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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. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. The Co-seismic Effects of 2010 Mw 8.8 Maule Earthquake

    NASA Astrophysics Data System (ADS)

    Huang, L.; Zhang, B.; Qu, W.; Zhang, H.; Shi, Y.

    2015-12-01

    The 2010 Chile Maule earthquake ranks as the sixth largest earthquake ever to be recorded by a seismograph. Plane assumption is inapplicability to the exceptionally large earthquakes, in this paper, with the finite element method considering Earth's layered structure and curvature, co-seismic deformation field and stress field are calculated. Based on the Coulomb stress change, seismic activity of surrounding faults and triggering of aftershocks is estimated. The results show that: the effects of Earth's layered structure and curvature on co-seismic horizontal and vertical displacement are significant. The plane layered model or plane half-space model may underestimate the far-field co-seismic displacement and strain near the equator and overestimate and underestimate the far-field displacement and strain near Antarctica, respectively. The range of influence of co-seismic displacement is about thousands of kilometers, relatively large horizontal displacements locate on the northwest and southeast of the seismic fault. Horizontal displacement in One-half of South America is about the magnitude order of 0.5 mm. Stress drop caused by this earthquake in Central Argentina is equivalent to 5-10 years tectonic stress accumulation while in Northern Argentina and Southern Argentina is equivalent to 1-5 years tectonic stress release. Coulomb stress change in earthquake fractured zone is equivalent to 15 years tectonic stress release which means next great earthquake will not come at this region in short time. Coulomb stress change in unfracture regions near the fracture zone is equivalent to 15 years tectonic stress accumulation, which means the seismicity increasing. Coulomb stress change on optimally orientated faults are calculated, 66.2% of aftershocks occur in regions where the failure stress exceed 10 kPa. The great Mw 6.9 and Mw 7.0 aftershocks near Pichilemu were triggered by the great Maule earthquake.

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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%.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. [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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  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-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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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)

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. [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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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…

  4. 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

  5. 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.

  6. 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

  7. Life Changes and Social Support: Stress and Its Moderators.

    DTIC Science & Technology

    1981-04-17

    V1979), and (3) reflect the multidimensionality of life changes (Ruch, 1977) are now being developed and bode well for progress in this area...situations more arousing than they would like. Sensation seeking as a personality attribute may well serve as an important moderator of life stress...is an important moderator between experiencing stressful life events and psychological well -being. A helping spouse seems to be particularly valuable

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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…

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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.

  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. 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.

  1. Co-seismic thermal dissociation of carbonate fault rocks: Naukluft Thrust, central Namibia

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Miller, J. A.; Sylvester, F.; Backeberg, N.; Faber, C.; Mapani, B.

    2009-12-01

    the coatings is never observed as pore-fill between grains or other geometries typical of cement precipitates. Smoothness and radial symmetry of the coatings suggest that the grains were coated in suspension by very fine material, potentially analogous to the frictionally-generated CaO developed on the base of some landslides in carbonate rocks (Hewitt, 1988). The very thick layers of cataclasite without internal crosscutting suggest free particle paths associated with fluidization at high fluid pressure and low effective normal stress. We suggest that co-seismic frictional heating along the Naukluft Thrust caused dissociation of dolomite fault rock, producing in-situ spikes in fluid pressure (CO2) and very fine caustic CaO which chemically attacked the carbonate grains in suspension causing the smoothing and rounding. These residues then coated individual grains prior to loss of fluid pressure and settling in the fault zone. Such an event would have been associated with near total strength drop along the Naukluft Thrust. Hewitt, K., 1988 Science, v. 242, no. 4875, p. 64-67.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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…

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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.

  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. Dynamic changes in saliva after acute mental stress.

    PubMed

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

    2014-05-08

    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.

  14. 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.

  15. 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…

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  17. 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.

  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. 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

  20. 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

  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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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. 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.

  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. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. The effect of stress and stress hormones on dynamic colour-change in a sexually dichromatic Australian frog.

