of sediment gouge cores established discrete lithostratigraphic units extend across the wetland. Detailed sediment analyses reveal abrupt changes in lithology, percent total organic matter, grain size, and magnetic susceptibility. Microfossil analyses indicate that predominantly freshwater deposits bury relic intertidal deposits at three distinct depths. Radiocarbon dating indicates that the three burial events occurred in the last 2000 calendar years. Two of the three events are contemporaneous with large-magnitude paleoearthquakes along the Newport-Inglewood/Rose Canyon fault system. From these data, we infer that during large magnitude earthquakes a step-over along the fault zone results in the vertical displacement of an approximately 5-km2 area that is consistent with the footprint of an estuary identified in pre-development maps. These findings provide insight on the evolution of the saltmarsh, coseismic deformation and earthquake recurrence in a wide area of southern California, and sensitive habitat already threatened by eustatic sea level rise. PMID:28317847

  2. Evidence for coseismic subsidence events in a southern California coastal saltmarsh

    NASA Astrophysics Data System (ADS)

    Leeper, Robert; Rhodes, Brady; Kirby, Matthew; Scharer, Katherine; Carlin, Joseph; Hemphill-Haley, Eileen; Avnaim-Katav, Simona; MacDonald, Glen; Starratt, Scott; Aranda, Angela

    2017-03-01

    Paleoenvironmental records from a southern California coastal saltmarsh reveal evidence for repeated late Holocene coseismic subsidence events. Field analysis of sediment gouge cores established discrete lithostratigraphic units extend across the wetland. Detailed sediment analyses reveal abrupt changes in lithology, percent total organic matter, grain size, and magnetic susceptibility. Microfossil analyses indicate that predominantly freshwater deposits bury relic intertidal deposits at three distinct depths. Radiocarbon dating indicates that the three burial events occurred in the last 2000 calendar years. Two of the three events are contemporaneous with large-magnitude paleoearthquakes along the Newport-Inglewood/Rose Canyon fault system. From these data, we infer that during large magnitude earthquakes a step-over along the fault zone results in the vertical displacement of an approximately 5-km2 area that is consistent with the footprint of an estuary identified in pre-development maps. These findings provide insight on the evolution of the saltmarsh, coseismic deformation and earthquake recurrence in a wide area of southern California, and sensitive habitat already threatened by eustatic sea level rise.

  3. Evidence for coseismic subsidence events in a southern California coastal saltmarsh.

    PubMed

    Leeper, Robert; Rhodes, Brady; Kirby, Matthew; Scharer, Katherine; Carlin, Joseph; Hemphill-Haley, Eileen; Avnaim-Katav, Simona; MacDonald, Glen; Starratt, Scott; Aranda, Angela

    2017-03-20

    Paleoenvironmental records from a southern California coastal saltmarsh reveal evidence for repeated late Holocene coseismic subsidence events. Field analysis of sediment gouge cores established discrete lithostratigraphic units extend across the wetland. Detailed sediment analyses reveal abrupt changes in lithology, percent total organic matter, grain size, and magnetic susceptibility. Microfossil analyses indicate that predominantly freshwater deposits bury relic intertidal deposits at three distinct depths. Radiocarbon dating indicates that the three burial events occurred in the last 2000 calendar years. Two of the three events are contemporaneous with large-magnitude paleoearthquakes along the Newport-Inglewood/Rose Canyon fault system. From these data, we infer that during large magnitude earthquakes a step-over along the fault zone results in the vertical displacement of an approximately 5-km(2) area that is consistent with the footprint of an estuary identified in pre-development maps. These findings provide insight on the evolution of the saltmarsh, coseismic deformation and earthquake recurrence in a wide area of southern California, and sensitive habitat already threatened by eustatic sea level rise.

  4. Grinding Induced Changes in Residual Stresses of Carburized Gears

    SciTech Connect

    Lemaster, Robert A; Boggs, Bryan L; Bunn, Jeffrey R; Hubbard, Camden R; Watkins, Thomas R

    2009-01-01

    This paper presents the results of a study performed to measure the change in residual stress that results from the finish grinding of carburized gears. Residual stresses were measured in five gears using the x-ray diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory. Two of the gears were hobbed, carburized, quenched and tempered, but not finished. The remaining three gears were processed similarly, but were finish ground. The residual stresses were measured at 64 different locations on a tooth from each gear. Residual stresses were also measured at fewer points on other teeth to determine the tooth-to-tooth variation. Tooth profile measurements were made of the finished and unfinished gear samples. The results show a fairly uniform and constant compressive residual field in the nonfinished gears. There was a significant reduction in the average residual stress measured in the finished gears. Additionally, there was a significant increase in the variability of the residual stress that was introduced by the grinding process. Analysis of the data suggests a linear relationship between the change in average residual stress and the amount of material removed by the grinding process.

  5. Coseismic Excitation of the Earth's Polar Motion

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2000-01-01

    Apart from the "shaking" near the epicenter that is the earthquake, a seismic event creates a permanent field of dislocation in the entire Earth. This redistribution of mass changes (slightly) the Earth's inertia tensor; and the Earth's rotation will change in accordance with the conservation of angular momentum. Similar to this seismic excitation of Earth rotation variations, the same mass redistribution causes (slight) changes in the Earth's gravitational field expressible in terms of changes in the Stokes coefficients of its harmonic expansion. In this paper, we give a historical background of the subject and discuss the related physics; we then compute the geodynamic effects caused by earthquakes based on normal-mode summation scheme. The effects are computed using the centroid moment tensor (CMT) solutions for 15,814 major earthquakes from Jan., 1977, through Feb., 1999, as provided in the Harvard CMT catalog. The computational results further strengthens these findings and conclusions: (i) the strong tendency for earthquakes to make the Earth rounder and more compact (however slightly) continues; (ii) so does the trend in the seismic "nudging" of the rotation pole toward the general direction of approx. 140 E, roughly opposite to that of the observed polar drift, but two orders of magnitude smaller in drift speed.

  6. College Freshman Stress and Weight Change: Differences by Gender

    ERIC Educational Resources Information Center

    Economos, Christina D.; Hildebrandt, M. Lise; Hyatt, Raymond R.

    2008-01-01

    Objectives: To examine how stress and health-related behaviors affect freshman weight change by gender. Methods: Three hundred ninety-six freshmen completed a 40-item health behavior survey and height and weight were collected at baseline and follow-up. Results: Average weight change was 5.04 lbs for males, 5.49 lbs for females. Weight gain was…

  7. The changing face of posttraumatic stress disorder in modern warfare.

    PubMed

    Wallace, Duncan; Heffernan, Kristi

    2017-08-01

    This study examined aspects of modern warfare and determined whether they have changed the clinical presentation of posttraumatic stress disorder (PTSD). The relationship between PTSD, mild traumatic brain injury, unmanned aerial vehicle operations and women in combat examined. It was concluded that there are significant changes in how contemporary combat veterans may present with PTSD.

  8. College Freshman Stress and Weight Change: Differences by Gender

    ERIC Educational Resources Information Center

    Economos, Christina D.; Hildebrandt, M. Lise; Hyatt, Raymond R.

    2008-01-01

    Objectives: To examine how stress and health-related behaviors affect freshman weight change by gender. Methods: Three hundred ninety-six freshmen completed a 40-item health behavior survey and height and weight were collected at baseline and follow-up. Results: Average weight change was 5.04 lbs for males, 5.49 lbs for females. Weight gain was…

  9. Analysis of Coseismic Fault Slip Models of the 2012 Indian Ocean Earthquake: Importance of GPS Data for Crustal Deformation Studies

    NASA Astrophysics Data System (ADS)

    Gunawan, Endra; Maulida, Putra; Meilano, Irwan; Irsyam, Masyhur; Efendi, Joni

    2016-12-01

    Based on continuous GPS data, we analyze coseismic deformation due to the 2012 Indian Ocean earthquake. We use the available coseismic slip models of the 2012 earthquake, derived from geodetic and/or seismic waveform inversion, to calculate the coseismic displacements in the Andaman-Nicobar, Sumatra and Java. In our analysis, we employ a spherical, layered model of the Earth and we find that Java Island experienced coseismic displacements up to 8 mm, as also observed by our GPS network. Compared to coseismic offsets measured from GPS data, a coseismic slip model derived from multiple observations produced better results than a model based on a single type of observation.

  10. Static Stress Changes Inverted from Microseismicity in Eastern Aegean Sea

    NASA Astrophysics Data System (ADS)

    Leptokaropoulos, Konstantinos; Papadimitriou, Eleftheria; Orlecka-Sikora, Beata; Karakostas, Vassilios

    2014-05-01

    In this study we attempted to derive static stress field variations from the changes of earthquake production rates in Kusadasi bay and Samos island (eastern Aegean), by applying the Dieterich et al. (2000) Rate/State formulation. The calculation of stress changes from earthquake occurrence rates fluctuations should be obtained from catalogues which achieve adequate spatial and temporal resolution and well determined hypocenter coordinates. For this reason we took advantage of the data from a regional network operating since July of 2007, providing continuous monitoring of microseismicity, along with data available from seismological stations of the permanent Hellenic Unified Seismological Network (HUSN). The high accuracy and large sized regional catalogue is utilized for inverting seismicity rate changes into stress variation through a Rate/State dependent friction model. After explicitly determining the physical parameters incorporating in the modeling (reference seismicity rates, characteristic relaxation time, constitutive properties of fault zones) we investigated stress changes in both space and time regime and their possible connection with earthquake clustering and fault interactions. The main interest is focused on the June 2009 Samos Mw=5.1 event, which was followed by an intense seismic activity for several days. We attempt to reproduce and interpret stress changes both before and after the initiation of this seismic burst. The differences between the earthquake occurrence rates before and after the main shock are used as input data in a stress inversion algorithm based upon the Rate/State dependent friction concept in order to provide an estimation of stress changes. Diverse assumptions and combinations of the parameters values are tested for the model performance and sensitivity to be evaluated. The approach followed here could provide evidence of the robustness of the seismicity rate changes usage as a stress meter for both positive and negative

  11. Stress in owned cats: behavioural changes and welfare implications.

    PubMed

    Amat, Marta; Camps, Tomàs; Manteca, Xavier

    2016-08-01

    Domestic cats are exposed to a variety of stressful stimuli, which may have a negative effect on the cats' welfare and trigger a number of behavioural changes. Some of the stressors most commonly encountered by cats include changes in environment, inter-cat conflict, a poor human-cat relationship and the cat's inability to perform highly motivated behaviour patterns. Stress is very likely to reduce feed intake, and stress-related anorexia may contribute to the development of potentially serious medical conditions. Stress also increases the risk of cats showing urine marking and some forms of aggression, including redirected aggression. A number of compulsive disorders such as over-grooming may also develop as a consequence of stressful environments. Some of the main strategies to prevent or reduce stress-related behavioural problems in cats are environmental enrichment, appropriate management techniques to introduce unfamiliar cats to each other and the use of the synthetic analogue of the feline facial pheromone. As the stress response in cats depends, to a large extent, on the temperament of the animal, breeding and husbandry strategies that contribute to the cat developing a well-balanced temperament are also very useful. © The Author(s) 2015.

  12. Stress distribution and dimensional changes in chromatographic columns

    SciTech Connect

    Chen, Feng; Drumm, Eric; Guiochon, Georges A

    2005-07-01

    High pressures, in the kilobar range, are now used in liquid chromatography. Basic equations from mechanics are applied to investigate the stress state in several idealized chromatography tubes, and these stresses are evaluated with respect to the maximum allowable stresses predicted by several methods used in pressure vessel design. An analytical solution is developed for the dimensional changes of idealized tubes subjected to internal pressure, and the analytical solutions used to verify the results from a numerical approximation. Numerical approximations are then used to explore the effects of the end restraint provided by the end frits. Conclusions are derived regarding the requirements for a safe operation of these high pressure chromatography tubes.

  13. Aftershocks are well aligned with the background stress field, contradicting the hypothesis of highly-heterogeneous crustal stress

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2010-01-01

    It has been proposed that the crustal stress field contains small-length-scale heterogeneity of much larger amplitude than the uniform background stress. This model predicts that earthquake focal mechanisms should reflect the loading stress rather than the uniform background stress. So, if the heterogeneous stress hypothesis is correct, focal mechanisms before and after a large earthquake should align with the tectonic loading and the earthquake-induced static stress perturbation, respectively. However, I show that the off-fault triggered aftershocks of the 1992 M7.3 Landers, California, earthquake align with the same stress field as the pre-Landers mechanisms. The aftershocks occurred on faults that were well oriented for failure in the pre-Landers stress field and then loaded by the Landers-induced static stress change. Aftershocks in regions experiencing a 0.05 to 5 MPa coseismic differential stress change align with the modeled Landers-induced static stress change, implying that they were triggered by the stress perturbation. Contrary to the heterogeneous stress hypothesis, these triggered aftershocks are also well aligned with the pre-Landers stress field obtained from inverting the pre-Landers focal mechanisms. Therefore, the inverted pre-Landers stress must represent the persistent background stress field. Earthquake focal mechanisms provide an unbiased sample of the spatially coherent background stress field, which is large relative to any small-scale stress heterogeneity. The counterexample provided by the Landers earthquake is strong evidence that the heterogeneous stress model is not widely applicable.

  14. Stress associated changes in Pavlovian-instrumental transfer in humans.

    PubMed

    Quail, Stephanie L; Morris, Richard W; Balleine, Bernard W

    2017-04-01

    Predictive learning is known to influence instrumental responding for reward. Cues associated with an instrumental outcome can influence performance in two ways: (a) by selectively promoting actions associated with the outcome predicted by the cue (specific transfer), and (b) by increasing motivation and the vigour of instrumental responding (general transfer). To examine these two distinct processes in humans we developed a novel behavioural task in which participants were able to liberate junk-food snacks from a virtual vending machine. Additionally, the relationship between stress and cue-driven reward seeking was examined using participant scores on the Depression Anxiety and Stress Scale (DASS). Reward-paired cues were found to separately bias action selection and influence the rate of responding for rewards. Furthermore, the effects of reward-paired cues on the rate of responding for reward was influenced by increased stress and anxiety. Increased levels of stress and anxiety were associated particularly with changes in cue-driven response vigour; whereas high levels of stress and anxiety were associated with elevated responding above baseline in the presence of a cue associated with a non-rewarding outcome, participants with low levels of anxiety and stress showed appropriate suppression of responding during this cue. These differences in performance between high and low anxiety and stress participants provides initial evidence that, as has been demonstrated in rodents, stress affects the influence of cue-driven response vigour in humans.

  15. Per capita interactions and stress tolerance drive stress-induced changes in biodiversity effects on ecosystem functions.

    PubMed

    Baert, Jan M; Janssen, Colin R; Sabbe, Koen; De Laender, Frederik

    2016-08-18

    Environmental stress changes the relationship between biodiversity and ecosystem functions, but the underlying mechanisms are poorly understood. Because species interactions shape biodiversity-ecosystem functioning relationships, changes in per capita interactions under stress (as predicted by the stress gradient hypothesis) can be an important driver of stress-induced changes in these relationships. To test this hypothesis, we measure productivity in microalgae communities along a diversity and herbicide gradient. On the basis of additive partitioning and a mechanistic community model, we demonstrate that changes in per capita interactions do not explain effects of herbicide stress on the biodiversity-productivity relationship. Instead, assuming that the per capita interactions remain unaffected by stress, causing species densities to only change through differences in stress tolerance, suffices to predict the stress-induced changes in the biodiversity-productivity relationship and community composition. We discuss how our findings set the stage for developing theory on how environmental stress changes biodiversity effects on ecosystem functions.

  16. Per capita interactions and stress tolerance drive stress-induced changes in biodiversity effects on ecosystem functions

    PubMed Central

    Baert, Jan M.; Janssen, Colin R.; Sabbe, Koen; De Laender, Frederik

    2016-01-01

    Environmental stress changes the relationship between biodiversity and ecosystem functions, but the underlying mechanisms are poorly understood. Because species interactions shape biodiversity–ecosystem functioning relationships, changes in per capita interactions under stress (as predicted by the stress gradient hypothesis) can be an important driver of stress-induced changes in these relationships. To test this hypothesis, we measure productivity in microalgae communities along a diversity and herbicide gradient. On the basis of additive partitioning and a mechanistic community model, we demonstrate that changes in per capita interactions do not explain effects of herbicide stress on the biodiversity–productivity relationship. Instead, assuming that the per capita interactions remain unaffected by stress, causing species densities to only change through differences in stress tolerance, suffices to predict the stress-induced changes in the biodiversity–productivity relationship and community composition. We discuss how our findings set the stage for developing theory on how environmental stress changes biodiversity effects on ecosystem functions. PMID:27534986

  17. Postseismic deformation and stress changes following the 1819 Rann of Kachchh, India earthquake: Was the 2001 Bhuj earthquake a triggered event?

    USGS Publications Warehouse

    To, A.; Burgmann, R.; Pollitz, F.

    2004-01-01

    The 2001 Mw 7.6 Bhuj earthquake occurred in an intraplate region with rather unusual active seismicity, including an earlier major earthquake, the 1819 Rann of Kachchh earthquake (M7.7). We examine if static coseismic and transient postseismic deformation following the 1819 earthquake contributed to the enhanced seismicity in the region and the occurrence of the 2001 Bhuj earthquake, ???100 km away and almost two centuries later. Based on the Indian shield setting, great rupture depth of the 2001 event and lack of significant early postseismic deformation measured following the 2001 event, we infer that little viscous relaxation occurs in the lower crust and choose an upper mantle effective viscosity of 1019 Pas. The predicted Coulomb failure stress (DCFS) on the rupture plane of the 2001 event increased by more than 0.1 bar at 20 km depth, which is a small but possibly significant amount. Stress change from the 1819 event may have also affected the occurrence of other historic earthquakes in this region. We also evaluate the postseismic deformation and ??CFS in this region due to the 2001 event. Positive ??CFS from the 2001 event occur to the NW and SE of the Bhuj earthquake rupture. Copyright 2004 by the American Geophysical Union.

  18. Coseismic Fault Slip of the September 16, 2015 Mw 8.3 Illapel, Chile Earthquake Estimated from InSAR Data

    NASA Astrophysics Data System (ADS)

    Zhang, Yingfeng; Zhang, Guohong; Hetland, Eric A.; Shan, Xinjian; Wen, Shaoyan; Zuo, Ronghu

    2016-04-01

    The complete surface deformation of 2015 Mw 8.3 Illapel, Chile earthquake is obtained using SAR interferograms obtained for descending and ascending Sentinel-1 orbits. We find that the Illapel event is predominantly thrust, as expected for an earthquake on the interface between the Nazca and South America plates, with a slight right-lateral strike slip component. The maximum thrust-slip and right-lateral strike slip reach 8.3 and 1.5 m, respectively, both located at a depth of 8 km, northwest to the epicenter. The total estimated seismic moment is 3.28 × 1021 N.m, corresponding to a moment magnitude Mw 8.27. In our model, the rupture breaks all the way up to the sea-floor at the trench, which is consistent with the destructive tsunami following the earthquake. We also find the slip distribution correlates closely with previous estimates of interseismic locking distribution. We argue that positive coulomb stress changes caused by the Illapel earthquake may favor earthquakes on the extensional faults in this area. Finally, based on our inferred coseismic slip model and coulomb stress calculation, we envision that the subduction interface that last slipped in the 1922 Mw 8.4 Vallenar earthquake might be near the upper end of its seismic quiescence, and the earthquake potential in this region is urgent.

  19. The Role of Fault Strength Heterogeneities in Earthquake Sequences and Dynamic Earthquake Ruptures with Enhanced Co-Seismic Weakening

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Lapusta, N.

    2011-12-01

    Natural faults are characterized by geometric complexities, variations in hydraulic and frictional properties, and non-uniform prestress. In simulations of isolated dynamic ruptures, these heterogeneities are used to produce complex earthquake scenarios, and often fault prestress and frictional strength are assigned independently. However, simulations of multiple earthquake cycles (e.g., Lapusta and Liu, 2009) show that fault prestress and strength are physically related through stress redistribution due to prior slip. Considering the interplay of stress redistribution and fault strength heterogeneity is important for understanding earthquake cycle patterns and characteristics of dynamic ruptures. Here we study long-term slip on faults with large-scale heterogeneous fault strength due to non-uniform normal stress and/or frictional properties, which could be related to geometric and/or material complexity. Using BICycle algorithm (Lapusta and Liu, 2009, Noda and Lapusta, 2011), we simulate the entire earthquake cycles, including fully dynamic seismic rupture and aseismic tectonic loading, on faults governed by Dieterich-Ruina rate-and-state friction with enhanced co-seismic weakening due to flash heating and thermal pressurization. Initial shear stresses are pre-assigned and developed into physically-consistent distribution through multiple cycles. In our simulations, incorporation of enhanced co-seismic weakening generally results in events with larger slip and enables the fault to operate at lower average stress level. Increasing heat production, and hence larger co-seismic weakening at the places of higher normal confinement, tends to partially compensate for the effect of heterogeneous static strength. The sequences are characterized by occasional large fault-spanning seismic events and many smaller events that rupture across only part of the fault. Shear stresses evolve and redistribute on the entire fault during the major events, in accordance with the fault

  20. Coseismic slip distribution of the 1923 Kanto earthquake, Japan

    USGS Publications Warehouse

    Pollitz, F.F.; Nyst, M.; Nishimura, T.; Thatcher, W.

    2005-01-01

    The slip distribution associated with the 1923 M = 7.9 Kanto, Japan, earthquake is reexamined in light of new data and modeling. We utilize a combination of first-order triangulation, second-order triangulation, and leveling data in order to constrain the coseismic deformation. The second-order triangulation data, which have not been utilized in previous studies of 1923 coseismic deformation, are associated with only slightly smaller errors than the first-order triangulation data and expand the available triangulation data set by about a factor of 10. Interpretation of these data in terms of uniform-slip models in a companion study by Nyst et al. shows that a model involving uniform coseismic slip on two distinct rupture planes explains the data very well and matches or exceeds the fit obtained by previous studies, even one which involved distributed slip. Using the geometry of the Nyst et al. two-plane slip model, we perform inversions of the same geodetic data set for distributed slip. Our preferred model of distributed slip on the Philippine Sea plate interface has a moment magnitude of 7.86. We find slip maxima of ???8-9 m beneath Odawara and ???7-8 m beneath the Miura peninsula, with a roughly 2:1 ratio of strike-slip to dip-slip motion, in agreement with a previous study. However, the Miura slip maximum is imaged as a more broadly extended feature in our study, with the high-slip region continuing from the Miura peninsula to the southern Boso peninsula region. The second-order triangulation data provide good evidence for ???3 m right-lateral strike slip on a 35-km-long splay structure occupying the volume between the upper surface of the descending Philippine Sea plate and the southern Boso peninsula. Copyright 2005 by the American Geophysical Union.

  1. Borehole Measurements of Interfacial and Co-seismic Seismoelectric Effects

    NASA Astrophysics Data System (ADS)

    Butler, K. E.; Dupuis, J. C.; Kepic, A. W.; Harris, B. D.

    2006-12-01

    We have recently carried out a series of seismoelectric field experiments employing various hammer seismic sources on surface and a multi-electrode `eel' lowered into slotted PVC-cased boreholes penetrating porous sediments. Deploying grounded dipole receivers in boreholes has a number of advantages over surface-based measurements. Ambient noise levels are reduced because earth currents from power lines and other sources tend to flow horizontally, especially near the surface. The earth also provides natural shielding from higher frequency spherics and radio frequency interference while the water-filled borehole significantly decreases the electrode contact impedance which in turn reduces Johnson noise and increases resilience to capacitively- coupled noise sources. From a phenomenological point of view, the potential for measuring seismoelectric conversions from various geological or pore fluid contacts at depth can be assessed by lowering antennas directly through those interfaces. Furthermore, co-seismic seismoelectric signals that are normally considered to be noise in surface measurements are of interest for well logging in the borehole environment. At Fredericton, Canada, broadband co-seismic effects, having a dominant frequency of 350-400 Hz were measured at quarter meter intervals in a borehole penetrating glacial sediments including tills, sands, and a silt/clay aquitard. Observed signal strengths of a few microvolts/m were found to be consistent with the predictions of a simplified theoretical model for the co-seismic effect expected to accompany the regular `fast' P-wave. In Australia we have carried out similar vertical profiling experiments in hydrogeological monitoring boreholes that pass through predominantly sandy sediments containing fresh to saline water near Ayr, QLD and Perth, WA. While co-seismic effects are generally seen to accompany P-wave and other seismic arrivals, the most interesting result has been the observation, at three sites, of

  2. Hippocampal gene expression changes underlying stress sensitization and recovery.

    PubMed

    Gray, J D; Rubin, T G; Hunter, R G; McEwen, B S

    2014-11-01

    Chronic and acute stressors have been linked to changes in hippocampal function and anxiety-like behaviors. Both produce changes in gene expression, but the extent to which these changes endure beyond the end of stress remains poorly understood. As an essential first step to characterize abnormal patterns of gene expression after stress, this study demonstrates how chronic restraint stress (CRS) modulates gene expression in response to a novel stressor in the hippocampus of wild-type mice and the extent to which these changes last beyond the end of CRS. Male C57/bl6 mice were subjected to (1) a forced swim test (FST), (2) corticosterone (Cort) or vehicle injections, (3) CRS for 21 days and then a FST, or (4) allowed to recover 21 days after CRS and subjected to FST. Hippocampal mRNA was extracted and used to generate cDNA libraries for microarray hybridization. Naive acute stressors (FST and vehicle injection) altered similar sets of genes, but Cort treatment produced a profile that was distinct from both FST and vehicle. Exposure to a novel stress after CRS activated substantially more and different genes than naive exposure. Most genes increased by CRS were decreased after recovery but many remained altered and did not return to baseline. Pathway analysis identified significant clusters of differentially expressed genes across conditions, most notably the nuclear factor kappa-light-chain-enhancer of B cells (NF-κB) pathway. Quantitative reverse transcription-PCR (qRT-PCR) validated changes from the microarrays in known stress-induced genes and confirmed alterations in the NF-κB pathway genes, Nfkbia, RelA and Nfkb1. FST increased anxiety-like behavior in both the naive and recovery from CRS conditions, but not in mice 24h subsequent to their CRS exposure. These findings suggest that the effects of naive stress are distinct from Cort elevation, and that a history of stress exposure can permanently alter gene expression patterns in the hippocampus and the

  3. Hippocampal gene expression changes underlying stress sensitization and recovery

    PubMed Central

    Gray, Jason D.; Rubin, Todd G.; Hunter, Richard G.; McEwen, Bruce S.

    2013-01-01

    Chronic and acute stressors have been linked to changes in hippocampal function and anxiety-like behaviors. Both produce changes in gene expression, but the extent to which these changes endure beyond the end of stress remains poorly understood. As an essential first step to characterize abnormal patterns of gene expression after stress, this study demonstrates how chronic restraint stress (CRS) modulates gene expression in response to a novel stressor in the hippocampus of wild type mice and the extent to which these changes last beyond the end of CRS. Male C57/bl6 mice were subjected to 1) a forced swim test (FST), 2) Corticosterone (Cort) or vehicle injections, 3) CRS for 21 days and then a FST, or 4) allowed to recover 21 days after CRS and subjected to FST. Hippocampal mRNA was extracted and used to generate cDNA libraries for microarray hybridization. Naïve acute stressors (FST and vehicle injection) altered similar sets of genes, but Cort treatment produced a profile that was distinct from both FST and vehicle. Exposure to a novel stress after CRS activated substantially more and different genes than naïve exposure. Most genes increased by CRS were decreased after recovery, but many remained altered and did not return to baseline. Pathway analysis identified significant clusters of differentially expressed genes across conditions, most notably the NfKB pathway. Quantitative RT-PCR validated changes from the microarrays in known stress-induced genes and confirmed alterations in the NfKb pathway genes, Ikbα, RelA and Nfkb1. FST increased anxiety-like behavior in both the naïve and recovery from CRS conditions, but not in mice 24hrs subsequent to their CRS exposure. These findings suggest the effects of naïve stress are distinct from Cort elevation and that a history of stress exposure can permanently alter gene expression patterns in the hippocampus and the behavioral response to a novel stressor. These findings establish a baseline profile of normal

  4. Stress

    MedlinePlus

    ... sudden negative change, such as losing a job, divorce, or illness Traumatic stress, which happens when you ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  5. [Changes of physiological functions in rats induced by immobilization stress].

    PubMed

    Kuriyama, T; Oishi, K; Kakazu, H; Machida, K

    1998-01-01

    A study was conducted on the changes of physiological function in rats due to immobilization stress. Male Fischer rats (SPF) of 32 weeks of age were housed in individual cages for 4 weeks. Then all rats were immobilized by stainless wire mesh for 6 hours daily for 3 days. Blood was collected before the 1st stress, immediately after the 1st stress, immediately after the 3rd stress and the day after the 3rd stress. The results of this experiment were as follows: (1) The total leukocyte counts in the blood of the rats after the 1st trial was significantly higher than that before the 1st trial. (2) The percentage of lymphocytes in the blood after the 1st trial was significantly lower than that before the 1st trial, whereas that of neutrophils was significantly higher. (3) Correlations between phagocytic activity and superoxide production of neutrophils by histochemical NBT reduction assay showed significantly a positive correlation before the 1st trial. However, no significant correlations were observed in immediately after the 1st trial and the 3rd trial. The day after the 3rd trial, a positive correlation was observed again. These correlations showed that an unsuitable state of the neutrophil function was induced by the immobilization stress. (4) Serum biochemical profiles were affected by the immobilization stress. Also, GOT, GPT, LDH, CK and UA were increased after the 1st trial, whereas, TG, TP, ALB and ALP were decreased after the 1st trial. T-CHO was increased only immediately after the 3rd stress. These results suggest that immobilization stress affected blood cells and serum components, and then the host defense and physiological functions were damaged respectively.

  6. From coseismic offsets to fault-block mountains

    NASA Astrophysics Data System (ADS)

    Thompson, George A.; Parsons, Tom

    2017-09-01

    In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (˜100 km) aseismic uplift symmetrically spanning the fault zone. Finally, after millions of years and hundreds of fault offsets, the mountain blocks display large uplift and tilting over a breadth of only about 10 km. These sparse but robust observations pose a problem in that the coesismic uplifts of the footwall are small and inadequate to raise the mountain blocks. To address this paradox we develop finite-element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift, which is predicted to take place within one to two decades after each large earthquake. Thus, the best-preserved topographic signature of earthquakes is expected to occur early in the postseismic period.

  7. From coseismic offsets to fault-block mountains

    USGS Publications Warehouse

    Thompson, George A.; Parsons, Thomas E.

    2017-01-01

    In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (∼100 km) aseismic uplift symmetrically spanning the fault zone. Finally, after millions of years and hundreds of fault offsets, the mountain blocks display large uplift and tilting over a breadth of only about 10 km. These sparse but robust observations pose a problem in that the coesismic uplifts of the footwall are small and inadequate to raise the mountain blocks. To address this paradox we develop finite-element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift, which is predicted to take place within one to two decades after each large earthquake. Thus, the best-preserved topographic signature of earthquakes is expected to occur early in the postseismic period.

  8. Coseismic magnetization of fault pseudotachylytes: 1. Thermal demagnetization experiments

    NASA Astrophysics Data System (ADS)

    Ferré, E. C.; Geissman, J. W.; Demory, F.; Gattacceca, J.; Zechmeister, M. S.; Hill, M. J.

    2014-08-01

    Fault pseudotachylytes form by quenching of silicate liquids produced through coseismic frictional melting. Here we show that in natural pseudotachylytes the main carrier of magnetic remanence blocked in during cooling of the frictional melt is fine-grained magnetite. This confirms previous studies on friction melt experiments. Stoichiometric magnetite, produced during earthquakes by the breakdown of ferromagnesian silicates, records the ambient magnetic field during seismic slip. We find that most fault pseudotachylytes exposed in the Santa Rosa Mountains, southern California, a classic pseudotachylyte locality, acquired their natural remanent magnetization (NRM) upon cooling of the frictional melt through the range of magnetization blocking temperatures of the magnetite grains and this primarily constitutes a thermal remanent magnetization. NRM intensities typical of most pseudotachylyte veins range from 1 to 60·10-4 Am2/kg. A few specimens, however, contain magnetizations significantly higher than that caused by the Earth's field as well as magnetization directions that are highly variable over short distances. Other magnetization processes, possibly related to coseismic electric currents, may be involved during the seismogenic process to control NRM acquisition.

  9. Separating triggered and stress-change induced seismcity

    NASA Astrophysics Data System (ADS)

    Zhuang, J.

    2013-12-01

    Once a major earthquake occurs, it usually not only triggers a sequence of many aftershock, but also changes the tectonic stress field in the regions nearby. According to the rate and state law (Dieterich, 1994), such stress changes result in a permanent change of the seismicity rate, increment or decrement. However, since aftershock sequence lasts quite a long time before it decays off, it is hard tell whether the high level of seismicity after a big earthquake is the continuation of the aftershock activity or caused by the changes of stress due this big earthquake. In this study, by making use of the space-time ETAS model (Ogata, 1998) and the stochastic declustering method (Zhuang et al., 2002, 2004), I developed a method to separate the seismicity induced by stress-change from the aftershock activity in a probability manner. For example, it is found that the probabilities that Lushan earthquakes belong the background seismcity, aftershock of the Wenchuan earthquake, are stress-change induced seismcity are, respectively, 38% and 12%, 50%. References Dieterich, J.H. (1994) A constitutive law for rate of earthquake production and its application to earthquake clustering, J. Geophys. Res. , 99 , 2601-2618. Ogata, Y. (1998. Space-time point-process models for earthquake occur- rences, Ann. Inst. Stat. Math., 50, 379-402. Zhuang J., Ogata Y. and Vere-Jones D. (2004). Analyzing earthquake clustering features by using stochastic reconstruction. Journal of Geophysical Research, 109, No. B5, B05301, doi:10.1029/2003JB002879. Zhuang J., Ogata Y. and Vere-Jones D. (2002). Stochastic declustering of space-time earthquake occurrences. Journal of the American Statistical Association, 97: 369-380.

  10. Seasonal changes in stress indicators in high level football.

    PubMed

    Faude, O; Kellmann, M; Ammann, T; Schnittker, R; Meyer, T

    2011-04-01

    This study aimed at describing changes in stress and performance indicators throughout a competitive season in high level football. 15 players (19.5±3.0 years, 181±5 cm, 75.7±9.0 kg) competing under professional circumstances were tested at baseline and 3 times during the season 2008/09 (in-season 1, 2, 3). Testing consisted of the Recovery-Stress Questionnaire for Athletes (Total Stress and Recovery score), vertical jump tests (counter movement and drop jump (DJ)), and a maximal ramp-like running test. Average match exposure was higher during a 3-weeks period prior to in-season 3 compared to in-season 1 and 2 (1.5 vs. 1 h/week, p=0.05). Total Stress score was elevated at in-season 1 and 2 compared to baseline (p<0.01) with a further increase at in-season 3 (p<0.03; generalized eta squared (η(2)(g))=0.37). Total Recovery score was decreased at in-season 1 and 3 compared to baseline (p<0.05; η(2)(g)=0.21). Maximal running velocity (V(max)) and jumping heights were not significantly affected (η(2)(g)≤0.04). Changes in DJ height and V (max) between baseline and in-season 3 were correlated with the corresponding changes in Total Stress score (r=-0.55 and r=-0.61, p<0.03). Usual match exposure during a professional football season does not induce relevant changes in performance indicators. Accumulated stress and a lack of recovery towards the end of a season might be indicated by psychometric deteriorations. © Georg Thieme Verlag KG Stuttgart · New York.

  11. Stress shadows - a controversial topic

    NASA Astrophysics Data System (ADS)

    Lasocki, Stanislaw; Karakostas, Vassilis G.; Papadimitriou, Eletheria E.; Orlecka-Sikora, Beata

    2010-05-01

    The spatial correlation between the positive Coulomb stress changes and the subsequent seismic activity has been firmly confirmed in many recent studies. If, however, the static stress transfer is a consistent expression of interaction between earthquakes one should also observe a decrease of the activity in the zones of negative stress changes. Instead, the existence of stress shadows is poorly evidenced and may be questioned. We tested the influence of the static stress changes associated with the coseismic slip of the 1995 Mw6.5 Kozani-Grevena (Greece) earthquake on locations of its aftershocks. The study was based on a detailed slip model for the main shock and accurate locations and reliable fault plane solutions of an adequate number of the aftershocks. We developed a statistical testing method, which tested whether the proportions of aftershocks located inside areas determined by a selected criterion on the static stress change could be attained if there were no effect of the stress change due to the main shock on aftershock locations. The areas of stress change were determined at the focus of every aftershock. The distribution of test statistic was constructed with the use of a two-dimensional nonparametric, kernel density estimator of the reference epicenter distribution. The tests highly confidently indicated a rise in probability to locate aftershocks inside areas of positive static stress change, which supported the hypothesis on the triggering effect in these areas. Furthermore, it was evidenced that a larger stress increase caused a stronger triggering effect. The analysis, however, did not evidence the existence of stress shadows inside areas of negative stress change. Contrary to expectations, the tests indicated a significant increase of the probability of event location in the areas of a stress decrease of more than or equal to 5.0 and 10.0 bar. It turned out that for areas of larger absolute stress change this probability increased regardless of

  12. Electrical Resistivity Changes in Saturated Rock under Stress.

    PubMed

    Brace, W F; Orange, A S

    1966-09-23

    Electrical resistivity of water-saturated crystalline rock such as granite, diabase, dunite, or quartzite changes by an order of magnitude prior to fracture of the rock in compression. The effect observed even under high confining pressure is due to formation of open cracks which first appear at one-third to two-thirds the fracture stress.

  13. Coseismic ruptures of the 24 August 2016, Mw 6.0 Amatrice earthquake (central Italy)

    NASA Astrophysics Data System (ADS)

    Pucci, S.; De Martini, P. M.; Civico, R.; Villani, F.; Nappi, R.; Ricci, T.; Azzaro, R.; Brunori, C. A.; Caciagli, M.; Cinti, F. R.; Sapia, V.; De Ritis, R.; Mazzarini, F.; Tarquini, S.; Gaudiosi, G.; Nave, R.; Alessio, G.; Smedile, A.; Alfonsi, L.; Cucci, L.; Pantosti, D.

    2017-03-01

    On 24 August 2016, a Mw 6.0 normal-faulting earthquake struck central Italy, causing about 300 fatalities and heavy damage. A geological survey collected the coseismic effects observed at the surface in order to evaluate two competing hypotheses about their nature: surface faulting versus gravitational deformation. We find that the most significant geological effect is a 5.2 km long alignment of ground ruptures along the Mount Vettore Fault System. These ruptures are independent from lithology, topography, morphology, and change in slope and exhibit an average dip-slip displacement of 13 cm. Geometry, kinematics, and dimensional properties of this zone of deformation strongly lead us to favor the primary surface faulting hypothesis that fits well the predicted estimates from experimental scaling law relationships. Our study provides relevant hints for surface faulting in extensional domains, contributing to implement the worldwide database of the moderate earthquakes.

  14. Rapid Detection of Coseismic Displacements with PALSAR ScanSAR-ScanSAR Interferometry

    NASA Astrophysics Data System (ADS)

    Hashimoto, M.; Ozawa, T.; Tobita, M.; Miyawaki, M.; Shimada, M.

    2010-12-01

    On large earthquake disasters, researchers and disaster managers eager to grasp the over-all image of the event immediately with as high resolution as possible. The rapid detection of coseismic deformation enables us to discriminate co- and postseismic deformations and estimate fault parameters, which definitely contributes to the evaluation of stress transfer which leads to aftershock forecast. The ScanSAR-ScanSAR interferometry is one of techniques that can provide information on coseismic displacement field in a wide region. Phased Array-type L-band SAR (PALSAR) onboard Japan’s Advanced Land Observation Satellite (ALOS) is capable to make an observation with ScanSAR mode with as wide swath as 350km. Owing to its long wavelength, coherence is high enough to perform interferometry in vegetated areas and steep mountains. We have applied this technique to images acquired before and after 4 events that occurred this year. We use the full-aperture algorithm to produce single look complex images for each swath and apply usual 2-pass interferometry to SLC’s. It is quite important to synchronize bursts of two ScanSAR images for interferometry, but this could be done only by the Japan Aerospace Exploration Agency (JAXA). Our first trial was the Haiti earthquake of January, 2010. After its occurrence, we requested JAXA to acquire a ScanSAR image of the western Hispaniola Island. On February 11, the acquisition was made. JAXA synchronized its bursts to the image acquired on Sept. 26, 2009. We observed coseismic fringes near the epicenter along the Enriquillo fault similar to those obtained from strip-map mode images. On the other hand, no notable deformation was found near the Septentrional fault, northern Haiti. The second example was the Chile earthquake of February 27, 2010. Post-earthquake observation was made on March 1, 2010. The observed area was as wide as 350km, from the Pacific coast to the eastern frank of the Andes, and as long as 1000km. This image was

  15. Enduring Personality Changes after Intense Stressful Event: Case Report

    PubMed Central

    Arsova, Slavica; Manusheva, Nensi; Kopacheva-Barsova, Gabriela; Bajraktarov, Stojan

    2016-01-01

    BACKGROUND World statistical data show that a large number of individuals suffer from posttraumatic stress disorder (PTSD) after exposure to the intense traumatic event. PTSD can have a chronic course with enduring changes in the functioning of the person. CASE PRESENTATION Here we report two adult individuals of different gender and education who were exposed to the extremely severe stressful event after which difficulties in psychological functioning developed. The first case we present is a 46-year-old man, with completed high education, divorced, father of two children, who lives with his parents, and is retired. Disorders appeared 20 years ago when he was exposed to extremely severe stressful events in war circumstances that included captivity, torture, and loss of fellow soldiers. The second case is a 50-year-old female patient, with a university degree, professor of art, married, and mother of two children of whom the son died six years ago. She suffered from disorders after the sudden injury of her son that ended with his death. CONCLUSION Posttraumatic stress disorder after the intense stress is a risk of development enduring personality changes with serious individual and social consequences. PMID:27703573

  16. Coseismic deformation observed with radar interferometry: Great earthquakes and atmospheric noise

    NASA Astrophysics Data System (ADS)

    Scott, Chelsea Phipps

    Spatially dense maps of coseismic deformation derived from Interferometric Synthetic Aperture Radar (InSAR) datasets result in valuable constraints on earthquake processes. The recent increase in the quantity of observations of coseismic deformation facilitates the examination of signals in many tectonic environments associated with earthquakes of varying magnitude. Efforts to place robust constraints on the evolution of the crustal stress field following great earthquakes often rely on knowledge of the earthquake location, the fault geometry, and the distribution of slip along the fault plane. Well-characterized uncertainties and biases strengthen the quality of inferred earthquake source parameters, particularly when the associated ground displacement signals are near the detection limit. Well-preserved geomorphic records of earthquakes offer additional insight into the mechanical behavior of the shallow crust and the kinematics of plate boundary systems. Together, geodetic and geologic observations of crustal deformation offer insight into the processes that drive seismic cycle deformation over a range of timescales. In this thesis, I examine several challenges associated with the inversion of earthquake source parameters from SAR data. Variations in atmospheric humidity, temperature, and pressure at the timing of SAR acquisitions result in spatially correlated phase delays that are challenging to distinguish from signals of real ground deformation. I characterize the impact of atmospheric noise on inferred earthquake source parameters following elevation-dependent atmospheric corrections. I analyze the spatial and temporal variations in the statistics of atmospheric noise from both reanalysis weather models and InSAR data itself. Using statistics that reflect the spatial heterogeneity of atmospheric characteristics, I examine parameter errors for several synthetic cases of fault slip on a basin-bounding normal fault. I show a decrease in uncertainty in fault

  17. Estimates of stress drop and crustal tectonic stress from the 27 February 2010 Maule, Chile, earthquake: Implications for fault strength

    USGS Publications Warehouse

    Luttrell, K.M.; Tong, X.; Sandwell, D.T.; Brooks, B.A.; Bevis, M.G.

    2011-01-01

    The great 27 February 2010 Mw 8.8 earthquake off the coast of southern Chile ruptured a ???600 km length of subduction zone. In this paper, we make two independent estimates of shear stress in the crust in the region of the Chile earthquake. First, we use a coseismic slip model constrained by geodetic observations from interferometric synthetic aperture radar (InSAR) and GPS to derive a spatially variable estimate of the change in static shear stress along the ruptured fault. Second, we use a static force balance model to constrain the crustal shear stress required to simultaneously support observed fore-arc topography and the stress orientation indicated by the earthquake focal mechanism. This includes the derivation of a semianalytic solution for the stress field exerted by surface and Moho topography loading the crust. We find that the deviatoric stress exerted by topography is minimized in the limit when the crust is considered an incompressible elastic solid, with a Poisson ratio of 0.5, and is independent of Young's modulus. This places a strict lower bound on the critical stress state maintained by the crust supporting plastically deformed accretionary wedge topography. We estimate the coseismic shear stress change from the Maule event ranged from-6 MPa (stress increase) to 17 MPa (stress drop), with a maximum depth-averaged crustal shear-stress drop of 4 MPa. We separately estimate that the plate-driving forces acting in the region, regardless of their exact mechanism, must contribute at least 27 MPa trench-perpendicular compression and 15 MPa trench-parallel compression. This corresponds to a depth-averaged shear stress of at least 7 MPa. The comparable magnitude of these two independent shear stress estimates is consistent with the interpretation that the section of the megathrust fault ruptured in the Maule earthquake is weak, with the seismic cycle relieving much of the total sustained shear stress in the crust. Copyright 2011 by the American

  18. Co-seismic dilation, fluid flow and mineralization in hydrothermal systems: Insight from numerical models of extensional linkage zones

    NASA Astrophysics Data System (ADS)

    Dempsey, D. E.; Sanchez-Alfaro, P.; Rowland, J. V.; O'Sullivan, J.

    2016-12-01

    The interplay between seismic activity, fluid flow and mineral precipitation plays a critical role in promoting the development of geothermal systems and the formation of ore deposits. In geothermal systems, fault rupture might dramatically change the thermodynamic conditions of fluids and trigger transient events of mineralization recorded as flashing textures in calcite and silica. Due to the heterogeneous nature of fault and fracture networks, specific geometries such as linkage zones, dilational jogs and wing cracks are likely to dilate. During fault rupture, pore volume is rapidly created by dilation resulting in a transient drop in pore fluid pressure which enables rapid precipitation. In this study we analyze the effect that fault rupture has on deformation and fluid flow within extensional stepovers that form a dilational jog. Geometrically, this structure is composed of two sub-parallel faults linked by an oblique fracture (jog). We used Poly3D, a boundary element code that solves the elastostatic equations for stress and displacement, to compute dilation of the faults. Boundary conditions were constrained by calibrating the magnitude of the remote stresses, earthquake magnitude and rupture surface with empirical earthquake scaling relationships. To identify the conditions that maximize dilation, several hundred numerical experiments were performed for various orientation and length of the jog, overlap and spacing between the parallel faults and regional stress tensor. Our preliminary results indicate that a 4 Mw magnitude earthquake may produce an average opening of 4.5 mm and create a volume of approximately 600 m3in the jog. Jog orientation and overlap between faults are the variables that have the greatest effect on opening of the jog. The computed dilation and volume increase are inputs for simulations of coupled heat and fluid flow performed in the TOUGH2 numerical model. Boundary and initial conditions are constrained with data of active geothermal

  19. Comparing Calculations of Far-Field Coseismic Deformation

    NASA Astrophysics Data System (ADS)

    Freymueller, J. T.; Dong, J.; Sun, W.

    2014-12-01

    Coseismic displacements from the largest earthquakes are easily detected in geodetic time series over a large area, up to a few thousand km from the fault. For example, detectable displacements from the 2004 Sumatra-Andaman earthquake were reported as far away as Korea, and detectable displacements from the 2011 Tohoku earthquake were reported as far away as Ulaanbaatar, Mongolia. The great reach of these events means that they can distort geodetic coordinates on a global scale, they impact the ability of users to access the reference frame. Point source (Centroid Moment Tensor) and finite fault models for large events are routinely available from purely seismological data (or potentially from local geodetic data), so it is worthwhile to know hwo well we can predict coseismic displacements at GPS sites from independent or quasi-independent data. Ultimately, a suite of geophysical models based on seismic or near-field geodetic data could provide estimates of far-field displacements and uncertainties that may be used for detection of subtle offsets in geodetic time series, and for correction of global coordinates. Slip models based only on teleseismic data do not predict displacments well near the earthquake rupture, because teleseismic data do not resolve spatial details of the slip distribution. Farther from the source, coseismic displacements are not so sensitive to the details of the earthquake source model. Different codes for computing displacements for spherical layered Earth models have not been compared carefully before. Here we compare computed displacements using the method of Pollitz (1996) and the method of Sun et al. (2009) and Sun and Dong (2013). These codes are semi-analytical, so results are sensitive to the number of terms summed for computing Greens functions. We also compare the impact of different Earth models, including PREM, modified versions of PREM, ak135f, and a homogeneous sphere. Our preliminary assessment is that the choice of Earth

  20. Effect of meditation on neurophysiological changes in stress mediated depression.

    PubMed

    Kasala, Eshvendar Reddy; Bodduluru, Lakshmi Narendra; Maneti, Yogeshwar; Thipparaboina, Rajesh

    2014-02-01

    Meditation is a complex mental practice involving changes in sensory perception, cognition, hormonal and autonomic activity. It is widely used in psychological and medical practices for stress management as well as stress mediated mental disorders like depression. A growing body of literature has shown that meditation has profound effects on numerous physiological systems that are involved in the pathophysiology of major depressive disorder (MDD). Although meditation-based interventions have been associated with improvement in depressive symptoms and prevention of relapse, the physiological mechanisms underlying the therapeutic effects of meditation are not clearly defined and even paradoxical. This paper reviews many of the physiological abnormalities found in cytokine & stress mediated depression and the reversal of these anomalies by different meditation techniques.

  1. Oxidative stress causes reversible changes in mitochondrial permeability and structure

    PubMed Central

    Cole, Nelson B.; Daniels, Mathew P.; Levine, Rodney L.; Kim, Geumsoo

    2010-01-01

    Mitochondria are a primary source as well a principal target of reactive oxygen species within cells. Using immunofluorescence microscopy, we have found that a number of mitochondrial matrix proteins are normally undetectable in formaldehyde fixed cells permeabilized with the cholesterol-binding detergent saponin. However, exogenous or endogenous oxidative stress applied prior to fixation altered the permeability of mitochondria, rendering these matrix proteins accessible to antibodies. Electron microscopy revealed a loss of matrix density and disorganization of inner-membrane cristae upon oxidative stress. Notably, the changes in permeability and in structure were rapidly reversed when the oxidative stress was relieved. The ability of reactive oxygen species to reversibly alter the permeability of the mitochondrial membrane provides a potential mechanism for communication within the cell such as between nucleus and mitochondria. PMID:20096768

  2. Coseismic surface deformation from air photos: The Kickapoo step over in the 1992 Landers rupture

    NASA Astrophysics Data System (ADS)

    Michel, RéMi; Avouac, Jean-Philippe

    2006-03-01

    Coseismic deformation of the ground can be measured from aerial views taken before and after an earthquake. We chose the area of the Kickapoo-Landers step over along the 1992 Landers earthquake zone, using air photos (scale 1:40,000) scanned at 0.4 m resolution. Two photos acquired after the earthquake are used to assess the accuracy and to evaluate various sources of noise. Optical distortions, film deformation, scanning errors, or errors in viewing parameters can yield metric bias at wavelength larger than 1 km. Offset field at shorter wavelength is more reliable and mainly affected by temporal decorrelation of the images induced by changes in radiometry with time. Temporal decorrelation and resulting uncertainty on offsets are estimated locally from the correlation degree between the images. Relative surface displacements are measured independently every about 15 m and with uncertainty typically below 10 cm (RMS). The offset field reveals most of the surface ruptures mapped in the field. The fault slip is accurate to about 7 cm (RMS) and measured independently every 200 m from stacked profiles. Slip distribution compares well with field measurements at the kilometric scale but reveals local discrepancies suggesting that deformation is generally, although not systematically, localized on the major fault zone located in the field. This type of data can provide useful insight into the fault zone's mechanical properties. Our measurements indicate that elastic coseismic strain near the fault zone can be as large as 0.5 × 10-3, while anelastic yielding was attained for strain in excess of about 1-2 × 10-3.

  3. Temporal pore pressure induced stress changes during injection and depletion

    NASA Astrophysics Data System (ADS)

    Müller, Birgit; Heidbach, Oliver; Schilling, Frank; Fuchs, Karl; Röckel, Thomas

    2016-04-01

    Induced seismicity is observed during injection of fluids in oil, gas or geothermal wells as a rather immediate response close to the injection wells due to the often high-rate pressurization. It was recognized even earlier in connection with more moderate rate injection of fluid waste on a longer time frame but higher induced event magnitudes. Today, injection-related induced seismicity significantly increased the number of events with M>3 in the Mid U.S. However, induced seismicity is also observed during production of fluids and gas, even years after the onset of production. E.g. in the Groningen gas field production was required to be reduced due to the increase in felt and damaging seismicity after more than 50 years of exploitation of that field. Thus, injection and production induced seismicity can cause severe impact in terms of hazard but also on economic measures. In order to understand the different onset times of induced seismicity we built a generic model to quantify the role of poro-elasticity processes with special emphasis on the factors time, regional crustal stress conditions and fault parameters for three case studies (injection into a low permeable crystalline rock, hydrothermal circulation and production of fluids). With this approach we consider the spatial and temporal variation of reservoir stress paths, the "early" injection-related induced events during stimulation and the "late" production induced ones. Furthermore, in dependence of the undisturbed in situ stress field conditions the stress tensor can change significantly due to injection and long-term production with changes of the tectonic stress regime in which previously not critically stressed faults could turn to be optimally oriented for fault reactivation.

  4. Regional extent of the large coseismic slip zone of the 2011 Mw 9.0 Tohoku-Oki Earthquake delineated by on-fault aftershocks

    NASA Astrophysics Data System (ADS)

    Kato, A.; Igarashi, T.; Fukuda, J.

    2012-12-01

    In order to image the rupture process of the 2011 Tohoku-Oki earthquake, many fault source models have recently been developed following this giant earthquake by inverting for slip on the fault plane, based on a variety of collected data, strong ground motion, geodetic, and tsunami recordings. Most of these studies suggest that the area of largest coseismic slip (~30-80 m) was located near the mainshock hypocenter, extending eastward to a location near the Japan Trench axis. However, the estimated outer edges of the large-slip zone are substantially different between these models, due to the currently limited spatial resolution of slip along the fault. Consequently, there are insufficient constraints as to how far the large-slip zone extended along the plate interface during the mainshock rupture. Here we delineate the outer edge of this large-slip zone in detail, by applying a spatial correlation between on-fault aftershocks and slip to the Tohoku aftershock sequence. We focus on the sharp density contrast observed for interplate, repeating, and down-dip compressional earthquakes induced by the Tohoku-Oki mainshock. The seismicity rate of interplate earthquakes changed significantly after the mainshock, probably as a result of stress perturbations by the large-slip, and here we use this information as qualitative constraints in constructing our model. The model that we present for the large-slip zone incorporates the main features of previously proposed fault source models, and also the observed fine-scale heterogeneities of fault slip associated with this event. It is important to highlight that the outer edge of this large-slip zone shows a remarkably complex shape. In particular, it is narrow and elongate southward along the ~35 km iso-depth contour of the plate boundary offshore of Fukushima and Ibaraki. This southward elongate slip zone corresponds to down-dip regions that appear to have produced higher relative levels of short-period seismic radiation. We

  5. Psychosocial Stress and Change in Weight Among US Adults

    PubMed Central

    Block, Jason P.; He, Yulei; Zaslavsky, Alan M.; Ding, Lin

    2009-01-01

    The association of psychosocial stress with weight gain may have important implications for clinical practice and workplace and public health interventions. To determine whether multiple domains of psychosocial stress were associated with weight gain from 1995 to 2004, the authors analyzed a nationally representative longitudinal cohort of 1,355 men and women in the United States. Change in body mass index was assessed for multiple domains of psychosocial stress related to work, personal relationships, life constraints, and finances, controlling for other factors associated with weight gain. All analyses were stratified by sex and weighted to account for the complex survey design. Among men with high baseline body mass index, weight gain was associated with increasing levels of psychosocial stress related to job-related demands (P < 0.001 for interaction with baseline body mass index), lack of skill discretion (P = 0.014), lack of decision authority (P = 0.026), and difficulty paying bills (P = 0.004). Among women with high baseline body mass index, weight gain was associated with job-related demands (P < 0.001 for interaction with baseline body mass index), perceived constraints in life (P < 0.001), strain in relations with family (P = 0.016), and difficulty paying bills (P = 0.010). Interventions to address psychosocial stress may limit weight gain among overweight and obese men and women. PMID:19465744

  6. Memory under stress: from single systems to network changes.

    PubMed

    Schwabe, Lars

    2017-02-01

    Stressful events have profound effects on learning and memory. These effects are mainly mediated by catecholamines and glucocorticoid hormones released from the adrenals during stressful encounters. It has been known for long that both catecholamines and glucocorticoids influence the functioning of the hippocampus, a critical hub for episodic memory. However, areas implicated in other forms of memory, such as the insula or the dorsal striatum, can be affected by stress as well. Beyond changes in single memory systems, acute stress triggers the reconfiguration of large scale neural networks which sets the stage for a shift from thoughtful, 'cognitive' control of learning and memory toward more reflexive, 'habitual' processes. Stress-related alterations in amygdala connectivity with the hippocampus, dorsal striatum, and prefrontal cortex seem to play a key role in this shift. The bias toward systems proficient in threat processing and the implementation of well-established routines may facilitate coping with an acute stressor. Overreliance on these reflexive systems or the inability to shift flexibly between them, however, may represent a risk factor for psychopathology in the long-run.

  7. Changes in Posttraumatic Stress Disorder and Depressive Symptoms during Cognitive Processing Therapy: Evidence for Concurrent Change

    ERIC Educational Resources Information Center

    Liverant, Gabrielle I.; Suvak, Michael K.; Pineles, Suzanne L.; Resick, Patricia A.

    2012-01-01

    Objective: Trauma-focused psychotherapies reduce both posttraumatic stress disorder (PTSD) and co-occurring depression. However, little is known about the relationship between changes in PTSD and depression during treatment. This study examined the association between changes in PTSD and depression during the course of cognitive processing therapy…

  8. Changes in Posttraumatic Stress Disorder and Depressive Symptoms during Cognitive Processing Therapy: Evidence for Concurrent Change

    ERIC Educational Resources Information Center

    Liverant, Gabrielle I.; Suvak, Michael K.; Pineles, Suzanne L.; Resick, Patricia A.

    2012-01-01

    Objective: Trauma-focused psychotherapies reduce both posttraumatic stress disorder (PTSD) and co-occurring depression. However, little is known about the relationship between changes in PTSD and depression during treatment. This study examined the association between changes in PTSD and depression during the course of cognitive processing therapy…

  9. Identifying coseismic subsidence in tidal-wetland stratigraphic sequences at the Cascadia subduction zone of western North America

    USGS Publications Warehouse

    Nelson, A.R.; Shennan, I.; Long, A.J.

    1996-01-01

    Tidal-wetland stratigraphy reveals that great plate boundary earthquakes have caused hundreds of kilometers of coast to subside at the Cascadia subduction zone. However, determining earthquake recurrence intervals and mapping the coastal extent of past great earthquake ruptures in this region are complicated by the effects of many sedimentologic, hydrographic, and oceanographic processes that occur on the coasts of tectonically passive as well as active continental margins. Tidal-wetland stratigraphy at many Cascadia estuaries differs little from that at similar sites on passive-margin coasts where stratigraphic sequences form through nonseismic processes unrelated to coseismic land level changes. Methods developed through study of similar stratigraphic sequences in Europe provide a framework for investigating the Cascadia estuarine record. Five kinds of criteria must be evaluated when inferring regional coastal subsidence due to great plate boundary earthquakes: the suddenness and amount of submergence, the lateral extent of submerged tidal-wetland soils, the coincidence of submergence with tsunami deposits, and the degree of synchroneity of submergence events at widely spaced sites. Evaluation of such criteria at the Cascadia subduction zone indicates regional coastal subsidence during at least two great earthquakes. Evidence for a coseismic origin remains equivocal, however, for the many peat-mud contacts in Cascadia stratigraphic sequences that lack (1) contrasts in lithology or fossils indicative of more than half a meter of submergence, (2) well-studied tsunami deposits, or (3) precise ages needed for regional correlation. Paleoecologic studies of fossil assemblages are particularly important in estimating the size of sudden sea level changes recorded by abrupt peat-mud contacts and in helping to distinguish erosional and gradually formed contacts from coseismic contacts. Reconstruction of a history of great earthquakes for the Cascadia subduction zone will

  10. Coseismic Faults and Crust Deformation Accompanied the 2008 Wenchuan Earthquake, China by Field Investigation and InSAR Interferogram

    NASA Astrophysics Data System (ADS)

    Hao, K.; Si, H.; Fujiwara, H.; Ozawa, T.

    2008-12-01

    -Anxian faults F1 that eastbound the Sichuan basin, Wenchuan-Maoxian fault F3 that westbound the Tibetan plateau, and Yingxiu- Beichuan faults F2 that located in the between. From X to AC in the middle section of LMS faults, the deformation zone occurred from F1 to F2 and even over F2. In the northeastern section, it almost fit the fault F2 from BC to Pingtong(PT), Nanba(NB), Shiba(SB) and Qingchuan (QC) in a narrow zone. The coseismic faults were confirmed by both field investigation and InSAR interferometry along the following segments: Segment 1: from/through BYD, YX to X along Yingxiu-Beichuan faults F2; Segment 2: changed direction at X as a corner to N60E, went along the N20W Xiaoyudong fault until BL as another corner; Segment 3: from/through BL, H along Guanxian-Anxian faults F1 until AC(Angchang); Segment 4: changed direction at AC as a corner to N00E, went along the Leigu fault through L, to BC; Segment 5: from/through BC, PT, NB and SB to QC along Yingxiu-Beichuan faults F2. Among these segments, the Segment 1 and Segment 4 supposedly played important roles for triggering or transferring the ruptured faults F1 to the ruptured faults F2. The InSAR interferogram from X to BC showed the grey belt, whose phase incoherence demonstrated strong earth-crust deformation, but it was difficult to identify whether the coseismic faults occurred or not. On the other hand, no coseismic faults from X to BC are reported, where road was/is blocked in the mountain area.

  11. Oxidative-stress-induced epigenetic changes in chronic diabetic complications.

    PubMed

    Feng, Biao; Ruiz, Michael Anthony; Chakrabarti, Subrata

    2013-03-01

    Oxidative stress plays an important role in the development and progression of chronic diabetic complications. Diabetes causes mitochondrial superoxide overproduction in the endothelial cells of both large and small vessels. This increased superoxide production causes the activation of several signal pathways involved in the pathogenesis of chronic complications. In particular, endothelial cells are major targets of glucose-induced oxidative damage in the target organs. Oxidative stress activates cellular signaling pathways and transcription factors in endothelial cells including protein kinase C (PKC), c-Jun-N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), forkhead box O (FOXO), and nuclear factor kappa-B (NF-κB). Oxidative stress also causes DNA damage and activates DNA nucleotide excision repair enzymes including the excision repair cross complimenting 1(ERCC1), ERCC4, and poly(ADP-ribose) polymerase (PARP). Augmented production of histone acetyltransferase p300, and alterations of histone deacetylases, including class III deacetylases sirtuins, are also involved in this process. Recent research has found that small noncoding RNAs, like microRNA, are a new kind of regulator associated with chronic diabetic complications. There are extensive and complicated interactions and among these molecules. The purpose of this review is to demonstrate the role of oxidative stress in the development of diabetic complications in relation to epigenetic changes such as acetylation and microRNA alterations.

  12. An adaptability limit to climate change due to heat stress

    PubMed Central

    Sherwood, Steven C.; Huber, Matthew

    2010-01-01

    Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation. Peak heat stress, quantified by the wet-bulb temperature TW, is surprisingly similar across diverse climates today. TW never exceeds 31 °C. Any exceedence of 35 °C for extended periods should induce hyperthermia in humans and other mammals, as dissipation of metabolic heat becomes impossible. While this never happens now, it would begin to occur with global-mean warming of about 7 °C, calling the habitability of some regions into question. With 11–12 °C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12 °C are possible from fossil fuel burning. One implication is that recent estimates of the costs of unmitigated climate change are too low unless the range of possible warming can somehow be narrowed. Heat stress also may help explain trends in the mammalian fossil record. PMID:20439769

  13. Coulomb stress changes in the South Iceland Seismic Zone due to two large earthquakes in June 2000

    NASA Astrophysics Data System (ADS)

    Arnadottir, Th.; Jonsson, S.; Pedersen, R.; Gudmundsson, G.

    2003-04-01

    The South Iceland Seismic Zone experienced the largest earthquakes for 88 years in June 2000. The earthquake sequence started with a M_S=6.6 earthquake on June 17, 2000 (15:40:41 UTC), located at 63.975^oN, 20.370^oW and 6.3 km depth. A second large event (M_S=6.6) occurred on June 21, 2000 (00:51:47 UTC), located 17 km west of the June 17 rupture, at 63.977^oN, 20.713^oW and 5.1 km depth. The June 17 and 21 mainshocks ruptured two parallel N--S striking, right-lateral strike slip faults. Seismicity increased over a large area in SW Iceland following the June 17 mainshock, with most of the off-fault activity located west and north of the epicenter. Surface waves from the June 17 mainshock probably triggered significant slip on three faults on the Reykjanes Peninsula. Less activity appears to have been triggered in the Hengill area and on Reykjanes Peninsula following the June 21 earthquake, although it occurred closer to these areas than the June 17 event. Coseismic crustal deformation due to these earthquakes was observed with continuous and network GPS and Interferometric Synthetic Aperture Radar (InSAR). The geodetic data have been combined to estimate fault geometries and distributed slip models for the June 17 and 21 mainshocks. In this study we use these slip models to calculate the static Coulomb failure stress (CFS) change for the June 2000 earthquakes. We find that the static CFS change caused by the June 17 event is about 0.1 MPa at the location of the June 21 hypocenter, promoting failure on the second fault. The locations of aftershocks agree well with areas of increased CFS. Seismicity in areas where the CFS increase was less than 0.01 MPa, such as on Reykjanes Peninsula and the Hengill volcanic area, may have been dynamically triggered. Our calculations indicate a positive CFS change in the area west of the southern end of the June 21 rupture, due to the two June 2000 mainshocks, which correlates well with a significant increase in seismicity

  14. Drinking water biofilm cohesiveness changes under chlorination or hydrodynamic stress.

    PubMed

    Mathieu, L; Bertrand, I; Abe, Y; Angel, E; Block, J C; Skali-Lami, S; Francius, G

    2014-05-15

    Attempts at removal of drinking water biofilms rely on various preventive and curative strategies such as nutrient reduction in drinking water, disinfection or water flushing, which have demonstrated limited efficiency. The main reason for these failures is the cohesiveness of the biofilm driven by the physico-chemical properties of its exopolymeric matrix (EPS). Effective cleaning procedures should break up the matrix and/or change the elastic properties of bacterial biofilms. The aim of this study was to evaluate the change in the cohesive strength of two-month-old drinking water biofilms under increasing hydrodynamic shear stress τw (from ∼0.2 to ∼10 Pa) and shock chlorination (applied concentration at T0: 10 mg Cl2/L; 60 min contact time). Biofilm erosion (cell loss per unit surface area) and cohesiveness (changes in the detachment shear stress and cluster volumes measured by atomic force microscopy (AFM)) were studied. When rapidly increasing the hydrodynamic constraint, biofilm removal was found to be dependent on a dual process of erosion and coalescence of the biofilm clusters. Indeed, 56% of the biofilm cells were removed with, concomitantly, a decrease in the number of the 50-300 μm(3) clusters and an increase in the number of the smaller (i.e., <50 μm(3)) and larger (i.e., >600 μm(3)) ones. Moreover, AFM evidenced the strengthening of the biofilm structure along with the doubling of the number of contact points, NC, per cluster volume unit following the hydrodynamic disturbance. This suggests that the compactness of the biofilm exopolymers increases with hydrodynamic stress. Shock chlorination removed cells (-75%) from the biofilm while reducing the volume of biofilm clusters. Oxidation stress resulted in a decrease in the cohesive strength profile of the remaining drinking water biofilms linked to a reduction in the number of contact points within the biofilm network structure in particular for the largest biofilm cluster volumes (>200

  15. Coulomb stress evolution in a diffuse plate boundary: 1400 years of earthquakes in eastern California and western Nevada, USA

    NASA Astrophysics Data System (ADS)

    Verdecchia, Alessandro; Carena, Sara

    2016-08-01

    Diffuse plate boundaries are characterized by deformation distributed over a wide area in a complex network of active faults and by relatively low strain rates. These characteristics make it difficult to understand the spatial and temporal distribution of seismicity. The area east of the Sierra Nevada, between longitudes 121°W and 116°W, is part of a diffuse plate boundary. At least 17 major surface-rupturing earthquakes have happened here in the last 1400 years. Our purpose is to determine whether these events influence each other or whether they are randomly distributed in time and space. We model the evolution of coseismic and postseismic Coulomb failure stress changes (ΔCFS) produced by these earthquakes, and we also model interseismic stresses on the entire fault network. Our results show that 80% of the earthquake ruptures are located in areas of combined coseismic and postseismic ΔCFS ≥ 0.2 bar. This relationship is robust, as shown by the control tests that we carried out using random earthquake sequences. We also show that the Fish Lake Valley, Pyramid Lake, and Honey Lake faults have accumulated 45, 37, and 27 bars, respectively, of total ΔCFS (i.e., coseismic + postseismic + interseismic) in the last 1400 years. Such values are comparable to the average stress drop in a major earthquake, and these three faults may be therefore close to failure.

  16. [Oxidative stress level and placental histological changes during preeclampsia].

    PubMed

    Medrano Rodríguez, Juan Carlos; Yahuaca Mendoza, Patricia; Presno Bernal, Manuel; Alvarado Acosta, José Luis

    2008-06-01

    Oxidative stress has been related to several conditions during pregnancy (preeclampsia, abortions and premature rupture of membranes); it causes higher sensitivity of the endothelial blood vessel constriction and aggravates the endothelium dependent vasodilatación. To determine the oxidative stress level and histological changes in preeclamptic women's placenta. Longitudinal and comparative study. There were included 25 patients referred from second level health units (IMSS, ISSSTE and Hospital General de Zacatecas). To evaluate oxidative stress level, a sample of blood and placenta were obtained during delivery and a second sample was taken during mediate puerperium (10 days). In control group, total lipidic peroxide levels in serum were 135.6 +/- 7.3 nmol of MDA/mL of serum, compared with the group of moderate hypertension, which registered 222.0 +/- 35.15 nmol MDA/mL. Total lipidic peroxides in serum during puerperium for control group were 150.4 +/- 30.8 and 183.3 +/- 18.51 nmol MDA/mL for the group of moderate hypertension. Placental lipoperoxidation for control group was 0.40 +/- 0.03 microg MDNg, and of 0.32 +/- 0.03 microg MDN/g for the group of mild hypertension. Patients of moderate hypertension group showed an increase at 34% on placental lipoperoxidation over control group. Placental histological alterations where characterized by vascular remodeling loss, deposits of proteinaceous material and macrophagic process. Total lipidic peroxide levels in serum increases during preeclampsia. Histological changes refer uterus-placental ischemia that, probably, induces the oxidative stress.

  17. Coseismic and postseismic deformation studies of the Wenchuan earthquake and seismo-tectonics of the Longmen Shan fault system (Invited)

    NASA Astrophysics Data System (ADS)

    Shen, Z.; Wang, M.; Sun, J.; Wang, F.; Wang, Y.; Tao, W.; Zhang, P.; Liao, H.; Hao, M.; Wang, Q.

    2013-12-01

    The 2008 Mw 7.9 Wenchuan earthquake is a devastating tragic event. In the meantime it also provided a rare opportunity for the study of seismo-tectonic processes of the Longmen Shan fault system. After the quake we collected GPS and InSAR data to deduce its coseismic and postseismic deformation fields, and combined that with geological and seismic observations to invert for the fault geometry, coseismic slip distribution, and postseismic deformation sources. Our results show the following. The Longmen Shan fault system has two major segments. The southern segment is listric in shape, and deforms primarily through reverse faulting. The northern segment is near vertical in shape, and deforms primarily through dextral shear. The Minjiang-Huya fault system branches obliquely off the central Longmen Shan fault, absorbing a portion of the ESEward extrusion of the eastern Tibet and causing slip partition between itself and the northern segment of the Longmen Shan fault. The Wenchuan earthquake ruptured a cluster of 'asperities' in a cascade style. These 'asperities' are stress strongholds not because of their friction properties on fault plane as interpreted for most of the large strike-slip and/or subduction zone faults, but because of their being geometric barriers. These geometric barriers were created due to complexity of the crust materials under tectonic loading and faulting, and could not be smoothed out by aberration in the fault process because its faulting direction is at high oblique angle with the fault strike direction and the overall aberration ranges are relatively short comparing to that of large strike-slip and subduction zone faults. Aftershocks of the Wenchuan earthquake concentrated mainly around the geometric barriers in upper crust, which cannot be explained by a conventional asperity model used to explain aftershock locations of strike-slip and/or subduction zone earthquakes, but can be interpreted as caused by secondary faulting around these

  18. Coseismic and postseismic deformation studies of the Wenchuan earthquake and seismo-tectonics of the Longmen Shan fault system (Invited)

    NASA Astrophysics Data System (ADS)

    Shen, Z.; Wang, M.; Sun, J.; Wang, F.; Wang, Y.; Tao, W.; Zhang, P.; Liao, H.; Hao, M.; Wang, Q.

    2011-12-01

    The 2008 Mw 7.9 Wenchuan earthquake is a devastating tragic event. In the meantime it also provided a rare opportunity for the study of seismo-tectonic processes of the Longmen Shan fault system. After the quake we collected GPS and InSAR data to deduce its coseismic and postseismic deformation fields, and combined that with geological and seismic observations to invert for the fault geometry, coseismic slip distribution, and postseismic deformation sources. Our results show the following. The Longmen Shan fault system has two major segments. The southern segment is listric in shape, and deforms primarily through reverse faulting. The northern segment is near vertical in shape, and deforms primarily through dextral shear. The Minjiang-Huya fault system branches obliquely off the central Longmen Shan fault, absorbing a portion of the ESEward extrusion of the eastern Tibet and causing slip partition between itself and the northern segment of the Longmen Shan fault. The Wenchuan earthquake ruptured a cluster of 'asperities' in a cascade style. These 'asperities' are stress strongholds not because of their friction properties on fault plane as interpreted for most of the large strike-slip and/or subduction zone faults, but because of their being geometric barriers. These geometric barriers were created due to complexity of the crust materials under tectonic loading and faulting, and could not be smoothed out by aberration in the fault process because its faulting direction is at high oblique angle with the fault strike direction and the overall aberration ranges are relatively short comparing to that of large strike-slip and subduction zone faults. Aftershocks of the Wenchuan earthquake concentrated mainly around the geometric barriers in upper crust, which cannot be explained by a conventional asperity model used to explain aftershock locations of strike-slip and/or subduction zone earthquakes, but can be interpreted as caused by secondary faulting around these

  19. [Changes of rat gastric mucosal barrier under stress conditions].

    PubMed

    Zhan, Xianbao; Li, Zhaoshen; Cui, Zhongmin; Duan, Yimin; Nie, Shinan; Liu, Jing; Xu, Guoming

    2002-06-01

    OBJECTIVE To explore the changes of rat gastric mucosal barrier under conditions of water immersion restraint stress. METHODS Eighty rats were randomly divided into Group A (20 rats), B (40 rats) and C (20 rats) after being fasted for 24 hours. And then Group A was divided into two subgroups with ten rats in each. The two subgroups in Group A were given normal saline or omeprazole respectively while under the stress condition. The changes of gastric acid or bicarbonate secretion were determined. Group B (40 rats) were randomly divided into four subgroups,which were subgroup control, 1h, 2h and 4h after beginning of the stress. The quantity of glandular mucosal adherent mucus, the thickness of mucus gel layer and ulcer index were measured after stress in Group B. The glandular mucosal samples were labeled by Lanthanum and observed by transmission electromicroscopy. Group C was randomly divided into two subgroups in the same way with Group A. And each subgroup received normal saline or omeprazole respectively H(+) loss in gastric lumen was calculated by determining the difference of acidity between lavage and drainage fluid H(+) concentration. RESULTS It was found that gastric alkaline secretion decreased progressively (P < 0.05), while gastric acid secretion increased progressively under stress conditions (P < 0.05). The mucus quantity(A/g) in the four subgroups in Group B were 0.137 +/- 0.030, 0.143 +/- 0.012, 0.066 +/- 0.016 and 0.016 +/- 0.016 respectively. The mucus gel thickness(microm) were 71.08 +/- 5.85, 74.50 +/- 12.85, 57.63 +/- 6.45 and 51.35 +/- 2.84 respectively. The ulcer index were 0.2 +/- 0.1,0.4 +/- 0.1,5.2 +/- 1.3 and 10.0 +/- 0.5 respectively. Statistics showed that the mucus quantity was correlated with the mucus gel thickness positively(r = 0.89), while either of them was correlated with the ulcer index negatively(r = 0.85 and "r = 0.83). And it was also found that Lanthanum rarely stained the glandular mucosa in control subgroup, while heavily

  20. Effects of Melatonin on Stress-Induced Changes in the Liver of Rats with Different Resistance to Stress.

    PubMed

    Serikov, V S; Lyashev, Yu D

    2015-07-01

    Effects of melatonin on changes in the liver structures were studied in stress-resistant and stress-sensitive rats exposed to chronic stress. It was found that the number of degenerative cells increased and intralobular sinusoidal capillary enlarged in the liver of animals of both groups. These parameters were significantly higher in stress-sensitive rats. Melatonin (1 mg/kg) reduced the severity of degenerative changes and stimulated the development of reparative processes in the liver tissue. The effects of the hormone was more pronounced in rats sensitive to stress and was noted after melatonin administration in a dose of 0.2 mg/kg.

  1. Sleep patterning changes in a prenatal stress model of depression.

    PubMed

    Sickmann, H M; Skoven, C; Bastlund, J F; Dyrby, T B; Plath, N; Kohlmeier, K A; Kristensen, M P

    2017-08-29

    Clinical depression is accompanied by changes in sleep patterning, which is controlled in a circadian fashion. It is thus desirable that animal models of depression mirror such diurnally-specific state alterations, along with other behavioral and physiological changes. We previously found several changes in behavior indicative of a depression-like phenotype in offspring of rats subjected to repeated, variable prenatal stress (PNS), including increased locomotor activity during specific periods of the circadian cycle. We, therefore, investigated whether PNS rats also exhibit alterations in sleep/wakefulness behavior around the change from light-to-dark phase. Control and PNS Sprague-Dawley rats were implanted with electrodes for continuous monitoring of electroencephalic activity used to determine behavioral state. The distribution of slow-wave sleep (SWS), rapid eye movement sleep (REMS) and wakefulness was compared for periods before and after lights were turned off, between baseline conditions and after exposure to an acute stressor. Both REMS and SWS amounts were increased in PNS rats relative to control animals in the beginning of the dark phase. REMS changes were due to an increase in REMS bout number, rather than in bout duration. During this circadian time period, we did not find any sex differences in the state changes. These results indicate that PNS affects baseline sleep patterning in both male and female rats around active-phase onset.

  2. Ultrastructural changes of Saccharomyces cerevisiae in response to ethanol stress.

    PubMed

    Ma, Manli; Han, Pei; Zhang, Ruimin; Li, Hao

    2013-09-01

    In the fermentative process using Saccharomyces cerevisiae to produce bioethanol, the performance of cells is often compromised by the accumulation of ethanol. However, the mechanism of how S. cerevisiae responds against ethanol stress remains elusive. In the current study, S. cerevisiae cells were cultured in YPD (yeast extract - peptone - dextrose) medium containing various concentrations of ethanol (0%, 2.5%, 5%, 7.5%, 10%, and 15% (v/v)). Compared with the control group without ethanol, the mean cell volume of S. cerevisiae decreased significantly in the presence of 7.5% and 10% ethanol after incubation for 16 h (P < 0.05), and in the presence of 15% ethanol at all 3 sampling time points (1, 8, and 16 h) (P < 0.05). The exposure of S. cerevisiae cells to ethanol also led to an increase in malonyldialdehyde content (P < 0.05) and a decrease in sulfhydryl group content (P < 0.05). Moreover, the observations through transmission electron microscopy enabled us to relate ultrastructural changes elicited by ethanol with the cellular stress physiology. Under ethanol stress, the integrity of the cell membrane was compromised. The swelling or distortion of mitochondria together with the occurrence of a single and large vacuole was correlated with the addition of ethanol. These results suggested that the cell membrane is one of the targets of ethanol, and the degeneration of mitochondria promoted the accumulation of intracellular reactive oxygen species.

  3. Stress-induced structural changes in thermoplastic composites

    SciTech Connect

    Kitano, A.

    1991-01-01

    Polymeric Composites: Cyclic stress effects on PEEK (Poly-ether-ether-ketone) matrix thermoplastic composite system were examined by thermal-analysis techniques: DSC (Differential Scanning Calorimeter), DMA (Dynamic Mechanical Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), TMA (Thermomechanical Analysis), TGA (Thermogravimetric Analysis), DGT (Density Gradient Technique), and WAXS (Wide angle X-ray Scattering). These measurements identified for the first time stress-induced crystallization of PEEK below the glass transition temperature (Tg). Also, PEEK crystallization above T[sub g] was kinetically studied by DSC and DMA, and a previously developed dual-crystallization methodology was extended to account for the influence of stress on crystallization. Finally, a fatigue kinetic model for un-notched PEEK films and a crack propagation model for PEEK composites were also developed providing a relation between matrix morphology and end-use performance. Collectively, this work established the importance of structural changes in thermoplastic-based composites that can be both monitored and influenced by dynamic (cyclic) mechanical experiments.

  4. Did a Stress Change due to a Long-Term Slow Slip Event in the Tokai Region Cause Distant Seismic Quiescence in the Tamba Region, Japan?

    NASA Astrophysics Data System (ADS)

    Sugaya, K.; Hiramatsu, Y.; Furumoto, M.; Katao, H.