    PubMed

    Kindermann, Christina; Narayan, Edward J; Wild, Francis; Wild, Clyde H; Hero, Jean-Marc

    2013-06-01

    Rapid colour changes in vertebrates have fascinated biologists for centuries, herein we demonstrate dynamic colour change in an anuran amphibian, the stony creek frog (Litoria wilcoxii), which turns from brown to bright (lemon) yellow during amplexus. We show this by comparing the colour of baseline (unpaired males) and amplecting (paired) males. We also investigate the possible role of stress and stress hormones on this colour change. Frogs were subjected to four different levels of stressors (handling, toe-clipping, saline injection and adrenocorticotropic hormone [ACTH] injection) and the colour change was measured using digital photography. A comparison of baseline colour and stress hormone (corticosterone) levels was also conducted to give further insight to this topic. From the images, the Red Blue Green (RGB) colour values were calculated, and a principal components analysis (PCA) was used to create a single colour metric (the major axis) as an index of colour in the visible spectrum. A moderate stressor (toe-clipping) led to a significant change in colour (within 10 min) similar to that of amplecting males. Surprisingly, neither a mild stressor (handling and saline injection) nor the maximum stressor (handling and ACTH injection) led to a lightening response. This study confirms that the dynamic male colour change in this species in response to medium stressors adds new knowledge to the understanding of the functional mechanisms of dynamic colour change in amphibians.

  1. 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

  2. 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.

  3. 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.

  4. 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…

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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…

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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 e.g., 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 three Copper butterfly species, which differ arguably in their vulnerability to climate change. Specifically, we investigated heat, cold and desiccation resistance after acclimatisation 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 three 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. This article is protected by copyright. All rights reserved.

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. Changes in the proteome of grapevine leaves (Vitis vinifera L.) during long-term drought stress.

    PubMed

    Król, Angelika; Weidner, Stanisław

    2017-04-01

    The essence of exploring and understanding mechanisms of plant adaptation to environmental stresses lies in the determination of patterns of the expression of proteins, identification of stress proteins and their association with the specific functions in metabolic pathways. To date, little information has been provided about the proteomic response of grapevine to the persistent influence of adverse environmental conditions. This article describes changes in the profile of protein accumulation in leaves of common grapevine (Vitis vinifera L.) seedlings in response to prolonged drought. Isolated proteins were separated by two-dimensional electrophoresis (2 DE), and the proteins whose level of accumulation changed significantly due to the applied stress factors were identified with tandem mass spectrometry MALDI TOF/TOF type. Analysis of the proteome of grapevine leaves led to the detection of many proteins whose synthesis changed in response to the applied stressor. Drought caused the most numerous changes in the accumulation of proteins associated with carbohydrate and energy metabolism, mostly connected with the pathways of glycolysis and photosystem II protein components. The biological function of the identified proteins is discussed with reference to the stress of drought. Some of the identified proteins, especially the ones whose accumulation increased during drought stress, may be responsible for the adaptation of grapevine to drought.

  9. Yeast adapts to a changing stressful environment by evolving cross-protection and anticipatory gene regulation.

    PubMed

    Dhar, Riddhiman; Sägesser, Rudolf; Weikert, Christian; Wagner, Andreas

    2013-03-01

    Organisms can protect themselves against future environmental change. An example is cross-protection, where physiological adaptation against a present environmental stressor can protect an organism against a future stressor. Another is anticipation, where an organism uses information about its present environment to trigger gene expression and other physiological changes adaptive in future environments. "Predictive" abilities like this exist in organisms that have been exposed to periodic changes in environments. It is unknown how readily they can evolve. To answer this question, we carried out laboratory evolution experiments in the yeast Saccharomyces cerevisiae. Specifically, we exposed three replicate populations of yeast to environments that varied cyclically between two stressors, salt stress and oxidative stress, every 10 generations, for a total of 300 generations. We evolved six replicate control populations in only one of these stressors for the same amount of time. We analyzed fitness changes and genome-scale expression changes in all these evolved populations. Our populations evolved asymmetric cross protection, where oxidative stress protects against salt stress but not vice versa. Gene expression data also suggest the evolution of anticipation and basal gene expression changes that occur uniquely in cyclic environments. Our study shows that highly complex physiological states that are adaptive in future environments can evolve on very short evolutionary time scales.

  10. Prenatal stress changes the glycoprotein GPM6A gene expression and induces epigenetic changes in rat offspring brain.

    PubMed

    Monteleone, Melisa C; Adrover, Ezequiela; Pallarés, María Eugenia; Antonelli, Marta C; Frasch, Alberto C; Brocco, Marcela A

    2014-01-01

    Prenatal stress (PS) exerts strong impact on fetal brain development and on adult offspring brain functions. Previous work demonstrated that chronic stress alters the mRNA expression of GPM6A, a neuronal glycoprotein involved in filopodium extension. In this work, we analyzed the effect of PS on gpm6a expression and the epigenetic mechanisms involved. Pregnant Wistar rats received restraint stress during the last week of gestation. Male offspring were sacrificed on postnatal days 28 and 60. Hippocampus and prefrontal cortex samples were analyzed for gene expression (qPCR for mRNAs and microRNAs), methylation status (bisulfite conversion) and protein levels. Hippocampal neurons in culture were used to analyze microRNA overexpression effects. Prenatal stress induced changes in gpm6a levels in both tissues and at both ages analyzed, indicating a persistent effect. Two CpG islands in the gpm6a gene were identified. Variations in the methylation pattern at three specific CpGs were found in hippocampus, but not in PFC samples from PS offspring. microRNAs predicted to target gpm6a were identified in silico. qPCR measurements showed that PS modified the expression of several microRNAs in both tissues, being microRNA-133b the most significantly altered. Further studies overexpressing this microRNA in neuronal cultures showed a reduction in gmp6a mRNA and protein level. Moreover filopodium density was also reduced, suggesting that GPM6A function was affected. Gestational stress affected gpm6a gene expression in offspring likely through changes in methylation status and in posttranscriptional regulation by microRNAs. Thus, our findings propose gpm6a as a novel target for epigenetic regulation during prenatal stress.

  11. Recent changes of rice heat stress in Jiangxi province, southeast China

    NASA Astrophysics Data System (ADS)

    Huang, Jin; Zhang, Fangmin; Xue, Yan; Lin, Jie

    2016-08-01

    Around the intensity, frequency, duration, accumulated temperature, and even extremes of high-temperature events, nine selected temperature-related indices were used to explore the space and time changes of rice heat stress in Jiangxi province, southeast China. Several statistical methods including Mann-Kendall trend test (M-K test) and principal component analysis (PCA) were used in this study, and main results were listed as follows: (1) The changes in the intensity indices for high-temperature events were more significant, it was mainly embodied in that more than 80 % of stations had positive trends. (2) R-mode PCA was applied to the multiannual average values of nine selected indices of whole stations, and the results showed that the higher hazard for rice heat stress could be mainly detected in the middle and northeast area of Jiangxi. (3) S-mode PCA was applied to the integrated heat stress index series, and the results demonstrated that Jiangxi could be divided into four sub-regions with different variability in rice heat stress. However, all the sub-regions are dominated by increasing tendencies in rice heat stress since 1990. (4) Further analysis indicated that the western north Pacific sub-tropical high (WPSH) had the significant dominant influence on the rice heat stress in Jiangxi province.

  12. Changes in perceived stress and recovery in overreached young elite soccer players.

    PubMed

    Brink, M S; Visscher, C; Coutts, A J; Lemmink, K A P M

    2012-04-01

    The aim of this study was to prospectively monitor sport-specific performance and assess the stress-recovery balance in overreached (OR) soccer players and controls. During two competitive seasons, 94 players participated in the study. The stress-recovery balance (RESTQ-Sport) and sport-specific performance (Interval Shuttle Run Test) were assessed monthly. Seven players with performance decrement of at least a month were classified as OR. Stress and recovery measures were assessed between groups (OR vs healthy players) and at different times within the OR group. An unfavorable total recovery score appeared 2 months before diagnosis when compared with the reference values of the healthy group established at the start of the season (P=0.009) and also over the two seasons (P=0.028). The scales Emotional Stress (P=0.044), Physical Recovery (P=0.009), General Well-being (P=0.001) and Sleep Quality (P=0.045) were sensitive to OR compared with the average of the healthy group over the two seasons. Finally, Fatigue and Being in Shape demonstrated the largest changes in stress and recovery within the OR players (effect size=1.14 and 1.50). The longitudinal monitoring of performance and changes in stress and recovery may be useful for the detection of OR in its earliest stage. The information obtained from these tests can be used to optimize individual training and recovery programs.

  13. 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. Roots 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 the response of these plant organs 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 whole roots. We identified 2,013 genes differentially regulated in root hairs in response to heat stress. Our gene regulatory module analysis identified ten, key modules that controlled the majority of the transcriptional response to heat stress. We also conducted proteomic analysis on membrane fractions isolated from roots and root hairs. These experiments identified a variety of proteins whose expression changed within 3 hours of application of heat stress. Most of these proteins were predicted to play a role in thermotolerance, 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.