    2008-12-01

    Seismic quiescence is useful information for the earthquake prediction. Relationships between seismicity rate change and stressing rate change have been reported by theoretical and observational studies (Dieterich, 1994; Toda et al., 2002). Recently, Ogata (2007) showed that a silent slip event might occur within the source region of an intraplate earthquake preceding the rupture from seismicity rate changes and GPS anomalies. The Tamba region in southwest Japan is located to the northeast of the rupture zone of the 1995 Hyogo-ken Nanbu Earthquake (Mjma 7.3). In the region, the seismicity was activated by a coseismic static stress change (+20kPa; Hiramatsu et al., 2000) due to the event. A distinct decrease in seismicity rate of microearthquakes was recognized in 2003 (Katao, 2005). Such a seismic quiescence had continued for two and a half years before the event (DPRI, 1999). It has, therefore, been controversial whether a major earthquake follows the quiescence or not (e.g., Umeda et al., 2005). We showed that the Tamba region was located in a region where Δ CFS decreased (-0.5kPa/yr) due to the long-term slow slip event (SSE) in the Tokai region and indicated that the beginning of the quiescence seemed to be associated with that of the event (Sugaya et al., 2007IUGG). Our purpose in this study is to investigate whether the quiescence in the Tamba region is caused by the stress change due to the long-term SSE or not based on the rate- and state- friction law (Dieterich, 1994). We use the hypocentral catalog of the DPRI from 1987 to 2001 and that relocated in this study from 2002 to 2006. We use declustered earthquakes (Reasenberg, 1985) greater than or equal to M 2.5 for following analyses. We find that the seismicity in the Tamba region after the 1995 Hyogo-ken Nanbu earthquake is explained by the Omori"fs law (p=1) than the ETAS model (Ogata, 1986). The seismicity is, thus, interpreted as the aftershock-type activity of the earthquake. We estimate Aσ (A is

  5. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES

    SciTech Connect

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarado; A. Alajmi; Z. Karpyn; N. Mohammed; S. Al-Enezi

    2005-06-15

    The main objectives of this project are to quantify the changes in fracture porosity and multiphase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (a) developing the direct experimental measurements of fracture aperture and topology and fluid occupancy using high-resolution x-ray micro-tomography, (b) quantifying the effect of confining stress on the distribution of fracture aperture, and (c) characterization of shear fractures and their impact on multi-phase flow. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. Several fractures have been scanned and the fracture aperture maps have been extracted. The success of the mapping of fracture aperture was followed by measuring the occupancy of the fracture by two immiscible phases, water and decane, and water and kerosene. The distribution of fracture aperture depends on the effective confining stress on the nature of the rock and the type and distribution of the asperities that keep the fracture open. Fracture apertures at different confining stresses were obtained by micro-tomography covering a range of about two thousand psig. Initial analysis of the data shows a significant aperture closure with increase in effective confining stress. Visual descriptions of the process are shown in the report while detailed analysis of the behavior of the distribution of fracture aperture is in progress. Both extensional and shear fractures are being considered. The initial multi-phase flow tests were done in extensional fractures. Several rock samples with induced shear fracture are being studies, and some of the new results are presented in this report. These samples are being scanned in order to

  6. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES

    SciTech Connect

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarado; A. Alajmi; Z. Karpyn; N. Mohammed; S. Al-Enezi

    2005-06-15

    The main objectives of this project are to quantify the changes in fracture porosity and multiphase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (a) developing the direct experimental measurements of fracture aperture and topology and fluid occupancy using high-resolution x-ray micro-tomography, (b) quantifying the effect of confining stress on the distribution of fracture aperture, and (c) characterization of shear fractures and their impact on multi-phase flow. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. Several fractures have been scanned and the fracture aperture maps have been extracted. The success of the mapping of fracture aperture was followed by measuring the occupancy of the fracture by two immiscible phases, water and decane, and water and kerosene. The distribution of fracture aperture depends on the effective confining stress on the nature of the rock and the type and distribution of the asperities that keep the fracture open. Fracture apertures at different confining stresses were obtained by micro-tomography covering a range of about two thousand psig. Initial analysis of the data shows a significant aperture closure with increase in effective confining stress. Visual descriptions of the process are shown in the report while detailed analysis of the behavior of the distribution of fracture aperture is in progress. Both extensional and shear fractures are being considered. The initial multi-phase flow tests were done in extensional fractures. Several rock samples with induced shear fracture are being studied, and some of the new results are presented in this report. These samples are being scanned in order to

  7. The response of skin disease to stress: changes in the severity of acne vulgaris as affected by examination stress.

    PubMed

    Chiu, Annie; Chon, Susan Y; Kimball, Alexa B

    2003-07-01

    Although emotional stress has long been suspected to exacerbate acne vulgaris, previous reports addressing its influence on acne severity have been mainly anecdotal. To elucidate the possible relationship between stress and acne exacerbation by evaluating changes in acne severity during nonexamination and examination periods and to assess the possible relationship of these changes in severity with perceived examination stress by using previously validated scales measuring acne severity and perceived stress. Prospective cohort study. General university community. A volunteer sample of 22 university students (15 women and 7 men) with a minimum acne vulgaris severity of 0.5 on the photonumeric Leeds acne scale (baseline scores, 0.50-1.75). Participants were graded on their acne severity using the Leeds acne scale, and had their subjective stress levels assessed with the Perceived Stress Scale questionnaire during both nonexamination and examination periods. Subjects had a higher mean grade of acne severity and mean perceived stress score (P<.01 for both) during examinations. Using regression analysis and adjusting for the effects of confounding variables, such as changes in sleep hours, sleep quality, diet quality, and number of meals per day, increased acne severity was significantly associated with increased stress levels (r = 0.61, P<.01), while self-assessed change in diet quality was the only other significant association (P =.02). Patients with acne may experience worsening of the disease during examinations. Furthermore, changes in acne severity correlate highly with increasing stress, suggesting that emotional stress from external sources may have a significant influence on acne.

  8. Personality Change at the Intersection of Autonomic Arousal and Stress

    PubMed Central

    Hart, Daniel; Eisenberg, Nancy; Valiente, Carlos

    2006-01-01

    We hypothesized that personality change in children would be predicted by the interaction of family risk with susceptibility to autonomic arousal, with children characterized by both families at high risk and highly reactive autonomic nervous systems showing maladaptive change. This hypothesis was tested in a six-year longitudinal study in which personality prototype, problem behavior, and negative emotional intensity were measured at two-year intervals. The results indicated that children with exaggerated skin conductance responses, a measure of autonomic reactivity, and living in families with multiple risk factors, were most likely to develop towards an under-controlled personality type and exhibit increases in problem behavior and negative emotional intensity. The implications of the results for understanding the relation of stress to biological vulnerability are discussed. PMID:17576260

  9. Thermal Stress Effect on Density Changes of Hemp Hurds Composites

    NASA Astrophysics Data System (ADS)

    Schwarzova, Ivana; Cigasova, Julia; Stevulova, Nadezda

    2016-12-01

    The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

  10. Lichen dating of coseismic landslide hazards in alpine mountains

    NASA Astrophysics Data System (ADS)

    Bull, William B.; King, John; Kong, Fanchen; Moutoux, Thomas; Phillips, William M.

    1994-08-01

    Studies of rockfalls and block slides provide insight about seismic shaking hazards in alpine mountains subject to earthquakes. Large samples of the longest axis of the largest lichen on each block can be used to identify regional landslide events; lichen-size distributions for many sites cluster consistenly at the same sizes. The coseismic rockfall lichenometry model can be used to (1) date and locate prehistorical earthquakes, (2) document regional frequency of earthquakes, and (3) describe regional patterns of seismic shaking. Determination of colonization time, great-growth phase, and especially uniform phase rates of lichen growth are essential for dating regional landslide events. Rocks that tumble downhill during historical earthquakes allow accurate calibration of the growth rate for Rhizocarpon subgenus Rhizocarpon; these plentiful fresh substrates are dated to their day of formation. An initial calibration of uniform growth rate, based on historical and tree-ring dated landslides was fine tuned by assigning earthquake dates to mean values of lichen-size peaks for regional rockfall events that increase in abundance towards epicenters of historical earthquakes. Calibration for each new site is unnecessary in the Southern Alps of New Zealand and in the Sierra Nevada of California because several species of yellow rhizocarpons within each climatic region have constant growth rates that are independent of altitude or substrate lithology.

  11. Coseismic ionospheric disturbances triggered by the Chi-Chi earthquake

    NASA Astrophysics Data System (ADS)

    Liu, J. Y.; Tsai, H. F.; Lin, C. H.; Kamogawa, M.; Chen, Y. I.; Lin, C. H.; Huang, B. S.; Yu, S. B.; Yeh, Y. H.

    2010-08-01

    At 17:47 UT on 20 September 1999, a large earthquake of magnitude Mw 7.6 struck the central Taiwan near a small town of Chi-Chi. The ground-based receivers of the global positioning system (GPS) in the Taiwan area detected coseismic ionospheric disturbances (CIDs) in the total electron content (TEC) triggered by the Chi-Chi earthquake. When the CIDs travel away from the origin on the Earth surface and then propagate into the ionosphere, their amplitudes and periods generally become smaller and longer, respectively. Moreover, two global grid searches, adapting the ray-tracing and the beam-forming techniques, have been used to analyze the observed GPS TEC. We have not only estimated the average speed of the CIDs propagating in the atmosphere and ionosphere but also determined the location of CID origin on the Earth surface by using the two techniques. The results show that the observed CIDs result from shock-acoustic waves triggered by sudden and large vertical motions of the Chi-Chi earthquake.

  12. Stress related to family change among Vietnamese refugees.

    PubMed

    Fox, P G

    1991-01-01

    Because life changes have been known to have consequences for emotional and physical well-being, this study demonstrates the need for community health nurses (CHNs) to assess structural and functional changes in Vietnamese refugee spousal relations as possible sources of stress following resettlement. The purpose of this study was to identify changes in the structural and functional dimensions of family life and assess their impact on spousal relations. The major variables considered in effecting change in spousal interactions were relocation, exposure to more liberal attitudes toward gender equality in the United States, and wife employment. Spousal power differentials and affectivity were used as measures of change. Intensive interviews, using a semistructured interview guide, were conducted with 30 Vietnamese refugee women; the sample was nonrandom and cross-sectional. Information was collected on sociodemographic characteristics and pre- and postresettlement spousal relations. Wife employment, associated with proficiency in English and longer length of residence in the U.S., was found to promote more egalitarian spousal relations and greater spousal affectivity. When wives were not employed, they tended to describe an increase in affectivity without an appreciable decrease in spousal power differentials. This effect was enhanced by isolation within the host society as a result of limited English skills, unemployment, and a shorter length of residence.

  13. Coagulation Changes During Graded Orhostatic Stress and Recovery

    NASA Astrophysics Data System (ADS)

    Goswami, Nandu; Cvirn, Gerhard; Schlagenhauf, Aaxel; Leschnik, Bettina; Koestenberger, Martin; Roessler, Andreas; Jantscher, Andreas; Waha, James Elvis; Wolf, Sabine; Vrecko, Karoline; Juergens, Guenther; Hinghofer-Szalkay, Helmut

    2013-02-01

    Background: Orthostatic stress has been introduced as a novel paradigm for activating the coagulation system. We examined whether graded orthostatic stress (using head up tilt, HUT + lower body negative pressure, LBNP) until presyncope leads to anti / pro-coagulatory changes and how rapidly they return to baseline during recovery. Methodology: Eight male subjects were enrolled in this study. Presyncopal runs were carried out using HUT + LBNP. At minute zero, the tilt table was brought from 0° (supine) to 70 ° head-up position for 4 min, after which pressure in the LBNP chamber was reduced to -15, -30, and -45 mm Hg every 4 min. At presyncope, the subjects were returned to supine position. Coagulatory responses and plasma mass density (for volume changes) were measured before, during and 20 min after the orthostatic stress. Whole blood coagulation was examined by means of thrombelastometry. Platelet aggregation in whole blood was examined by using impedance aggregometry. Thrombin generation parameters, prothrombin levels, and markers of endothelial activation were measured in plasma samples. Results: At presyncope, plasma volume was 20 % below the initial supine value. Blood cell counts, prothrombin levels, thrombin peak, endogenous thrombin potential (ETP), and tissue factor pathway inhibitor (TFPI) levels increased during the protocol, commensurate with hemoconcentration. The markers of endothelial activation (tissue factor, TF, tissue plasminogen activator, t-PA) and the markers of thrombin generation (Prothrombin fragments 1 and 2, F1+2, and thrombin-antithrombin complex, TAT) increased significantly. During recovery, all the coagulation parameters returned to initial supine values except F1 +2 and TAT. Conclusion: Head-up tilt/LBNP leads to activation of the coagulation system. Some of the markers of thrombin formation are still at higher than supine levels during recovery.

  14. Coulomb Stress Change and Seismic Hazard of Rift Zones in Southern Tibet after the 2015 Mw7.8 Nepal Earthquake and Its Mw7.3 Aftershock

    NASA Astrophysics Data System (ADS)

    Dai, Z.; Zha, X.; Lu, Z.

    2015-12-01

    In southern Tibet (30~34N, 80~95E), many north-trending rifts, such as Yadong-Gulu and Lunggar rifts, are characterized by internally drained graben or half-graben basins bounded by active normal faults. Some developed rifts have become a portion of important transportation lines in Tibet, China. Since 1976, eighty-seven >Mw5.0 earthquakes have happened in the rift regions, and fifty-five events have normal faulting focal mechanisms according to the GCMT catalog. These rifts and normal faults are associated with both the EW-trending extension of the southern Tibet and the convergence between Indian and Tibet. The 2015 Mw7.8 Nepal great earthquake and its Mw7.3 aftershock occurred at the main Himalayan Thrust zone and caused tremendous damages in Kathmandu region. Those earthquakes will lead to significant viscoelastic deformation and stress changes in the southern Tibet in the future. To evaluate the seismic hazard in the active rift regions in southern Tibet, we modeled the slip distribution of the 2015 Nepal great earthquakes using the InSAR displacement field from the ALOS-2 satellite SAR data, and calculated the Coulomb failure stress (CFS) on these active normal faults in the rift zones. Because the estimated CFS depends on the geometrical parameters of receiver faults, it is necessary to get the accurate fault parameters in the rift zones. Some historical earthquakes have been studied using the field data, teleseismic data and InSAR observations, but results are in not agreement with each other. In this study, we revaluated the geometrical parameters of seismogenic faults occurred in the rift zones using some high-quality coseismic InSAR observations and teleseismic body-wave data. Finally, we will evaluate the seismic hazard in the rift zones according to the value of the estimated CFS and aftershock distribution.

  15. Antioxidant and oxidative stress changes in experimental cor pulmonale.

    PubMed

    Farahmand, Firoozeh; Hill, Michael F; Singal, Pawan K

    2004-05-01

    Although right heart failure (RHF) contributes to 20% of all cardiovascular complications, most of the information available on RHF in general is based on the experiences with left heart failure. This study on RHF investigates changes in antioxidants and oxidative stress which are suggested to play a role in the transition from hypertrophy to failure. RHF subsequent to pulmonary hypertension was produced in rats by a single injection of monocrotaline (MCT, 60 mg/kg, i.p.). Based on hemodynamic, clinical and histopathologic observations, the animals were grouped in three functional stages at 1-, 2- and 6-week post-injection periods. In the 1-week group, RV pressure overload and hypertrophy, and a mild increase in antioxidant enzymes was seen. In the 2-week group, compensated HF, a significant increase in antioxidant enzymes, an increase in septal (IVS) wall thickness and leftward displacement of IVS without change in LV free wall were seen. In the 6-week group, lung and liver congestion, RVF and dilation, a decrease in antioxidant enzyme activities, increase in lipid peroxidation and severe bulging of the IVS into the left ventricle were seen. These changes in the hemodynamic, biochemical and histopathologic characteristics suggest that in early stages of MCT-induced pulmonary hypertension at 1 and 2 weeks, RV hypertrophy was accompanied by sustained hemodynamic function and an increase in antioxidant reserve. In the later stage at 6 weeks, clinical RHF was associated with abnormalities of the right heart systolic and diastolic function along with a decrease in antioxidant reserve. These biphasic changes in RV antioxidant enzymes, i.e. an increase during hypertrophy and a decrease in failure may suggest a role of oxidative stress in the pathogenesis of right ventricular dysfunction.

  16. The stress shadow problem in physics-based aftershock forecasting: Does incorporation of secondary stress changes help?

    NASA Astrophysics Data System (ADS)

    Segou, M.; Parsons, T.

    2014-06-01

    Main shocks are calculated to cast stress shadows across broad areas where aftershocks occur. Thus, a key problem with stress-based operational forecasts is that they can badly underestimate aftershock occurrence in the shadows. We examine the performance of two physics-based earthquake forecast models (Coulomb rate/state (CRS)) based on Coulomb stress changes and a rate-and-state friction law for their predictive power on the 1989 Mw = 6.9 Loma Prieta aftershock sequence. The CRS-1 model considers the stress perturbations associated with the main shock rupture only, whereas CRS-2 uses an updated stress field with stresses imparted by M ≥ 3.5 aftershocks. Including secondary triggering effects slightly improves predictability, but physics-based models still underestimate aftershock rates in locations of initial negative stress changes. Furthermore, CRS-2 does not explain aftershock occurrence where secondary stress changes enhance the initial stress shadow. Predicting earthquake occurrence in calculated stress shadow zones remains a challenge for stress-based forecasts, and additional triggering mechanisms must be invoked.

  17. Gene expression changes in response to aging compared to heat stress, oxidative stress and ionizing radiation in Drosophila melanogaster

    PubMed Central

    Landis, Gary; Shen, Jie; Tower, John

    2012-01-01

    Gene expression changes in response to aging, heat stress, hyperoxia, hydrogen peroxide, and ionizing radiation were compared using microarrays. A set of 18 genes were up-regulated across all conditions, indicating a general stress response shared with aging, including the heat shock protein (Hsp) genes Hsp70, Hsp83 and l(2)efl, the glutathione-S-transferase gene GstD2, and the mitochondrial unfolded protein response (mUPR) gene ref(2)P. Selected gene expression changes were confirmed using quantitative PCR, Northern analysis and GstD-GFP reporter constructs. Certain genes were altered in only a subset of the conditions, for example, up-regulation of numerous developmental pathway and signaling genes in response to hydrogen peroxide. While aging shared features with each stress, aging was more similar to the stresses most associated with oxidative stress (hyperoxia, hydrogen peroxide, ionizing radiation) than to heat stress. Aging is associated with down-regulation of numerous mitochondrial genes, including electron-transport-chain (ETC) genes and mitochondrial metabolism genes, and a sub-set of these changes was also observed upon hydrogen peroxide stress and ionizing radiation stress. Aging shared the largest number of gene expression changes with hyperoxia. The extensive down-regulation of mitochondrial and ETC genes during aging is consistent with an aging-associated failure in mitochondrial maintenance, which may underlie the oxidative stress-like and proteotoxic stress-like responses observed during aging. PMID:23211361

  18. Gene expression changes in response to aging compared to heat stress, oxidative stress and ionizing radiation in Drosophila melanogaster.

    PubMed

    Landis, Gary; Shen, Jie; Tower, John

    2012-11-01

    Gene expression changes in response to aging, heat stress, hyperoxia, hydrogen peroxide, and ionizing radiation were compared using microarrays. A set of 18 genes were up-regulated across all conditions, indicating a general stress response shared with aging, including the heat shock protein (Hsp) genes Hsp70, Hsp83 and l(2)efl, the glutathione-S-transferase gene GstD2, and the mitochondrial unfolded protein response (mUPR) gene ref(2)P. Selected gene expression changes were confirmed using quantitative PCR, Northern analysis and GstD-GFP reporter constructs. Certain genes were altered in only a subset of the conditions, for example, up-regulation of numerous developmental pathway and signaling genes in response to hydrogen peroxide. While aging shared features with each stress, aging was more similar to the stresses most associated with oxidative stress (hyperoxia, hydrogen peroxide, ionizing radiation) than to heat stress. Aging is associated with down-regulation of numerous mitochondrial genes, including electron-transport-chain (ETC) genes and mitochondrial metabolism genes, and a sub-set of these changes was also observed upon hydrogen peroxide stress and ionizing radiation stress. Aging shared the largest number of gene expression changes with hyperoxia. The extensive down-regulation of mitochondrial and ETC genes during aging is consistent with an aging-associated failure in mitochondrial maintenance, which may underlie the oxidative stress-like and proteotoxic stress-like responses observed during aging.

  19. Frictional and transport properties of the 2008 Wenchuan Earthquake fault zone: Implications for coseismic slip-weakening mechanisms

    NASA Astrophysics Data System (ADS)

    Chen, Jianye; Yang, Xiaosong; Yao, Lu; Ma, Shengli; Shimamoto, Toshi

    2013-09-01

    This paper reports on the frictional and transport properties of fault rocks collected from a surface exposure associated with the 2008 Wenchuan earthquake. The water-dampened gouges showed high-velocity frictional behavior characterized by a rapid stress drop at the start of slip, and by intermittent jumps after attaining steady state, suggesting operation of thermal pressurization (TP). A novel fluid-flow system, allowing for parallel measurements of permeability, porosity and specific storage has been developed. Strong pore fluid pressurization induced by elevated confining pressure was observed during the porosity measurements. Analogical analysis of this compaction-induced pressurization succeeded in predicting the pore pressure build-up for a faulting process. Our measurements revealed that the fault zone consists of low-permeability fault gouges (2.6 × 10- 20 m2 at 165 MPa) and high-permeability damaged-zone rocks. The fault gouges and intact country rocks act as barriers to fluid flow across the fault, whereas the damaged zone acts as a fluid conduit, hence the fault zone displays a "conduit/barrier" hydrological structure. With our lab data as input, we performed numerical modeling of coseismic slip weakening including TP and mineral decomposition. The results indicate that fluid pressurization played an important role during the Wenchuan earthquake at the exposure site, where dynamic stress reduction was strongly enhanced by increase of pore pressure due to frictional heating and smectite dehydration. Our modeling further suggests less importance of high-velocity weakening compared with weakening due to pore fluid pressurization. Taken together, our experimental and modeling results as well as the microstructure observed, all suggest that thermochemical pressurization has been an important slip-weakening mechanism during the Wenchuan earthquake rupture. The dramatic weakening predicted may explain the large coseismic displacements and rupture

  20. Ecological consequences of coseismic uplift on the intertidal kelp belts of Lessonia nigrescens in central Chile

    NASA Astrophysics Data System (ADS)

    Castilla, J. C.; Oliva, D.

    1990-07-01

    Coseismic uplift from the Chilean earthquake of 3 March 1985 caused changes in the biomass and vertical zonation of rocky intertidal organisms at four sites along 150 km of the central Chilean coast. The 11-60 cm uplift caused widespread mortality mainly of the dominant intertidal kelp Lessonia nigrescens, reducing its biomass in the upper part of its pre-earthquake range and altering the vertical zonation. The L. nigrescens belt shrank from the top by about 0·5-1 m within 1 year of the shock, then expanded downward by about 1 m. An important part of the primary space liberated at the pre-earthquake upper border of Lessonia was invaded by the barnacles Chthamalus scabrosus and Jehlius cirratus. None of the foregoing changes occurred at two control sites located outside the shock area. The ecological effects of these recurrent sudden and drastic environmental processes on rocky intertidal communities include the liberation of primary space, enhancement of mosaic areas and modification of the vertical zonation of competitively dominant organisms.

  1. Preseismic Velocity Changes Observed from Active Source Monitoringat the Parkfield SAFOD Drill Site

    SciTech Connect

    Daley, Thomas; Niu, Fenglin; Silver, Paul G.; Daley, Thomas M.; Cheng, Xin; Majer, Ernest L.

    2008-06-10

    Measuring stress changes within seismically active fault zones has been a long-sought goal of seismology. Here we show that such stress changes are measurable by exploiting the stress dependence of seismic wave speed from an active source cross-well experiment conducted at the SAFOD drill site. Over a two-month period we observed an excellent anti-correlation between changes in the time required for an S wave to travel through the rock along a fixed pathway--a few microseconds--and variations in barometric pressure. We also observed two large excursions in the traveltime data that are coincident with two earthquakes that are among those predicted to produce the largest coseismic stress changes at SAFOD. Interestingly, the two excursions started approximately 10 and 2 hours before the events, respectively, suggesting that they may be related to pre-rupture stress induced changes in crack properties, as observed in early laboratory studies.

  2. The Effects of Differing Sequences of Earthquake Ground-Shaking on Coseismic Slope Stability

    NASA Astrophysics Data System (ADS)

    Brain, M.; Rosser, N. J.; Vann Jones, E. C.; Tunstall, N.

    2015-12-01

    Studies of earthquake-induced landsliding typically consider slope stability during high-magnitude ground shaking events only. During such events, downslope movement of the landslide mass occurs when seismic ground accelerations are sufficient to overcome shear resistance at the landslide shear surface. This approach does not consider the potential effects that sequences of low-magnitude ground shaking events can have on material strength and, hence, coseismic slope stability. Since such events are more common in nature relative to high-magnitude shaking events, it is important to constrain their geomorphic effectiveness. Using an experimental laboratory approach, we present results that address this key issue. We used a bespoke geotechnical testing apparatus, the Dynamic Back-Pressured Shear Box, that permits realistic simulation of earthquake ground-shaking conditions within a hillslope. We tested both cohesive and granular materials that displayed ductile behaviour under standard strain-controlled monotonic shear tests. We applied dynamic stresses of varying amplitude, frequency and sequence, and monitored the resultant strain response to determine which factors, when combined, created notable deviations from standard monotonic shear behaviour. We observed that multiple dynamic stress/shaking events that are largely insufficient to cause large strains (and hence are conventionally deemed geomorphologically ineffective) can affect material stiffness such that the future behaviour of the sediment/landslide differs considerably from that observed in standard monotonic shear tests. In other words, low-magnitude ground shaking events can be effective precursory geomorphic processes. Critically, the sequence of ground-shaking events is an important control; where shaking conditions cause progressive densification of sediment, the frictional strength of the material subsequently increases. In turn, the resultant strain response to high-magnitude ground shaking events

  3. Probabilistic estimates of surface coseismic slip and afterslip for Hayward fault earthquakes

    USGS Publications Warehouse

    Aagaard, Brad T.; Lienkaemper, James J.; Schwartz, David P.

    2012-01-01

    We examine the partition of long‐term geologic slip on the Hayward fault into interseismic creep, coseismic slip, and afterslip. Using Monte Carlo simulations, we compute expected coseismic slip and afterslip at three alinement array sites for Hayward fault earthquakes with nominal moment magnitudes ranging from about 6.5 to 7.1. We consider how interseismic creep might affect the coseismic slip distribution as well as the variability in locations of large and small slip patches and the magnitude of an earthquake for a given rupture area. We calibrate the estimates to be consistent with the ratio of interseismic creep rate at the alinement array sites to the geologic slip rate for the Hayward fault. We find that the coseismic slip at the surface is expected to comprise only a small fraction of the long‐term geologic slip. The median values of coseismic slip are less than 0.2 m in nearly all cases as a result of the influence of interseismic creep and afterslip. However, afterslip makes a substantial contribution to the long‐term geologic slip and may be responsible for up to 0.5–1.5 m (median plus one standard deviation [S.D.]) of additional slip following an earthquake rupture. Thus, utility and transportation infrastructure could be severely impacted by afterslip in the hours and days following a large earthquake on the Hayward fault that generated little coseismic slip. Inherent spatial variability in earthquake slip combined with the uncertainty in how interseismic creep affects coseismic slip results in large uncertainties in these slip estimates.

  4. Changes in Stress Perception and Coping during Adolescence: The Role of Situational and Personal Factors

    ERIC Educational Resources Information Center

    Seiffge-Krenke, Inge; Aunola, Kaisa; Nurmi, Jari-Erik

    2009-01-01

    The present study investigated the interplay between developmental changes in stress and coping during early and late adolescence. Using a longitudinal design, stress perception and coping styles of 200 adolescents in 7 different stressful situations were investigated. Multilevel piecewise latent growth curve models showed that stress perception…

  5. Changes in Stress Perception and Coping during Adolescence: The Role of Situational and Personal Factors

    ERIC Educational Resources Information Center

    Seiffge-Krenke, Inge; Aunola, Kaisa; Nurmi, Jari-Erik

    2009-01-01

    The present study investigated the interplay between developmental changes in stress and coping during early and late adolescence. Using a longitudinal design, stress perception and coping styles of 200 adolescents in 7 different stressful situations were investigated. Multilevel piecewise latent growth curve models showed that stress perception…

  6. Earthquake-induced static stress change in promoting volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Bonali, Fabio Luca; Tibaldi, Alessandro; Corazzato, Claudia

    2014-05-01

    The aim of this work is to study how earthquakes could favour new eruptions, focusing the attention on earthquake-induced static effects in two different case sites, where 9 seismic events with Mw ≥ 8 occurred in the last century: the Alaska-Aleutian and Chilean volcanic arcs. We followed a novel approach that resolves the earthquake-induced static stress change normal to the magma pathway of each volcano instead of considering the general crustal volume. We also considered other parameters that may contribute to control eruptions, such as magma composition and viscosity, magma chamber depth and local tectonic settings. The dataset includes a total of 51 eruptions following the earthquakes; 33 represent first new eruptions occurred at each single volcano. Comparison of the eruption rate before and after each earthquake suggests that 26 out of the 33 first new eruptions have a positive relation with the studied earthquakes; 13 out of 26 represent awakening events, which are first new eruptions occurred at volcanoes with non-continuous eruptive activity that had no eruptions in the five years before the earthquake. The sensitivity analysis performed for the 2010 Chile earthquake shows that the N-S- and NE-SW-striking magma pathways suffered a larger unclamping in comparison with those striking NW-SE and E-W. Magma pathway geometry contributes to control the magnitude of the static stress change induced by large earthquakes, with differences of up to 8 times among magma-feeding planes of different orientation at the same volcano. This range of diverse values is larger for the volcanoes closer to the epicentre. The possible error in the estimate of magma chamber depth has a minimum effect on the results since the sensitivity analysis shows that the range of stress changes with depth is about 1.5 orders of magnitude smaller than the range linked to variations in the magma pathway strike. Results suggest that unclamping effect promoted eruptions that occurred at non

  7. Co-seismic fault geometry and slip distribution of the 26 December 2004, giant Sumatra-Andaman earthquake constrained by GPS, coral reef, and remote sensing data

    NASA Astrophysics Data System (ADS)

    Wan, Yongge; Shen, Zheng-kang; Wang, Min; Zeng, Yuehua; Huang, Jichao; Li, Xiang; Cui, Huawei; Gao, Xiwei

    2015-06-01

    We analyze co-seismic displacement field of the 26 December 2004, giant Sumatra-Andaman earthquake derived from Global Position System observations, geological vertical measurement of coral head, and pivot line observed through remote sensing. Using the co-seismic displacement field and AK135 spherical layered Earth model, we invert co-seismic slip distribution along the seismic fault. We also search the best fault geometry model to fit the observed data. Assuming that the dip angle linearly increases in downward direction, the postfit residual variation of the inversed geometry model with dip angles linearly changing along fault strike are plotted. The geometry model with local minimum misfits is the one with dip angle linearly increasing along strike from 4.3o in top southernmost patch to 4.5o in top northernmost path and dip angle linearly increased. By using the fault shape and geodetic co-seismic data, we estimate the slip distribution on the curved fault. Our result shows that the earthquake ruptured ~200-km width down to a depth of about 60 km. 0.5-12.5 m of thrust slip is resolved with the largest slip centered around the central section of the rupture zone 7ºN-10ºN in latitude. The estimated seismic moment is 8.2 × 1022 N m, which is larger than estimation from the centroid moment magnitude (4.0 × 1022 N m), and smaller than estimation from normal-mode oscillation data modeling (1.0 × 1023 N m).

  8. Magnetic Field Disturbances Associated with changes in Lithologic Stress

    NASA Astrophysics Data System (ADS)

    Johnston, J. M.; Budker, D.; Johnson, R. M.; Tchernychev, M.; Craig, M. S.

    2013-12-01

    In August 2013 demolition by implosion of a multistory building on the campus of California State University East Bay (CSUEB) provided a strong seismic wave source. Anticipating that this event might provide an opportunity to acquire measurements of magnetic phenomena that could be associated with temporal changes in the lithologic stress regime, we placed several total-field magnetometers in the vicinity of CSUEB. The proximity of the implosion site to the active trace of the Hayward Fault provided additional incentive to measure any magnetic response to the propagation of seismic waves. The instruments used at the implosion site included three total-field cesium vapor magnetometers. These were distributed so as to acquire measurements within 200 m of the implosion site and to straddle the Hayward fault. This experiment also used the total magnetic field measurements acquired at the Jasper Ridge Biological Preserve (JRBP) cesium vapor magnetometer in the foothills behind Stanford University, some 20 km from the implosion site, as a distant reference. All magnetometers were configured to sample at a rate of 10 Hz and were synchronized to better that 1 mSec relative to GPS time. The Magnetic field measurements were coordinated with seismic motion measurements recorded at approximately 600 residential seismic stations and several multichannel seismographs located around the demolition site. Magnetic phenomena that may be associated with lithologic stress phenomena are compared to the seismic measurements in an effort to the observe correlations between lithologic stress and the generation of an anomalous magnetic field. The coherence of the magnetic and seismic events should provide insight into the character of possible earthquake precursor magnetic signals.

  9. The Effects of Static Coulomb, Normal and Shear Stress Changes on Earthquake Occurrence in Southern California

    NASA Astrophysics Data System (ADS)

    Strader, A. E.; Jackson, D. D.

    2011-12-01

    Deng & Sykes (1997) found a strong correlation between receiver earthquake location and positive increase in Coulomb stress (ΔCFF). Assuming a coefficient of friction of 0.6, and resolving stresses onto assumed fault planes with uniform orientation parallel to average Pacific-North American plate motion, they found that only 15% of receiver earthquakes occur in "stress shadows" where the Coulomb stress change should impede faulting. We extended their study by adding two source earthquakes (Hector Mine, 1999 and El Mayor-Cucupah, 2010), and calculating the stress changes at the locations of 134 receiver earthquakes with magnitude 4.4 and greater after 1999. We examined shear stress, normal stress, and Coulomb stress, resolving stresses onto four different hypothetical fault planes: smoothed seismicity-based planes, a weighted average of nearby fault-plane orientations, and the two nodal planes of weighed average moment tensors of nearby earthquakes. We also computed shear, normal, and Coulomb stress histories oriented according to the four choices of fault orientation, and tested the effect of total stress change on receiver earthquake magnitude. Our chi square test results indicate that, with 95% confidence, receiver earthquakes do not tend to avoid stress shadows, and that the choice of plane onto which stress is resolved does not affect the result. On average, 39% of earthquakes occur at the time of maximum stress at the event location, with no significant variation depending on the choice of rupture plane or type of stress change. We found no correlation between earthquake magnitude and total stress change at the events' locations. These results suggest that instantaneous cumulative Coulomb stress, as we and Deng & Sykes modeled it, does not strongly control the locations of future earthquakes. The lack of correlation between Coulomb stress change and magnitude suggests that modeled Coulomb stress change does not control the size of earthquakes once they

  10. Stress related changes during TeamGym competition.

    PubMed

    DE Pero, Roberta; Cibelli, Giuseppe; Cortis, Cristina; Sbriccoli, Paola; Capranica, Laura; Piacentini, Maria F

    2016-05-01

    The aim of the present study was to investigate the stress-related changes of a TeamGym competition considering both physiological (i.e. salivary cortisol [sC] and alpha-amylase [sAA]) and psychological (i.e. state anxiety) responses in relation to exercise intensity and competition outcomes. Eleven (5 males and 6 females) elite TeamGym athletes (age: 21-28 yrs) were administered the State-Trait Anxiety Inventory before an official international TeamGym competition. sAA and sC samples were collected 15 minutes prior to competition, after each apparatus, 10-min and 30-min after competition. Exercise intensity was estimated by heart rate (HR) recording and performance was evaluated by three international judges. All these parameters were correlated with competition outcomes. TeamGym competition posed a low exercise load (most of exercise was performed below 85% of the individual HRmax). Significant increases (P<0.004) in sAA (3.53 fold induction) and state anxiety (P=0.045) were observed, with respect to baseline values. Conversely, sC remained stable throughout the competition. Significant (P=0.029) correlation between sAA, state anxiety and competition outcomes emerged. Present findings provide the first evidence that the psycho-physiological stress response prior to and during competition can affect performance outcome, especially in a technical sport such as TeamGym.

  11. Stress related changes during TeamGym competition.

    PubMed

    De Pero, R; Cibelli, G; Cortis, C; Sbriccoli, P; Capranica, L; Piacentini, M F

    2015-03-18

    The aim of the present study was to investigate the stress--related changes of a TeamGym competition considering both physiological [i.e. salivary cortisol (sC) and alpha--amylase (sAA)] and psychological (i.e. state anxiety) responses in relation to exercise intensity and competition outcomes. Eleven (5 males and 6 females) elite TeamGym athletes (age: 21--28 yrs) were administered the State--Trait Anxiety Inventory before an official international TeamGym competition. sAA and sC samples were collected 15 minutes prior to competition, after each apparatus, 10--min and 30--min after competition. Exercise intensity was estimated by heart rate (HR) recording and performance was evaluated by three international judges. All these parameters were correlated with competition outcomes. TeamGym competition posed a low exercise load (most of exercise was performed below 85% of the individual HR max ). Significant increases (P<0.004) in sAA (3.53 fold induction) and state anxiety (P=0.045) were observed, with respect to baseline values. Conversely, sC remained stable throughout the competition. Significant (P=0.029) correlation between sAA, state anxiety and competition outcomes emerged. Present findings provide the first evidence that the psycho--physiological stress response prior to and during competition can affect performance outcome, especially in a technical sport such as TeamGym.

  12. Carbaryl stress induced cellular changes in Calothrix brevissima.

    PubMed

    Habib, Khalid; Manikar, Ningthoujam; Ansari, Sabbir; Fatma, Tasneem

    2013-02-01

    Cyanobacterial biofertilizers are affected by paddy field pesticides as nontarget organism. Carbaryl is a carbamate pesticide and is commonly used against rice thrip pest in paddy fields. In the present work, cellular changes caused by exposure of the cyanobacterial biofertilizer namely Calothrix brevissima to carbaryl were studied with special reference to fatty acids, electrolyte leakage, sulfur metabolism, and osmolytes. To study the toxic effect of carbaryl, the test cyanobacterium was exposed to varying concentrations of pesticide (0, 10, 20, 30, and 40 mg L(-1)) for biochemical analyses. At 40 mg L(-1) carbaryl, polyunsaturated fatty acids were reduced by 32 % and membrane leakage was increased by 27 % suggesting that free radical-mediated lipid peroxidation took place. The sulfur-containing metabolites namely cysteine, cystine, and methionine were increased by 79, 64, and 52 %, respectively. The enzymatic and nonenzymatic antioxidants namely glutathione S-transferase, glutathione reductase, reduced glutathione, and oxidized glutathione were increased to 56, 71, 72, and 60 %, respectively. Osmolytes that serve as stress enzyme protectors as well as nonenzymatic free radical scavenger were also increased, indicating their protective nature in context with carbaryl-induced stress. The respective increase in mannitol, trehalose, and glycogen were 158, 98, and 159 %. In C. brevissima, carbaryl-induced membrane leakage was counteracted by increasing enzymatic and nonenzymatic parameters that helped in scavenging free radicals.

  13. Climate Change Impact on Evapotranspiration, Heat Stress and Chill Requirements

    NASA Astrophysics Data System (ADS)

    Snyder, R. L.; Marras, S.; Spano, D.

    2013-12-01

    Carbon dioxide concentration scenarios project an increase in CO2 from 372 ppm to between 500 and 950 ppm by the year 2100, and the potential effect on temperature, humidity, and plant responses to environmental factors are complex and concerning. For 2100, mean daily temperature increase projections range from 1.2oC to 6.8oC depending on greenhouse gas emissions. On the bad side, higher temperatures are often associated with increases in evapotranspiration (ET), heat stress, and pest infestations. On the good side, increased temperature is commonly related to less frost damage, faster growth, and higher production in some cases. One misconception is that global warming will increase evapotranspiration and, hence, agricultural water demand. As the oceans and other water bodies warm, evaporation and humidity are likely to increase globally, but higher humidity tends to reduce plant transpiration and hence ET. Higher CO2 concentrations also tend to reduce ET, and, in the end, the increase in ET due to higher temperature is likely to be offset by a decrease in ET due to higher humidity and CO2. With a decrease in daytime evapotranspiration, the canopy temperature is likely to rise relative to the air temperature, and this implies that heat stress could be worse than predicted by increased air temperature. Daily minimum temperatures are generally increasing about twice as fast as maximum temperatures presumably because of the increasing dew point temperatures as more water vapor is added to the atmosphere. This could present a serious problem to meet the chill requirement for fruit and nut crops. Growing seasons, i.e., from the last spring to the first fall frost, are likely to increase, but the crop growth period is likely to shorten due to higher temperature. Thus, spring frost damage is unlikely to change but there should be fewer damaging fall frost events. In this paper, we will present some ideas on the possible impact of climate change on evapotranspiration and

  14. Multi-Phase Fracture-Matrix Interactions Under Stress Changes

    SciTech Connect

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarao; A. Alajmi; Z. Karpyn; N. Mohammed; S. Al-Enezi

    2005-12-07

    The main objectives of this project are to quantify the changes in fracture porosity and multi-phase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (a) developing the direct experimental measurements of fracture aperture and topology and fluid occupancy using high-resolution x-ray micro-tomography, (b) counter-current fluid transport between the matrix and the fracture, (c) studying the effect of confining stress on the distribution of fracture aperture and two-phase flow, and (d) characterization of shear fractures and their impact on multi-phase flow. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. Several fractures have been scanned and the fracture aperture maps have been extracted. The success of the mapping of fracture aperture was followed by measuring the occupancy of the fracture by two immiscible phases, water and decane, and water and kerosene. The distribution of fracture aperture depends on the effective confining stress, on the nature of the rock, and the type and distribution of the asperities that keep the fracture open. Fracture apertures at different confining stresses were obtained by micro-tomography covering a range of about two thousand psig. Initial analysis of the data shows a significant aperture closure with increase in effective confining stress. Visual and detailed descriptions of the process are shown in the report. Both extensional and shear fractures have been considered. A series of water imbibition tests were conducted in which water was injected into a fracture and its migration into the matrix was monitored with CT and DR x-ray techniques. The objective was to understand the impact of the

  15. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES

    SciTech Connect

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarad; H. Yasuhara; A. Alajmi

    2002-04-20

    The main objectives of this project are to quantify the changes in fracture porosity and multi-phase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (1) developing the direct experimental measurements of fracture aperture and topology using high-resolution x-ray micro-tomography, (2) modeling of fracture permeability in the presence of asperities and confining stress, and (3) simulation of two-phase fluid flow in a fracture and a layered matrix. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. The distribution of fracture aperture is a difficult issue that we are studying and developing methods of quantification. The difficulties are both numerical and conceptual. Numerically, the three-dimensional data sets include millions, and sometimes, billions of points, and pose a computational challenge. The conceptual difficulties derive from the rough nature of the fracture surfaces, and the heterogeneous nature of the rock matrix. However, the high-resolution obtained by the imaging system provides us a much needed measuring environment on rock samples that are subjected to simultaneous fluid flow and confining stress. The absolute permeability of a fracture depends on the behavior of the asperities that keep it open. A model is being developed that predicts the permeability and average aperture of a fracture as a function of time under steady flow of water including the pressure solution at the asperity contact points. Several two-phase flow experiments in the presence of a fracture tip were performed in the past. At the present time, we are developing an inverse process using a simulation model to understand the fluid flow patterns in

  16. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES

    SciTech Connect

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarado; H. Yasuhara; A. Alajmi; Z. Karpyn

    2002-10-28

    The main objectives of this project are to quantify the changes in fracture porosity and multiphase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (1) developing the direct experimental measurements of fracture aperture and topology using high-resolution x-ray microtomography, (2) modeling of fracture permeability in the presence of asperities and confining stress, and (3) simulation of two-phase fluid flow in a fracture and a layered matrix. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. The distribution of fracture aperture is a difficult issue that we are studying and developing methods of quantification. The difficulties are both numerical and conceptual. Numerically, the three-dimensional data sets include millions, and sometimes, billions of points, and pose a computational challenge. The conceptual difficulties derive from the rough nature of the fracture surfaces, and the heterogeneous nature of the rock matrix. However, the high-resolution obtained by the imaging system provides us a much needed measuring environment on rock samples that are subjected to simultaneous fluid flow and confining stress. Pilot multi-phase experiments have been performed, proving the ability to detect two phases in certain large fractures. The absolute permeability of a fracture depends on the behavior of the asperities that keep it open. A model is being developed that predicts the permeability and average aperture of a fracture as a function of time under steady flow of water including the pressure solution at the asperity contact points. Several two-phase flow experiments in the presence of a fracture tip were performed in the past. At the

  17. Probing Coulomb stress triggering effects for a Mw > 6.0 earthquake sequence from 1997 to 2014 along the periphery of the Bayan Har block on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Jianjun; Xu, Caijun; Freymueller, Jeffrey T.; Li, Zhenhong

    2017-01-01

    Recently there have occurred the Manyi-Kangding earthquake sequence, including the 1997 Manyi, 2001 Kokoxili, 2008 Yutian, 2008 Wenchuan, 2010 Yushu, 2013 Lushan, 2014 Yutian and 2014 Kangding earthquakes, along the periphery of the Bayan Har block on the northern Tibetan Plateau. We employ the Coulomb failure model to probe the stress triggering effects on this sequence in terms of coseismic, postseismic and interseismic Coulomb stress changes. We examine the Coulomb stress changes from both the Manyi-Kangding sequence and other large earthquakes from 1411 to 2012 around the Bayan Har block and interseismic tectonic stressing. We use a stratified spherical postseismic relaxation model to compute postseismic Coulomb stress changes. We develop an explicit spherical least-squares collocation model to calculate interseismic Coulomb stress changes. Our results indicate that when merely considering triggering effects because of earthquakes from the Manyi-Kangding sequence, the compounded Coulomb stress changes of the coseismic and postseismic Coulomb stress changes are generally insignificant, except for the 2013 Lushan earthquake (0.14 bar). This general insignificance of Coulomb stress changes imparted by the Manyi-Kangding sequence agrees with previous studies, although interseismic Coulomb stress changes always load each hypocenter. On the other hand, when surrounding prior M ≥ 6.0 earthquakes are considered, we found that the compounded Coulomb stress changes become significant, ranging from 0.14 to 10.4 bars according to the constant apparent friction Coulomb failure model with an intermediate coefficient of 0.4. Therefore, all eight earthquakes are well explained by Coulomb stress changes when thoroughly considering large earthquakes around the Bayan Har block. Our findings indicate the importance of considering a broader group of neighboring large earthquakes for Coulomb stress analysis.

  18. Frictional melting experiments investigate coseismic behaviour of pseudotachylyte-bearing faults in the Outer Hebrides Fault Zone, UK.

    NASA Astrophysics Data System (ADS)

    Campbell, L.; De Paola, N.; Nielsen, S. B.; Holdsworth, R.; Lloyd, G. E. E.; Phillips, R. J.; Walcott, R.

    2015-12-01

    Recent experimental studies, performed at seismic slip rates (≥ 1 m/s), suggest that the friction coefficient of seismic faults is significantly lower than at sub-seismic (< 1 mm/s) speeds. Microstructural observations, integrated with theoretical studies, suggest that the weakening of seismic faults could be due to a range of thermally-activated mechanisms (e.g. gel, nanopowder and melt lubrication, thermal pressurization, viscous flow), triggered by frictional heating in the slip zone. The presence of pseudotachylyte within both exhumed fault zones and experimental slip zones in crystalline rocks suggests that lubrication plays a key role in controlling dynamic weakening during rupture propagation. The Outer Hebrides Fault Zone (OHFZ), UK contains abundant pseudotachylyte along faults cutting varying gneissic lithologies. Our field observations suggest that the mineralogy of the protolith determines volume, composition and viscosity of the frictional melt, which then affects the coseismic weakening behaviour of the fault and has important implications for the magnitudes and distribution of stress drops during slip episodes. High velocity friction experiments at 18 MPa axial load, 1.3 ms-1 and up to 10 m slip were run on quartzo-feldspathic, metabasic and mylonitic samples, taken from the OHFZ in an attempt to replicate its coseismic frictional behaviour. These were configured in cores of a single lithology, or in mixed cores with two rock types juxtaposed. All lithologies produce a general trend of frictional evolution, where an initial peak followed by transient weakening precedes a second peak which then decays to a steady state. Metabasic and felsic single-lithology samples both produce sharper frictional peaks, at values of μ = 0.19 and μ= 0.37 respectively, than the broader and smaller (μ= 0.15) peak produced by a mixed basic-felsic sample. In addition, both single-lithology peaks occur within 0.2 m slip, whereas the combined-lithology sample displays a

  19. Responsible corporate change: detecting and managing employee stress.

    PubMed

    McBride, D I; Lovelock, K; Dirks, K N; Welch, D; Shepherd, D

    2015-04-01

    All 120 health and safety inspectors employed by the New Zealand regulatory agency had their jobs disestablished during a restructuring process and were required to undergo an assessment process with tight time frames. To report on psychological morbidity during the transition to change. The Hospital Anxiety and Depression Scale (HADS) questionnaire was emailed to all 120 current inspectors to measure levels of anxiety (HAD-A) and depression (HAD-D). A score of <7 is in the normal range, scores of between 8 and 10 are suggestive of an anxiety (HADS-A) or mood (HADS-D) disorder and a score of >11 is indicative of a clinical disorder. Replies were received from 36% (43) of the inspectors. Of the 40 usable responses, 47% (19) and 55% (22), respectively, had HAD-A and HAD-D scores greater than the case cut-off. Only 28% (11) and 15% (6), respectively, had scores that would be considered normal. The high scores evident in this sample are comparable to those found in patients with serious psychopathology. Change managers should recognize that the onus for primary prevention lies with the organization, in this case designing an assessment process that takes place over a reasonable time frame. They should also realize the requirement for the active monitoring of stress. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Stress Changes the Representational Landscape: Evidence from Word Segmentation

    ERIC Educational Resources Information Center

    Curtin, S.; Mintz, T.H.; Christiansen, M.H.

    2005-01-01

    Over the past couple of decades, research has established that infants are sensitive to the predominant stress pattern of their native language. However, the degree to which the stress pattern shapes infants' language development has yet to be fully determined. Whether stress is merely a cue to help organize the patterns of speech or whether it is…

  1. The use of earthquake rate changes as a stress meter at Kilauea volcano.

    PubMed

    Dieterich, J; Cayol, V; Okubo, P

    2000-11-23

    Stress changes in the Earth's crust are generally estimated from model calculations that use near-surface deformation as an observational constraint. But the widespread correlation of changes of earthquake activity with stress has led to suggestions that stress changes might be calculated from earthquake occurrence rates obtained from seismicity catalogues. Although this possibility has considerable appeal, because seismicity data are routinely collected and have good spatial and temporal resolution, the method has not yet proven successful, owing to the non-linearity of earthquake rate changes with respect to both stress and time. Here, however, we present two methods for inverting earthquake rate data to infer stress changes, using a formulation for the stress- and time-dependence of earthquake rates. Application of these methods at Kilauea volcano, in Hawaii, yields good agreement with independent estimates, indicating that earthquake rates can provide a practical remote-sensing stress meter.

  2. Geodetically inferred coseismic and postseismic slip due to the M 5.4 31 October 2007 Alum Rock earthquake

    USGS Publications Warehouse

    Murray-Moraleda, J. R.; Simpson, R.W.

    2009-01-01

    On 31 October 2007 the M 5.4 Alum Rock earthquake occurred near the junction between the Hayward and Calaveras faults in the San Francisco Bay Area, producing coseismic and postseismic displacements recorded by 10 continuously operating Global Positioning System (GPS) instruments. The cumulative postseismic displacements over the four months following the earthquake are linearly related to the cumulative number of aftershocks and are comparable in magnitude to the coseis mic displacements. The postseismic signal suggests that, in addition to afterslip at seismogenic depths, localized right-lateral/reverse slip occurred on dipping shallow fault surfaces southwest of the Calaveras. The spatial distribution of slip inferred by inverting the GPS data is compatible with a model in which moderate Calaveras fault earthquakes rupture locked patches surrounded by areas of creep, afterslip, and microseismicity (Oppenheimer et al., 1990). If this model and existing Calaveras fault slip rate estimates are correct, a slip deficit remains on the 2007 Alum Rock rupture patch that may be made up by aseismic slip or slip in larger earthquakes. Recent studies (e.g., Manaker et al., 2005) suggest that at depth the Hayward and central Calaveras faults connect via a simple continuous surface illuminated by the Mission Seismic Trend (MST), implying that a damaging earthquake rupture could involve both faults (Graymer et al., 2008). If this geometry is correct, the combined coseismic and postseismic slip we infer for the 2007 Alum Rock event predicts static Coulomb stress increases of ???0:6 bar on the MST surface and on the northern Calaveras fault ???5 km northwest of the Alum Rock hypocenter.

  3. Residual strain change resulting from stress corrosion in Carrara marble

    NASA Astrophysics Data System (ADS)

    Voigtlaender, Anne; Leith, Kerry; Krautblatter, Michael

    2016-04-01

    Residual stresses and strains have been shown to play a fundamental role in determining the elastic behavior of engineering materials, yet the effect of these strains on brittle and elastic behavior of rocks remains unclear. In order to evaluate the impact of stored elastic strains on fracture propagation in rock, we undertook a four-month-long three-point bending test on three large 1100 x 100 x 100 mm Carrara Marble samples. This test induced stable low stress conditions in which strains were concentrated at the tip of a saw cut and pre-cracked notch. A corrosive environment was created at the tip of the notch on two samples (M2 and M4) by dripping calcite saturated water (pH ~ 7.5-8). Sample M5 was loaded in the same way, but kept dry. Samples were unloaded prior to failure, and along with an additional non-loaded reference sample (M0), cored into cylindrical subsamples (ø = 50 mm, h = 100 mm) before being tested for changes in residual elastic strains at the SALSA neutron diffractometer at the Institute Laue-Langevin (ILL), Grenoble, France. Three diffraction peaks corresponding to crystallographic planes hkl (110), (104) and (006) were measured in all three spatial directions relative to the notch. Shifts in the diffraction peak position (d) with respect to a strain free state are indicative of intergranular strain, while changes in the width of the peak (FWHM) reflect changes in intragranular strain. We observe distinctly different patterns in residual and volumetric strains in hkℓ (104) and (006) for the dry M5 and wet tested samples (M2 and M4) indicating the presence of water changes the deformation mechanism, while (110) is strained in compression around 200 μstrain in all samples. A broadening of the diffraction peaks (006) and (110) in front of the crack tip is observed in M2 and M4, while M5 shows no changes in the peak width throughout the depth of the sample. We suggest water present at the crack tip increased the rate of corrosion, allowing a

  4. Coseismic and postseismic motion of a landslide: Observations, modeling, and analogy with tectonic faults

    NASA Astrophysics Data System (ADS)

    Lacroix, P.; Perfettini, H.; Taipe, E.; Guillier, B.

    2014-10-01

    We document the first time series of a landslide reactivation by an earthquake using continuous GPS measurements over the Maca landslide (Peru). Our survey shows a coseismic response of the landslide of about 2 cm, followed by a relaxation period of 5 weeks during which postseismic slip is 3 times greater than the coseismic displacement itself. Our results confirm the coseismic activation of landslides and provide the first observation of a postseismic displacement. These observations are consistent with a mechanical model where slip on the landslide basal interface is governed by rate and state friction, analogous to the mechanics of creeping tectonic faults, opening new perspectives to study the mechanics of landslides and active faults.

  5. Temporal versus spatial variation in leaf reflectance under changing water stress conditions

    NASA Technical Reports Server (NTRS)

    Cohen, Warren B.

    1991-01-01

    Leaf reflectance changes associated with changes in water stress were analyzed in two separate experiments. Results indicate that the variation in reflectance among collections of leaves of a given species all at the same level of water stress is at least as great as the variation in reflectance associated with changes in water stress for a given leaf collection of that species. The implications is that results from leaf reflectance-water stress studies have only limited applicability to the remote sensing of plant canopy water stress.

  6. Temporal versus spatial variation in leaf reflectance under changing water stress conditions

    NASA Technical Reports Server (NTRS)

    Cohen, Warren B.

    1991-01-01

    Leaf reflectance changes associated with changes in water stress were analyzed in two separate experiments. Results indicate that the variation in reflectance among collections of leaves of a given species all at the same level of water stress is at least as great as the variation in reflectance associated with changes in water stress for a given leaf collection of that species. The implications is that results from leaf reflectance-water stress studies have only limited applicability to the remote sensing of plant canopy water stress.

  7. Coseismic and post-seismic deformation fields mapped using satellite radar interferometry and fault slip inversion of the 2015 Mw8.3 Illapel earthquake, Chile

    NASA Astrophysics Data System (ADS)

    Chunyan, Qu; Ronghu, Zuo; XinJian, Shan; Guohong, Zhang; Yingfeng, Zhang; Xiaogang, Song; Yunhua, Liu; Guifang, Zhang

    2017-02-01

    We analyzed Sentinel-1A (S1A)/IW satellite descending data from multiple acquisitions to map coseismic and post-seismic deformation fields and invert the fault slip and afterslip models associated with the seismic moment magnitude (Mw)8.3 earthquake that occurred at Illapel, Chile, on September 16th, 2015. We generated one coseismic and four post-seismic interferograms to analyze temporal and spatial variations in the deformation field after the mainshock; we found that the coseismic deformation field has a semicircular shape and covers a 300-km long and 190-km wide area. The maximum displacement reaches ca. 1.33 m in the LOS subsidence direction, while post-seismic deformation derived from four interferograms with different time intervals is mainly distributed within a long narrow area approximately 65 km wide. Maximum displacement is ca. 8 cm, including two regions of line of sight (LOS) uplift and sinking. Major regions of deformation exhibit opposite directions to the mainshock just after the event, before reverting to consistency. We inverted the coseismic fault slip and afterslip models based on a shallow-dip single fault plane in a homogeneous elastic half space. Our inversion suggests that coseismic slip is mainly concentrated in a shallow region to the northwest of the source, and that rupture length along strike is close to 340 km, with a maximum slip of about 8.16 m to the trench. The estimated moment is 3.126 × 1021 N m (Mw8.27), and the maximum rupture depth is 50 km. Inverted residual slip also shows just one region of slip in the shallow subsurface, which is shifted slightly to the south. In the early stage of deformation, the residual is along the down-dip direction, with a maximum value of ca. 32 cm, before turning into the up-dip direction, with a maximum value of ca. 23 cm. Finally, we present a preliminary analysis of these complex changes in space and time.

  8. Contrasting urban and rural heat stress responses to climate change

    NASA Astrophysics Data System (ADS)

    Fischer, E. M.; Oleson, K. W.; Lawrence, D. M.

    2012-02-01

    Hot temperatures in combination with high humidity cause human discomfort and may increase morbidity and mortality. A global climate model with an embedded urban model is used to explore the urban-rural contrast in the wet-bulb globe temperature, a heat stress index accounting for temperature and humidity. Wet-bulb globe temperatures are calculated at each model time step to resolve the heat stress diurnal cycle. The model simulates substantially higher heat stress in urban areas compared to neighbouring rural areas. Urban humidity deficit only weakly offsets the enhanced heat stress due to the large night-time urban heat island. The urban-rural contrast in heat stress is most pronounced at night and over mid-latitudes and subtropics. During heatwaves, the urban heat stress amplification is particularly pronounced. Heat stress strongly increases with doubled CO2 concentrations over both urban and rural surfaces. The tropics experience the greatest increase in number of high-heat-stress nights, despite a relatively weak ˜2°C warming. Given the lack of a distinct annual cycle and high relative humidity, the modest tropical warming leads to exceedance of the present-day record levels during more than half of the year in tropical regions, where adaptive capacity is often low. While the absolute urban and rural heat stress response to 2 × CO2 is similar, the occurrence of nights with extremely high heat stress increases more in cities than surrounding rural areas.

  9. Changes in posttraumatic stress disorder and depressive symptoms during cognitive processing therapy: evidence for concurrent change.

    PubMed

    Liverant, Gabrielle I; Suvak, Michael K; Pineles, Suzanne L; Resick, Patricia A

    2012-12-01

    Trauma-focused psychotherapies reduce both posttraumatic stress disorder (PTSD) and co-occurring depression. However, little is known about the relationship between changes in PTSD and depression during treatment. This study examined the association between changes in PTSD and depression during the course of cognitive processing therapy (CPT) and its treatment components. Data were drawn from a dismantling trial investigating the comparative efficacy of the components of CPT (Resick, Galovski, et al., 2008). One hundred twenty-six women (mean age = 36.14 years) from the original randomized intent-to-treat sample (N = 150) who attended at least 1 treatment session were included in this study. Participants diagnosed with PTSD were assigned to 1 of 3 treatment conditions: the full CPT protocol (n = 44), the cognitive therapy component of CPT (n = 39), and the written account component of CPT (n = 43). The majority of the sample self-identified as Caucasian (67%; 29% African American and 4% Other). Primary outcome measures included the Posttraumatic Diagnostic Scale and Beck Depression Inventory-II, administered at 8 time points (baseline, weekly throughout 6 weeks of treatment, and posttreatment). Multilevel regression analyses were conducted to examine relationships between PTSD and depression during treatment. Results indicated that changes in PTSD and depression were strongly related. Multilevel mediation analyses revealed that changes in PTSD and depression occurred concurrently, with lagged analyses providing no evidence that changes in symptoms of 1 disorder preceded changes in the other. Results suggest that changes in PTSD and depression occur contemporaneously during CPT.

  10. Prehistoric and Modern Stress Evolution and Seismicity in Central Idaho in Relation to the 1983 Borah Peak Earthquake

    NASA Astrophysics Data System (ADS)

    Chung, B. A.; Puskas, C.; Phillips, D.

    2013-12-01

    The M7.3 1983 Borah Peak earthquake occurred along the Lost River fault and was the largest historic earthquake in Idaho. The Lost River fault is one of several large normal faults in the central Intermountain Seismic Belt. The stress evolution of this family of faults, including the Lost River, Lemhi, Beaverhead, and Sawtooth, is analyzed by computing Coulomb stress changes from paleoearthquakes and interseismic loading. The event can be understood with respect to prehistoric stress interactions between the brittle and creeping segments of the central Idaho fault system. Paleoseismic dates, offsets, and slip rates are acquired from published scarp and trench analyses. Coulomb stress change models are based on coseismic earthquake offsets in the upper seismogenic crust and on cumulative slip from fault creep in the lower crust. Models of Coulomb stress change are based on known current fault geometry and inferred geometry from the Borah Peak event. The time-lapse models commence at 9.5 ka. Mean dates and slip rates are used in a preliminary model in light of large age ranges on the order of thousands of years. Coulomb stresses from creeping segments are modeled as slipping fault planes from the brittle-ductile boundary down to the crust-mantle boundary. The Borah Peak earthquake and most paleoearthquakes occurred in regions of increased Coulomb stress of up to 5 bars. These stress changes are dominantly dictated by single-segment coseismic displacements rather than interseismic loading in this preliminary model. Coseismic stress drops on a segment are about 5 bars, while interseismic loading contributes to approximately 2-bar Coulomb stress increases in the overriding brittle lithosphere of the same segment. Coulomb stress increases from adjacent segment earthquakes are approximately 4 bars. Both the isolated Borah Peak model and the total stress model are consistent with the distribution of post-Borah Peak earthquakes north of the Lost River fault. Additional

  11. Time-dependent changes in altruistic punishment following stress.

    PubMed

    Vinkers, Christiaan H; Zorn, Jelle V; Cornelisse, Sandra; Koot, Susanne; Houtepen, Lotte C; Olivier, Berend; Verster, Joris C; Kahn, René S; Boks, Marco P M; Kalenscher, Tobias; Joëls, Marian

    2013-09-01

    Decisions are rarely made in social isolation. One phenomenon often observed in social interactions is altruistic punishment, i.e. the punishment of unfair behavior by others at a personal cost. The tendency for altruistic punishment is altered by affective states including those induced by stress exposure. Stress is thought to exert bi-directional effects on behavior: immediately after stress, reflex-like and habitual behavior is promoted while later on more far-sighted, flexible and goal-directed behavior is enhanced. We hypothesized that such time-dependent effects of stress would also be present in the context of altruistic punishment behavior. Healthy male participants (N=80) were exposed to either a grouped stress test or a control condition. Participants were tested in prosocial decision making tasks either directly after stress or 75 min later. Altruistic punishment was assessed using the Ultimatum Game. General altruism was assessed with a one-shot version of the Dictator Game in which an anonymous donation could be offered to a charitable organization. We found that stress caused a bi-directional effect on altruistic punishment, with decreased rejection rates in the late aftermath of stress in response to ambiguous 30% offers. In the Dictator Game, stressed participants were less generous than controls, but no time-dependent effect was observed, indicating that the general reward sensitivity remained unchanged at various time-points after stress. Overall, during the late aftermath after acute stress exposure (i.e. 75 min later), participants acted more consistent with their own material self-interest, and had a lower propensity for altruistic punishment, possibly through upregulation of cognitive self-control mechanisms. Thus, our findings underscore the importance of time as a factor in simple, real-life economic decisions in a stressful social context.

  12. Dynamic changes in saliva after acute mental stress

    PubMed Central

    Naumova, Ella A.; Sandulescu, Tudor; Bochnig, Clemens; Khatib, Philipp Al; Lee, Wing-Kee; Zimmer, Stefan; Arnold, Wolfgang H.

    2014-01-01

    Stress-related variations of fluoride concentration in supernatant saliva and salivary sediment, salivary cortisol, total protein and pH after acute mental stress were assessed. The hypothesis was that stress reactions have no influence on these parameters. Thirty-four male students were distributed into two groups: first received the stress exposure followed by the same protocol two weeks later but without stress exposure, second underwent the protocol without stress exposure followed by the stress exposure two weeks later. The stressor was a public speech followed by tooth brushing. Saliva was collected before, immediately after stress induction and immediately, at 10, 30 and 120 min. after tooth brushing. Cortisol concentrations, total protein, intraoral pH, and fluoride content in saliva were measured. The data were analyzed statistically. Salivary sediment was ca 4.33% by weight of whole unstimulated saliva. Fluoride bioavailability was higher in salivary sediment than in supernatant saliva. The weight and fluoride concentration was not altered during 2 hours after stress exposure. After a public speech, the salivary cortisol concentration significantly increased after 20 minutes compared to the baseline. The salivary protein concentration and pH also increased. Public speaking influences protein concentration and salivary pH but does not alter the fluoride concentration of saliva. PMID:24811301

  13. Feelings, Body Changes and Stress. A Curriculum for Pre-Schoolers on Stress Education.

    ERIC Educational Resources Information Center

    Humphrey, Gloria S.; Trotter, Jennie C.

    The Pre-School Stress Relief Project (PSSRP) is a primary mental health and substance abuse prevention project developed to provide training, consultation and educational resources in stress management. The Project's goal is to enable teachers to instruct high risk pre-schoolers in developing positive coping skills for stress reduction in their…

  14. Feelings, Body Changes and Stress. A Curriculum for Pre-Schoolers on Stress Education.

    ERIC Educational Resources Information Center

    Humphrey, Gloria S.; Trotter, Jennie C.

    The Pre-School Stress Relief Project (PSSRP) is a primary mental health and substance abuse prevention project developed to provide training, consultation and educational resources in stress management. The Project's goal is to enable teachers to instruct high risk pre-schoolers in developing positive coping skills for stress reduction in their…

  15. Stress habituation and alterations in perceived stress predict BMI percentile changes across a school year

    USDA-ARS?s Scientific Manuscript database

    Adolescents experience stressful situations at a high rate during school. Indeed, school is the most common source of stress for teens. This high rate of stress may promote increases in adiposity during a developmental period important for establishing the adult physique. Adiposity gains may be th...

  16. Geodetic Inversion Analysis Method of Coseismic Slip Distribution Using a Three-dimensional Finite Element High-fidelity Model

    NASA Astrophysics Data System (ADS)

    Agata, R.; Ichimura, T.; Hirahara, K.; Hori, T.; Hyodo, M.; Hori, M.

    2013-12-01

    Many studies have focused on geodetic inversion analysis method of coseismic slip distribution with combination of observation data of coseismic crustal deformation on the ground and simplified crustal models such like analytical solution in elastic half-space (Okada, 1985). On the other hand, displacements on the seafloor or near trench axes due to actual earthquakes has been observed by seafloor observatories (e.g. the 2011 Tohoku-oki Earthquake (Tohoku Earthquake) (Sato et. al. 2011) (Kido et. al. 2011)). Also, some studies on tsunamis due to the Tohoku Earthquake indicate that large fault slips near the trench axis may have occurred. Those facts suggest that crustal models considering complex geometry and heterogeneity of the material property near the trench axis should be used for geodetic inversion analysis. Therefore, our group has developed a mesh generation method for finite element models of the Japanese Islands of higher fidelity and a fast crustal deformation analysis method for the models. Degree-of-freedom of the models generated by this method is about 150 million. In this research, the method is extended for inversion analyses of coseismic slip distribution. Since inversion analyses need computation of hundreds of slip response functions due to a unit fault slip assigned for respective divided cells on the fault, parallel computing environment is used. Plural crustal deformation analyses are simultaneously run in a Message Passing Interface (MPI) job. In the job, dynamic load balancing is implemented so that a better parallel efficiency is obtained. Submitting the necessary number of serial job of our previous method is also possible, but the proposed method needs less computation time, places less stress on file systems, and allows simpler job management. A method for considering the fault slip right near the trench axis is also developed. As the displacement distribution of unit fault slip for computing response function, 3rd order B

  17. The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasting

    NASA Astrophysics Data System (ADS)

    Strader, Anne Elizabeth

    I investigate how inclusion of static Coulomb stress changes, caused by tectonic loading and previous seismicity, contributes to the effectiveness and reliability of prospective earthquake forecasts. Several studies have shown that positive static Coulomb stress changes are associated with increased seismicity, relative to stress shadows. However, it is difficult to avoid bias when the learning and testing intervals are chosen retrospectively. I hypothesize that earthquake forecasts based on static Coulomb stress fields may improve upon existing earthquake forecasts based on historical seismicity. Within southern California, I have confirmed the aforementioned relationship between earthquake location and Coulomb stress change, but found no identifiable triggering threshold based on static Coulomb stress history at individual earthquake locations. I have also converted static Coulomb stress changes into spatially-varying earthquake rates by optimizing an index function and calculating probabilities of cells containing at least one earthquake based on Coulomb stress ranges. Inclusion of Coulomb stress effects gives an improvement in earthquake forecasts that is significant with 95% confidence, compared to smoothed seismicity null forecasts. Because of large uncertainties in Coulomb stress calculations near faults (and aftershock distributions), I combine static Coulomb stress and smoothed seismicity into a hybrid earthquake forecast. Evaluating such forecasts against those in which only Coulomb stress or smoothed seismicity determines earthquake rates indicates that Coulomb stress is more effective in the far field, whereas statistical seismology outperforms Coulomb stress near faults. Additionally, I test effects of receiver plane orientation, stress type (normal and shear components), and declustering receiver earthquakes. While static Coulomb stress shows significant potential in a prospective earthquake forecast, simplifying assumptions compromise its

  18. Changes to DNA methylation and homologous recombination frequency in the progeny of stressed plants.

    PubMed

    Migicovsky, Zoë; Kovalchuk, Igor

    2013-02-01

    Plants undergo changes in response to biotic and abiotic stresses that help them adjust and survive. Some of these changes may even be passed on to progeny and eventually lead to adaptive evolution. Transgenerational changes in response to stress include alterations in DNA methylation and changes in homologous recombination frequency (HRF). The progeny of plants that were stressed often show elevated HRF as well as genomic hypermethylation, although specific loci that are beneficial in times of stress may be hypomethylated. One of the possible mechanisms responsible for passing the memory to the progeny involves small interfering RNAs; Dicer-like proteins, DCL2 and DCL3, are in part required for this process. However, while epigenetic modifications are often present in the untreated progeny of stressed plants, they are not usually sustained for multiple unexposed generations. Still, transgenerational inheritance of such changes has already begun to provide evidence for an important role of epigenetics in enhancing stress resistance.

  19. Coseismic deformation due to the 2011 Tohoku-oki earthquake: influence of 3-D elastic structure around Japan

    NASA Astrophysics Data System (ADS)

    Hashima, Akinori; Becker, Thorsten W.; Freed, Andrew M.; Sato, Hiroshi; Okaya, David A.

    2016-09-01

    We investigated the effects of elastic heterogeneity on coseismic deformation associated with the 2011 Tohoku-oki earthquake, Japan, using a 3-D finite element model, incorporating the geometry of regional plate boundaries. Using a forward approach, we computed displacement fields for different elastic models with a given slip distribution. Three main structural models are considered to separate the effects of different kinds of heterogeneity: a homogeneous model, a two-layered model with crust-mantle stratification, and a crust-mantle layered model with a strong subducting slab. We observed two counteracting effects: (1) On large spatial scales, elastic layering with increasing rigidity with depth leads to a decrease in surface displacement. (2) An increase in rigidity from above the slab interface to below causes an increase in surface displacement, because the weaker hanging wall deforms to accommodate coseismic slip. Results for slip inversions associated with the Tohoku-oki earthquake show that slip patterns are modified when comparing homogeneous and heterogeneous models. However, the maximum slip only changes slightly: It increases from 38.5 m in the homogeneous to 39.6 m in the layered case and decreases to 37.3 m when slabs are introduced. Potency, i.e., the product of slip and fault area, changes accordingly. Layering leads to inferred slip distributions that are broader and deeper compared to the homogeneous case, particularly to the south of the overall slip maximum. The introduction of a strong slab leads to a reduction in slip around the slip maximum near the trench. We also find that details of the vertical deformation patterns for heterogeneous models are sensitive to the Poisson's ratio. While elastic heterogeneity does therefore not have a dramatic effect on bulk quantities such as inferred potency, the mechanical response of a layered medium with a slab does lead to a systematically modified slip response, and such effects may bias studies of

  20. Using a microfossil-based approach to constrain megathrust-induced coseismic land displacement in coastal Oregon, USA

    NASA Astrophysics Data System (ADS)

    Hawkes, A. D.; Horton, B. P.

    2007-05-01

    Paleoseismologists infer the amount of coseismic subsidence during plate-boundary earthquakes from stratigraphic changes in microfossils across sharp peat-mud and peat-sand contacts. However, the use of lithostratigraphic-based reconstructions is associated with a number of limitations, and these become particularly significant when examining low amplitude, short period variations that occur during a plate-boundary earthquake. To address this, paleoecologists working in the coastal zone have recently adopted a transfer- function approach to environmental reconstruction. Continuing subduction of the Juan de Fuca plate beneath the North America plate constitutes a major seismic hazard in the Pacific Northwest. The subduction zone interface presently lacks seismicity. The timing of the last great earthquake along the Cascadia subduction zone (1700AD) is now well refined by Japanese records of an orphan tsunami (no causal earthquake was felt in Japan) that was generated from an earthquake off the Pacific Northwest on the evening of January 26th 1700AD. I will apply the transfer function to modern foraminiferal datasets along coastal Oregon to analyze the fossil record and quantitatively determine the amount of vertical land movement associated with the 1700AD earthquake event. To date, we have collected 7 modern transects totaling 132 samples from the intertidal zone to the upland. We have also collected 9 cores recording the 1700AD earthquake. Furthermore, a 4m vibracore was collected and contains between 3 and 5 potential earthquake horizons. The 1700AD earthquake in the vibracore shows a distinct litho- and biostratigraphical change representing an instantaneous episode of subsidence of approximately 1m. However, development and application of the transfer function to such events will provide quantitative constrained estimates of coseismic land movement. Measurements that are more accurate are necessary to help modelers develop simulations that are more realistic in

  1. Epigenetic-Imprinting Changes Caused by Neonatal Fasting Stress Protect From Future Fasting Stress.

    PubMed

    Jiang, Y; Denbow, C; Meiri, N; Denbow, D M

    2016-01-01

    Unfavourable nutritional conditions during the neonatal critical period can cause both acute metabolic disorders and severe metabolic syndromes in later life. These phenomena have been tightly related to the epigenetic modification controlling the balance between satiety and hunger in the hypothalamus. In the present study, we investigated epigenetic modification associated with both the fasting stress effects and the short-term resilience to fasting stress in the hypothalamic paraventricular nucleus (PVN) of chicks. Fasting for 24 h at 3 days of age (D) (i.e. D3) significantly increased global methylation at lysine 27 of histone 3 (H3K27) and its specific histone methyltransferase (HMT) expression level in the PVN. Because global methylation could not fully reveal the changes at specific genes, the regulation of the gene for brain-derived neurotrophic factor (Bdnf), which was recently also found to have an anorexigenic effect, was evaluated as a potential target. Chromatin immunoprecipitation assay analysis revealed that tri- (me3) and di-methylated (me2) H3K27 exhibited an instant (on D4 only) and latent increase (on both D11 and D41), respectively, at the putative promoter of Bdnf after 24 h of fasting on D3. This indicated that fasting could regulate energy-expenditure-related genes via modifying methylation at H3K27, which we suspected might be a protective mechanism for keeping the inner environment homeostatic. To test this hypothesis, a short-term repetitive fasting stress was applied to chickens, which were fasted for 24 h either on D10 only or on both D3 and D10. It was found that pre-existing fasting on D3 could induce a short-term fasting resilience, which rescued the reduction of Bdnf expression from future fasting on D10. We call this phenomenon the ‘molecular memory’, which was mainly conducted by HMTs and H3K27me2/me3 in the PVN. In conclusion, chicks respond to fasting with dynamic methylation at H3K27 in the PVN during the neonatal critical

  2. Proteomic changes in the roots of germinating Phaseolus vulgaris seeds in response to chilling stress and post-stress recovery.

    PubMed

    Badowiec, Anna; Weidner, Stanisław

    2014-03-15

    Plants respond to different environmental cues in a complex way, entailing changes at the cellular and physiological levels. An important step to understand the molecular foundation of stress response in plants is the analysis of stress-responsive proteins. In this work we attempted to investigate and compare changes in the abundance of proteins in the roots of bean (Phaseolus vulgaris L.) germinating under long continuous chilling conditions (10°C, 16 days), exposed to short rapid chilling during germination (10°C, 24h), as well as subjected to recovery from stress (25°C, 24h). The results we obtained indicate that germination under continuous chilling causes alterations in the accumulation of the proteins involved in stress response, energy production, translation, vesicle transport, secondary metabolism and protein degradation. The subsequent recovery influences the accumulation of the proteins implicated in calcium-dependent signal transduction pathways, secondary metabolism and those promoting cell division and expansion. Subjecting the germinating bean seeds to short rapid chilling stress resulted in a transient changes in the relative content of the proteins taking part in energy production, DNA repair, RNA processing and translation. Short stress triggers also the mechanisms of protection against oxidative stress and promotes expression of anti-stress proteins. Subjecting bean seeds to the subsequent recovery influences the abundance of the proteins involved in energy metabolism, protection against stress and production of phytohormones. The exposure to long and short chilling did not result in the alterations of any proteins common to both treatments. The same situation was observed with respect to the recovery after stresses. Bean response to chilling is therefore strongly correlated with the manner and length of exposure to low temperature, which causes divergent proteomic alterations in the roots.

  3. Proteome changes induced by aluminum stress in tomato roots

    USDA-ARS?s Scientific Manuscript database

    Growth inhibition in acid soils due to Al stress affects crop production worldwide. To understand mechanisms in sensitive crops that are affected by Al stress, a proteomic analysis of primary tomato root tissue, grown in Alamended and non-amended liquid cultures, was performed. DIGE-SDS-MALDI-TOF-TO...

  4. A new fault-thermometer based on vitrinite maturation by coseismic frictional heating

    NASA Astrophysics Data System (ADS)

    Kitamura, Manami; Mukoyoshi, Hideki; Hirose, Takehiro

    2014-05-01

    To detect frictional heating effects along faults provides key insight into the dynamics of earthquakes and faulting [e.g., Brodsky et al., 2010]. Evidence of substantial frictional heating along a fault is also a reliable indicator determining whether a fault has slipped at high velocity in the past, which is crucial for assessing earthquake and tsunami hazard. The reflectance (R) measurement of vitrinite, one of the primary components of coals, has been considered a possible thermometer of fault zones, especially in accretionary wedges where vitrinite fragments are common [e.g., Sakaguchi et al., 2011]. Under normal burial conditions, vitrinite reflectance (R) increases by irreversible maturation reaction as temperature is elevated and thus sensitively records the maximum temperature to which the vitrinite is subjected. However, the commonly used kinetic models of vitrinite maturation [e.g., Sweeney and Burnham, 1990] may not yield accurate estimates of the peak temperature in a fault zone resulting from fast frictional heating rates [Kitamura et al., 2012; Fulton and Harris, 2012]. Thus, we performed high-velocity friction experiments aimed at revealing coal maturation by frictional heat generated at slip velocities representative of natural earthquakes up to 1.3 m/s. Our experimental results indicate that coal can mature in typical earthquake rise time (e.g., ~10 seconds) and R increases exponentially with increasing peak temperature [Kitamura et al., 2012]. In addition to these results, we will present the effects of water, atmosphere condition (oxygenic/anoxic), and initial R value and grain size of coal on coal maturation during coseismic faulting, and eventually propose a new fault-thermometer based on coal maturation by rapid frictional heating. Using the correlation between R and temperature rises we estimate the dynamic friction during coseismic faulting in the shallow portions of a megasplay fault in the Nankai trough. The fault zone has a ~20 mm

  5. Predicting change in parenting stress across early childhood: child and maternal factors.

    PubMed

    Williford, Amanda P; Calkins, Susan D; Keane, Susan P

    2007-04-01

    This study examined maternal parenting stress in a sample of 430 boys and girls including those at risk for externalizing behavior problems. Children and their mothers were assessed when the children were ages 2, 4, and 5. Hierarchical linear modeling (HLM) was used to examine stability of parenting stress across early childhood and to examine child and maternal factors predicting parenting stress at age 2 and changes in parenting stress across time. Results indicated that single parenthood, maternal psychopathology, child anger proneness, and child emotion dysregulation predicted 2-year parenting stress. Child externalizing behaviors predicted initial status and changes across time in parenting stress. Stability of parenting stress was dependent upon child externalizing problems, as well as interactions between child externalizing problems and gender, and child externalizing problems and emotion regulation. Results are discussed in the context of mechanisms by which parenting stress may influence the development of child externalizing behaviors.

  6. Co-Seismic Mass Displacement and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2004-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) displacements in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field. The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross. The calculation uses the normal mode summation scheme, applied to over twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Centroid Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies, conspiring to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards approx. 140 deg.E, roughly opposite to the observed polar drift direction. Currently, the Gravity Recovery And Climate Experiment (GRACE) is measuring the time-variable gravity to high degree and order with unprecedented accuracy. Our results show that great earthquakes such as the 1960 Chilean or 1964 Alaskan events cause gravitational field changes that are large enough to be detected by GRACE.

  7. Elastic moduli evolution and accompanying stress changes with increasing crack damage during the cyclic stressing of rocks

    NASA Astrophysics Data System (ADS)

    Faulkner, Dan; Heap, Michael; Meredith, Philip

    2010-05-01

    The elastic moduli of rock present in areas susceptible to crack damage, such as within fault zones or volcanic edifices, can be subject to large modifications. Knowledge of how elastic moduli may vary in such situations is important for both the reliable modelling of volcano deformation and stability, and for linear and non-linear elastic crack models for earthquake rupture. It has previously been shown that changes in elastic moduli can induce changes in the stress field surrounding faults (Faulkner et al., 2006). Here therefore we report both uniaxial experimental measurements of changes in elastic moduli during increasing-amplitude cyclic stressing experiments on a range of different rock types (basalts, sandstones and granite), and the results of modelled stress modifications. The trend in elastic moduli evolution with increasing damage was remarkably similar for each rock type, with the exception of an essentially crack-free intrusive basalt that exhibited negligible changes. In general, Young's modulus decreased by between 11 and 32% and Poisson's ratio increased by between 72 and 600% over the total sequence of loading cycles. Our results also demonstrate that acoustic emission (AE) output during any loading cycle only commenced when new crack damage was generated. This corresponded to the level of stress where AE ceased during the unloading portion of the previous cycle. Using the multi-layer elastic model of Faulkner et al. (2006) we demonstrate that the damage-induced changes in elastic moduli also result in significant decreases in differential stress, increases in mean stress and rotation of the applied greatest principal stress relative to the orientation of the mechanical layering. The similar trend in the evolution of the elastic moduli of all the rocks tested suggests that stress modification in the damage zone of faults might take the same form, regardless of the lithology through which the fault runs. These observations are discussed in terms of

  8. Changes in hypothalamic-pituitary-adrenal stress responsiveness before and after puberty in rats.

    PubMed

    Klein, Zoe A; Romeo, Russell D

    2013-07-01

    This article is part of a Special Issue "Puberty and Adolescence". Many endocrine changes are associated with pubertal and adolescent development. One such change is the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis to physical and/or psychological stressors. Recent human and non-human animal studies have shown that hormonal stress reactivity increases significantly throughout puberty and adolescence. Specifically, exposure to various stressors results in greater adrenocorticotropic hormone (ACTH) and glucocorticoid responses in peripubertal compared to adult animals. This review will focus on how stress reactivity changes throughout puberty and adolescence, as well as potential mechanisms that mediate these changes in stress responsiveness. Though the implications of these pubertal shifts in stress responsiveness are not fully understood, the significant increase in stress-related mental and physical dysfunctions during this stage of development highlights the importance of studying pubertal and adolescent maturation of HPA function and its reactivity to stress.