  14. 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.

  15. A hyperspectral index sensitive to subtle changes in the canopy chlorophyll content under arsenic stress

    NASA Astrophysics Data System (ADS)

    Li, Xuqing; Liu, Xiangnan; Liu, Meiling; Wang, Cuicui; Xia, Xiaopeng

    2015-04-01

    Arsenic stress induces in subtle changes in the canopy chlorophyll content (CCC). Therefore, the establishment of a spectral index that is sensitive to subtle changes in the CCC is important for monitoring crop arsenic contamination in large areas by remote sensing. Experimental sites with three contamination levels were selected and were located in Chang Chun City, Jilin City, Jilin Province, China. Arsenic stress can induce small changes in the CCC, reflecting in the crop spectrum. This study created a new index to monitor the CCC. Then, the results from the index were compared with these from other indices and the random forest model, respectively. The final purpose of this study is to find an optimal index, which is sensitive to small changes in the CCC under arsenic stress for monitoring regional CCC in rice. The results indicate that the distribution of the CCC is aligned with the distribution of the arsenic stress level and that NVI (R640, R732, and R752) is the best index for monitoring CCC. The correlation coefficient R2 between the predicated values using NVI and the measured values of canopy chlorophyll content is 0.898, which performs better than the random forest model and other indices.

  16. Drought stress-induced changes of microRNAs in diploid and autotetraploid Paulownia tomentosa.

    PubMed

    Cao, Xibing; Fan, Guoqiang; Cao, Lin; Deng, Minjie; Zhao, Zhenli; Niu, Suyan; Wang, Zhe; Wang, Yuanlong

    2017-01-01

    Drought stress adversely affects plant productivity. Growth and timber production of Paulownia trees are limited under drought stress. Changes in gene expression patterns and miRNA in different ploidy of Paulownia tomentosa have been investigated. However, the responses of P. tomentosa to drought stress at the microRNA (miRNA) level have not been reported so far. To identify miRNA candidates and their target genes involved in the drought stress response in diploid and tetraploid P. tomentosa, four small RNA and four degradome libraries from diploid and autotetraploid P. tomentosa under normal and drought stress conditions were constructed and sequenced. A total of 41 conserved and 90 novel miRNAs were identified. Among these miRNAs, 67 (26 conserved and 41 novel) and 53 (six conserved and 47 novel) were significantly differentially expressed in response to drought stress in diploid and autotetraploid P. tomentosa, respectively. Degradome analysis identified 356 candidate miRNA target genes that encoded proteins with functions that included plant defense, transcriptional regulation, and hormone metabolism. In particular, miR4 and miR156 were identified only in autotetraploid P. tomentosa under drought stress. These results will help us build a foundation for future studies of the biological functions of miRNA-mediated gene regulation in P. tomentosa.

  17. Laboratory observations of fault strength in response to changes in normal stress

    USGS Publications Warehouse

    Kilgore, Brian D.; Lozos, Julian; Beeler, Nicholas M.; Oglesby, David

    2012-01-01

    Changes in fault normal stress can either inhibit or promote rupture propagation, depending on the fault geometry and on how fault shear strength varies in response to the normal stress change. A better understanding of this dependence will lead to improved earthquake simulation techniques, and ultimately, improved earthquake hazard mitigation efforts. We present the results of new laboratory experiments investigating the effects of step changes in fault normal stress on the fault shear strength during sliding, using bare Westerly granite samples, with roughened sliding surfaces, in a double direct shear apparatus. Previous experimental studies examining the shear strength following a step change in the normal stress produce contradictory results: a set of double direct shear experiments indicates that the shear strength of a fault responds immediately, and then is followed by a prolonged slip-dependent response, while a set of shock loading experiments indicates that there is no immediate component, and the response is purely gradual and slip-dependent. In our new, high-resolution experiments, we observe that the acoustic transmissivity and dilatancy of simulated faults in our tests respond immediately to changes in the normal stress, consistent with the interpretations of previous investigations, and verify an immediate increase in the area of contact between the roughened sliding surfaces as normal stress increases. However, the shear strength of the fault does not immediately increase, indicating that the new area of contact between the rough fault surfaces does not appear preloaded with any shear resistance or strength. Additional slip is required for the fault to achieve a new shear strength appropriate for its new loading conditions, consistent with previous observations made during shock loading.