  9. Change in radiosensitivity of rats during hypokinetic stress

    NASA Technical Reports Server (NTRS)

    Chernov, I. P.

    1980-01-01

    The laws governing stress modification of radiation sickness in relation to hypokinetic stress were investigated. It was found that gamma irradiation (800 rad) of rats on the third day of exposure to hypokinesia increased the radiosensitivity of the animals which was determined by the survival rate and the dynamics of body weight and the weight of some internal organs. The same radiation dose was given on the 20th day of hypokinesia and on the third day of recovery from the 20 day hypokinesia decreased the radiosensitivity of rats. It is concluded that the variations in the radiosensitivity observed may be due to a stress effect of hypokinesia.

  10. Coseismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data

    USGS Publications Warehouse

    Johanson, I.A.; Fielding, E.J.; Rolandone, F.; Burgmann, R.

    2006-01-01

    We invert interferometric synthetic aperture radar (InSAR) data jointly with campaign and continuous global positioning system (GPS) data for slip in the coseismic and postseismic periods of the 2004 Parkfield earthquake. The InSAR dataset consists of eight interferograms from data collected by the Envisat and Radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period. The two datasets complement each other, with the InSAR providing dense sampling of motion in the range direction of the satellite and the GPS providing more sparse, but three-dimensional measurements of ground motion. The model assumes exponential decay of the postseismic slip with a decay time constant of 0.087 years, determined from time series modeling of continuous GPS and creepmeter data. We find a geodetic moment magnitude of M 6.2 for a 1-day coseismic model and Mw 6.1 for the entire postseismic period. The coseismic rupture occurred mainly in two slip asperities; one near the hypocenter and the other 15-20 km north. Postseismic slip occurred on the shallow portions of the fault and near the rupture areas of two M 5.0 aftershocks. A comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the Parkfield earthquake is as little as 25% of the total. This underlines the importance of aseismic slip in the slip budget for the Parkfield segment.

  11. Coseismic slip of the 2010 Mw 8.8 Great Maule, Chile, earthquake quantified by the inversion of GRACE observations

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shum, C. K.; Simons, Frederik J.; Tassara, Andrés; Erkan, Kamil; Jekeli, Christopher; Braun, Alexander; Kuo, Chungyen; Lee, Hyongki; Yuan, Dah-Ning

    2012-06-01

    The 27 February 2010 Mw 8.8 Maule, Chile, earthquake ruptured over 500 km along a mature seismic gap between 34° S and 38° S—the Concepción-Constitución gap, where no large megathrust earthquakes had occurred since the 1835 Mw ˜8.5 event. Notable discrepancies exist in slip distribution and moment magnitude estimated by various models inverted using traditional observations such as teleseismic networks, coastal/river markers, tsunami sensors, Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR). We conduct a spatio-spectral localization analysis, based on Slepian basis functions, of data from Gravity Recovery And Climate Experiment (GRACE) to extract coseismic gravity change signals of the Maule earthquake with improved spatial resolution (350 km half-wavelength). Our results reveal discernible differences in the average slip between the GRACE observation and predictions from various coseismic models. The sensitivity analysis reveals that GRACE observation is sensitive to the size of the fault, but unable to separate depth and slip. Here we assume the depth of the fault is known, and simultaneously invert for the fault-plane area and the average slip using the simulated annealing algorithm. Our GRACE-inverted fault plane length and width are 429±6 km, 146±5 km, respectively. The estimated slip is 8.1±1.2 m, indicating that most of the strain accumulated since 1835 in the Concepción-Constitución gap was released by the 2010 Maule earthquake.

  12. Quantifying Coseismic Normal Fault Rupture at the Seafloor: The 2004 Les Saintes Earthquake Along the Roseau Fault (French Antilles)

    NASA Astrophysics Data System (ADS)

    Olive, J. A. L.; Escartin, J.; Leclerc, F.; Garcia, R.; Gracias, N.; Odemar Science Party, T.

    2016-12-01

    While >70% of Earth's seismicity is submarine, almost all observations of earthquake-related ruptures and surface deformation are restricted to subaerial environments. Such observations are critical for understanding fault behavior and associated hazards (including tsunamis), but are not routinely conducted at the seafloor due to obvious constraints. During the 2013 ODEMAR cruise we used autonomous and remotely operated vehicles to map the Roseau normal Fault (Lesser Antilles), source of the 2004 Mw6.3 earthquake and associated tsunami (<3.5m run-up). These vehicles acquired acoustic (multibeam bathymetry) and optical data (video and electronic images) spanning from regional (>1 km) to outcrop (<1 m) scales. These high-resolution submarine observations, analogous to those routinely conducted subaerially, rely on advanced image and video processing techniques, such as mosaicking and structure-from-motion (SFM). We identify sub-vertical fault slip planes along the Roseau scarp, displaying coseismic deformation structures undoubtedly due to the 2004 event. First, video mosaicking allows us to identify the freshly exposed fault plane at the base of one of these scarps. A maximum vertical coseismic displacement of 0.9 m can be measured from the video-derived terrain models and the texture-mapped imagery, which have better resolution than any available acoustic systems (<10 cm). Second, seafloor photomosaics allow us to identify and map both additional sub-vertical fault scarps, and cracks and fissures at their base, recording hangingwall damage from the same event. These observations provide critical parameters to understand the seismic cycle and long-term seismic behavior of this submarine fault. Our work demonstrates the feasibility of extensive, high-resolution underwater surveys using underwater vehicles and novel imaging techniques, thereby opening new possibilities to study recent seafloor changes associated with tectonic, volcanic, or hydrothermal activity.

  13. Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity

    USGS Publications Warehouse

    Panet, I.; Mikhailov, V.; Diament, M.; Pollitz, F.; King, G.; de Viron, O.; Holschneider, M.; Biancale, R.; Lemoine, J.-M.

    2007-01-01

    The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December (Mw = 9.2) and 2005 March (Mw = 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

  14. The July 12, 1993, Hokkaido-Nansei-Oki, Japan, earthquake: Coseismic slip pattern from strong-motion and teleseismic recordings

    USGS Publications Warehouse

    Mendoza, C.; Fukuyama, E.

    1996-01-01

    We employ a finite fault inversion scheme to infer the distribution of coseismic slip for the July 12, 1993, Hokkaido-Nansei-Oki earthquake using strong ground motions recorded by the Japan Meteorological Agency within 400 km of the epicenter and vertical P waveforms recorded by the Global Digital Seismograph Network at teleseismic distances. The assumed fault geometry is based on the location of the aftershock zone and comprises two fault segments with different orientations: a northern segment striking at N20??E with a 30?? dip to the west and a southern segment with a N20??W strike. For the southern segment we use both westerly and easterly dip directions to test thrust orientations previously proposed for this portion of the fault. The variance reduction is greater using a shallow west dipping segment, suggesting that the direction of dip did not change as the rupture propagated south from the hypocenter. This indicates that the earthquake resulted from the shallow underthrusting of Hokkaido beneath the Sea of Japan. Static vertical movements predicted by the corresponding distribution of fault slip are consistent with the general pattern of surface deformation observed following the earthquake. Fault rupture in the northern segment accounts for about 60% of the total P wave seismic moment of 3.4 ?? 1020 N m and includes a large circular slip zone (4-m peak) near the earthquake hypocenter at depths between 10 and 25 km. Slip in the southern segment is also predominantly shallower than 25 km, but the maximum coseismic displacements (2.0-2.5 m) are observed at a depth of about 5 km. This significant shallow slip in the southern portion of the rupture zone may have been responsible for the large tsunami that devastated the small offshore island of Okushiri. Localized shallow faulting near the island, however, may require a steep westerly dip to reconcile the measured values of ground subsidence.

  15. Modeling forest mortality caused by drought stress: implications for climate change

    Treesearch

    Eric J Gustafson; Brian R. Sturtevant

    2013-01-01

    Climate change is expected to affect forest landscape dynamics in many ways, but it is possible that the most important direct impact of climate change will be drought stress. We combined data from weather stations and forest inventory plots (FIA) across the upper Great Lakes region (USA) to study the relationship between measures of drought stress and mortality for...

  16. Modeling changes in rill erodibility and critical shear stress on native surface roads

    Treesearch

    Randy B. Foltz; Hakjun Rhee; William J. Elliot

    2008-01-01

    This study investigated the effect of cumulative overland flow on rill erodibility and critical shear stress on native surface roads in central Idaho. Rill erodibility decreased exponentially with increasing cumulative overland flow depth; however, critical shear stress did not change. The study demonstrated that road erodibility on the studied road changes over the...

  17. Electroencephalographic changes in albino rats subjected to stress

    NASA Technical Reports Server (NTRS)

    Mercier, J.; Assouline, G.; Fondarai, J.

    1980-01-01

    Twenty one albino Wistar rats were subjected to stress for 7 hours. There was a significant difference in the slopes of regression lines for 7 nonulcerous rats and those for 14 ulcerous rats. Nonulcerous rats subjected to stress showed greater EEG curve synchronization than did ulcerous rats. If curve synchronization can be equated to a relaxed state, it may therefore be possible to explain the protective action of hypnotics, tranquilizers and analgesics on ulcers.

  18. Chronic stress and brain plasticity: mechanisms underlying adaptive and maladaptive changes and implications for stress-related CNS disorders

    PubMed Central

    Radley, Jason; Morilak, David; Viau, Victor; Campeau, Serge

    2015-01-01

    Stress responses entail neuroendocrine, autonomic, and behavioral changes to promote effective coping with real or perceived threats to one’s safety. While these responses are critical for the survival of the individual, adverse effects of repeated exposure to stress are widely known to have deleterious effects on health. Thus, a considerable effort in the search for treatments to stress-related CNS disorders necessitates unraveling the brain mechanisms responsible for adaptation under acute conditions and their perturbations following chronic stress exposure. This paper is based upon a symposium from the 2014 International Behavioral Neuroscience Meeting, summarizing some recent advances in understanding the effects of stress on adaptive and maladaptive responses subserved by limbic forebrain networks. An important theme highlighted in this review is that the same networks mediating neuroendocrine, autonomic, and behavioral processes during adaptive coping also comprise targets of the effects of repeated stress exposure in the development of maladaptive states. Where possible, reference is made to the similarity of neurobiological substrates and effects observed following repeated exposure to stress in laboratory animals and the clinical features of stress-related disorders in humans. PMID:26116544

  19. Climate change and occupational heat stress: methods for assessment

    PubMed Central

    Holmér, Ingvar

    2010-01-01

    Background Presumed effects of global warming on occupational heat stress aggravate conditions in many parts of the world, in particular in developing countries. In order to assess and evaluate conditions, heat stress must be described and measured correctly. Objective Assessment of heat stress using internationally recognized methods. Design Two such methods are wet bulb globe temperature (WBGT; ISO 7243) and predicted heat strain (PHS; ISO 7933). Both methods measure relevant climatic factors and provide recommendations for limit values in terms of time when heat stress becomes imminent. The WBGT as a heat stress index is empirical and widely recognized. It requires, however, special sensors for the climatic factors that can introduce significant measurement errors if prescriptions in ISO 7243 are not followed. The PHS (ISO 7933) is based on climatic factors that can easily be measured with traditional instruments. It evaluates the conditions for heat balance in a more rational way and it applies equally to all combinations of climates. Results Analyzing similar climatic conditions with WBGT and PHS indicates that WBGT provides a more conservative assessment philosophy that allows much shorter working time than predicted with PHS. Conclusions PHS prediction of physiological strain appears to fit better with published data from warm countries. Both methods should be used and validated more extensively worldwide in order to give reliable and accurate information about the actual heat stress. PMID:21139697

  20. Stress-induced immune changes in the oyster Crassostrea gigas.

    PubMed

    Lacoste, Arnaud; Malham, Shelagh K; Gélébart, Florence; Cueff, Anne; Poulet, Serge A

    2002-01-01

    Information concerning the effect of stress on invertebrate immune functions are scarce. The present study investigated the consequences of a 15-min mechanical disturbance on immune parameters in oysters Crassostrea gigas. As indicated by noradrenaline and dopamine measurements, the mechanical disturbance caused a transient state of stress in oysters. The number of circulating hemocytes, the migratory and phagocytic activities and reactive oxygen species production of hemocytes were measured before, during and after application of the stressor. Results show that all immune functions were significantly downregulated during stress and a transient period of immunostimulation was observed 30-240 min after the end of the disturbance. Taken together, these results suggest that stress can exert a profound influence on oyster immune functions and they may explain why stress and the outbreak of disease are often linked in shellfish culture. Furthermore, the present study strongly suggests that checking the stress status of animals may be necessary to avoid biases when studying oyster immune responses in vivo.

  1. Vertical deformation associated with normal fault systems evolved over coseismic, postseismic, and multiseismic periods

    NASA Astrophysics Data System (ADS)

    Thompson, George A.; Parsons, Tom

    2016-03-01

    Vertical deformation of extensional provinces varies significantly and in seemingly contradictory ways. Sparse but robust geodetic, seismic, and geologic observations in the Basin and Range province of the western United States indicate that immediately after an earthquake, vertical change primarily occurs as subsidence of the normal fault hanging wall. A few decades later, a ±100 km wide zone is symmetrically uplifted. The preserved topography of long-term rifting shows bent and tilted footwall flanks rising high above deep basins. We develop finite element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. We replicate observations with a model that has a weak upper mantle overlain by a stronger lower crust and a breakable elastic upper crust. A 60° dipping normal fault cuts through the upper crust and extends through the lower crust to simulate an underlying shear zone. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift under the footwall; the breakable upper crust is a necessary model feature to replicate footwall bending over the observed width (<10 km), which is predicted to take place within 1-2 decades after each large earthquake. Thus the best-preserved topographic signature of rifting is expected to occur early in the postseismic period. The relatively stronger lower crust in our models is necessary to replicate broader postseismic uplift that is observed geodetically in subsequent decades.

  2. Co-Seismic Mass Dislocation and Its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    1999-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results. The calculation uses the normal mode summation scheme, applied to 15,814 major earthquakes that occurred during 1976-1998, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J(sub 2) and J(sub 22) while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards about 140 degree E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  3. Coseismic liquefaction phenomenon analysis by COSMO-SkyMed: 2012 Emilia (Italy) earthquake

    NASA Astrophysics Data System (ADS)

    Chini, Marco; Albano, Matteo; Saroli, Michele; Pulvirenti, Luca; Moro, Marco; Bignami, Christian; Falcucci, Emanuela; Gori, Stefano; Modoni, Giuseppe; Pierdicca, Nazzareno; Stramondo, Salvatore

    2015-07-01

    The liquefaction phenomenon that occurred in the coseismic phase of the May 20, 2012 Emilia (Italy) earthquake (ML 5.9) is investigated. It was induced by the water pressure increase in the buried and confined sand layers. The level-ground liquefaction was the result of a chaotic ground oscillation caused by the earthquake shaking and the observed failures were due to the upward water flow caused by the excess of pore pressures. We exploited the capability of the differential synthetic aperture radar interferometry (DInSAR) technique to detect soil liquefactions and estimate their surface displacements, as well as the high sensitivity to surface changes of complex coherence, SAR backscattering and intensity correlation. To this aim, a set of four COSMO-SkyMed X-band SAR images, covering the period April 1-June 6, 2012, was used. Geological-geotechnical analysis was also performed in order to ascertain if the detected SAR-based surface effects could be due to the compaction induced by liquefaction of deep sandy layers. In this regards, the results obtained from 13 electrical cone penetrometer tests show the presence of a fine to medium sandy layer at depths, ranging between 9 and 13 m, which probably liquefied during the earthquake, inducing vertical displacements between 3 and 16 cm. The quantitative results from geological-geotechnical analysis and the surface punctual effects measured by DInSAR are in good agreement, even if some differences are present, probably ascribable to the local thickness and depth variability of the sandy layer, or to lack of deformation detection due to DInSAR decorrelation. The adopted approach permitted us to define the extent of the areas that underwent liquefaction and to quantify the local subsidence related to these phenomena. The latter achievement provides useful information that must be considered in engineering practices, in terms of expected vertical deformations.

  4. Vertical deformation associated with normal fault systems evolved over coseismic, postseismic, and multiseismic periods

    USGS Publications Warehouse

    Thompson, George A.; Parsons, Thomas E.

    2016-01-01

    Vertical deformation of extensional provinces varies significantly and in seemingly contradictory ways. Sparse but robust geodetic, seismic, and geologic observations in the Basin and Range province of the western United States indicate that immediately after an earthquake, vertical change primarily occurs as subsidence of the normal fault hanging wall. A few decades later, a ±100 km wide zone is symmetrically uplifted. The preserved topography of long-term rifting shows bent and tilted footwall flanks rising high above deep basins. We develop finite element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. We replicate observations with a model that has a weak upper mantle overlain by a stronger lower crust and a breakable elastic upper crust. A 60° dipping normal fault cuts through the upper crust and extends through the lower crust to simulate an underlying shear zone. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift under the footwall; the breakable upper crust is a necessary model feature to replicate footwall bending over the observed width ( < 10 km), which is predicted to take place within 1-2 decades after each large earthquake. Thus the best-preserved topographic signature of rifting is expected to occur early in the postseismic period. The relatively stronger lower crust in our models is necessary to replicate broader postseismic uplift that is observed geodetically in subsequent decades.

  5. Coseismic and Post-seismic landsliding: insights from seismological modeling and landslide map time series.

    NASA Astrophysics Data System (ADS)

    Marc, Odin; Hovius, Niels; Meunier, Patrick; Uchida, Taro; Gorum, Tolga

    2016-04-01

    Earthquakes impart a catastrophic forcing on hillslopes, that often lead to widespread landsliding and can contribute significantly to sedimentary and organic matter fluxes. We present a new expression for the total area and volume of populations of earthquake-induced landslides.This model builds on a set of scaling relationships between key parameters, such as landslide density, ground acceleration, fault size, earthquake source depth and seismic moment, derived from geomorphological and seismological observations. To assess the model we have assembled and normalized a catalogue of landslide inventories for 40 earthquakes. We have found that low landscape steepness systematically leads to over-prediction of the total area and volume of landslides.When this effect is accounted for, the model is able to predict within a factor of 2 the landslide areas and associated volumes for about two thirds of the cases in our databases. This is a significant improvement on a previously published empirical expression based only on earthquake moment. This model is suitable for integration into landscape evolution models, and application to the assessment of secondary hazards and risks associated with earthquakes. However, it only models landslides associated to the strong ground shaking and neglects the intrinsic permanent damage that also occurred on hillslopes and persist for longer period. With time series of landslide maps we have constrained the magnitude of the change in landslide susceptibility in the epicentral areas of 4 intermediate to large earthquakes. We propose likely causes for this transient ground strength perturbations and compare our observations to other observations of transient perturbations in epicentral areas, such as suspended sediment transport increases, seismic velocity reductions and hydrological perturbations. We conclude with some preliminary observations on the coseismic mass wasting and post-seismic landslide enhancement caused by the 2015 Mw.7

  6. Co-Seismic Mass Dislocation and Its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, Benjamin F.

    1999-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the "shaking" that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results. The calculation uses the normal mode summation scheme, applied to 15,814 major earthquakes that occurred during 1976-1998, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J(sub 2) and J(sub 22) while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to "nudge" the Earth rotation pole towards about 140 degree E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  7. Co-Seismic Mass Dislocation and its Effect on Earth's Rotation and Gravity

    NASA Technical Reports Server (NTRS)

    Chao, B. F.; Gross, R. S.

    2002-01-01

    Mantle processes often involve large-scale mass transport, ranging from mantle convection, tectonic motions, glacial isostatic adjustment, to tides, atmospheric and oceanic loadings, volcanism and seismicity. On very short time scale of less than an hour, co-seismic event, apart from the shaking that is the earthquake, leaves behind permanent (step-function-like) dislocations in the crust and mantle. This redistribution of mass changes the Earth's inertia tensor (and hence Earth's rotation in both length-of-day and polar motion), and the gravity field (in terms of spherical harmonic Stokes coefficients). The question is whether these effects are large enough to be of any significance. In this paper we report updated calculation results based on Chao & Gross (1987). The calculation uses the normal mode summation scheme, applied to nearly twenty thousand major earthquakes that occurred during 1976-2002, according to source mechanism solutions given by the Harvard Central Moment Tensor catalog. Compared to the truly large ones earlier in the century, the earthquakes we study are individually all too small to have left any discernible signature in geodetic records of Earth rotation or global gravity field. However, their collective effects continue to exhibit an extremely strong statistical tendencies. For example, earthquakes conspire to decrease J2 and J22 while shortening LOD, resulting in a rounder and more compact Earth. Strong tendency is also seen in the earthquakes trying to nudge the Earth rotation pole towards approximately 140 degrees E, roughly opposite to the observed polar drift direction. The geophysical significance and implications will be further studied.

  8. Investigation of the best coseismic fault model of the 2006 Java tsunami earthquake based on mechanisms of postseismic deformation

    NASA Astrophysics Data System (ADS)

    Gunawan, Endra; Meilano, Irwan; Abidin, Hasanuddin Z.; Hanifa, Nuraini Rahma; Susilo

    2016-03-01

    We investigate three available coseismic fault models of the 2006 M7.8 Java tsunami earthquake, as reported by Fujii and Satake (2006), Bilek and Engdahl (2007), and Yagi and Fukahata (2011), in order to find the best coseismic model based on mechanisms of postseismic deformation associated with viscoelastic relaxation and afterslip. We construct a preliminary rheological model using vertical data, obtaining a final rheological model after we include horizontal and vertical components of afterslip in the further process. Our analysis indicates that the coseismic fault model of Fujii and Satake (2006) provides a better and more realistic result for a rheological model than the others. The best-fit rheological model calculated using the coseismic fault model of Fujii and Satake (2006) comprises a 60 ± 5 km elastic layer thickness with a viscosity of 2.0 ± 1.0 × 1017 Pa s in the asthenosphere. Also, we find that afterslip is dominant over the horizontal displacements, while viscoelastic relaxation is dominant over the vertical displacement. Additionally, in comparison to the coseismic displacement found through GPS data taken at BAKO station, our calculation indicates that Fujii and Satake (2006) modeled coseismic displacements with less GPS data misfit than the other examined models. Finally, we emphasize that our methodology for evaluating the best coseismic fault model can satisfactorily explain the postseismic deformation of the 2006 Java tsunami earthquake.

  9. Coseismic and Afterslip Model Related to 25 April 2015, Mw7.8 Gorkha, Nepal Earthquake and its Potential Future Risk Regions

    NASA Astrophysics Data System (ADS)

    Wang, S.; Xu, C.; Jiang, G.

    2016-12-01

    Evidences from geologic, geophysical and geomorphic prove that 2015 Mw 7.8 Gorkha(Nepal) earthquake happened on the two ramp-flats fault structure of Main Himalayan Thrust(MHT). We approximated this more realistic fault model by a smooth curved fault surface, which was derived by the method of hybrid iterative inversion algorithm(HIIA) with additional constraints from coseismic geodetic data. Then the coseismic slip distribution of 2015 Gorkha earthquake was imaged based on this curved variably triangular sized fault model. The inverted maximum thrust and right-lateral slip components are 6 and 1.5 m, respectively, with the maximum slip magnitude 6.2 m located at a depth of 15 km. The released seismic moment derived from our best slip model is 8.58×1020 Nm, equivalent to a moment magnitude of Mw 7.89. We find two interesting tongue-shape slip areas, the maximum slip is about 1.5 m, along the up-dip of fault plane, which tappers off at the depth of 7 km, the up-dip propagation of ruptures may be impeded by the complicated geometry structures on the MHT interface. Coulomb Failure Stress(CFS), triggered by our optimal slip model, indicating a potential shallower rupture in the future. Considering historical earthquakes distribution and the calculated strain and strain gradient before this earthquake, earthquakes are expected to occur in the northwest areas of the epicenter. The spatio-temporal afterslip model over the first 180 days following the Mw 7.8 main shock was infered from the post-seismic GPS time series. One significant afterslip region can be observed in the downdip of the regions that ruptured by coseismic slip. Another afterslip region arresting our attention, is located around 40 km depth, with about 180 mm slip amplitude, but tappers off at the depth of 50 km. What's more, afterslip mainly occurs within 100 days after the 2015 Gorkha earthquake. Under the assumption of rigidity modulus u = 30 GPa, the released seismic moment by afterslip corresponding

  10. Hypoxia-induced and stress-specific changes in chromatin structure and function.

    PubMed

    Johnson, Amber Buescher; Barton, Michelle Craig

    2007-05-01

    Cellular adaptation to stress relies on specific, regulated responses to evoke changes in gene expression. Stresses such as hypoxia, heat shock, oxidative stress and DNA-damage activate signaling cascades that ultimately lead to either induction or repression of stress-responsive genes. In this review, we concentrate on the mechanisms by which stress-induced signaling promotes alterations in chromatin structure, whether the read-out is activation or repression of transcription. Specific alterations in chromatin are highly regulated and dictated by the type of imposed stress. Our primary focus is on the types of chromatin alterations that occur under hypoxic conditions, which exist within a majority of tumors, and to compare these to changes in chromatin structure that occur in response to a wide variety of cellular stresses.

  11. Hypoxia-induced and stress-specific changes in chromatin structure and function

    PubMed Central

    Johnson, Amber Buescher; Barton, Michelle Craig

    2007-01-01

    Cellular adaptation to stress relies on specific, regulated responses to evoke changes in gene expression. Stresses such as hypoxia, heat shock, oxidative stress and DNA-damage activate signaling cascades that ultimately lead to either induction or repression of stress-responsive genes. In this review, we concentrate on the mechanisms by which stress-induced signaling promotes alterations in chromatin structure, whether the read-out is activation or repression of transcription. Specific alterations in chromatin are highly regulated and dictated by the type of imposed stress. Our primary focus is on the types of chromatin alterations that occur under hypoxic conditions, which exist within a majority of tumors, and to compare these to changes in chromatin structure that occur in response to a wide variety of cellular stresses. PMID:17292925

  12. Static stress change from the 8 October, 2005 M = 7.6 Kashmir earthquake

    USGS Publications Warehouse

    Parsons, T.; Yeats, R.S.; Yagi, Y.; Hussain, A.

    2006-01-01

    We calculated static stress changes from the devastating M = 7.6 earthquake that shook Kashmir on 8 October, 2005. We mapped Coulomb stress change on target fault planes oriented by assuming a regional compressional stress regime with greatest principal stress directed orthogonally to the mainshock strike. We tested calculation sensitivity by varying assumed stress orientations, target-fault friction, and depth. Our results showed no impact on the active Salt Range thrust southwest of the rupture. Active faults north of the Main Boundary thrust near Peshawar fall in a calculated stress-decreased zone, as does the Raikot fault zone to the northeast. We calculated increased stress near the rupture where most aftershocks occurred. The greatest increase to seismic hazard is in the Indus-Kohistan seismic zone near the Indus River northwest of the rupture termination, and southeast of the rupture termination near the Kashmir basin.

  13. Stress-induced traveltime variations at SAFOD revealed by continuous cross-well active source monitoring

    NASA Astrophysics Data System (ADS)

    Yang, C.; Niu, F.; Daley, T. M.; Taira, T.

    2016-12-01

    The time-varying stress/strain field at seismogenic depths is arguable the single most important property controlling the sequencing and nucleation of seismic events. The measurement of stress, however, is notoriously difficult, particularly at seismogenic depths. Seismic imaging, in principle, has the capability to provide this critical depth component. Numerous laboratory studies over the last few decades have shown that the elastic properties of crustal rocks clearly exhibit stress dependence. Such dependence is attributed to the opening/closing of fluid-filled cracks in response to changes in the stress normal to the crack surface. Temporal changes in stress are thus, in principle, measurable through seismic imaging of changes in elastic properties, such as seismic velocity field. We have been conducting continuous cross-well active source experiments utilizing the SAFOD (San Andreas Fault Observatory at Depth) pilot and main holes to develop a seismic stress meter to monitor the subsurface stress field by exploring the velocity-stress sensitivity. In a two-month period in 2005-2006, we found a 0.3% change in the average S-wave velocity, which shows a good correlation with barometric pressure, corresponding to a stress sensitivity of 2.4x10-7Pa-1. We also observed two large excursions in the delay time measurement, corresponding to 0.55% and 0.15% decreases of seismic velocity, that are coincident with two earthquakes that are among those predicted to produce the largest coseismic stress changes. The two excursions started approximately 10 and 2 hours before the events, respectively, suggesting that they may be related to pre-rupture stress induced changes in crack properties, as observed in early laboratory studies. We repeated the experiment in early 2010 with a slightly different experiment configuration, and collected 40-days data. The new data confirmed the negative correlation between traveltime and barometric pressure. The estimated stress sensitivity is

  14. Postseismic gravity change after the 2006–2007 great earthquake doublet and constraints on the asthenosphere structure in the central Kuril Islands

    USGS Publications Warehouse

    Han, Shin-Chan; Sauber, Jeanne; Pollitz, Fred

    2016-01-01

    Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in Gravity Recovery and Climate Experiment (GRACE) but without a discernible coseismic gravity change. The gravity increase of ~4 μGal, observed consistently from various GRACE solutions around the epicentral area during 2007–2015, is interpreted as resulting from gradual seafloor uplift by ~6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25–35 km for the elastic thickness and ~1018 Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault-locking scenarios in the Kuril subduction zone.

  15. Influence of pore pressure and production-induced changes in pore pressure on in situ stress

    SciTech Connect

    Teufel, L.W.

    1996-02-01

    Knowledge of in situ stress and how stress changes with reservoir depletion and pore pressure drawdown is important in a multi-disciplinary approach to reservoir characterization, reservoir management, and improved oil recovery projects. This report summarizes a compilation of in situ stress data from six fields showing the effects of pore pressure and production-induced changes in pore pressure on the minimum horizontal stress. The in situ stress data and corresponding pore pressure data were obtained from field records of the operating companies and published reports. Horizontal stress was determined from closure pressure data of hydraulic fractures and leak-off tests. The stress measurements clearly demonstrate that the total minimum-horizontal stress is dependent on pore pressure. A decrease in pore pressure either by geologic processes or production of a reservoir will result in a decrease in the total minimum-horizontal stress. The magnitude of changes in stress state with net changes in pore pressure is dependent on local field conditions and cannot be accurately predicted by the uniaxial strain model that is commonly used by the petroleum industry.

  16. Change in dynamic young's modulus of nuclear-grade isotropic graphite during tensile and compressive stressing

    NASA Astrophysics Data System (ADS)

    Yoda, S.; Eto, M.; Oku, T.

    1983-12-01

    The effect of mechanical stresses on the dynamic Young's modulus measured by the ultrasonic wave method was examined for an isotropic graphite. Young's modulus of the graphite decreased with increasing applied stress, though the amount of its decrease was different between tensile and compressive stresses. The change in Young's modulus under mechanical stresses clearly corresponded to the stress-strain behavior of the graphite. Change in pore volume caused by mechanical stressing plays an important role in the decrease in Young's modulus under tension and compression. The change in Young's modulus was well represented by the formula E/E 0 = exp(- Aɛ + B) within a limited strain. A and B in the equation appeared to differ between tension and compression. The strain above which the formula showed deviation would be associated with the formation of cracks as observed in previous work.

  17. Sensitivity of stress inversion of focal mechanisms to pore pressure changes

    NASA Astrophysics Data System (ADS)

    Martínez-Garzón, Patricia; Vavryčuk, Václav; Kwiatek, Grzegorz; Bohnhoff, Marco

    2016-08-01

    We investigate the sensitivity of stress inversion from focal mechanisms to pore pressure changes. Synthetic tests reveal that pore pressure variations can cause apparent changes in the retrieved stress ratio R relating the magnitude of the intermediate principal stress with respect to the maximum and minimum principal stresses. Pore pressure and retrieved R are negatively correlated when R is low (R < 0.6). The spurious variations in retrieved R are suppressed when R > 0.6. This observation is independent of faulting style, and it may be related to different performance of the fault plane selection criterion and variability in orientation of activated faults under different pore pressures. Our findings from synthetic data are supported by results obtained from induced seismicity at The Geysers geothermal field. Therefore, the retrieved stress ratio variations can be utilized for monitoring pore pressure changes at seismogenic depth in stress domains with overall low R.

  18. Intraindividual change and variability in daily stress processes: Findings from two measurement-burst diary studies

    PubMed Central

    Sliwinski, Martin J.; Almeida, David M.; Smyth, Joshua; Stawski, Robert S.

    2010-01-01

    There is little longitudinal information on aging-related changes in emotional responses to negative events. The present manuscript examined intraindividual change and variability in the within-person coupling of daily stress and negative affect (NA) using data from two-measurement burst daily diary studies. Three main findings emerged. First, average reactivity to daily stress increased longitudinally, and this increase was evident across most the adult lifespan. Second, individual differences in emotional reactivity to daily stress exhibited long-term temporal stability, but this stability was greatest in midlife and decreased in old age. And third, reactivity to daily stress varied reliably within-persons (across-time), with individual exhibiting higher levels of reactivity during times when reporting high levels of global subject stress in previous month. Taken together, the present results emphasize the importance of modeling dynamic psychosocial and aging processes that operate across different time scales for understanding age-related changes in daily stress processes. PMID:20025399

  19. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

    PubMed

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-02-19

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

  20. Stress responses sculpt the insect immune system, optimizing defense in an ever-changing world.

    PubMed

    Adamo, Shelley Anne

    2017-01-01

    A whole organism, network approach can help explain the adaptive purpose of stress-induced changes in immune function. In insects, mediators of the stress response (e.g. stress hormones) divert molecular resources away from immune function and towards tissues necessary for fight-or-flight behaviours. For example, molecules such as lipid transport proteins are involved in both the stress and immune responses, leading to a reduction in disease resistance when these proteins are shifted towards being part of the stress response system. Stress responses also alter immune system strategies (i.e. reconfiguration) to compensate for resource losses that occur during fight-or flight events. In addition, stress responses optimize immune function for different physiological conditions. In insects, the stress response induces a pro-inflammatory state that probably enhances early immune responses.

  1. Monitoring eruption activity using temporal stress changes at Mount Ontake volcano

    PubMed Central

    Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

    2016-01-01

    Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards. PMID:26892716

  2. Stressful life transitions and wellbeing: A comparison of the stress buffering hypothesis and the social identity model of identity change.

    PubMed

    Praharso, Nurul F; Tear, Morgan J; Cruwys, Tegan

    2017-01-01

    The relationship between stressful life transitions and wellbeing is well established, however, the protective role of social connectedness has received mixed support. We test two theoretical models, the Stress Buffering Hypothesis and the Social Identity Model of Identity Change, to determine which best explains the relationship between social connectedness, stress, and wellbeing. Study 1 (N=165) was an experiment in which participants considered the impact of moving cities versus receiving a serious health diagnosis. Study 2 (N=79) was a longitudinal study that examined the adjustment of international students to university over the course of their first semester. Both studies found limited evidence for the buffering role of social support as predicted by the Stress Buffering Hypothesis; instead people who experienced a loss of social identities as a result of a stressor had a subsequent decline in wellbeing, consistent with the Social Identity Model of Identity Change. We conclude that stressful life events are best conceptualised as identity transitions. Such events are more likely to be perceived as stressful and compromise wellbeing when they entail identity loss.

  3. Physiological changes induced by chromium stress in plants: an overview.

    PubMed

    Hayat, Shamsul; Khalique, Gulshan; Irfan, Mohammad; Wani, Arif Shafi; Tripathi, Bhumi Nath; Ahmad, Aqil

    2012-07-01

    This article presents an overview of the mechanism of chromium (Cr) stress in plants. Toxic effects of Cr on plant growth and development depend primarily on its valence state. Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Cr-induced oxidative stress involves induction of lipid peroxidation in plants that cause severe damage to cell membranes which includes degradation of photosynthetic pigments causing deterioration in growth. The potential of plants with the adequacy to accumulate or to stabilize Cr compounds for bioremediation of Cr contamination has gained engrossment in recent years.

  4. Implications for stress changes along the Motagua fault and other nearby faults using GPS and seismic constraints on the M=7.3 2009 Swan Islands earthquake

    NASA Astrophysics Data System (ADS)

    Graham, S. E.; Rodriguez, M.; Rogers, R. D.; Strauch, W.; Hernandez, D.; Demets, C.

    2010-12-01

    The May 28, 2009 M=7.3 Swan Islands earthquake off the north coast of Honduras caused significant damage in the northern part of the country, including seven deaths. This event, the largest in the region for several decades, ruptured the offshore continuation of the Motagua-Polochic fault system, whose 1976 earthquake (located several hundred kilometers to the southwest of the 2009 epicenter) caused more than 23,000 deaths in Central America and left homeless 20% of Guatemala’s population. We use elastic half-space modeling of coseismic offsets measured at 39 GPS stations in Honduras, El Salvador, and Guatemala to better understand the slip source of the recent Swan Islands earthquake. Measured offsets range from .32 meters at a campaign site near the Motagua fault in northern Honduras to 4 millimeters at five continuous sites in El Salvador. Coulomb stress calculations based on the estimated distribution of coseismic slip will be presented and compared to earthquake focal mechanisms and aftershock locations determined from a portable seismic network that was installed in northern Honduras after the main shock. Implications of the Swan Islands rupture for the seismically hazardous Motagua-Polochic fault system will be described.

  5. The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasts

    NASA Astrophysics Data System (ADS)

    Strader, A. E.; Jackson, D. D.

    2013-12-01

    In previous studies, we confirmed an association between static Coulomb stress change and earthquake location in southern California, when resolving stress tensors onto uniformly oriented northwest right-lateral strike-slip planes (Deng & Sykes, 1997). Using an optimized index function to convert static Coulomb stress change into normalized seismicity rates, we found that the Coulomb stress-based forecasts were not significantly more effective indicators of future earthquake locations than forecasts based on smoothed seismicity (Hiemer et al., 2011). These results were likely due to Coulomb stress uncertainties, particularly near stress singularities at the ends of fault sections where many earthquakes occurred. We evaluate hybrid Coulomb stress/smoothed seismicity earthquake forecasts against those with earthquake rates derived from only one component, within a southern California study area (32°N-37°N latitude, 122°W-114°W longitude). Using a weighted linear combination of earthquake rates derived from static Coulomb stress change and smoothed seismicity, we mitigate the effects of stress uncertainty through increasing the influence of Coulomb stress on earthquake rates with increasing distance from faults. We also evaluate time-dependent Coulomb stress earthquake forecasts based on rate-and-state friction (Toda & Enescu, 2011 and Dieterich, 1996) against a Poissonian null hypothesis, from the 10/16/1999 Hector Mine earthquake to the 4/4/2010 El Mayor Cucapah earthquake. From numerical integration, we establish a normalized seismicity rate for each day, during the target time interval, from Coulomb stress evolution and the times since all preceding source earthquakes. During each day we assume seismicity follows a Poissonian process, with expected rates defined as the rate-and-state seismicity rates. By pseudo-prospectively testing these spatial and spatiotemporal earthquake forecasts, we ascertain the role of static and quasi-static Coulomb stress change in

  6. Sex-dependent changes in anxiety, memory, and monoamines following one week of stress.

    PubMed

    Bowman, R E; Micik, R; Gautreaux, C; Fernandez, L; Luine, V N

    2009-04-20

    Chronic restraint stress alters performance of rats on cognitive tasks, and anxiety measurements, and these stress-induced behavioral alterations are sexually dimorphic. Following a long stress period (21 days restraint) males show cognitive impairments while females are either not affected or enhanced on the same tasks. The current study examined whether sexually differentiated responses are also induced following shorter restraint stress durations. Male and female Sprague Dawley rats, aged 2.5 months, served as controls or received restraint stress (6 h/day, 7 days) and were tested for anxiety (plus maze), non-spatial memory (object recognition), and spatial memory (object placement). Plus maze performance was altered by sex and stress exposure. Stress impaired male object recognition but did not affect female performance. Stress did not affect male spatial memory; however, control females could not significantly discriminate between the old and new locations, but stress exposure enhanced female performance. Following behavioral testing, monoamines and metabolites were measured in prefrontal cortex (PFC), hippocampus (CA1, CA3), and amygdala. Notably, PFC and CA3 indices for noradrenergic activity (MHPG levels and MHPG/NE ratios) were increased in stress females, but decreased in males, and similar changes were found in CA1 and BLA dopaminergic indices. Thus, these sexually dimorphic neurochemical changes following stress may underlie the behavioral differences. Current results show that short-term restraint elicits sex-dependent behavioral and neural changes different from those previously reported for longer term stresses and suggest that the temporal relationship between the change from adaptive to maladaptive responses to stress is shorter in male than female rats.

  7. Gender, stress in childhood and adulthood, and trajectories of change in body mass.

    PubMed

    Liu, Hui; Umberson, Debra

    2015-08-01

    Despite substantial evidence of the linkage between stress and weight change, previous studies have not considered how stress trajectories that begin in childhood and fluctuate throughout adulthood may work together to have long-term consequences for weight change. Working from a stress and life course perspective, we investigate the linkages between childhood stress, adulthood stress and trajectories of change in body mass (i.e., Body Mass Index, BMI) over time, with attention to possible gender variation in these processes. Data are drawn from a national longitudinal survey of the Americans' Changing Lives (N = 3617). Results from growth curve analyses suggest that both women and men who experienced higher levels of childhood stress also report higher levels of stress in adulthood. At the beginning of the study period, higher levels of adulthood stress are related to greater BMI for women but not men. Moreover, women who experienced higher levels of childhood stress gained weight more rapidly throughout the 15-year study period than did women who experienced less childhood stress, but neither childhood nor adulthood stress significantly modified men's BMI trajectories. These findings add to our understanding of how childhood stress-a more important driver of long-term BMI increase than adult stress-reverberates throughout the life course to foster cumulative disadvantage in body mass, and how such processes differ for men and women. Results highlight the importance of considering sex-specific social contexts of early childhood in order to design effective clinical programs that prevent or treat overweight and obesity later in life.

  8. Inheritance of stress-induced, ATF-2-dependent epigenetic change.

    PubMed

    Seong, Ki-Hyeon; Li, Dong; Shimizu, Hideyuki; Nakamura, Ryoichi; Ishii, Shunsuke

    2011-06-24

    Atf1, the fission yeast homolog of activation transcription factor-2 (ATF-2), contributes to heterochromatin formation. However, the role of ATF-2 in chromatin assembly in higher organisms remains unknown. This study reveals that Drosophila ATF-2 (dATF-2) is required for heterochromatin assembly, whereas the stress-induced phosphorylation of dATF-2, via Mekk1-p38, disrupts heterochromatin. The dATF-2 protein colocalized with HP1, not only on heterochromatin but also at specific loci in euchromatin. Heat shock or osmotic stress induced phosphorylation of dATF-2 and resulted in its release from heterochromatin. This heterochromatic disruption was an epigenetic event that was transmitted to the next generation in a non-Mendelian fashion. When embryos were exposed to heat stress over multiple generations, the defective chromatin state was maintained over multiple successive generations, though it gradually returned to the normal state. The results suggest a mechanism by which the effects of stress are inherited epigenetically via the regulation of a tight chromatin structure.

  9. mRNA stability changes precede changes in steady-state mRNA amounts during hyperosmotic stress.

    PubMed

    Molin, Claes; Jauhiainen, Alexandra; Warringer, Jonas; Nerman, Olle; Sunnerhagen, Per

    2009-04-01

    Under stress, cells need to optimize the activity of a wide range of gene products during the response phases: shock, adaptation, and recovery. This requires coordination of several levels of regulation, including turnover and translation efficiencies of mRNAs. Mitogen-activated protein (MAP) kinase pathways are implicated in many aspects of the environmental stress response, including initiation of transcription, translation efficiency, and mRNA turnover. In this study, we analyze mRNA turnover rates and mRNA steady-state levels at different time points following mild hyperosmotic shock in Saccharomyces cerevisiae cells. The regulation of mRNA stability is transient and affects most genes for which there is a change in transcript level. These changes precede and prepare for the changes in steady-state levels, both regarding the initial increase and the later decline of stress-induced mRNAs. The inverse is true for stress-repressed genes, which become stabilized during hyperosmotic stress in preparation of an increase as the cells recover. The MAP kinase Hog1 affects both steady-state levels and stability of stress-responsive transcripts, whereas the Hog1-activated kinase Rck2 influences steady-state levels without a major effect on stability. Regulation of mRNA stability is a wide-spread, but not universal, effect on stress-responsive transcripts during transient hyperosmotic stress. By destabilizing stress-induced mRNAs when their steady-state levels have reached a maximum, the cell prepares for the subsequent recovery phase when these transcripts are to return to normal levels. Conversely, stabilization of stress-repressed mRNAs permits their rapid accumulation in the recovery phase. Our results show that mRNA turnover is coordinated with transcriptional induction.

  10. A Potential of Borehole Strainmeters for Continuous Monitoring of Stress Change Associated with Earthquakes

    NASA Astrophysics Data System (ADS)

    Soh, Inho; Chang, Chandong

    2016-04-01

    The borehole strainmeter data, which often detect the crustal deformation signals associated with earthquake occurrence, were utilized to investigate earthquake-induced stress changes. Eight strainmeters installed in Anza, southern California, USA recorded sudden deformation signals caused by two earthquakes that occurred in 2010: M7.2 Baja California (BC) earthquake and M5.4 Southern California (SC) earthquake. The strainmeter data we compiled are noise-filtered, from which effects of earth tide, grout curing, and barometric pressure change have been eliminated and are thus deemed to represent tectonic deformation. In an attempt to calculate stress changes from what we observed from the strainmeter data, we derive a simple equation that relates the deformation to the stress change by assuming that the rock around the strainmeters is homogeneous, isotropic, and linear-elastic. The application of the equation to the strainmeter data enable us to observe the variations in the axes and the magnitudes of stress change with time during several hours before and after the earthquakes. Before the earthquakes, the axes of the maximum stress change in compression are predominantly N-S direction, which is subparallel to the compression axes of the two earthquakes' focal mechanism solutions. This may suggest that the strainmeter data captured pre-earthquake stress buildups that triggered the earthquakes. Upon the onset of earthquakes, the stress magnitudes in N-S direction tend to decrease, which may represent earthquake induced stress relief. The stress drops at the strainmeter site are evaluated at an order of 10-2 MPa for the BC earthquake and 10-3 MPa for the SC earthquake. These values of stress drops are two and three order of magnitude lower than those at the respective focal points. We interpret that the difference between the stress drops at the strainmeter site and the focal points may be due to stress dissipation. In order to verify this interpretation, we conduct

  11. Proteome changes induced by aluminium stress in tomato roots.

    PubMed

    Zhou, Suping; Sauvé, Roger; Thannhauser, Theodore W

    2009-01-01

    Growth inhibition in acid soils due to Al stress affects crop production worldwide. To understand mechanisms in sensitive crops that are affected by Al stress, a proteomic analysis of primary tomato root tissue, grown in Al-amended and non-amended liquid cultures, was performed. DIGE-SDS-MALDI-TOF-TOF analysis of these tissues resulted in the identification of 49 proteins that were differentially accumulated. Dehydroascorbate reductase, glutathione reductase, and catalase enzymes associated with antioxidant activities were induced in Al-treated roots. Induced enzyme proteins associated with detoxification were mitochondrial aldehyde dehydrogenase, catechol oxidase, quinone reductase, and lactoylglutathione lyase. The germin-like (oxalate oxidase) proteins, the malate dehydrogenase, wali7 and heavy-metal associated domain-containing proteins were suppressed. VHA-ATP that encodes for the catalytic subunit A of the vacuolar ATP synthase was induced and two ATPase subunit 1 isoforms were suppressed. Several proteins in the active methyl cycle, including SAMS, quercetin 3-O-methyltransferase and AdoHcyase, were induced by Al stress. Other induced proteins were isovaleryl-CoA dehydrogenase and the GDSL-motif lipase hydrolase family protein. NADPH-dependent flavin reductase and beta-hydroxyacyl-ACP dehydratase were suppressed.

  12. Environmental Heat and Salt Stress Induce Transgenerational Phenotypic Changes in Arabidopsis thaliana

    PubMed Central

    Suter, Léonie; Widmer, Alex

    2013-01-01

    Plants that can adapt their phenotype may be more likely to survive changing environmental conditions. Heritable epigenetic variation could provide a way to rapidly adapt to such changes. Here we tested whether environmental stress induces heritable, potentially adaptive phenotypic changes independent of genetic variation over few generations in Arabidopsis thaliana. We grew two accessions (Col-0, Sha-0) of A. thaliana for three generations under salt, heat and control conditions and tested for induced heritable phenotypic changes in the fourth generation (G4) and in reciprocal F1 hybrids generated in generation three. Using these crosses we further tested whether phenotypic changes were maternally or paternally transmitted. In generation five (G5), we assessed whether phenotypic effects persisted over two generations in the absence of stress. We found that exposure to heat stress in previous generations accelerated flowering under G4 control conditions in Sha-0, but heritable effects disappeared in G5 after two generations without stress exposure. Previous exposure to salt stress increased salt tolerance in one of two reciprocal F1 hybrids. Transgenerational effects were maternally and paternally inherited. Lacking genetic variability, maternal and paternal inheritance and reversibility of transgenerational effects together indicate that stress can induce heritable, potentially adaptive phenotypic changes, probably through epigenetic mechanisms. These effects were strongly dependent on plant genotype and may not be a general response to stress in A. thaliana. PMID:23585834

  13. Changes in thermal infrared spectra of plants caused by temperature and water stress

    NASA Astrophysics Data System (ADS)

    Buitrago, Maria F.; Groen, Thomas A.; Hecker, Christoph A.; Skidmore, Andrew K.

    2016-01-01

    Environmental stress causes changes in leaves and the structure of plants. Although physiological adaptations to stress by plants have been explored, the effect of stress on the spectral properties in the thermal part of the electromagnetic spectrum (3-16 μm) has not yet been investigated. In this research two plant species (European beech, Fagus sylvatica and rhododendron, Rhododendron cf. catawbiense) that both grow naturally under temperature limited conditions were selected, representing deciduous and evergreen plants respectively. Besides TIR spectra, Leaf Water Content (LWC) and cuticle thickness were measured as possible variables that can explain the changes in TIR spectra. The results demonstrated that both species, when exposed to either water or temperature stress, showed significant changes in their TIR spectra. The changes in TIR in response to stress were similar within a species, regardless of the stress imposed on them. However, changes in TIR spectra differed between species. For rhododendron emissivity in TIR increased under stress while for beech it decreased. Both species showed depletion of Leaf Water Content (LWC) under stress, ruling LWC out as a main cause for the change in the TIR spectra. Cuticle thickness remained constant for beech, but increased for rhododendron. This suggests that changes in emissivity may be linked to changes in the cuticle thickness and possibly the structure of cuticle. It is known that spectral changes in this region have a close connection with microstructure and biochemistry of leaves. We propose detailed measurements of these changes in the cuticle to analyze the effect of microstructure on TIR spectra.

  14. Stress and Stress-Induced Neuroendocrine Changes Increase the Susceptibility of Juvenile Oysters (Crassostrea gigas) to Vibrio splendidus

    PubMed Central

    Lacoste, Arnaud; Jalabert, Fabienne; Malham, Shelagh K.; Cueff, Anne; Poulet, Serge A.

    2001-01-01

    Oysters are permanently exposed to various microbes, and their defense system is continuously solicited to prevent accumulation of invading and pathogenic organisms. Therefore, impairment of the animal's defense system usually results in mass mortalities in cultured oyster stocks or increased bacterial loads in food products intended for human consumption. In the present study, experiments were conducted to examine the effects of stress on the juvenile oyster's resistance to the oyster pathogen Vibrio splendidus. Oysters (Crassostrea gigas) were challenged with a low dose of a pathogenic V. splendidus strain and subjected to a mechanical stress 3 days later. Both mortality and V. splendidus loads increased in stressed oysters, whereas they remained low in unstressed animals. Injection of noradrenaline or adrenocorticotropic hormone, two key components of the oyster neuroendocrine stress response system, also caused higher mortality and increased accumulation of V. splendidus in challenged oysters. These results suggest that the physiological changes imposed by stress, or stress hormones, influenced host-pathogen interactions in oysters and increased juvenile C. gigas vulnerability to Vibrio splendidus. PMID:11319116

  15. Proteomic changes in female rat hippocampus following exposure to a terrified sound stress.

    PubMed

    Yang, Juan; Hu, Lili; Song, Tusheng; Liu, Yong; Wu, Qiuhua; Zhao, Lingyu; Liu, Liying; Zhao, Xiaoge; Zhang, Dianzeng; Huang, Chen

    2014-06-01

    Stress plays a profound role in the onset of affective disorders, including an elevation in risk factors for depression and anxiety. Women are twice as vulnerable to stress as men because of greater sensitivity to a substance produced during times of anxiety. To better define the abnormal proteins implicated in cognitive deficits and other stress-induced dysfunction, female rats were exposed to terrified sound stress, and two-dimensional electrophoresis (2-DE) and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) were utilized to determine the differential protein expression in the hippocampus in sound-stressed female rats compared with controls. Quantitative differences were found in 44 protein spots which were differentially expressed between the stressed and control groups (fold change of >2; p < 0.01). Eighteen protein spots were downregulated, and 26 protein spots were upregulated in the stressed group. The seven most differentially expressed proteins were identified and validated as follows: dihydropyrimidinase-related protein 2 (DRP-2), creatine kinase B type, dynamin-1 protein, alpha-internexin, glial fibrillary acidic protein beta, gamma-enolase, and peptidyl-prolyl cis-trans isomerase A. Changes in protein levels were detected in the hippocampus of female rats subjected to terrified sound stress. The findings herein may open new opportunities for further investigations on the modulation induced in the hippocampus by stress at the molecular level, especially with respect to females stress.

  16. Changes in ST, QT and RR ECG intervals during acute stress in firefighters: a pilot study.

    PubMed

    Paiva, Joana S; Rodrigues, Susana; Cunha, Joao Paulo Silva

    2016-08-01

    Firefighting is a stressful occupation. The monitoring of psychophysiological measures in those professionals can be a way to prevent and early detect cardiac diseases and other stress-related problems. The current study aimed to assess morphological changes in the ECG signal induced by acute stress. A laboratory protocol was conducted among 6 firefighters, including a laboratory stress-inducer task - the Trier Social Stress Task (TSST) - and a 2-choice reaction time task (CRTT) that was performed before (CRTT1) and after (CRTT2) the stress condition. ECG signals were continuously acquired using the VitalJacket®, a wearable t-shirt that acts as a medical certified ECG monitor. Results showed that ECG morphological features such as QT and ST intervals are able to differentiate stressful from non stressful events in first responders. Group mean Visual Analogue Scale (VAS) for stress assessment significantly increased after the stress task (TSST), relatively to the end of CRTT2 (after TSST: 4.67±1.63; after CRTT2: 3.17±0.75), a change that was accompanied by a significant increase in group mean QT and ST segments corrected for heart rate during TSST. These encouraging results will be followed by larger studies in order to explore those measures and its physiological impact under realistic environments in a higher scalability.

  17. Overcommitment but not effort-reward imbalance relates to stress-induced coagulation changes in teachers.

    PubMed

    von Känel, Roland; Bellingrath, Silja; Kudielka, Brigitte M

    2009-02-01

    Stress-related hypercoagulability might link job stress with atherosclerosis. This paper aims to study whether overcommitment, effort-reward imbalance, and the overcommitment by effort-reward imbalance interaction relate to an exaggerated procoagulant stress response. We assessed job stress in 52 healthy teachers (49 +/- 8 years, 63% women) at study entry and, after a mean follow-up of 21 +/- 4 months, when they underwent an acute psychosocial stressor and had coagulation measures determined in plasma. In order to increase the reliability of job stress measures, entry and follow-up scores of overcommitment and of effort-reward imbalance were added up to total scores. During recovery from stress, elevated overcommitment correlated with D-dimer increase and with smaller fibrinogen decrease. In contrast, overcommitment was not associated with coagulation changes from pre-stress to immediately post-stress. Effort-reward imbalance and the interaction between overcommitment and effort-reward imbalance did not correlate with stress-induced changes in coagulation measures. Overcommitment predicted acute stress-induced hypercoagulability, particularly during the recovery period.

  18. The determination of interseismic, coseismic and postseismic deformations caused by the Gökçeada-Samothraki earthquake (2014, Mw: 6.9) based on GNSS data

    NASA Astrophysics Data System (ADS)

    Tiryakioglu, Ibrahim; Yigit, Cemal Ozer; Yavasoglu, Hakan; Saka, Mehmet Halis; Alkan, Reha Metin

    2017-09-01

    Since the 1990s, seismic deformations have been commonly determined using the Global Navigation Satellite System (GNSS). Recently, the GNSS systems have become even more powerful with the use of new technologies in innovative studies. In this study, the GNSS data was used to investigate interseismic, coseismic and postseismic deformation and velocity of the Gökçeada-Samothraki earthquake (Mw = 6.9) that occurred on May 24, 2014. The data was obtained at 30 s (0.033 Hz) and 1 s (1 Hz) intervals from the GNSS receivers in the network of Continuously Operating Reference Stations, Turkey (CORS-TR). For the interseismic period, the daily coordinate time series of 12 stations located within 90-250 km of the earthquake epicenter was evaluated for the displacement of stations over a period of approximately 2000 days prior to the day of the earthquakes, from October 1, 2008 to May 23, 2014. In order to analyze the ground motion displacement during the Gökçeada-Samothraki earthquake, 1 Hz data from 8 continuous GNSS stations was processed using precise point positioning (PPP) and relative positioning methods to estimate the epoch-by-epoch positions of the stations. During the earthquake, coseismic displacements of approximately 7 and 30 mm were detected in the NW direction at the YENC and CANA stations, respectively. However, at the IPSA station, a coseismic deformation of 20 mm was observed in the NE direction. There were no significant changes at the other stations during the earthquake. For the postseismic period, the daily coordinate time series of the 12 stations were evaluated for station displacements for 570 days after the day of the earthquakes, from May 24, 2014 to January 1, 2016. The results demonstrated that no significant postseismic deformation with the exception of the EDIR station. An abnormal deformation caused by local factors was determined at the EDIR station. In this study, the PPP and the relative solution were also compared in terms of capturing

  19. Genome wide association of changes in feeding behavior due to heat stress in pigs

    USDA-ARS?s Scientific Manuscript database

    Heat stress negatively impacts pork production, losses include decreased growth, reduced feed intake, and mortality. Therefore, the objective of this study was to identify genetic markers associated with changes in feeding behavior due to heat stress in grow-finish pigs. Data were collected on grow-...

  20. Stress, Life Events, and Socioeconomic Disparities in Health: Results from the Americans' Changing Lives Study

    ERIC Educational Resources Information Center

    Lantz, Paula M.; House, James S.; Mero, Richard P.; Williams, David R.

    2005-01-01

    It has been hypothesized that exposure to stress and negative life events is related to poor health outcomes, and that differential exposure to stress plays a role in socioeconomic disparities in health. Data from three waves of the Americans' Changing Lives study (n = 3,617) were analyzed to investigate prospectively the relationship among…

  1. The effects of climate change associated abiotic stresses on maize phytochemical defenses

    USDA-ARS?s Scientific Manuscript database

    Reliable large-scale maize production is an essential component of global food security; however, sustained efforts are needed to ensure optimized resilience under diverse crop stress conditions. Climate changes are expected to increase the frequency and intensity of both abiotic and biotic stress. ...

  2. Organizational Decision-Making and the Change Agent: The Controlled Use of Stress.

    ERIC Educational Resources Information Center

    Hanson, Mark

    This document asks whether a stress situation created in an organization could be controlled and used to influence the decisionmaking process. The hypothesis tested was that stress induced intentionally by a change agent in a target agency, with consequent generation of strain between the actors of the organizational, would result in the…

  3. GPS coseismic and postseismic surface displacements of the El Mayor-Cucapah earthquake

    NASA Astrophysics Data System (ADS)

    Gonzalez, A.; Gonzalez-Garcia, J. J.; Sandwell, D. T.; Fialko, Y.; Agnew, D. C.; Lipovsky, B.; Fletcher, J. M.; Nava Pichardo, F. A.

    2010-12-01

    GPS surveys were performed after the El Mayor Cucapah earthquake Mw 7.2 in northern Baja California by scientists from CICESE, UCSD, and UCR. Six of the sites were occupied for several weeks to capture the postseismic deformation within a day of the earthquake. We calculated the coseismic displacement for 22 sites with previous secular velocity in ITRF2005 reference frame and found 1.160±0.016 m of maximum horizontal displacement near the epicentral area at La Puerta location, and 0.636±0.036 m of vertical offset near Ejido Durango. Most of the GPS sites are located East of the main rupture in Mexicali Valley, 5 are located West at Sierra Juarez and South near San Felipe. We present a velocity field before, along with coseismic displacements and early postseismic features related to the El Mayor-Cucapah earthquake.

  4. Seafloor observations indicate spatial separation of coseismic and postseismic slips in the 2011 Tohoku earthquake

    PubMed Central

    Iinuma, Takeshi; Hino, Ryota; Uchida, Naoki; Nakamura, Wataru; Kido, Motoyuki; Osada, Yukihito; Miura, Satoshi

    2016-01-01

    Large interplate earthquakes are often followed by postseismic slip that is considered to occur in areas surrounding the coseismic ruptures. Such spatial separation is expected from the difference in frictional and material properties in and around the faults. However, even though the 2011 Tohoku Earthquake ruptured a vast area on the plate interface, the estimation of high-resolution slip is usually difficult because of the lack of seafloor geodetic data. Here using the seafloor and terrestrial geodetic data, we investigated the postseismic slip to examine whether it was spatially separated with the coseismic slip by applying a comprehensive finite-element method model to subtract the viscoelastic components from the observed postseismic displacements. The high-resolution co- and postseismic slip distributions clarified the spatial separation, which also agreed with the activities of interplate and repeating earthquakes. These findings suggest that the conventional frictional property model is valid for the source region of gigantic earthquakes. PMID:27853138

  5. Seafloor observations indicate spatial separation of coseismic and postseismic slips in the 2011 Tohoku earthquake.

    PubMed

    Iinuma, Takeshi; Hino, Ryota; Uchida, Naoki; Nakamura, Wataru; Kido, Motoyuki; Osada, Yukihito; Miura, Satoshi

    2016-11-17

    Large interplate earthquakes are often followed by postseismic slip that is considered to occur in areas surrounding the coseismic ruptures. Such spatial separation is expected from the difference in frictional and material properties in and around the faults. However, even though the 2011 Tohoku Earthquake ruptured a vast area on the plate interface, the estimation of high-resolution slip is usually difficult because of the lack of seafloor geodetic data. Here using the seafloor and terrestrial geodetic data, we investigated the postseismic slip to examine whether it was spatially separated with the coseismic slip by applying a comprehensive finite-element method model to subtract the viscoelastic components from the observed postseismic displacements. The high-resolution co- and postseismic slip distributions clarified the spatial separation, which also agreed with the activities of interplate and repeating earthquakes. These findings suggest that the conventional frictional property model is valid for the source region of gigantic earthquakes.

  6. Coseismic rupturing stopped by Aso volcano during the 2016 Mw 7.1 Kumamoto earthquake, Japan.

    PubMed

    Lin, A; Satsukawa, T; Wang, M; Mohammadi Asl, Z; Fueta, R; Nakajima, F

    2016-11-18

    Field investigations and seismic data show that the 16 April 2016 moment magnitude (Mw) 7.1 Kumamoto earthquake produced a ~40-kilometer-long surface rupture zone along the northeast-southwest-striking Hinagu-Futagawa strike-slip fault zone and newly identified faults on the western side of Aso caldera, Kyushu Island, Japan. The coseismic surface ruptures cut Aso caldera, including two volcanic cones inside it, but terminate therein. The data show that northeastward propagation of coseismic rupturing terminated in Aso caldera because of the presence of magma beneath the Aso volcanic cluster. The seismogenic faults of the 2016 Kumamoto earthquake may require reassessment of the volcanic hazard in the vicinity of Aso volcano.

  7. Seafloor observations indicate spatial separation of coseismic and postseismic slips in the 2011 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Iinuma, Takeshi; Hino, Ryota; Uchida, Naoki; Nakamura, Wataru; Kido, Motoyuki; Osada, Yukihito; Miura, Satoshi

    2016-11-01

    Large interplate earthquakes are often followed by postseismic slip that is considered to occur in areas surrounding the coseismic ruptures. Such spatial separation is expected from the difference in frictional and material properties in and around the faults. However, even though the 2011 Tohoku Earthquake ruptured a vast area on the plate interface, the estimation of high-resolution slip is usually difficult because of the lack of seafloor geodetic data. Here using the seafloor and terrestrial geodetic data, we investigated the postseismic slip to examine whether it was spatially separated with the coseismic slip by applying a comprehensive finite-element method model to subtract the viscoelastic components from the observed postseismic displacements. The high-resolution co- and postseismic slip distributions clarified the spatial separation, which also agreed with the activities of interplate and repeating earthquakes. These findings suggest that the conventional frictional property model is valid for the source region of gigantic earthquakes.

  8. Coseismic rupturing stopped by Aso volcano during the 2016 Mw 7.1 Kumamoto earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Lin, A.; Satsukawa, T.; Wang, M.; Mohammadi Asl, Z.; Fueta, R.; Nakajima, F.

    2016-11-01

    Field investigations and seismic data show that the 16 April 2016 moment magnitude (Mw) 7.1 Kumamoto earthquake produced a ~40-kilometer-long surface rupture zone along the northeast-southwest-striking Hinagu-Futagawa strike-slip fault zone and newly identified faults on the western side of Aso caldera, Kyushu Island, Japan. The coseismic surface ruptures cut Aso caldera, including two volcanic cones inside it, but terminate therein. The data show that northeastward propagation of coseismic rupturing terminated in Aso caldera because of the presence of magma beneath the Aso volcanic cluster. The seismogenic faults of the 2016 Kumamoto earthquake may require reassessment of the volcanic hazard in the vicinity of Aso volcano.

  9. An investigation of coseismic OSL / TL time zeroing of quartz gouge based on low- to high-velocity friction experiments

    NASA Astrophysics Data System (ADS)

    Akasegawa, K.; Oohashi, K.; Hasebe, N.; Miura, K.

    2016-12-01

    To determine an age of coseismic event of an active fault, we generally examine crosscutting relationship between faults and overlying strata by trenching. However, we could not apply this method in case there are no overlying young strata in the vicinity of the fault zones. The alternative is a dating of fault zone materials whose age experienced resetting with seismic fault slip (for example, the ESR method;. Ikeya et al,1982; the OSL and TL methods). The idea behinds to the OSL (optically stimulated luminescence) and TL (thermoluminescence) dating methods for a determination of paleo-earthquake event is the accumulated natural radiation damage becomes to zero (time zeroing) by the frictional heating and grinding. However, physical and geological conditions required to induce time zeroing is not well understood because there is only few experimental investigations under the limited conditions (Hiraga et al,2004;. Kim et al, 2014) . In this study, we conduct low- to high-velocity friction experiments using quartz gouge under various experimental conditions (e.g., normal stress, displacement, moisture content) to establish an empirical relationship and physical and geological conditions of coseismic OSL time zeroing. In this experiment, we carry out the friction experiments using quartz in Tsushigawa granite taken from the east wall of the Nojima fault Ogura trench site, which was excavated in 2015. Samples were taken from the most distant position from the fault in the trench site. The samples were clashed using a mortar and sieved to a grain size of <250 micrometer. After that, we removed feldspar, phyllosilicates, and pyrite by performing magnetic separation and acid treatment. The residual is user for the friction experiments after having known radiation dose using an artificial gamma-ray source. In this presentation, we show results of the friction experiments and dating of the quartz gouge and discuss physical and geological conditions of OSL time zeroing

  10. Climate change hampers endangered species through intensified moisture-related plant stresses (Invited)

    NASA Astrophysics Data System (ADS)

    Bartholomeus, R.; Witte, J.; van Bodegom, P.; Dam, J. V.; Aerts, R.

    2010-12-01

    With recent climate change, extremes in meteorological conditions are forecast and observed to increase globally, and to affect vegetation composition. More prolonged dry periods will alternate with more intensive rainfall events, both within and between years, which will change soil moisture dynamics. In temperate climates, soil moisture, in concert with nutrient availability and soil acidity, is the most important environmental filter in determining local plant species composition, as it determines the availability of both oxygen and water to plant roots. These resources are indispensable for meeting the physiological demands of plants. The consequences of climate change for our natural environment are among the most pressing issues of our time. The international research community is beginning to realise that climate extremes may be more powerful drivers of vegetation change and species extinctions than slow-and-steady climatic changes, but the causal mechanisms of such changes are presently unknown. The roles of amplitudes in water availability as drivers of vegetation change have been particularly elusive owing to the lack of integration of the key variables involved. Here we show that the combined effect of increased rainfall variability, temperature and atmospheric CO2-concentration will lead to an increased variability in both wet and dry extremes in stresses faced by plants (oxygen and water stress, respectively). We simulated these plant stresses with a novel, process-based approach, incorporating in detail the interacting processes in the soil-plant-atmosphere interface. In order to quantify oxygen and water stress with causal measures, we focused on interacting meteorological, soil physical, microbial, and plant physiological processes in the soil-plant-atmosphere system. As both the supply and demand of oxygen and water depend strongly on the prevailing meteorological conditions, both oxygen and water stress were calculated dynamically in time to

  11. Coseismic slip model of offshore moderate interplate earthquakes on March 9, 2011 in Tohoku using tsunami waveforms

    NASA Astrophysics Data System (ADS)

    Kubota, Tatsuya; Hino, Ryota; Inazu, Daisuke; Ito, Yoshihiro; Iinuma, Takeshi; Ohta, Yusaku; Suzuki, Syuichi; Suzuki, Kensuke

    2017-01-01

    We estimated the coseismic slip distribution associated with the Mw 7.2 and 6.5 foreshocks of the 2011 Tohoku-Oki earthquake based on analysis of the tsunami waveform records obtained just above their focal areas. The results show that the main rupture areas of each of the foreshocks do not overlap with each other, and show a distribution that is complementary to the postseismic slip area of the first Mw 7.2 foreshock as well as to the epicenters of smaller earthquakes during foreshock activity. After the second largest foreshock, seismicity increased in the area between the rupture area of the second largest foreshock and the mainshock epicenter, suggesting propagation of aseismic slip towards the mainshock epicenter. The calculated stress drop of the second largest foreshock was smaller than the largest one, implying strength reduction during the postseismic period of the largest foreshock. Based on a comparison of coastal tsunami records, it is suggested that the asperity ruptured in the M 7.0 earthquake in 1981 ruptured again during the largest foreshock in 2011, but it expanded to the updip side of the 1981 rupture area and became larger in magnitude, exemplifying the irregularity of earthquake recurrence in the area.

  12. Microstructural and petrophysical characterization of a "structurally oversimplified" fault zone in poorly lithified sands: evidence for a coseismic rupture?

    NASA Astrophysics Data System (ADS)

    Balsamo, Fabrizio; Storti, Fabrizio

    2010-05-01

    We studied an extensional fault zone developed in poorly lithified, quartz-rich high porosity sandy sediments of the seismically active Crotone basin (southern Italy). The fault zone cuts across interlayered fine- to coarse-grained sands and consists of a cm-thick, discrete fault core embedded in virtually undeformed wall sediments. Consequently, it can be described as "structurally oversimplified" due to the lack of footwall and hanging wall damage zones. We acquired microstructural, grain size, grain shape, porosity, mineralogical and permeability data to investigate the influence of initial sedimentological characteristics of sands on the final faulted granular products and related hydrologic properties. Faulting evolves by a general grain size and porosity reduction with a combination of intragranular fracturing, spalling, and flaking of grain edges, irrespective of grain mineralogy. The dominance of cataclasis, also confirmed by fractal dimensions >2.6, is generally not expected at a deformation depth <1 km. Coarse-grained sand shows a much higher comminution intensity, grain shape variations and permeability drop than fine-grained sands. This is because coarser aggregates have (i) fewer grain-to-grain contacts for a given area, which results in higher stress concentration at contact points, and (ii) a higher probability of pre-existing intragranular microstructural defects that result in a lower grain strength. The peculiar structural architecture, the dominance of cataclasis over non-destructive particulate flow, and the compositional variations of clay minerals in the fault core, strongly suggest that the studied fault zone developed by a coseismic rupture.

  13. Elastic moduli evolution and accompanying stress changes with increasing crack damage: implications for stress changes around fault zones and volcanoes during deformation

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Faulkner, D. R.; Meredith, P. G.; Vinciguerra, S.

    2010-10-01

    The elastic moduli of rock in areas susceptible to crack damage, such as within fault zones or volcanic edifices, can be subject to large modifications. Knowledge of how elastic moduli may vary in such situations is important for both the reliable modelling of volcano deformation and stability and for linear and non-linear elastic crack models for earthquake rupture. Furthermore, it has previously been shown that changes in elastic moduli can induce changes in the stress field surrounding faults. Here we report both uniaxial experimental measurements of changes in elastic moduli during increasing-amplitude cyclic stressing experiments on a range of different rock types (basalts, sandstones and granite) and the results of modelled stress modifications. The trend in elastic moduli evolution with increasing damage was remarkably similar for each rock type, with the exception of essentially crack-free intrusive basalt that exhibited very minor changes. In general, Young's modulus decreased by between 11 and 32 per cent and Poisson's ratio increased by between 72 and 600 per cent over the total sequence of loading cycles. These changes are attributed to an increasing level of anisotropic crack damage within the samples. Our results also show that acoustic emission (AE) output during any loading cycle only commenced when new crack damage was generated. This corresponded to the level of stress where AE ceased during the unloading portion of the previous cycle. Using the multilayer elastic model of Faulkner et al. we demonstrate that the damage-induced changes in elastic moduli also result in significant decreases in differential stress, increases in mean stress and rotation of the applied greatest principal stress relative to the orientation of the mechanical layering. The similar trend in the evolution of the elastic moduli of all the rocks tested suggests that stress modification in the damage zone of faults might take the same form, regardless of the lithology through

  14. Gravitational gradient changes following the 2004 December 26 Sumatra-Andaman Earthquake inferred from GRACE

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shum, C. K.; Jekeli, Christopher

    2012-12-01

    It has been demonstrated that the Gravity Recovery And Climate Experiment (GRACE) spaceborne gravimetry data are capable of observing coseismic gravity changes resulting from great earthquakes, such as the 2004 December 26 Sumatra-Andaman event (Mw 9.1-9.3). Here, we show for the first time that refined deformation signals from the 2004 December 26 Sumatra-Andaman Earthquake (Mw 9.1-9.3) together with the 2005 March 28 Nias earthquake (Mw 8.6) can be revealed by deriving the full gravitational gradient tensor from GRACE monthly gravitational field. The GRACE-inferred coseismic gravitational gradient changes agree well with coseismic slip model predictions. Since the high-frequency contents in gravitational field variation can be amplified by deriving the gravitational gradients, the GRACE-derived coseismic gravitational gradient changes clearly delineate the fault lines, locate significant slips, and better define the extent of the coseismic deformation.

  15. Gender, Stress in Childhood and Adulthood, and Trajectories of Change in Body Mass

    PubMed Central

    Liu, Hui; Umberson, Debra

    2015-01-01

    Despite substantial evidence of the linkage between stress and weight change, previous studies have not considered how stress trajectories that begin in childhood and fluctuate throughout adulthood may work together to have long-term consequences for weight change. Working from a stress and life course perspective, we investigate the linkages between childhood stress, adulthood stress and trajectories of change in body mass (i.e., Body Mass Index, BMI) over time, with attention to possible gender variation in these processes. Data are drawn from a national longitudinal survey of the Americans’ Changing Lives (N=3,617). Results from growth curve analyses suggest that both women and men who experienced higher levels of childhood stress also report higher levels of stress in adulthood. At the beginning of the study period, higher levels of adulthood stress are related to greater BMI for women but not men. Moreover, women who experienced higher levels of childhood stress gained weight more rapidly throughout the 15-year study period than did women who experienced less childhood stress, but neither childhood nor adulthood stress significantly modified men’s BMI trajectories. These findings add to our understanding of how childhood stress—a more important driver of long-term BMI increase than adult stress—reverberates throughout the life course to foster cumulative disadvantage in body mass, and how such processes differ for men and women. Results highlight the importance of considering sex-specific social contexts of early childhood in order to design effective clinical programs that prevent or treat overweight and obesity later in life. PMID:26151391

  16. On the Derivation of Coseismic Displacement Fields Using Differential Radar Interferometry: The Landers Eartquake

    NASA Technical Reports Server (NTRS)

    Zebker, H.; Rosen, P.

    1994-01-01

    We present a map of the coseismic displacement field resulting from the Landers, CA, June 28, 1992 earthquake derived using data acquired from an orbiting high resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS-1 synthetic aperture radar instrument acquired in April, July, and August 1992 are used to generate a high resolution, wide area map of the displacements.

  17. Neural circuit changes mediating lasting brain and behavioral response to predator stress.

    PubMed

    Adamec, Robert E; Blundell, Jacqueline; Burton, Paul

    2005-01-01

    This paper reviews recent work which points to critical neural circuitry involved in lasting changes in anxiety like behavior following unprotected exposure of rats to cats (predator stress). Predator stress may increase anxiety like behavior in a variety of behavioral tests including: elevated plus maze, light dark box, acoustic startle, and social interaction. Studies of neural transmission in two limbic pathways, combined with path and covariance analysis relating physiology to behavior, suggest long term potentiation like changes in one or both of these pathways in the right hemisphere accounts for stress induced changes in all behaviors changed by predator stress except light dark box and social interaction. Findings will be discussed within the context of what is known about neural substrates activated by predator odor.

  18. A case of rapid rock riverbed incision in a coseismic uplift reach and its implications

    NASA Astrophysics Data System (ADS)

    Huang, Ming-Wan; Pan, Yii-Wen; Liao, Jyh-Jong

    2013-02-01

    During the 1999 Chi-Chi earthquake (Mw = 7.6) in Taiwan, the coseismic displacement induced fault scarps and a pop-up structure in the Taan River. The fault scarps across the river experienced maximum vertical slip of 10 m, which disturbed the dynamic equilibrium of the fluvial system. As a result, rapid incision in the weak bedrock, with a maximum depth of 20 m, was activated within a decade after its armor layer was removed. This case provides an excellent opportunity for closely tracking and recording the progressive evolution of river morphology that is subjected to coseismic uplift. Based on multistaged orthophotographs and digital elevation model (DEM) data, the process of morphology evolution in the uplift reach was divided into four consecutive stages. Plucking is the dominant mechanism of bedrock erosion associated with channel incision and knickpoint migration. The astonishingly high rate of knickpoint retreat (KPR), as rapid as a few hundred meters per year, may be responsible for the rapid incision in the main channel. The reasons for the high rate of KPR are discussed in depth. The total length of the river affected by the coseismic uplift is 5 km: 1 km in the uplift reach and 4 km in the downstream reach. The downstream reach was affected by a reduction in sediment supply and increase in stream power. The KPR cut through the uplift reach within roughly a decade; further significant flooding in the future will mainly cause widening instead of deepening of the channel.

  19. Coseismic deformation and triggered landslides of the 2016 Mw 6.2 Amatrice earthquake in Italy

    NASA Astrophysics Data System (ADS)

    Huang, Mong-Han; Fielding, Eric J.; Liang, Cunren; Milillo, Pietro; Bekaert, David; Dreger, Douglas; Salzer, Jacqueline

    2017-02-01

    The Central Apennines in Italy have had multiple moderate-size but damaging shallow earthquakes. In this study, we optimize the fault geometry and invert for fault slip based on coseismic GPS and interferometric synthetic aperture radar (InSAR) for the 2016 Mw 6.2 Amatrice earthquake in Italy. Our results show that nearly all the fault slip occurred between 3 and 6 km depth but extends 20 km along strike. There was less than 4 cm static surface displacement at the town Amatrice where the most devastating damage occurred. Landslides triggered by earthquake ground shaking are not uncommon, but triggered landslides with submeter movement are challenging to be observed in the field. We find evidence of coseismically triggered deep-seated landslides northwest and northeast of the epicenter where coseismic peak ground acceleration was estimated >0.5 g. By combining ascending and descending InSAR data, we are able to estimate the landslide thickness as at least 100 and 80 m near Monte Vettore and west of Castelluccio, respectively. The landslide near Monte Vettore terminates on the preexisting fault Monte Vettore Fault (MVEF) scarp. Our results imply that the long-term fault slip rate of MVEF estimated based on paleoseismic studies could potentially have errors due to triggered landslides from nearby earthquake events.

  20. An oxidative stress paradox: time for a conceptual change?

    PubMed

    Haas, Joel T; Staels, Bart

    2016-12-01

    Oxidative stress has long been considered a key driving factor of many obesity-related health problems. However, recent work by Merry, Tran et al (Diabetologia DOI 10.1007/s00125-016-4084-3 ) challenges this idea with an interesting study using a hepatocyte-specific Gpx1-knockout (HGKO) mouse. GPX1 is an important detoxification enzyme that converts H2O2 to water. The authors found that high-fat diet-fed HGKO mice were more insulin sensitive than wildtype controls, despite elevated hepatic levels of H2O2 and evidence of increased systemic oxidative stress. When challenged with a non-alcoholic steatohepatitis (NASH)-inducing diet, HGKO mice were also protected, displaying reduced levels of inflammation and fibrosis with similar levels of steatosis compared with controls. These findings call into question the role of reactive oxygen species in NASH pathogenesis and highlight a potential paradox whereby increased H2O2 may be beneficial in some contexts.

  1. Ploidy variation in multinucleate cells changes under stress

    PubMed Central

    Anderson, Cori A.; Roberts, Samantha; Zhang, Huaiying; Kelly, Courtney M.; Kendall, Alexxy; Lee, ChangHwan; Gerstenberger, John; Koenig, Aaron B.; Kabeche, Ruth; Gladfelter, Amy S.

    2015-01-01

    Ploidy variation is found in contexts as diverse as solid tumors, drug resistance in fungal infection, and normal development. Altering chromosome or genome copy number supports adaptation to fluctuating environments but is also associated with fitness defects attributed to protein imbalances. Both aneuploidy and polyploidy can arise from multinucleate states after failed cytokinesis or cell fusion. The consequences of ploidy variation in syncytia are difficult to predict because protein imbalances are theoretically buffered by a common cytoplasm. We examined ploidy in a naturally multinucleate fungus, Ashbya gossypii. Using integrated lac operator arrays, we found that chromosome number varies substantially among nuclei sharing a common cytoplasm. Populations of nuclei range from 1N to >4N, with different polyploidies in the same cell and low levels of aneuploidy. The degree of ploidy variation increases as cells age. In response to cellular stress, polyploid nuclei diminish and haploid nuclei predominate. These data suggest that mixed ploidy is tolerated in these syncytia; however, there may be costs associated with variation as stress homogenizes the genome content of nuclei. Furthermore, the results suggest that sharing of gene products is limited, and thus there is incomplete buffering of ploidy variation despite a common cytosol. PMID:25631818

  2. Hydration Changes upon DNA Folding Studied by Osmotic Stress Experiments

    PubMed Central

    Nakano, Shu-ichi; Yamaguchi, Daisuke; Tateishi-Karimata, Hisae; Miyoshi, Daisuke; Sugimoto, Naoki

    2012-01-01

    The thermal stability of nucleic acid structures is perturbed under the conditions that mimic the intracellular environment, typically rich in inert components and under osmotic stress. We now describe the thermodynamic stability of DNA oligonucleotide structures in the presence of high background concentrations of neutral cosolutes. Small cosolutes destabilize the basepair structures, and the DNA structures consisting of the same nearest-neighbor composition show similar thermodynamic parameters in the presence of various types of cosolutes. The osmotic stress experiments reveal that water binding to flexible loops, unstable mismatches, and an abasic site upon DNA folding are almost negligible, whereas the binding to stable mismatch pairs is significant. The studies using the basepair-mimic nucleosides and the peptide nucleic acid suggest that the sugar-phosphate backbone and the integrity of the basepair conformation make important contributions to the binding of water molecules to the DNA bases and helical grooves. The study of the DNA hydration provides the basis for understanding and predicting nucleic acid structures in nonaqueous solvent systems. PMID:22735531

  3. Inversion of GPS velocity and seismicity data to yield changes in stress in the Japanese Islands

    NASA Astrophysics Data System (ADS)

    Iinuma, Takeshi; Kato, Teruyuki; Hori, Muneo

    2005-02-01

    To estimate stress changes within the crust from observed displacement rates, we have devised a new stress inversion method for a 2-D plate subjected to a planar stress which uses Airy's stress function. The merits of this stress inversion method are that it allows us to estimate the stress field without full knowledge of the elastic properties of the object and it improves precision because it is not necessary to take derivatives of observed quantities. We applied this stress inversion method to the Japanese Islands where the Geographical Survey Institute has been operating a nationwide GPS array called `GEONET'. We make the assumption that the inelastic deformation in the Japanese Islands has no dilatational component. We used velocity data derived from 3 yr of GPS observations. We estimated the change in boundary traction from the seismic parameters of large earthquakes (stress drop, slip direction and recurrence interval). We compared the observed `total' strain and estimated the `elastic' strain. The results suggest that the latter looks larger than the former, indicating that it is feasible to estimate the distribution of rigidity from the stress inversion. Comparison with seismicity data suggests that inland shallow earthquakes occur where rigidity is lower.