  18. [EEG changes and stress reactions in rat induced by millimeter wave].

    PubMed

    Xie, Taorong; Pei, Jian; Li, Fen; Huang, Xin; Chen, Shude; Qiao, Dengjiang

    2011-02-01

    The present paper is aimed to study the processes of stress reaction and their judgment bases in rat induced by 35 GHz millimeter wave quantitatively. The relative change in the average energy of each EEG frequency band decomposed by wavelet analysis was calculated for extracting the stress indicator for the purpose. The rat would experience quiet period, guarding period, deadlock period and prostrating period in sequence. The judgment bases of different stress periods in rat induced by millimeter wave were obtained by analyzing the skin temperature, skin injury and changes of blood biochemical indexes during each stress period. The stress period changed from quiet period to guarding period when the skin temperature of irradiated area reached the thermal pain threshold. It was from guarding period to deadlock period when the skin had gotten serious injury. Then the rat reaction sensitivity decreased, and injury of its visceral organs occurred. The rat got to prostrating period when the sustained irradiation caused the rat's visceral organs to get more serious injury. The further sustained irradiation finally induced death of the rat.

  19. Changes in anxiety levels are followed by changes in behavioral strategy in mice subjected to stress and in the extent of stress-induced analgesia.

    PubMed

    Kenunen, O G; Prakh'e, I V; Kozlovskii, V L

    2006-02-01

    The experiments reported here demonstrated that corasol increased the extent of analgesia induced by stress and decreased the duration of immobility in mice in a forced swimming test in cold water. Administration of diazepam led to the opposite changes and counteracted the actions of the anxiogen. The effects of the anxiolytic were more apparent in NMRI than mongrel mice, while in mongrel mice the effects of the anxiogen were more marked. Changes in measures following administration of agents were reciprocal in nature. These results lead to the conclusion that that these changes are determined by the level of anxiety, and that the strain differences between mongrel and NMRI mice are also linked with this factor.

  20. Diverging sensitivity of soil water stress to changing snowmelt timing in the Western U.S.

    NASA Astrophysics Data System (ADS)

    Harpold, Adrian A.

    2016-06-01

    Altered snowpack regimes from regional warming threaten mountain ecosystems with greater water stress and increased likelihood of vegetation disturbance. The sensitivity of vegetation to changing snowpack conditions is strongly mediated by soil water storage, yet a framework to identify areas sensitive to changing snowpack regimes is lacking. In this study we ask two questions: (1) How will changing snowmelt alter the duration of soil water stress and length of the soil-mediated growing season (shortened to water stress and growing season, respectively)? and (2) What site characteristics increase the sensitivity of water stress and growing season duration to changes in snowmelt? We compiled soil moisture at 5, 20 and 50 cm depths from 62 SNOTEL sites with > 5 years of records and detailed soil properties. Soil water stress was estimated based on measured wilting point water content. The day of snow disappearance consistently explained the greatest variability in water stress across all site-years and within individual sites, while summer precipitation explained the most variability in growing season length. On average, a one day earlier snow disappearance resulted in 0.62 days greater water stress and 36 of 62 sites had significant relationships between snow disappearance and water stress. Despite earlier snow disappearance leading to greater water stress at nearly all sites, earlier snow disappearance led to both significant increases (4 of 62) and decreases (5 of 62) in growing season length. Satellite derived vegetation greenness confirmed site-dependent changes could both increase and reduce maximum annual vegetation greenness with earlier snow disappearance. A simple soil moisture model demonstrated the potential for diverging growing season length with earlier snow disappearance was more likely in areas with finer soil texture, greater rooting depth, greater potential evapotranspiration, and greater precipitation. More work is needed to understand the role of

  1. 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 carrier-phase measurements in real time. The performance of the proposed approach is validated using 5 Hz GPS data collected during the 2012 Nicoya Peninsula Earthquake (Mw 7.6, 2012 September 5) in Costa Rica. This shows that the proposed approach improves the accuracy of the displacement of a single-frequency GPS station, and coseismic displacements with an accuracy of a few centimetres are achieved over a 10-min interval.