  4. Changes of testicular phosphorylated proteins in response to restraint stress in male rats*

    PubMed Central

    Arun, Supatcharee; Burawat, Jaturon; Sukhorum, Wannisa; Sampannang, Apichakan; Uabundit, Nongnut; Iamsaard, Sitthichai

    2016-01-01

    Objective: To investigate male reproductive parameters via changes of potential testicular protein markers in restraint-stress rats. Methods: Male Sprague-Dawley rats were divided into two groups (non-immobilized control and restraint-immobilized/stress groups, n=8 each group). The stress animals were immobilized (12 h/d) by a restraint cage for 7 consecutive days. All reproductive parameters, morphology and histology were observed and compared between groups. In addition, the expression of steroidogenic acute regulatory (StAR) and phosphotyrosine proteins (previously localized in Sertoli and late spermatid cells) in testicular lysate was assayed by immuno-Western blotting. Results: Testosterone level, sperm concentration and sperm head normality of stress rats were significantly decreased while the corticosterone level was increased as compared with the control (P<0.05). Histologically, stress rats showed low sperm mass in epididymal lumen and some atrophy of seminiferous tubules. Although the expression of testicular StAR protein was not significantly different between groups, changed patterns of the 131, 95, and 75 kDa testicular phosphorylated proteins were observed in the stress group compared with the control group. The intensity of a testicular 95-kDa phosphorylated protein was significantly decreased in stress rats. Conclusions: This study has demonstrated the alteration of testicular phosphorylated protein patterns, associated with adverse male reproductive parameters in stress rats. It could be an explanation of some infertility in stress males. PMID:26739523

  5. Ultrastructural and physiological changes induced by different stress conditions on the human parasite Trypanosoma cruzi.

    PubMed

    Pérez-Morales, Deyanira; Hernández, Karla Daniela Rodríguez; Martínez, Ignacio; Agredano-Moreno, Lourdes Teresa; Jiménez-García, Luis Felipe; Espinoza, Bertha

    2017-01-01

    Trypanosoma cruzi is the etiological agent of Chagas disease. The life cycle of this protozoan parasite is digenetic because it alternates its different developmental forms through two hosts, a vector insect and a vertebrate host. As a result, the parasites are exposed to sudden and drastic environmental changes causing cellular stress. The stress response to some types of stress has been studied in T. cruzi, mainly at the molecular level; however, data about ultrastructure and physiological state of the cells in stress conditions are scarce or null. In this work, we analyzed the morphological, ultrastructural, and physiological changes produced on T. cruzi epimastigotes when they were exposed to acid, nutritional, heat, and oxidative stress. Clear morphological changes were observed, but the physiological conditions varied depending on the type of stress. The maintenance of the physiological state was severely affected by heat shock, acidic, nutritional, and oxidative stress. According to the surprising observed growth recovery after damage by stress alterations, different adaptations from the parasite to these harsh conditions were suggested. Particular cellular death pathways are discussed.

  6. Stratigraphic and paleoecologic criteria that distinguish coseismically submerged from gradually submerged tidal wetland deposits, Oregon and Washington

    SciTech Connect

    Nelson, A.R. )

    1993-04-01

    Widespread buried tidal-wetland soils exposed in outcrop in southern Washington and northern Oregon suggest that sudden coastal subsidence accompanied great (M>8) Cascadia subduction zone earthquakes at least twice in the past 2,000 years. But interpretation of the estuarine stratigraphic record along the subduction zone is complicated by the interplay of many coastal-sedimentation and sea-level factors found on passive as well as active continental margins. In this presentation, the author outlines-some simple models of sea-level and land-level change along subduction zone coasts, explain how these types of changes might be recorded in the tidal-wetland stratigraphic record, compare stratigraphies from the active-margin coasts of Oregon and Washington with stratigraphies from similar sites along passive continental margins in North America and Europe, and identify criterion that can help distinguish stratigraphic sequences produced by gradual sea-level change from those that may have been produced by coseismic subsidence. Field stratigraphic data alone are an inadequate basis for mapping the coastal extent of past great earthquakes -- only through detailed paleoecologic and dating analyses can one test proposed models of crustal subsidence and recovery during great earthquakes. Rigorous testing of such models is essential if the coastal paleoseismic record is to be used in forecasting the timing and magnitude of future subduction zone earthquakes in Oregon and Washington.

  7. Co-seismic strike-slip fault displacement determined from push-up structures: the Selsund Fault case, South Iceland

    NASA Astrophysics Data System (ADS)

    Angelier, Jacques; Bergerat, Françoise; Bellou, Magalie; Homberg, Catherine

    2004-04-01

    We analysed push-up structures along the Selsund Fault, a N-S right-lateral strike-slip fault activated during the 1912 earthquake in the South Iceland Seismic Zone. Volume changes and syn-tectonic collapse affected push-ups during the earthquake, followed by post-seismic gravitational sagging. To determine the push-up shortening, and hence the strike-slip fault motion, we define a virtual push-up structure, without volume change and collapse, and we compare it with the present-day configuration. Whereas length comparisons are subject to errors, volumetric analysis allows determination of shortening through evaluation of the thickness of the deformed layer affected by the push-ups. We determine a co-seismic peak displacement of 2.4 m along the rupture trace. This value is consistent with the magnitude 7 of the earthquake, based on empirical relationships. Neglecting volume changes and collapse effects gives underestimated displacement. The new method for analysing push-up structures thus allows better determination of magnitudes of ancient earthquakes along strike-slip faults.

  8. Neural plasticity and stress induced changes in defense in the rat.

    PubMed

    Adamec, R E; Blundell, J; Collins, A

    2001-12-01

    We investigated the effects of predator stress on behavior and amygdala afferent and efferent neural transmission in rats. Pathways studied were: ventral angular bundle input to the basolateral amygdala; central and basolateral amygdala output to the periaqueductal gray (PAG). Predator stress was 'anxiogenic' in elevated plus maze, light/dark box and acoustic startle tests one week after stress. Lasting changes were also observed in neural transmission. Predator stress appeared to potentiate right and depotentiate left hemisphere afferent amygdala transmission. In contrast, predator stress potentiated amygdala efferent transmission to right and left PAG, depending on the amygdala nucleus stimulated. Paired pulse and intensity series analysis suggests that transmission changes may be postsynaptic or presynaptic, depending on the pathway. Path analysis relating brain and behavioral changes suggests that potentiation and depotentiation in both hemispheres participate jointly in effecting some, but not all, of the behavioral changes produced by predator stress. Potentiation in left hemisphere amygdala afferents and efferents predicts anxiolytic-like effects, while potentiation in the right hemisphere amygdala afferents predicts anxiogenic-like effects. Path analysis also supports the view that changes in different neural systems mediate changes in different behaviors. These findings have their parallel in studies in the cat, but there are species differences.

  9. Investigation of an alternative generic model for predicting pharmacokinetic changes during physiological stress.

    PubMed

    Peng, Henry T; Edginton, Andrea N; Cheung, Bob

    2013-10-01

    Physiologically based pharmacokinetic models were developed using MATLAB Simulink® and PK-Sim®. We compared the capability and usefulness of these two models by simulating pharmacokinetic changes of midazolam under exercise and heat stress to verify the usefulness of MATLAB Simulink® as a generic PBPK modeling software. Although both models show good agreement with experimental data obtained under resting condition, their predictions of pharmacokinetics changes are less accurate in the stressful conditions. However, MATLAB Simulink® may be more flexible to include physiologically based processes such as oral absorption and simulate various stress parameters such as stress intensity, duration and timing of drug administration to improve model performance. Further work will be conducted to modify algorithms in our generic model developed using MATLAB Simulink® and to investigate pharmacokinetics under other physiological stress such as trauma. © The Author(s) 2013.

  10. Role of NMDA receptors in the syndrome of behavioral changes produced by predator stress.

    PubMed

    Blundell, Jacqueline; Adamec, Robert; Burton, Paul

    2005-09-15

    Effects on behavioral response to predator stress of competitive block of NMDA receptors with doses of .1, 1.0 and 10 mg/kg of CPP (3-(2-carboxypiperazin4-yl)propyl-l-phosphonic acid) were studied. An affect test battery assessed behavioral response to stress and employed hole board, elevated plus maze, light/dark box, social interaction, social avoidance and response to acoustic startle tests. Doses of 1-10 mg/kg of CPP administered ip 30 min prior to predator stress blocked the effects of predator stress on some but not all behaviors measured 8-9 days later. Predator stress normally reduces open arm exploration and risk assessment in the plus maze, decreases entries into the lighted arm of the light dark box and delays habituation of the acoustic startle response. CPP blocked all of these effects of predator stress. A dose of 10 mg/kg of CPP was required for all behaviors except habituation to startle. Block of effects on habituation to startle occurred at 1 and 10 mg/kg. Behaviors in which effects of predator stress were not blocked by CPP included reduction in unprotected head dips in the elevated plus maze and reduced social interaction. In addition, predator stress was without effect on social avoidance measured with the Haller test. These findings extend previous work showing NMDA receptor dependence of effects of predator stress on behavior in the elevated plus maze and on amplitude of acoustic startle response. Novel findings include NMDA receptor dependence of predator stress effects on light dark box behavior and startle habituation. Taken together, the findings add to a body of evidence showing that a syndrome of behavioral changes follows predator stress. Components of this syndrome of behavioral changes likely depend on changes in separable neural substrates initiated in part by NMDA receptors as well as by other neurochemical means.

  11. Future Changes in Heat Stress over East Asia Resulting from Different Target Temperature Increases

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Min; Min, Seung-Ki

    2017-04-01

    In assessing the impact of global warming, it is very important to understand the change in comprehensive heat stress as a function of several variables, rather than only temperature. Furthermore, in order to assess and implement the target temperature goals of the 2015 Paris Agreement, it is essential to have effective and scientifically valid information to predict and measure regional impact. In this study, the future changes in summer heat stress over East Asia were examined based on the Wet-Bulb Globe Temperature (WBGT) using CMIP5 multimodel simulations (historical and RCP scenario simulations), and differences in heat stress changes were assessed between 1.5-degree and 2-degree warmer worlds. Future boreal summer heat stress of land regions over East Asia, in excess of the 50-year return value, shows a rapid and nonlinear increase from the 2000s, and it is expected that severe heat stress will occur in the overall East Asia region by the 2040s. In particular, extreme heat stress events were found to occur much more frequently than summer mean intensity of heat stress. Comparisons of the increase in heat stress between 1.5-degree and 2-degree warmer worlds indicated a 20% decrease in the area experiencing severe heat stress over East Asia, and relatively large benefits (i.e. less frequent and less severe heat stress) were found in the southeastern China, the Korean Peninsula and Japan compared to other regions. Further, the equilibrium scenarios showed a larger increase in heat stress over East Asia than the transient scenarios, particularly in case of the 1.5-degree warmer world, which was found due to warmer water in the northwestern North Pacific in the equilibrium scenarios.

  12. Contrasting Changes Caused by Drought and Submergence Stresses in Bermudagrass (Cynodon dactylon)

    PubMed Central

    Ye, Tiantian; Shi, Haitao; Wang, Yanping; Chan, Zhulong

    2015-01-01

    In this study, we investigated the mechanisms by which bermudagrass withstands the drought and submergence stresses through physiological, proteomic and metabolomic approaches. The results showed that significant physiological changes were observed after drought treatment, while only slight changes after submergence treatment, including compatible solute contents, ROS levels and antioxidant enzyme activities. Proteomics results showed that 81 proteins regulated by drought or submergence treatment were identified by MALDI-TOF-MS. Among them, 76 proteins were modulated by drought stress with 46 increased abundance and 30 decreased abundance. Forty-five showed abundance changes after submergence treatment with 10 increased and 35 decreased. Pathway enrichment analysis revealed that pathways of amino acid metabolism and mitochondrial electron transport/ATP synthesis were only enriched by drought treatment, while other pathways including photosynthesis, biodegradation of xenobiotics, oxidative pentose phosphate, glycolysis and redox were commonly over-represented after both drought and submergence treatments. Metabolomic analysis indicated that most of the metabolites were up-regulated by drought stress, while 34 of 40 metabolites contents exhibited down-regulation or no significant changes when exposed to submergence stress, including sugars and sugar alcohols. These data indicated that drought stress extensively promoted photosynthesis and redox metabolisms while submergence stress caused declined metabolisms and dormancy in Cynodon dactylon. Taken together, the quiescence strategy with retarded growth might allow bermudagrass to be adaptive to long-term submerged environment, while activation of photosynthesis and redox, and accumulation of compatible solutes and molecular chaperones increased bermudagrass tolerance to drought stress. PMID:26617615

  13. Salt stress induces changes in the proteomic profile of micropropagated sugarcane shoots.

    PubMed

    Passamani, Lucas Z; Barbosa, Roberta R; Reis, Ricardo S; Heringer, Angelo S; Rangel, Patricia L; Santa-Catarina, Claudete; Grativol, Clícia; Veiga, Carlos F M; Souza-Filho, Gonçalo A; Silveira, Vanildo

    2017-01-01

    Salt stress is one of the most common stresses in agricultural regions worldwide. In particular, sugarcane is affected by salt stress conditions, and no sugarcane cultivar presently show high productivity accompanied by a tolerance to salt stress. Proteomic analysis allows elucidation of the important pathways involved in responses to various abiotic stresses at the biochemical and molecular levels. Thus, this study aimed to analyse the proteomic effects of salt stress in micropropagated shoots of two sugarcane cultivars (CB38-22 and RB855536) using a label-free proteomic approach. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD006075. The RB855536 cultivar is more tolerant to salt stress than CB38-22. A quantitative label-free shotgun proteomic analysis identified 1172 non-redundant proteins, and 1160 of these were observed in both cultivars in the presence or absence of NaCl. Compared with CB38-22, the RB855536 cultivar showed a greater abundance of proteins involved in non-enzymatic antioxidant mechanisms, ion transport, and photosynthesis. Some proteins, such as calcium-dependent protein kinase, photosystem I, phospholipase D, and glyceraldehyde-3-phosphate dehydrogenase, were more abundant in the RB855536 cultivar under salt stress. Our results provide new insights into the response of sugarcane to salt stress, and the changes in the abundance of these proteins might be important for the acquisition of ionic and osmotic homeostasis during exposure to salt stress.

  14. Salt stress induces changes in the proteomic profile of micropropagated sugarcane shoots

    PubMed Central

    Reis, Ricardo S.; Heringer, Angelo S.; Rangel, Patricia L.; Santa-Catarina, Claudete; Grativol, Clícia; Veiga, Carlos F. M.; Souza-Filho, Gonçalo A.

    2017-01-01

    Salt stress is one of the most common stresses in agricultural regions worldwide. In particular, sugarcane is affected by salt stress conditions, and no sugarcane cultivar presently show high productivity accompanied by a tolerance to salt stress. Proteomic analysis allows elucidation of the important pathways involved in responses to various abiotic stresses at the biochemical and molecular levels. Thus, this study aimed to analyse the proteomic effects of salt stress in micropropagated shoots of two sugarcane cultivars (CB38-22 and RB855536) using a label-free proteomic approach. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD006075. The RB855536 cultivar is more tolerant to salt stress than CB38-22. A quantitative label-free shotgun proteomic analysis identified 1172 non-redundant proteins, and 1160 of these were observed in both cultivars in the presence or absence of NaCl. Compared with CB38-22, the RB855536 cultivar showed a greater abundance of proteins involved in non-enzymatic antioxidant mechanisms, ion transport, and photosynthesis. Some proteins, such as calcium-dependent protein kinase, photosystem I, phospholipase D, and glyceraldehyde-3-phosphate dehydrogenase, were more abundant in the RB855536 cultivar under salt stress. Our results provide new insights into the response of sugarcane to salt stress, and the changes in the abundance of these proteins might be important for the acquisition of ionic and osmotic homeostasis during exposure to salt stress. PMID:28419154

  15. Sensitivity of Southern Ocean overturning to wind stress changes: Role of surface restoring time scales

    NASA Astrophysics Data System (ADS)

    Zhai, Xiaoming; Munday, David R.

    2014-12-01

    The influence of different surface restoring time scales on the response of the Southern Ocean overturning circulation to wind stress changes is investigated using an idealised channel model. Regardless of the restoring time scales chosen, the eddy-induced meridional overturning circulation (MOC) is found to compensate for changes of the direct wind-driven Eulerian-mean MOC, rendering the residual MOC less sensitive to wind stress changes. However, the extent of this compensation depends strongly on the restoring time scale: residual MOC sensitivity increases with decreasing restoring time scale. Strong surface restoring is shown to limit the ability of the eddy-induced MOC to change in response to wind stress changes and as such suppresses the eddy compensation effect. These model results are consistent with qualitative arguments derived from residual-mean theory and may have important implications for interpreting past and future observations.

  16. Stress-induced DNA methylation changes and their heritability in asexual dandelions.

    PubMed

    Verhoeven, Koen J F; Jansen, Jeroen J; van Dijk, Peter J; Biere, Arjen

    2010-03-01

    *DNA methylation can cause heritable phenotypic modifications in the absence of changes in DNA sequence. Environmental stresses can trigger methylation changes and this may have evolutionary consequences, even in the absence of sequence variation. However, it remains largely unknown to what extent environmentally induced methylation changes are transmitted to offspring, and whether observed methylation variation is truly independent or a downstream consequence of genetic variation between individuals. *Genetically identical apomictic dandelion (Taraxacum officinale) plants were exposed to different ecological stresses, and apomictic offspring were raised in a common unstressed environment. We used methylation-sensitive amplified fragment length polymorphism markers to screen genome-wide methylation alterations triggered by stress treatments and to assess the heritability of induced changes. *Various stresses, most notably chemical induction of herbivore and pathogen defenses, triggered considerable methylation variation throughout the genome. Many modifications were faithfully transmitted to offspring. Stresses caused some epigenetic divergence between treatment and controls, but also increased epigenetic variation among plants within treatments. *These results show the following. First, stress-induced methylation changes are common and are mostly heritable. Second, sequence-independent, autonomous methylation variation is readily generated. This highlights the potential of epigenetic inheritance to play an independent role in evolutionary processes, which is superimposed on the system of genetic inheritance.

  17. Effects of City Expansion on Heat Stress under Climate Change Conditions

    PubMed Central

    Argüeso, Daniel; Evans, Jason P.; Pitman, Andrew J.; Di Luca, Alejandro

    2015-01-01

    We examine the joint contribution of urban expansion and climate change on heat stress over the Sydney region. A Regional Climate Model was used to downscale present (1990–2009) and future (2040–2059) simulations from a Global Climate Model. The effects of urban surfaces on local temperature and vapor pressure were included. The role of urban expansion in modulating the climate change signal at local scales was investigated using a human heat-stress index combining temperature and vapor pressure. Urban expansion and climate change leads to increased risk of heat-stress conditions in the Sydney region, with substantially more frequent adverse conditions in urban areas. Impacts are particularly obvious in extreme values; daytime heat-stress impacts are more noticeable in the higher percentiles than in the mean values and the impact at night is more obvious in the lower percentiles than in the mean. Urban expansion enhances heat-stress increases due to climate change at night, but partly compensates its effects during the day. These differences are due to a stronger contribution from vapor pressure deficit during the day and from temperature increases during the night induced by urban surfaces. Our results highlight the inappropriateness of assessing human comfort determined using temperature changes alone and point to the likelihood that impacts of climate change assessed using models that lack urban surfaces probably underestimate future changes in terms of human comfort. PMID:25668390

  18. Effects of city expansion on heat stress under climate change conditions.

    PubMed

    Argüeso, Daniel; Evans, Jason P; Pitman, Andrew J; Di Luca, Alejandro

    2015-01-01

    We examine the joint contribution of urban expansion and climate change on heat stress over the Sydney region. A Regional Climate Model was used to downscale present (1990-2009) and future (2040-2059) simulations from a Global Climate Model. The effects of urban surfaces on local temperature and vapor pressure were included. The role of urban expansion in modulating the climate change signal at local scales was investigated using a human heat-stress index combining temperature and vapor pressure. Urban expansion and climate change leads to increased risk of heat-stress conditions in the Sydney region, with substantially more frequent adverse conditions in urban areas. Impacts are particularly obvious in extreme values; daytime heat-stress impacts are more noticeable in the higher percentiles than in the mean values and the impact at night is more obvious in the lower percentiles than in the mean. Urban expansion enhances heat-stress increases due to climate change at night, but partly compensates its effects during the day. These differences are due to a stronger contribution from vapor pressure deficit during the day and from temperature increases during the night induced by urban surfaces. Our results highlight the inappropriateness of assessing human comfort determined using temperature changes alone and point to the likelihood that impacts of climate change assessed using models that lack urban surfaces probably underestimate future changes in terms of human comfort.

  19. Stress and serial adult metamorphosis: multiple roles for the stress axis in socially regulated sex change

    PubMed Central

    Solomon-Lane, Tessa K.; Crespi, Erica J.; Grober, Matthew S.

    2013-01-01

    Socially regulated sex change in teleost fishes is a striking example of social status information regulating biological function in the service of reproductive success. The establishment of social dominance in sex changing species is translated into a cascade of changes in behavior, physiology, neuroendocrine function, and morphology that transforms a female into a male, or vice versa. The hypothalamic-pituitary-interrenal axis (HPI, homologous to HP-adrenal axis in mammals and birds) has been hypothesized to play a mechanistic role linking status to sex change. The HPA/I axis responds to environmental stressors by integrating relevant external and internal cues and coordinating biological responses including changes in behavior, energetics, physiology, and morphology (i.e., metamorphosis). Through actions of both corticotropin-releasing factor and glucocorticoids, the HPA/I axis has been implicated in processes central to sex change, including the regulation of agonistic behavior, social status, energetic investment, and life history transitions. In this paper, we review the hypothesized roles of the HPA/I axis in the regulation of sex change and how those hypotheses have been tested to date. We include original data on sex change in the bluebanded goby (Lythyrpnus dalli), a highly social fish capable of bidirectional sex change. We then propose a model for HPA/I involvement in sex change and discuss how these ideas might be tested in the future. Understanding the regulation of sex change has the potential to elucidate evolutionarily conserved mechanisms responsible for translating pertinent information about the environment into coordinated biological changes along multiple body axes. PMID:24265604

  20. General formulations of global co-seismic deformations caused by an arbitrary dislocation in a spherically symmetric earth model-applicable to deformed earth surface and space-fixed point

    NASA Astrophysics Data System (ADS)

    Sun, Wenke; Okubo, Shuhei; Fu, Guangyu; Araya, Akito

    2009-06-01

    Based on the authors' previous work, co-seismic deformations for a spherical symmetric earth model are summarized and reformulated. Unified expressions presented herein accommodate physical deformations: displacement, potential, gravity, geoid and strain changes. The corresponding Green's functions are derived by combining spheroidal and toroidal deformations. Sign errors in previous publications are corrected in these new formulas. These expressions are developed basically for a deformed earth surface because most traditional geodetic measurements are performed on the terrain surface. However, through development of space geodetic techniques, such as the satellite gravity missions, co-seismic gravity changes can be detected from space. In this case, the above dislocation theory (e.g., the co-seismic gravity change) cannot be applied directly to the observed data because the data do not include surface crustal deformation (the free air gravity change). Correspondingly, the contribution by the vertical displacement part must be removed from the traditional expressions. For this purpose, we present the corresponding expressions applicable to space observations. Some numerical technical problems are discussed. In addition, a smoothing technique is necessary to damp the high-frequency contribution so that the theory can be applied reasonably. Global co-seismic deformations caused by the 2004 Sumatra-Andaman earthquake (M9.3) are studied as an application of the new Green's function. That earthquake caused a global deformation detected by GPS, strain metres and even a satellite gravity mission. These global deformations are calculated based on the derived Green's functions and the seismic-wave derived earth model. A segment-summation scheme is used considering the slip distribution on a limited fault plane. The results are useful for interpreting observed deformations, especially those in the far field. The earthquake reveals global co-seismic deformations and effects

  1. Coseismic and interseismic displacements at a subduction zone - a parameter study using finite-element modelling

    NASA Astrophysics Data System (ADS)

    Li, Tao; Hampel, Andrea

    2013-04-01

    Tide-gauge and geodetic measurements of coseismic and interseismic displacements in the forearc of subduction zones showed that the coastal region undergoes uplift during the interseismic phase and subsidence during the coseismic phase, while opposite vertical movements are observed in the neighbouring regions (e.g., Savage & Thatcher 1992; Hyndman & Wang 1995). Horizontal displacements during the interseismic phase are typically directed landward, whereas the forearc moves seaward during the earthquake (e.g., Klotz et al. 1999). Here we use two-dimensional finite-element modelling to evaluate how the friction coefficient along the plate interface, the length and the position of the downdip end of the locked zone affect the coseismic and interseismic displacements. Our model consists of a deformable, rheologically stratified upper plate and an undeformable oceanic plate, which rotates at a prescribed angular velocity (cf. Cailleau & Oncken, 2008). The frictional plate interface is divided - from the trench to the base of the continental lithosphere - into a seismogenic zone, a transition zone and a landward free slip zone. During an initial phase, the seismogenic zone is locked, which leads to the accumulation of elastic strain in the forearc. During the subsequent coseismic phase, the strain is released and causes sudden slip of several meters on the plate interface. During the next interseismic phase, the seismogenic zone is locked again. Our model results show patterns of vertical and horizontal displacements that are in general agreement with geodetically observed patterns. A sensitivity analysis reveals that the magnitude of the vertical displacements is strongly influenced by the friction coefficients of the seismogenic zone and the transition zone. The location of the zones of maximum interseismic uplift and coseismic subsidence in the coastal regions depends on the length and position of the locked zone. Preliminary results from three-dimensional models

  2. Metabolite profiling and network analysis reveal coordinated changes in grapevine water stress response

    PubMed Central

    2013-01-01

    Background Grapevine metabolism in response to water deficit was studied in two cultivars, Shiraz and Cabernet Sauvignon, which were shown to have different hydraulic behaviors (Hochberg et al. Physiol. Plant. 147:443–453, 2012). Results Progressive water deficit was found to effect changes in leaf water potentials accompanied by metabolic changes. In both cultivars, but more intensively in Shiraz than Cabernet Sauvignon, water deficit caused a shift to higher osmolality and lower C/N ratios, the latter of which was also reflected in marked increases in amino acids, e.g., Pro, Val, Leu, Thr and Trp, reductions of most organic acids, and changes in the phenylpropanoid pathway. PCA analysis showed that changes in primary metabolism were mostly associated with water stress, while diversification of specialized metabolism was mostly linked to the cultivars. In the phloem sap, drought was characterized by higher ABA concentration and major changes in benzoate levels coinciding with lower stomatal conductance and suberinization of vascular bundles. Enhanced suberin biosynthesis in Shiraz was reflected by the higher abundance of sap hydroxybenzoate derivatives. Correlation-based network analysis revealed that compared to Cabernet Sauvignon, Shiraz had considerably larger and highly coordinated stress-related changes, reflected in its increased metabolic network connectivity under stress. Network analysis also highlighted the structural role of major stress related metabolites, e.g., Pro, quercetin and ascorbate, which drastically altered their connectedness in the Shiraz network under water deficit. Conclusions Taken together, the results showed that Vitis vinifera cultivars possess a common metabolic response to water deficit. Central metabolism, and specifically N metabolism, plays a significant role in stress response in vine. At the cultivar level, Cabernet Sauvignon was characterized by milder metabolic perturbations, likely due to a tighter regulation of stomata

  3. Signals for Change: Stress Indicators for Colleges and Universities.

    ERIC Educational Resources Information Center

    Glenny, Lyman A.; Bowen, Frank M.

    Thirty-five indicators of the need for change in a higher education institution are outlined. They are divided into two large categories: those over which the institution has little or no control, and those over which it has some or total control. Within those categories are subcategories: indicators for short-range planning, and those for…

  4. Life Changes and Social Support: Stress and Its Moderators.

    DTIC Science & Technology

    1981-04-17

    his or her developmental state. Life changes are important milestones in life span development (Brim & Ryff , 1980). An inspection of both the SRE and...0. G., Jr., & Ryff , C. D. On the properties of life events. In P. B. Baltes & 0. G. Brim, Jr. (Eds.), Life-span development and behavior, Vol. 3. New

  5. Effects of exercise on stress-induced changes of norepinephrine and serotonin in rat hippocampus.

    PubMed

    Wang, Jing; Chen, Xuewei; Zhang, Na; Ma, Qiang

    2013-10-31

    Exercise is beneficial to brain and can attenuate stress-induced hippocampal damages. However, the details involved monoamine neurotransmitter in exercise to counteract stress have not been well elucidated. The aim of this study was to examine exercise-induced responses of the norepinephrine (NE) and serotonin (5-HT) systems in counteracting stress-induced hippocampal damages. Rats were divided into exercise (four weeks of voluntary wheel running), stress (three weeks of restraint stress), exercise-stress (three weeks of stress following four weeks of exercise), and control groups. Levels of NE and 5-HT were detected with high-performance liquid chromatography (HPLC), mRNA expression was detected with real-time fluorescence quantitative reverse transcription polymerase reaction (FQ-RT-PCR) and proteins associated with 5-HT₁Α receptors (5-HT₁Α-R) and β₂-adrenergic receptors (β₂-AR) were analyzed by western blotting. 5-HT levels were highest (P < 0.01) in the exercised group, lowest (P < 0.05) in the stressed rats, and were similar (P = 0.065) in stressed and exercise-stressed rats. NE levels were highest (P < 0.01) in the exercised group, and higher in the exercise-stressed than the stressed rats (P < 0.01). 5-HT₁A-R mRNA expression was highest (P < 0.01) in the exercised group, lowest in the stressed group. The 5-HT₁Α-R protein expression changed in the same tendency as its mRNA levels. The β₂-AR mRNA was highest in exercised rats (P < 0.05), and its protein expression was higher in the exercised and exercise-stress rats than in the control and stress rats (P < 0.05). In conclusion, norepinephrine may represent endophenotypic features of exercise states. Serotonin levels may be more susceptible to stress and responsible for deleterious stress-induced effects. Norepinephrine and serotonin may both contribute to counteraction of stress-induced hippocampal damages of physical exercises.

  6. Transgenerational phenotypic and epigenetic changes in response to heat stress in Arabidopsis thaliana

    PubMed Central

    Migicovsky, Zoë; Yao, Youli; Kovalchuk, Igor

    2014-01-01

    Exposure to heat stress causes physiological and epigenetic changes in plants, which may also be altered in the progeny. We compared the progeny of stressed and control Arabidopsis thaliana wild type and Dicer-like mutant dcl2, dcl3, and dcl4 plants for variations in physiology and molecular profile, including global genome methylation, mRNA levels, and histone modifications in the subset of differentially expressed genes at normal conditions and in response to heat stress. We found that the immediate progeny of heat-stressed plants had fewer, but larger leaves, and tended to bolt earlier. Transposon expression was elevated in the progeny of heat-stressed plants, and heat stress in the same generation tended to decrease global genome methylation. Progeny of stressed plants had increased expression of HSFA2, and reduction in MSH2, ROS1, and several SUVH genes. Gene expression positively correlated with permissive histone marks and negatively correlated with repressive marks. Overall, the progeny of heat stressed plants varied in both their physiology and epigenome and dcl2 and dcl3 mutants were partially deficient for these changes. PMID:24513700

  7. Transgenerational phenotypic and epigenetic changes in response to heat stress in Arabidopsis thaliana.

    PubMed

    Migicovsky, Zoë; Yao, Youli; Kovalchuk, Igor

    2014-01-01

    Exposure to heat stress causes physiological and epigenetic changes in plants, which may also be altered in the progeny. We compared the progeny of stressed and control Arabidopsis thaliana wild type and Dicer-like mutant dcl2, dcl3, and dcl4 plants for variations in physiology and molecular profile, including global genome methylation, mRNA levels, and histone modifications in the subset of differentially expressed genes at normal conditions and in response to heat stress. We found that the immediate progeny of heat-stressed plants had fewer, but larger leaves, and tended to bolt earlier. Transposon expression was elevated in the progeny of heat-stressed plants, and heat stress in the same generation tended to decrease global genome methylation. Progeny of stressed plants had increased expression of HSFA2, and reduction in MSH2, ROS1, and several SUVH genes. Gene expression positively correlated with permissive histone marks and negatively correlated with repressive marks. Overall, the progeny of heat stressed plants varied in both their physiology and epigenome and dcl2 and dcl3 mutants were partially deficient for these changes.

  8. Climate change threatens endangered plant species by stronger and interacting water-related stresses

    NASA Astrophysics Data System (ADS)

    Bartholomeus, Ruud P.; Witte, Jan-Philip M.; van Bodegom, Peter M.; van Dam, Jos C.; Aerts, Rien

    2011-12-01

    Atmospheric CO2-concentration, temperature and rainfall variability are all expected to increase in the near future. The resulting increased dynamics of soil moisture contents, together with increased plant physiological demands for both oxygen and water, will lead to an increased occurrence of wet and dry extremes of plant stresses, i.e., of oxygen and drought stress, respectively, alone and in interaction. The use of indirect environmental variables in previous studies and a focus on individual stresses rather than their combined effects has hampered understanding of the causal impact of climate change on plant species composition through changes in abiotic site conditions. Here, we use process-based simulations of oxygen and drought stresses in conjunction with a downscaled national version of IPCC scenarios in order to show that these stresses will increase (on average by ˜20% at sites where both stresses occur) in a warmer and more variable future (2050) climate. These two types of stresses will increasingly coincide, i.e. both stresses will occur more often (but not at the same time) within a single vegetation plot. We further show that this increased coincidence of water-related stresses will negatively affect the future occurrence of currently endangered plant species (causing a reduction of ˜16%), while apparently no such decrease will occur among common species. Individual stresses did not appear to affect the occurrence of endangered plant species. Consequently, our study demonstrates that species that are already threatened under the current climate will suffer most from the effects of climate change.

  9. Minimal evidence for consistent changes in maize DNA methylation patterns following environmental stress

    PubMed Central

    Eichten, Steven R.; Springer, Nathan M.

    2015-01-01

    DNA methylation is a chromatin modification that is sometimes associated with epigenetic regulation of gene expression. As DNA methylation can be reversible at some loci, it is possible that methylation patterns may change within an organism that is subjected to environmental stress. In order to assess the effects of abiotic stress on DNA methylation patterns in maize (Zea mays), seeding plants were subjected to heat, cold, and UV stress treatments. Tissue was later collected from individual adult plants that had been subjected to stress or control treatments and used to perform DNA methylation profiling to determine whether there were consistent changes in DNA methylation triggered by specific stress treatments. DNA methylation profiling was performed by immunoprecipitation of methylated DNA followed by microarray hybridization to allow for quantitative estimates of DNA methylation abundance throughout the low-copy portion of the maize genome. By comparing the DNA methylation profiles of each individual plant to the average of the control plants it was possible to identify regions of the genome with variable DNA methylation. However, we did not find evidence of consistent DNA methylation changes resulting from the stress treatments used in this study. Instead, the data suggest that there is a low-rate of stochastic variation that is present in both control and stressed plants. PMID:25999972

  10. Water deficit stress-induced changes in carbon and nitrogen partitioning in Chenopodium quinoa Willd.

    PubMed

    Bascuñán-Godoy, Luisa; Reguera, Maria; Abdel-Tawab, Yasser M; Blumwald, Eduardo

    2016-03-01

    Water deficit stress followed by re-watering during grain filling resulted in the induction of the ornithine pathway and in changes in Quinoa grain quality. The genetic diversity of Chenopodium quinoa Willd. (Quinoa) is accompanied by an outstanding environmental adaptability and high nutritional properties of the grains. However, little is known about the biochemical and physiological mechanisms associated with the abiotic stress tolerance of Quinoa. Here, we characterized carbon and nitrogen metabolic changes in Quinoa leaves and grains in response to water deficit stress analyzing their impact on the grain quality of two lowland ecotypes (Faro and BO78). Differences in the stress recovery response were found between genotypes including changes in the activity of nitrogen assimilation-associated enzymes that resulted in differences in grain quality. Both genotypes showed a common strategy to overcome water stress including the stress-induced synthesis of reactive oxygen species scavengers and osmolytes. Particularly, water deficit stress induced the stimulation of the ornithine and raffinose pathways. Our results would suggest that the regulation of C- and N partitioning in Quinoa during grain filling could be used for the improvement of the grain quality without altering grain yields.

  11. Monitoring eruption activity from temporal stress changes at Mt. Ontake volcano, Japan

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Kato, A.; Yamanaka, Y.; Maeda, Y.; Horikawa, S.; Matsuhiro, K.; Okuda, T.

    2015-12-01

    On 27 September 2014, Mt. Ontake in Japan produced a phreatic (steam type) eruption with a Volcanic Explosivity Index value of 2 after being dormant for seven years. The local stress field around volcanoes is the superposition of the regional stress field and stress perturbations related to volcanic activity. Temporal stress changes over periods of weeks to months are generally attributed to volcanic processes. Here we show that monitoring temporal changes in the local stress field beneath Mt. Ontake, using focal mechanism solutions of volcano-tectonic (VT) earthquakes, is an effective tool for assessing the state of volcanic activity. We estimated focal mechanism solutions of 157 VT earthquakes beneath Mt. Ontake from August 2014 to March 2015, assuming that the source was double-couple. Pre-eruption seismicity was dominated by normal faulting with east-west tension, whereas most post-eruption events were reverse faulting with east-west compression. The misfit angle between observed slip vectors and those derived theoretically from the regional (i.e., background) stress pattern is used to evaluate the deviation of the local stress field, or the stress perturbation related to volcanic activity. The moving average of misfit angles tended to exceed 90° before the eruption, and showed a marked decrease immediately after the eruption. This indicates that during the precursory period the local stress field beneath Mt. Ontake was rotated by stress perturbations caused by the inflation of magmatic/hydrothermal fluids. Post-eruption events of reverse faulting acted to shrink the volcanic edifice after expulsion of volcanic ejecta, controlled by the regional stress field. The misfit angle is a good indicator of the state of volcanic activity. The monitoring method by using this indicator is applicable to other volcanoes and may contribute to the mitigation of volcanic hazards.

  12. [Leaf cell damage and changes in photosynthetic pigment contents of three moss species under cadmium stress].

    PubMed

    Gong, Shuang-jiao; Ma, Tao-wu; Li, Jing; Liu, Ying-di

    2010-10-01

    A hydroponic experiment was conducted to study the leaf cell damage and the changes in photosynthetic pigment contents of three moss species under Cd stress, aimed to reveal the Cd sensibility and tolerance of the species. Even though the Cd stress was relatively low (1 mg Cd x L(-1)), the leaf cells of Dolichomitriopsis diversiformis and Plagiomnium acutum were damaged. With the increasing level of Cd stress, the leaf cell damage of the three moss species aggravated significantly, and the resulted damage under high level (100 mg x L(-1)) Cd stress was in the order Brachythecium procumbens > P. acutum > D. diversiformis. Relatively low (1 mg x L(-1)) Cd stress had no significant effects on the total chlorophyll content of the three species. However, with the increase of Cd stress (> or = 10 mg x L(-1)), the total chlorophyll content decreased significantly, with the order of B. procumbens > P. acutum > D. diversiformis. The Cd stress at 1 and 10 mg x L(-1) had no significant effects on the chlorophyll a/b, but the Cd stress at 100 mg x L(-1) led to a significant decrease of chlorophyll a/b in P. acutum and B. procumbens. The maximal decline of carotenoid content in B. procumbens was observed at 1 mg x L(-1) of Cd. The three moss species could significantly enrich Cd, and the Cd enrichment was D. diversiformis > P. acutum > B. procumbens. The leaf cell damage rate and the changes of chlorophyll and carotenoid contents could be used to indicate the differences in the sensitivity of D. diversiformis, P. acutum, and B. procumbens to Cd stress. D. diversiformis had the strongest tolerance to Cd stress, while P. acutum and B. procumbens had weaker tolerance. The tolerance of the three moss species to Cd stress was positively correlated to the capability of their Cd enrichment.

  13. Observation of laser-induced stress waves and mechanism of structural changes inside rock-salt crystals.

    PubMed

    Sakakura, Masaaki; Tochio, Takaya; Eida, Masaaki; Shimotsuma, Yasuhiko; Kanehira, Shingo; Nishi, Masayuki; Miura, Kiyotaka; Hirao, Kazuyuki

    2011-08-29

    The structural changes inside rock-salt crystals after femtosecond (fs) laser irradiation are investigated using a microscopic pump-probe technique and an elastic simulation. The pump-probe imaging shows that a squircle-shaped stress wave is generated after the fs laser irradiation as a result of the relaxation of thermal stress in the photoexcited region. Pump-probe crossed-Nicols imaging and elastic simulation elucidate that shear stresses and tensile stresses are concentrated in specific regions during the propagation of the stress wave. The shear stresses and tensile stresses observed in this study can explain the characteristic laser-induced structural changes inside rock-salt crystals.

  14. Stress evolution following the 1999 Chi-Chi, Taiwan, earthquake: Consequences for afterslip, relaxation, aftershocks and departures from Omori decay

    USGS Publications Warehouse

    Chan, C.-H.; Stein, R.S.

    2009-01-01

    We explore how Coulomb stress transfer and viscoelastic relaxation control afterslip and aftershocks in a continental thrust fault system. The 1999 September 21 Mw = 7.6 Chi-Chi shock is typical of continental ramp-d??collement systems throughout the world, and so inferences drawn from this uniquely well-recorded event may be widely applicable. First, we find that the spatial and depth distribution of aftershocks and their focal mechanisms are consistent with the calculated Coulomb stress changes imparted by the coseismic rupture. Some 61 per cent of the M ??? 2 aftershocks and 83 per cent of the M ??? 4 aftershocks lie in regions for which the Coulomb stress increased by ???0.1 bars, and there is a 11-12 per cent gain in the percentage of aftershocks nodal planes on which the shear stress increased over the pre-Chi Chi control period. Second, we find that afterslip occurred where the calculated coseismic stress increased on the fault ramp and d??collement, subject to the condition that friction is high on the ramp and low on the d??collement. Third, viscoelastic relaxation is evident from the fit of the post-seismic GPS data on the footwall. Fourth, we find that the rate of seismicity began to increase during the post-seismic period in an annulus extending east of the main rupture. The spatial extent of the seismicity annulus resembles the calculated ???0.05-bar Coulomb stress increase caused by viscoelastic relaxation and afterslip, and we find a 9-12 per cent gain in the percentage of focal mechanisms with >0.01-bar shear stress increases imparted by the post-seismic afterslip and relaxation in comparison to the control period. Thus, we argue that post-seismic stress changes can for the first time be shown to alter the production of aftershocks, as judged by their rate, spatial distribution, and focal mechanisms. ?? Journal compilation ?? 2009 RAS.

  15. Blood Viscosity Changes Following Surgical Stress and Trauma.

    DTIC Science & Technology

    1980-01-01

    fluoroscopy a number 3 French teflon radiopaque catheter was inserted through the right jugular vein and its tip placed into the pulmonary artery. A...investigation into the metabolic and vascular effects of trauma and in order to define changes due to a difference in oxygen availability, 0 consumption...then performed to confirm whether the increase in packed cell (PC) viscosity that occurs in humans after elective surgery is accompanied by a

  16. Residual Stress Changes in Fatigue. Volume 2. A Simulation Model for Stress Measurements in Notched Test Specimens by X-Ray Diffraction

    DTIC Science & Technology

    1989-03-01

    Report No. NADC-88141-60 (Volume II) DTIC S F-!. r-CT E MAY 2 6 1~98D RESIDUAL STRESS CHANGES IN FATIGUE VOLUME II - A SIMULATION MODEL FOR STRESS ...Residual Stress Changes in Fatigue: Vol. II. A Simulation Model for Stress Measurements in Notched Test Specimens by X-Ray Diffraction 12 PERSONAL...Simulation; Residual Stress ; X-Ray Difraction ’/ -, . .. 20 11 1 19 ABSTRACT (Continue on reverse if necessary and identif by block number) The state of

  17. Blind Faulting and Surface Folding: Coseismic and Postseismic Observations of the Mw 6.3 2015 Pishan (China) Earthquake and their Relationship to Longer-Term Growth of Structures

    NASA Astrophysics Data System (ADS)

    Ainscoe, E. A.; Elliott, J. R.; Copley, A.; Craig, T. J.; Li, T.; Parsons, B.; Walker, R. T.

    2016-12-01

    The relationship between individual earthquakes and the longer-term growth of topography and of geological structures is not yet fully understood, but is key to our ability to interpret these ubiquitous datasets in the contexts of seismic hazard and the wider-scale tectonics. We present observations of the coseismic and early postseismic parts of the seismic cycle for the 3 July 2015 Pishan Mw 6.3 earthquake in Xinjiang, China, and compare our results to the cumulative effects of multiple seismic cycles which are recorded in the local geology and geomorphology. We use teleseismic body waveform modelling and Sentinel-1A interferometric synthetic aperture radar (InSAR) to determine the fault parameters and slip distribution of the mainshock - a gently dipping reverse faulting earthquake in the southwest corner of the Tarim Basin. Our mechanism and location correspond closely to the fault geometry mapped independently from seismic reflection profiles and show that the earthquake was blind and on a pre-existing ramp fault over a depth range of 9-13km. We further identify a postseismic signal in Sentinal-1A interferograms, the first six months of which has a line of sight change around one fifth that of the coseismic signal. By mapping the geomorphology of the overlying area using high resolution optical imagery and digital elevation models, we find long wavelength folding and numerous small scarps distributed over several kilometres across-strike. The geomorphic folding is consistent with blind reverse faulting but the geometry of the folding cannot be fully explained by repeated coseismic slip in events such as the 2015 earthquake. By comparing the coseismic and postseismic slip on faulting at depth with the geomorphic and geological constraints on folding, we are able to discuss the mechanism of fold growth, and the consequences for models of structure at depth inferred purely from surface data.

  18. Change of Rin1 and Stathmin in the Animal Model of Traumatic Stresses

    PubMed Central

    Han, Fang; Jiang, Jingzhi; Ding, Jinlan; Liu, Hong; Xiao, Bing; Shi, Yuxiu

    2017-01-01

    The molecular mechanism of fear memory is poorly understood. Therefore, the pathogenesis of post-traumatic stress disorder (PTSD), whose symptom presentation can enhance fear memory, remains largely unclear. Recent studies with knockout animals have reported that Rin1 and stathmin regulate fear memory. Rin1 inhibits acquisition and promotes memory extinction, whereas stathmin regulates innate and basal fear. The aim of our study was to examine changes in the expression of Rin1 and stathmin in different animal models of stress, particluarly traumatic stress. We used three animal traumatic stresses: single prolonged stress (SPS, which is a rodent model of PTSD), an immobilization-stress (IM) and a Loud sound stress (LSS), to examine the change and uniqueness in Rin1/stathmin expression. Behavioral tests of SPS rats demonstrated increased anxiety and contextual fear-conditioning. They showed decreased long-term potentiation (LTP), as well as decreased stathmin and increased Rin1 expression in the hippocampus and the amygdala. Expression of the stathmin effector, tubulin, and downstream molecules Rin1, Rab5, and Abl, appeared to increase. Rin1 and EphA4 were endogenously coexpressed in primary neurons after SPS stimulation. IM rats exhibited increased anxiety behavior and enhanced fear-conditioning to contextual and auditory stimuli. Similar changes in expression of Rin1/stathmin were observed in IM rats whereas no changes were observed in rats exposed to a loud sound. These data suggest that changes in expression of the Rin1 and stathmin genes may be involved in rodents with SPS and IM stresses, which provide valuable insight into fear memories under abnormal conditions, particularly in PTSD. PMID:28491025

  19. Neonatal maternal separation stress elicits lasting DNA methylation changes in the hippocampus of stress-reactive Wistar Kyoto rats.

    PubMed

    McCoy, Chelsea R; Rana, Samir; Stringfellow, Sara Anne; Day, Jeremy J; Wyss, J Michael; Clinton, Sarah M; Kerman, Ilan A

    2016-11-01

    Early-life stress (ELS) can alter neurodevelopment in variable ways, ranging from producing deleterious outcomes to stress resilience. While most ELS studies focus on its harmful effects, recent work by our laboratory and others shows that ELS elicits positive effects in certain individuals. We exposed Wistar Kyoto (WKY) rats, known for a stress reactive, anxiety/depression-like phenotype, to maternal separation (MS), a model of ELS. MS exposure elicited anxiolytic and antidepressant behavioral effects as well as improved cardiovascular function in adult WKY offspring. This study interrogates an epigenetic mechanism (DNA methylation) that may confer the adaptive effects of MS in WKY offspring. We quantified global genome methylation levels in limbic brain regions of adult WKYs exposed to daily 180-min MS or neonatal handling from postnatal day 1-14. MS exposure triggered dramatic DNA hypermethylation specifically in the hippocampus. Next-generation sequencing methylome profiling revealed reduced methylation at intragenic sites within two key nodes of insulin signaling pathways: the insulin receptor and one of its major downstream targets, mitogen-activated protein kinase kinase kinase 5 (Map3k5). We then tested the hypothesis that enhancing DNA methylation in WKY rats would elicit adaptive changes akin to the effects of MS. Dietary methyl donor supplementation improved WKY rats' anxiety/depression-like behaviors and also improved cardiovascular measures, similar to previous observations following MS. Overall, these data suggest a potential molecular mechanism that mediates a predicted adaptive response, whereby ELS induces DNA methylation changes in the brain that may contribute to successful stress coping and adaptive physiological changes in adulthood. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  20. Cognitive Change Predicts Symptom Reduction with Cognitive Therapy for Posttraumatic Stress Disorder

    ERIC Educational Resources Information Center

    Kleim, Birgit; Grey, Nick; Wild, Jennifer; Nussbeck, Fridtjof W.; Stott, Richard; Hackmann, Ann; Clark, David M.; Ehlers, Anke

    2013-01-01

    Objective: There is a growing body of evidence for the effectiveness of trauma-focused cognitive behavior therapy (TF-CBT) for posttraumatic stress disorder (PTSD), but few studies to date have investigated the mechanisms by which TF-CBT leads to therapeutic change. Models of PTSD suggest that a core treatment mechanism is the change in…

  1. Cognitive Change Predicts Symptom Reduction with Cognitive Therapy for Posttraumatic Stress Disorder

    ERIC Educational Resources Information Center

    Kleim, Birgit; Grey, Nick; Wild, Jennifer; Nussbeck, Fridtjof W.; Stott, Richard; Hackmann, Ann; Clark, David M.; Ehlers, Anke

    2013-01-01

    Objective: There is a growing body of evidence for the effectiveness of trauma-focused cognitive behavior therapy (TF-CBT) for posttraumatic stress disorder (PTSD), but few studies to date have investigated the mechanisms by which TF-CBT leads to therapeutic change. Models of PTSD suggest that a core treatment mechanism is the change in…

  2. Alteration of masticatory function by diet change induces stress responses in Wistar rats.

    PubMed

    Suzuki, Hirohito; Tanaka, Maki; Kawanishi, Katsuya; Koshino, Hisashi; Hirai, Toshihiro; Fujii, Hirotada; Takeda, Hidekatsu; Kuribayashi, Kageaki; Watanabe, Naoki

    2013-01-01

    The occlusion-mastication system has extradigestive functions; however, whether liquid feeding evokes stress responses remains unclear. In this study, reactions to low masticatory performance were analyzed using a diet-alteration model in Wistar rats. Seven days after the diet of the rats was changed from solid to liquid, serum epinephrine and norepinephrine concentrations were found to be elevated by 205% and 158% compared to baseline values, respectively. Superoxide production by peritoneal neutrophils was higher in rats fed with a liquid diet than in those fed with a solid diet. Serum superoxide dismutase activity (i.e. the potential to eradicate serum superoxide) was lower in rats fed with liquid than in those fed with a solid diet, indicating that the former experienced oxidative stress. Conversely, the oxidative stress was removed following reversion of the liquid diet to solid diet. These results suggest that liquid diet mastication can cause mental stress, including an oxidative stress response.

  3. Response of regional seismicity to the static stress change produced by the loma prieta earthquake.

    PubMed

    Reasenberg, P A; Simpson, R W

    1992-03-27

    The 1989 Loma Prieta, California, earthquake perturbed the static stress field over a large area of central California. The pattern of stress changes on major faults in the region predicted by models of the earthquake's dislocation agrees closely with changes in the regional seismicity rate after the earthquake. The agreement is best for models with low values of the coefficient of friction (0.1 stress models and measurements suggest that stresses were increased on the San Andreas fault north of the Loma Prieta rupture, but decreased slightly on the Hayward fault. This relaxation does not warrant lower probability estimates for large earthquakes on the Hayward fault in the next 30 years, however.

  4. Magnetization changes in 2% Mn pipeline steel induced by uniaxial tensile stress cycles of increasing amplitude

    SciTech Connect

    Guo, X.; Atherton, D.L.

    1995-09-01

    The application of cyclic stress to a ferromagnetic normally gives irreversible magnetization shifts towards the anhysteretic magnetization. Here experimental measurements are presented that show the irreversible magnetization changes induced by cyclic uniaxial isofield stress applied after magnetization at particular points on minor hysteresis loops. Selecting the (M,H) point and magnetization history, then applying stress cycles of increasing amplitude enables irreversible changes, initially away from and later toward the anhysteretic curve, to be obtained. Examples of a second inversion (i.e., irreversible shifts initially toward, then away and subsequently, toward the anhysteretic magnetization) with increasing amplitude cyclic uniaxial stress are also given. Preisach diagrams are used to interpret these results qualitatively in terms of local, more extensive and global anhysteretic states.

  5. Response of regional seismicity to the static stress change produced by the Loma Prieta earthquake

    USGS Publications Warehouse

    Reasenberg, P.A.; Simpson, R.W.

    1992-01-01

    The 1989 Loma Prieta, California, earthquake perturbed the static stress field over a large area of central California. The pattern of stress changes on major faults in the region predicted by models of the earthquake's dislocation agrees closely with changes in the regional seismicity rate after the earthquake. The agreement is best for models with low values of the coefficient of friction (0.1 ??? ?? ??? 0.3) on Bay Area faults. Both the stress models and measurements suggest that stresses were increased on the San Andreas fault north of the Loma Prieta rupture, but decreased slightly on the Hayward fault. This relaxation does not warrant lower probability estimates for large earthquakes on the Hayward fault in the next 30 years, however.

  6. Stress-induced changes in abundance differ among obligate and facultative endosymbionts of the soybean aphid.

    PubMed

    Enders, Laramy S; Miller, Nicholas J

    2016-02-01

    Bacterial endosymbionts can drive evolutionary novelty by conferring adaptive benefits under adverse environmental conditions. Among aphid species there is growing evidence that symbionts influence tolerance to various forms of stress. However, the extent to which stress inflicted on the aphid host has cascading effects on symbiont community dynamics remains poorly understood. Here we simultaneously quantified the effect of host-plant induced and xenobiotic stress on soybean aphid (Aphis glycines) fitness and relative abundance of its three bacterial symbionts. Exposure to soybean defensive stress (Rag1 gene) and a neurotoxic insecticide (thiamethoxam) substantially reduced aphid composite fitness (survival × reproduction) by 74 ± 10% and 92 ± 2%, respectively, which in turn induced distinctive changes in the endosymbiont microbiota. When challenged by host-plant defenses a 1.4-fold reduction in abundance of the obligate symbiont Buchnera was observed across four aphid clonal lines. Among facultative symbionts of Rag1-stressed aphids, Wolbachia abundance increased twofold and Arsenophonus decreased 1.5-fold. A similar pattern was observed under xenobiotic stress, with Buchnera and Arsenophonus titers decreasing (1.3-fold) and Wolbachia increasing (1.5-fold). Furthermore, variation in aphid virulence to Rag1 was positively correlated with changes in Arsenophonus titers, but not Wolbachia or Buchnera. A single Arsenophonus multi-locus genotype was found among aphid clonal lines, indicating strain diversity is not primarily responsible for correlated host-symbiont stress levels. Overall, our results demonstrate the nature of aphid symbioses can significantly affect the outcome of interactions under stress and suggests general changes in the microbiome can occur across multiple stress types.

  7. Restraint Stress-Induced Morphological Changes at the Blood-Brain Barrier in Adult Rats

    PubMed Central

    Sántha, Petra; Veszelka, Szilvia; Hoyk, Zsófia; Mészáros, Mária; Walter, Fruzsina R.; Tóth, Andrea E.; Kiss, Lóránd; Kincses, András; Oláh, Zita; Seprényi, György; Rákhely, Gábor; Dér, András; Pákáski, Magdolna; Kálmán, János; Kittel, Ágnes; Deli, Mária A.

    2016-01-01

    Stress is well-known to contribute to the development of both neurological and psychiatric diseases. While the role of the blood-brain barrier is increasingly recognized in the development of neurodegenerative disorders, such as Alzheimer's disease, dysfunction of the blood-brain barrier has been linked to stress-related psychiatric diseases only recently. In the present study the effects of restraint stress with different duration (1, 3, and 21 days) were investigated on the morphology of the blood-brain barrier in male adult Wistar rats. Frontal cortex and hippocampus sections were immunostained for markers of brain endothelial cells (claudin-5, occluding, and glucose transporter-1) and astroglia (GFAP). Staining pattern and intensity were visualized by confocal microscopy and evaluated by several types of image analysis. The ultrastructure of brain capillaries was investigated by electron microscopy. Morphological changes and intensity alterations in brain endothelial tight junction proteins claudin-5 and occludin were induced by stress. Following restraint stress significant increases in the fluorescence intensity of glucose transporter-1 were detected in brain endothelial cells in the frontal cortex and hippocampus. Significant reductions in GFAP fluorescence intensity were observed in the frontal cortex in all stress groups. As observed by electron microscopy, 1-day acute stress induced morphological changes indicating damage in capillary endothelial cells in both brain regions. After 21 days of stress thicker and irregular capillary basal membranes in the hippocampus and edema in astrocytes in both regions were seen. These findings indicate that stress exerts time-dependent changes in the staining pattern of tight junction proteins occludin, claudin-5, and glucose transporter-1 at the level of brain capillaries and in the ultrastructure of brain endothelial cells and astroglial endfeet, which may contribute to neurodegenerative processes, cognitive and

  8. Changes in Atlantic salmon Salmo salar mucus components following short- and long-term handling stress.

    PubMed

    Easy, R H; Ross, N W

    2010-11-01

    This study examined changes in Atlantic salmon Salmo salar epidermal mucus proteins following short- and long-term handling stress. Short-term stress consisted of a single removal of fish from water for 15 s with long-term stress consisting of daily removal of fish from water for 15 s over 21 days. In the long-term handling stress study, there was a high level of individual variability with respect to mucus alkaline phosphatase, cathepsin B and lysozyme activities, with no correlation to treatment group. There was limited or no positive correlation between lysozyme, cathepsin B or alkaline phosphatase activities and plasma cortisol. There was a significant difference in lysozyme activity for both control and stressed fish at day 21 compared to other sampling days. In the short-term study, there was again high variability in mucus enzyme activities with no difference observed between groups. Immunoblotting also showed variability in mucus actin breakdown products in both short- and long-term handling stress studies. There appeared, however, to be a shift towards a more thorough breakdown of actin at day 14 in the stressed group. This shift suggested changes in mucus proteases in response to long-term handling stress. In summary, there were correlations of some mucus enzyme/protein profiles with stress or cortisol; however, the variability in S. salar mucus enzyme levels and actin fragmentation patterns suggested other triggers for inducing changes in mucus protein composition that need to be investigated further in order to better understand the role of mucus in the response of S. salar to external stressors. © 2010 The Authors. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

  9. Postdeployment Symptom Changes and Traumatic Brain Injury and/or Posttraumatic Stress Disorder in Men

    DTIC Science & Technology

    2012-01-01

    Naval Health Research Center Postdeployment Symptom Changes and Traumatic Brain Injury and/or Posttraumatic Stress Disorder in Men Caroline A... disorder in men Caroline A. Macera, PhD;1 Hilary J. Aralis, MS;1* Andrew J. MacGregor, PhD;2 Mitchell J. Rauh, PhD, PT, MPH;1 Michael R. Galarneau, MS2...associated with blast-related TBI and posttraumatic stress disorder (PTSD) that were reported immedi- ately after deployment were compared with

  10. Soybean Roots Grown under Heat Stress Show Global Changes in Their Transcriptional and Proteomic Profiles.

    PubMed

    Valdés-López, Oswaldo; Batek, Josef; Gomez-Hernandez, Nicolas; Nguyen, Cuong T; Isidra-Arellano, Mariel C; Zhang, Ning; Joshi, Trupti; Xu, Dong; Hixson, Kim K; Weitz, Karl K; Aldrich, Joshua T; Paša-Tolić, Ljiljana; Stacey, Gary

    2016-01-01

    Heat stress is likely to be a key factor in the negative impact of climate change on crop production. Heat stress significantly influences the functions of roots, which provide support, water, and nutrients to other plant organs. Likewise, roots play an important role in the establishment of symbiotic associations with different microorganisms. Despite the physiological relevance of roots, few studies have examined their response to heat stress. In this study, we performed genome-wide transcriptomic and proteomic analyses on isolated root hairs, which are a single, epidermal cell type, and compared their response to stripped roots. On average, we identified 1849 and 3091 genes differentially regulated in root hairs and stripped roots, respectively, in response to heat stress. Our gene regulatory module analysis identified 10 key modules that might control the majority of the transcriptional response to heat stress. We also conducted proteomic analysis on membrane fractions isolated from root hairs and compared these responses to stripped roots. These experiments identified a variety of proteins whose expression changed within 3 h of application of heat stress. Most of these proteins were predicted to play a significant role in thermo-tolerance, as well as in chromatin remodeling and post-transcriptional regulation. The data presented represent an in-depth analysis of the heat stress response of a single cell type in soybean.

  11. Soybean Roots Grown under Heat Stress Show Global Changes in Their Transcriptional and Proteomic Profiles

    PubMed Central

    Valdés-López, Oswaldo; Batek, Josef; Gomez-Hernandez, Nicolas; Nguyen, Cuong T.; Isidra-Arellano, Mariel C.; Zhang, Ning; Joshi, Trupti; Xu, Dong; Hixson, Kim K.; Weitz, Karl K.; Aldrich, Joshua T.; Paša-Tolić, Ljiljana; Stacey, Gary

    2016-01-01

    Heat stress is likely to be a key factor in the negative impact of climate change on crop production. Heat stress significantly influences the functions of roots, which provide support, water, and nutrients to other plant organs. Likewise, roots play an important role in the establishment of symbiotic associations with different microorganisms. Despite the physiological relevance of roots, few studies have examined their response to heat stress. In this study, we performed genome-wide transcriptomic and proteomic analyses on isolated root hairs, which are a single, epidermal cell type, and compared their response to stripped roots. On average, we identified 1849 and 3091 genes differentially regulated in root hairs and stripped roots, respectively, in response to heat stress. Our gene regulatory module analysis identified 10 key modules that might control the majority of the transcriptional response to heat stress. We also conducted proteomic analysis on membrane fractions isolated from root hairs and compared these responses to stripped roots. These experiments identified a variety of proteins whose expression changed within 3 h of application of heat stress. Most of these proteins were predicted to play a significant role in thermo-tolerance, as well as in chromatin remodeling and post-transcriptional regulation. The data presented represent an in-depth analysis of the heat stress response of a single cell type in soybean. PMID:27200004

  12. Soybean Roots Grown under Heat Stress Show Global Changes in Their Transcriptional and Proteomic Profiles

    DOE PAGES

    Valdés-López, Oswaldo; Batek, Josef; Gomez-Hernandez, Nicolas; ...

    2016-04-25

    Heat stress is likely to be a key factor in the negative impact of climate change on crop production. Heat stress significantly influences the functions of roots, which provide support, water, and nutrients to other plant organs. Likewise, roots play an important role in the establishment of symbiotic associations with different microorganisms. Despite the physiological relevance of roots, few studies have examined their response to heat stress. Here in this study, we performed genome-wide transcriptomic and proteomic analyses on isolated root hairs, which are a single, epidermal cell type, and compared their response to stripped roots. On average, we identifiedmore » 1849 and 3091 genes differentially regulated in root hairs and stripped roots, respectively, in response to heat stress. Our gene regulatory module analysis identified 10 key modules that might control the majority of the transcriptional response to heat stress. We also conducted proteomic analysis on membrane fractions isolated from root hairs and compared these responses to stripped roots. These experiments identified a variety of proteins whose expression changed within 3 h of application of heat stress. Most of these proteins were predicted to play a significant role in thermo-tolerance, as well as in chromatin remodeling and post-transcriptional regulation. In conclusion, the data presented represent an in-depth analysis of the heat stress response of a single cell type in soybean.« less

  13. EEG changes as heat stress reactions in rats irradiated by high intensity 35 GHz millimeter waves.

    PubMed

    Xie, Taorong; Pei, Jian; Cui, Yibin; Zhang, Jie; Qi, Hongxing; Chen, Shude; Qiao, Dengjiang

    2011-06-01

    As the application of millimeter waves for civilian and military use increases, the possibility of overexposure to millimeter waves will also increase. This paper attempts to evaluate stress reactions evoked by 35 GHz millimeter waves. The stress reactions in Sprague-Dawley (SD) rats were quantitatively studied by analyzing electroencephalogram (EEG) changes induced by overexposure to 35 GHz millimeter waves. The relative changes in average energy of the EEG and its wavelet decompositions were used for extracting the stress reaction indicators. Incident average power densities (IAPDs) of 35 GHz millimeter waves from 0.5 W cm(-2) to 7.5 W cm(-2) were employed to investigate the relation between irradiation dose and the stress reactions in the rats. Different stress reaction periods evoked by irradiation were quantitatively evaluated by EEG results. The results illustrate that stress reactions are more intense during the first part of the irradiation than during the later part. The skin temperature increase produced by millimeter wave irradiation is the principle reason for stress reactions and skin injuries. As expected, at the higher levels of irradiation, the reaction time decreases and the reaction intensity increases.

  14. Soybean Roots Grown under Heat Stress Show Global Changes in Their Transcriptional and Proteomic Profiles

    SciTech Connect

    Valdés-López, Oswaldo; Batek, Josef; Gomez-Hernandez, Nicolas; Nguyen, Cuong T.; Isidra-Arellano, Mariel C.; Zhang, Ning; Joshi, Trupti; Xu, Dong; Hixson, Kim K.; Weitz, Karl K.; Aldrich, Joshua T.; Paša-Tolić, Ljiljana; Stacey, Gary

    2016-04-25

    Heat stress is likely to be a key factor in the negative impact of climate change on crop production. Heat stress significantly influences the functions of roots, which provide support, water, and nutrients to other plant organs. Likewise, roots play an important role in the establishment of symbiotic associations with different microorganisms. Despite the physiological relevance of roots, few studies have examined their response to heat stress. Here in this study, we performed genome-wide transcriptomic and proteomic analyses on isolated root hairs, which are a single, epidermal cell type, and compared their response to stripped roots. On average, we identified 1849 and 3091 genes differentially regulated in root hairs and stripped roots, respectively, in response to heat stress. Our gene regulatory module analysis identified 10 key modules that might control the majority of the transcriptional response to heat stress. We also conducted proteomic analysis on membrane fractions isolated from root hairs and compared these responses to stripped roots. These experiments identified a variety of proteins whose expression changed within 3 h of application of heat stress. Most of these proteins were predicted to play a significant role in thermo-tolerance, as well as in chromatin remodeling and post-transcriptional regulation. In conclusion, the data presented represent an in-depth analysis of the heat stress response of a single cell type in soybean.

  15. Stress, life events, and socioeconomic disparities in health: results from the Americans' Changing Lives Study.

    PubMed

    Lantz, Paula M; House, James S; Mero, Richard P; Williams, David R

    2005-09-01

    It has been hypothesized that exposure to stress and negative life events is related to poor health outcomes, and that differential exposure to stress plays a role in socioeconomic disparities in health. Data from three waves of the Americans' Changing Lives study (n = 3,617) were analyzed to investigate prospectively the relationship among socioeconomic indicators, five measures of stress/negative life events, and the health outcomes of mortality, functional limitations, and self-rated health. The results revealed that (1) life events and other types of stressors are clearly related to socioeconomic position; (2) a count of negative lifetime events was positively associated with mortality; (3) a higher score on a financial stress scale was predictive of severe/moderate functional limitations and fair/poor self-rated health at wave 3; and (4) a higher score on a parental stress scale was predictive of fair/poor self-rated health at wave 3. The negative effects of low income on functional limitations attenuated to insignificance when waves 1 and 2 stress/life event measures were controlled for, but other socioeconomic disparities in health change remained sizable and significant when adjusted for exposure to stressors. The results support the hypothesis that differential exposure to stress and negative life events is one of many ways in which socioeconomic inequalities in health are produced in society.

  16. Variation in adult stress resistance does not explain vulnerability to climate change in copper butterflies.

    PubMed

    Klockmann, Michael; Wallmeyer, Leonard; Fischer, Klaus

    2017-03-15

    Ongoing climate change is a major threat to biodiversity. However, although many species clearly suffer from ongoing climate change, others benefit from it, for example, by showing range expansions. However, which specific features determine a species' vulnerability to climate change? Phenotypic plasticity, which has been described as the first line of defence against environmental change, may be of utmost importance here. Against this background, we here compare plasticity in stress tolerance in 3 copper butterfly species, which differ arguably in their vulnerability to climate change. Specifically, we investigated heat, cold and desiccation resistance after acclimatization to different temperatures in the adult stage. We demonstrate that acclimation at a higher temperature increased heat but decreased cold tolerance and desiccation resistance. Contrary to our predictions, species did not show pronounced variation in stress resistance, though plastic capacities in temperature stress resistance did vary across species. Overall, our results seemed to reflect population-rather than species-specific patterns. We conclude that the geographical origin of the populations used should be considered even in comparative studies. However, our results suggest that, in the 3 species studied here, vulnerability to climate change is not in the first place determined by stress resistance in the adult stage. As entomological studies focus all too often on adults only, we argue that more research effort should be dedicated to other developmental stages when trying to understand insect responses to environmental change. © 2017 Institute of Zoology, Chinese Academy of Sciences.

  17. Change in paleo-stress state before and after large earthquake, in the Chelung-pu fault, Taiwan

    NASA Astrophysics Data System (ADS)

    Hashimoto, Y.; Kota, T.; Yeh, E. C.; Lin, W.

    2014-12-01

    Stress state close to seismogenic fault is a key parameter to understand earthquake mechanics. Changes in stress state after large earthquakes were documented recently in the 1999 Chi-Chi earthquake, Taiwan, and 2011 Tohoku-Oki earthquake, Northeast Japan. If the temporal changes are common in the past and in the future, the change in paleostress related to large earthquakes are expected to be obtained from micro-faults preserved in outcrops or drilled cores. In this study, we show a change in paleostress from micro-fault slip data observed around the Chelung-pu fault in the Taiwan Chelung-pu fault Drilling Project (TCDP), which is possibly associated with the stress drop by large earthquakes along the Chelung-pu fault. Combining obtained stress orientations, stress ratio and stress polygons, stress magnitude for each stress state and difference in stress magnitude between obtained stresses are estimated. For stress inversion analysis, multiple inversion method (MIM, Yamaji et al., 2000) was carried out. To estimate the centers of clusters automatically, K-means clustering (Otsubo et al., 2006) was conducted on the result of MIM. In the result, four stress states were estimated. The stress states are named C1, C2, C3 and C4 in ascending order of stress ratio (Φ). Stress ratio is defined as (σ1-σ2) / (σ1-σ3). To constraint the stress magnitude, stress polygons are employed combining with the inverted stress states. The principal stress vectors for four stress states (C1-C4) was projected to the SHmax or the Shmin and vertical stress directions. SHmax is larger than Shmin as definition. Stress ratio was estimated by inversion method. Combining those conditions, a linear function in SHmax and Shmin space respected to Sv is obtained from inverted stress states. We obtained two groups of stress state from the slip data in the TCDP core. One stress state has WNW-ESE horizontal sigma1 and larger stress magnitude including reverse fault regime. Another stress state

  18. Aging-related changes in oxidative stress response of human endothelial cells.

    PubMed

    Conti, Valeria; Corbi, Graziamaria; Simeon, Vittorio; Russomanno, Giusy; Manzo, Valentina; Ferrara, Nicola; Filippelli, Amelia

    2015-08-01

    Oxidative stress is strongly associated with aging and age-related diseases and plays a crucial role in endothelial dysfunction development. To better understand the molecular mechanisms of aging and stress response in humans, we examined changes to young and older human endothelial cells over time (72, 96 and 120 h), before and after H2O2-induced stress. We measured the expression of the deacetylase Sirtuin 1 (Sirt1) and its transcriptional target Forkhead box O3a (Foxo3a); TBARS, a well-known marker of overall oxidative stress, and catalase activity as index of antioxidation. Moreover, we quantified levels of cellular senescence by senescence-associated β galactosidase (SA-βgal) assay. Under oxidative stress induction older cells showed a progressive decrease of Sirt1 and Foxo3a expression, persistently high TBARS levels with high, but ineffective Cat activity to counteract such levels. In addition cellular senescence drastically increased in older cells compared with Young cells both in presence and in the absence of oxidative stress. By following the cell behavior during the time course, we can hypothesize that while in young cells an oxidative stress induction stimulated an adequate response through activation of molecular factor crucial to counteract oxidative stress, the older cells are not able to adequately adapt themselves to external stress stimuli. During their life, endothelial cells impair the ability to defend themselves from oxidative stress stimuli. This dysfunction involves the pathway of Sirt1 a critical regulator of oxidative stress response and cellular lifespan, underlining its crucial role in endothelial homeostasis control during aging and age-associated diseases.

  19. Social stress induces changes in urinary bladder function, bladder NGF content, and generalized bladder inflammation in mice.

    PubMed

    Mingin, Gerald C; Peterson, Abbey; Erickson, Cuixia Shi; Nelson, Mark T; Vizzard, Margaret A

    2014-10-01

    Social stress may play a role in urinary bladder dysfunction in humans, but the underlying mechanisms are unknown. In the present study, we explored changes in bladder function caused by social stress using mouse models of stress and increasing stress. In the stress paradigm, individual submissive FVB mice were exposed to C57BL/6 aggressor mice directly/indirectly for 1 h/day for 2 or 4 wk. Increased stress was induced by continuous, direct/indirect exposure of FVB mice to aggressor mice for 2 wk. Stressed FVB mice exhibited nonvoiding bladder contractions and a decrease in both micturition interval (increased voiding frequency) and bladder capacity compared with control animals. ELISAs demonstrated a significant increase in histamine protein expression with no change in nerve growth factor protein expression in the urinary bladder compared with controls. Unlike stressed mice, mice exposed to an increased stress paradigm exhibited increased bladder capacities and intermicturition intervals (decreased voiding frequency). Both histamine and nerve growth factor protein expression were significantly increased with increased stress compared with control bladders. The change in bladder function from increased voiding frequency to decreased voiding frequency with increased stress intensity suggests that changes in social stress-induced urinary bladder dysfunction are context and duration dependent. In addition, changes in the bladder inflammatory milieu with social stress may be important contributors to changes in urinary bladder function.

  20. Differential changes in platelet reactivity induced by acute physical compared to persistent mental stress.

    PubMed

    Hüfner, Katharina; Koudouovoh-Tripp, Pia; Kandler, Christina; Hochstrasser, Tanja; Malik, Peter; Giesinger, Johannes; Semenitz, Barbara; Humpel, Christian; Sperner-Unterweger, Barbara

    2015-11-01

    Platelets are important in hemostasis, but also contain adhesion molecules, pro-inflammatory and immune-modulatory compounds, as well as most of the serotonin outside the central nervous system. Dysbalance in the serotonin pathways is involved in the pathogenesis of depressive symptoms. Thus, changes in platelet aggregation and content of bioactive compounds are of interest when investigating physiological stress-related mental processes as well as stress-related psychiatric diseases such as depression. In the present study, a characterization of platelet reactivity in acute physical and persistent mental stress was performed (aggregation, serotonin and serotonin 2A-receptor, P-selectin, CD40 ligand, matrix metalloproteinase-2 and -9 (MMP-2 and -9), platelet/endothelial adhesion molecule-1 (PECAM-1), intercellular adhesion molecule-1 (ICAM-1), β-thromboglobulin (β-TG) and platelet factor 4 (PF-4). Acute physical stress increased platelet aggregability while leaving platelet content of bioactive compounds unchanged. Persistent mental stress led to changes in platelet content of bioactive compounds and serotonin 2A-receptor only. The values of most bioactive compounds correlated with each other. Acute physical and persistent mental stress influences platelets through distinct pathways, leading to differential changes in aggregability and content of bioactive compounds.

  1. Analysis of 2012 M8.6 Indian Ocean earthquake coseismic slip model based on GPS data

    NASA Astrophysics Data System (ADS)

    Maulida, Putra; Meilano, Irwan; Gunawan, Endra; Efendi, Joni

    2016-05-01

    The CGPS (Continuous Global Position System) data of Sumatran GPS Array (CGPS) and Indonesian Geospatial Agency (BIG) in Sumatra are processed to estimate the best fit coseismic model of 2012 M8.6 Indian Ocean earthquake. For GPS data processing, we used the GPS Analysis at Massachusetts Institute of Technology (GAMIT) 10.5 software and Global Kalman Filter (GLOBK) to generate position time series of each GPS stations and estimate the coseismic offset due to the Earthquake. The result from GPS processing indicates that the earthquake caused displacement northeast ward up to 25 cm in northern Sumatra. Results also show subsidence at the northern Sumatran while the central part of Sumatra show northwest direction displacement, but we cannot find whether the subsidence or the uplift signal associated to the earthquake due to the vertical data quality. Based on the GPS coseismic data, we evaluate the coseismic slip model of Indian Ocean Earthquake produced by previous study [1], [2], [3]. We calculated coseismic displacement using half-space with earthquake slip model input and compare it with the displacement produced form GPS data.

  2. Climate change projections of heat stress in Europe: From meteorological variables to impacts on productivity

    NASA Astrophysics Data System (ADS)

    Casanueva, Ana; Kotlarski, Sven; Liniger, Mark A.

    2017-04-01

    Future climate change is likely to have important impacts in many socio-economic sectors. In particular, higher summer temperatures or more prolonged heat waves may be responsible for health problems and productivity losses related to heat stress, especially affecting people exposed to such situations (e.g. working under outside settings or in non-acclimatized workplaces). Heat stress on the body under work load and consequently their productivity loss can be described through heat stress indices that are based on multiple meteorological parameters such as temperature, humidity, wind and radiation. Exploring the changes of these variables under a warmer climate is of prime importance for the Impacts, Adaptation and Vulnerability communities. In particular, the H2020 project HEAT-SHIELD aims at analyzing the impact of climate change on heat stress in strategic industries in Europe (manufacturing, construction, transportation, tourism and agriculture) within an inter-sectoral framework (climate scientists, biometeorologists, physiologists and stakeholders). In the present work we explore present and future heat stress over Europe using an ensemble of the state-of-the-art RCMs from the EURO-CORDEX initiative. Since RCMs cannot be directly used in impact studies due to their partly substantial biases, a standard bias correction method (empirical quantile mapping) is applied to correct the individual variables that are then used to derive heat stress indices. The objectives of this study are twofold, 1) to test the ability of the separately bias corrected variables to reproduce the main characteristics of heat stress indices in present climate conditions and 2) to explore climate change projections of heat stress indices. We use the wet bulb globe temperature (WBGT) as primary heat stress index, considering two different versions for indoor (or in the shade, based on temperature and humidity conditions) and outdoor settings (including also wind and radiation). The WBGT

  3. Stress-induced changes in circadian rhythms of body temperature and activity in rats are not caused by pacemaker changes.

    PubMed

    Meerlo, P; van den Hoofdakker, R H; Koolhaas, J M; Daan, S

    1997-02-01

    Previous work has shown that social stress in rats (i.e., defeat by an aggressive male conspecific) causes a variety of behavioral and physiological changes including alterations in the daily rhythms of body temperature and activity. To study the role of the circadian pacemaker in these stress-induced changes, three experiments were performed, successively addressing pacemaker period, phase, and sensitivity to light. In all experiments, rats were subjected to social stress by placing them in the home cage of a dominant conspecific for 1 h. This was done on 2 consecutive days, between the second and fifth hours of the activity phase. Experimental animals were attacked by the resident and lost the fight as indicated by submissive behavior. Control animals were placed in an unfamiliar but clean and empty cage for 1 h. In Experiment 1, the effects of social stress on the period of the free-running activity rhythm were studied. Rats were individually housed under constant dim red light. Activity was measured with infrared detectors. Social defeat caused a reduction of activity for a number of days, but the period of the free-running rhythm was not affected. In Experiment 2, the authors studied whether social defeat induced acute phase shifts. Body temperature and activity were measured by means of radiotelemetry with intraperitoneally implanted transmitters. After the social interactions, experimental animals were kept under constant dim red light. Social stress caused a profound reduction in the amplitude of the body temperature and activity rhythm, but no significant phase shifts occurred. In Experiment 3, the authors studied whether social defeat affected the circadian pacemaker's sensitivity to light given that the size of light-induced phase shifts is thought to reflect pacemaker amplitude. Again, body temperature and activity were measured by means of telemetry. After double social defeat, animals were kept under continuous dim red light. One day after the second

  4. High-precision coseismic displacement estimation with a single-frequency GPS receiver

    NASA Astrophysics Data System (ADS)

    Guo, Bofeng; Zhang, Xiaohong; Ren, Xiaodong; Li, Xingxing

    2015-07-01

    To improve the performance of Global Positioning System (GPS) in the earthquake/tsunami early warning and rapid response applications, minimizing the blind zone and increasing the stability and accuracy of both the rapid source and rupture inversion, the density of existing GPS networks must be increased in the areas at risk. For economic reasons, low-cost single-frequency receivers would be preferable to make the sparse dual-frequency GPS networks denser. When using single-frequency GPS receivers, the main problem that must be solved is the ionospheric delay, which is a critical factor when determining accurate coseismic displacements. In this study, we introduce a modified Satellite-specific Epoch-differenced Ionospheric Delay (MSEID) model to compensate for the effect of ionospheric error on single-frequency GPS receivers. In the MSEID model, the time-differenced ionospheric delays observed from a regional dual-frequency GPS network to a common satellite are fitted to a plane rather than part of a sphere, and the parameters of this plane are determined by using the coordinates of the stations. When the parameters are known, time-differenced ionospheric delays for a single-frequency GPS receiver could be derived from the observations of those dual-frequency receivers. Using these ionospheric delay corrections, coseismic displacements of a single-frequency GPS receiver can be accurately calculated based on time-differenced ca