  2. Changes in cellular infrastructure after induced endoplasmic reticulum stress in Moniliophthora perniciosa.

    PubMed

    Basso, Tatiana Setenta; Vita-Santos, Evelyn; Marisco, Gabriele; Pungartnik, Cristina; Brendel, Martin

    2016-09-01

    Moniliophthora perniciosa is a basidiomycete fungus that causes witches' broom disease in Theobroma cacao We analyzed the morphology and survival of fungal hyphae and endoplasmic reticulum (ER) remodeling in either glucose- or glycerol-grown M. perniciosa after treatment with ER stress-inducing chemicals dithiothreitol (DTT) or tunicamycin (TM). Changes in intracellular redox potential can cause endoplasmic reticulum (ER) stress due to diminished efficiency in protein folding that could in turn reduce cell survival. Such stress diminishes protein-folding efficiency that could in turn reduce cell survival. Light microscopy revealed morphological changes in hyphae after TM but not after DTT treatment, regardless of the media carbon source. Decrease in fungal survival, after both TM and DTT treatments, was dose-dependent and glycerol-grown cells showed a higher resistance to both chemicals compared to glucose-grown cells. Electron microscopy showed TM and DDT-induced ER stress in M. perniciosa as evidenced by structural alterations of the organelle. The volume of ER structures increased as a typical consequence of unfolded protein stress, and the number of autophagosomes was higher. In glycerol-grown fungus DTT treatment slightly induced expression of molecular chaperone BiP. The TM exposure-induced expression of gene MpIRE1, involved in signaling of the unfolded protein response, was higher in glycerol than glucose-grown cells. Such difference was not observable with expression of gene MpATG8, encoding a key protein in autosome formation, that was induced 1.4-fold and 1.2-fold in glucose or glycerol-grown cells, respectively. DHE-based fluorescence assay showed M. perniciosa oxidative stress induced by H2O2, and treated cells had a higher level of oxidative stress compared to control. A comprehensive study of remodeling of ER is important in understanding M. perniciosa fungus resistance to oxidative stress and its ability to implement a successful infection in T

  3. Oxidative stress-induced epigenetic changes associated with malignant transformation of human kidney epithelial cells.

    PubMed

    Mahalingaiah, Prathap Kumar S; Ponnusamy, Logeswari; Singh, Kamaleshwar P

    2016-09-17

    Renal Cell Carcinoma (RCC) in humans is positively influenced by oxidative stress status in kidneys. We recently reported that adaptive response to low level of chronic oxidative stress induces malignant transformation of immortalized human renal tubular epithelial cells. Epigenetic alterations in human RCC are well documented, but its role in oxidative stress-induced malignant transformation of kidney cells is not known. Therefore, the objective of this study was to evaluate the potential role of epigenetic changes in chronic oxidative stress-induced malignant transformation of HK-2, human renal tubular epithelial cells. The results revealed aberrant expression of epigenetic regulatory genes involved in DNA methylation (DNMT1, DNMT3a and MBD4) and histone modifications (HDAC1, HMT1 and HAT1) in HK-2 cells malignantly transformed by chronic oxidative stress. Additionally, both in vitro soft agar assay and in vivo nude mice study showing decreased tumorigenic potential of malignantly transformed HK-2 cells following treatment with DNA de-methylating agent 5-aza 2' dC further confirmed the crucial role of DNA hypermethyaltion in oxidative stress-induced malignant transformation. Changes observed in global histone H3 acetylation (H3K9, H3K18, H3K27 and H3K14) and decrease in phospho-H2AX (Ser139) also suggest potential role of histone modifications in increased survival and malignant transformation of HK-2 cells by oxidative stress. In summary, the results of this study suggest that epigenetic reprogramming induced by low levels of oxidative stress act as driver for malignant transformation of kidney epithelial cells. Findings of this study are highly relevant in potential clinical application of epigenetic-based therapeutics for treatments of kidney cancers.

  4. Spatio-temporal stress states estimated from seismicity rate changes in the Tokai region, central Japan

    NASA Astrophysics Data System (ADS)

    Toda, Shinji; Matsumura, Shozo

    2006-04-01

    Since unprecedented large-scale silent slip was detected by GPS in 2001 in the Tokai region, evaluating whether such movement is uniquely connected to the expected Tokai earthquake or repeatedly occurs in this area becomes vitally important. Because of short history of GPS observations and the limited areal coverage surrounding the Suruga trough, we take advantage of continuously recorded seismicity that is presumed to be sensitive to the deformation at seismogenic depth. Together with the well-maintained NIED earthquake data, we employ the seismicity-to-stress inversion approach of rate/state friction to infer the spatio-temporal stress changes in and around the presumed hypocentral zone of the future Tokai earthquake. Mapping stress changes inverted from microseismicity year by year, we find that the stress under Lake Hamana, the western expected future Tokai source, has been decreasing since 1999, during which the GPS data showed a normal trend of plate coupling. In contrast, stresses in the surrounding regions are calculated to have increased by transfer from Lake Hamana region. We interpret that this continuous process is associated with the 2000-2004 Tokai slow slip event. The characteristic patterns related to aseismic stress-release are also identified in the early 1980s and during 1987-1989, when slow events are inferred to have occurred on the basis of conventional geodetic measurements. Revisiting the seismotectonics and taking into account the mechanical implications of the inversion results, we argue that the transition zone situated between a deep stable creeping zone and a locked zone undergoes episodic creep and plays an important role in the transfer of stress to the locked zone. Consequently, even though we speculate that the current (2000 to present-day) silent slip event might be one of the repeating events, the inferred enlargement of the stress releasing area is significant and possibly raises the likelihood of the next Tokai earthquake.

  5. The response of the yeast Saccharomyces cerevisiae to sudden vs. gradual changes in environmental stress monitored by expression of the stress response protein Hsp12p.

    PubMed

    Nisamedtinov, Ildar; Lindsey, George G; Karreman, Robert; Orumets, Kerti; Koplimaa, Mariane; Kevvai, Kaspar; Paalme, Toomas

    2008-09-01

    The response of the yeast Saccharomyces cerevisiae to sudden vs. gradual changes in different environmental stress conditions during both respiratory growth and aerobic fermentative growth in the presence of excess glucose was investigated by monitoring the level and rate of expression of the stress response protein Hsp12p using the fluorescent fusion construct Hsp12p-Gfp2p. The initial expression level and the rate of Hsp12p synthesis was significantly greater under glucose-limited conditions in the chemostat (D<0.14 h(-1)) compared with when excess glucose was present in the auxostat. Decreasing the dilution rate and the glucose concentration further in the A-stat resulted in increased Hsp12p expression, which was more marked when a rapid rather than a gradual change was affected. Common stress factors such as NaCl, ethanol and elevated temperature caused stress responses in both D-stat and auxo-accelerostat culture. The magnitude of the stress response depended on the stress factor, cultivation conditions as well as the rate of change of the stress factor. The rate of Hsp12p synthesis increased due to all applied stresses, with the observed increase between 2 and 20 times lower when the stress was applied gradually rather than rapidly. The results suggested that the Hsp12p expression rate is a good indicator of applied stress in S. cerevisiae.

  6. Sudden, probably coseismic submergence of Holocene trees and grass in coastal Washington State

    USGS Publications Warehouse

    Atwater, B.F.; Yamaguchi, D.K.

    1991-01-01

    Growth-position plant fossils in coastal Washington State imply a suddenness of Holocene submergence that is better explained by coseismic lowering of the land than by decade- or century-long rise of the sea. Growth-position fossils implying sudden submergence include the stems and leaves of salt-marsh grass entombed in tide-flat mud close to 300 yr ago and roughly 1700 and 3100 yr ago. In some places the stems and leaves close to 300 yr old are surrounded by sand left by an extraordinary, landward-directed surge - probably a tsunami from a great thrust earthquake on the Cascadia subduction zone. -from Authors

  7. [Changes in Kinetics of Chemiluminescence of Plasma as a Measure of Systemic Oxidative Stress in Humans].

    PubMed

    Sozarukova, M M; Polimova, A M; Proskurnina, E V; Vladimirov, Yu A

    2016-01-01

    Oxidative stress is a pathogenetic factor of many diseases. The control of its level is important for early diagnosis and therapy adjustment. In this work, antioxidant status was estimated in blood plasma. In the system of 2,2'-azo-bis(2-amidinopropane)dihydrochloride-luminol a set of chemiluminescence kinetic curve parameters is proposed for oxidative stress level estimation (the latent period τ(lat) and the increasing of analytical signal ΔI(CL)). Uric acid and albumin were shown as the main components that responsible for changes in chemiluminescence kinetic curve of plasma. Serum albumin undergoes oxidative modification in dose-depend manner under the action of UV irradiation, it causes the enhancement of antioxidant properties. Changes in plasma chemiluminescence kinetics are proposed as a measure of oxidative stress in human body.

  8. Quantitative changes of secondary metabolites of Matricaria chamomilla by abiotic stress.

    PubMed

    Eliasová, Adriana; Repcák, Miroslav; Pastírová, Andrea

    2004-01-01

    The responses of young plants of diploid and tetraploid Matricaria chamomilla cultivars to abiotic stress were studied. The course of quantitative changes of main leaf secondary metabolites was evaluated within an interval from 6 h before to 54 h after spraying the leaf rosettes with aqueous CuCl2 solution. The content of herniarin in the treated plants rose approximately 3 times, simultaneously with a decline of its precursor (Z)- and (E)-2-beta-D-glucopyranosyloxy-4-methoxycinnamic acid. The highest amounts of umbelliferone in stressed plants exceeded 9 times and 20 times those observed in control plants of the tetraploid and diploid cultivar, respectively. Due to stress the concentration of ene-yne-dicycloether in leaves decreased by more than 40%. The pattern of quantity changes of the examined compounds in tetraploid and diploid plants was similar.

  9. Changes in effective stress during the 2003-2004 Ubaye seismic swarm, France

    NASA Astrophysics Data System (ADS)

    Daniel, G.; Prono, E.; Renard, F.; Thouvenot, F.; Hainzl, S.; Marsan, D.; Helmstetter, A.; Traversa, P.; Got, J. L.; Jenatton, L.; Guiguet, R.

    2011-01-01

    We study changes in effective stress (normal stress minus pore pressure) that occurred in the French Alps during the 2003-2004 Ubaye earthquake swarm. Two complementary data sets are used. First, a set of 974 relocated events allows us to finely characterize the shape of the seismogenic area and the spatial migration of seismicity during the crisis. Relocations are performed by a double-difference algorithm. We compute differences in travel times at stations both from absolute picking times and from cross-correlation delays of multiplets. The resulting catalog reveals a swarm alignment along a single planar structure striking N130°E and dipping 80°W. This relocated activity displays migration properties consistent with a triggering by a diffusive fluid overpressure front. This observation argues in favor of a deep-seated fluid circulation responsible for a significant part of the seismic activity in Ubaye. Second, we analyze time series of earthquake detections at a single seismological station located just above the swarm. This time series forms a dense chronicle of +16,000 events. We use it to estimate the history of effective stress changes during this sequence. For this purpose we model the rate of events by a stochastic epidemic-type aftershock sequence model with a nonstationary background seismic rate λ0(t). This background rate is estimated in discrete time windows. Window lengths are determined optimally according to a new change-point method on the basis of the interevent times distribution. We propose that background events are triggered directly by a transient fluid circulation at depth. Then, using rate-and-state constitutive friction laws, we estimate changes in effective stress for the observed rate of background events. We assume that changes in effective stress occurred under constant shear stressing rate conditions. We finally obtain a maximum change in effective stress close to -8 MPa, which corresponds to a maximum fluid overpressure of about

  10. Metabolic Changes in Masseter Muscle of Rats Submitted to Acute Stress Associated with Exodontia

    PubMed Central

    Iyomasa, Mamie Mizusaki; Fernandes, Fernanda Silva; Iyomasa, Daniela Mizusaki; Pereira, Yamba Carla Lara; Fernández, Rodrigo Alberto Restrepo; Calzzani, Ricardo Alexandre; Nascimento, Glauce Crivelaro; Leite-Panissi, Christie Ramos Andrade; Issa, João Paulo Mardegan

    2015-01-01

    Clinical evidence has shown that stress may be associated with alterations in masticatory muscle functions. Morphological changes in masticatory muscles induced by occlusal alterations and associated with emotional stress are still lacking in the literature. The objective of this study was to evaluate the influence of acute stress on metabolic activity and oxidative stress of masseter muscles of rats subjected to occlusal modification through morphological and histochemical analyses. In this study, adult Wistar rats were divided into 4 groups: a group with extraction and acute stress (E+A); group with extraction and without stress (E+C); group without extraction and with acute stress (NO+A); and control group without both extraction and stress (NO+C). Masseter muscles were analyzed by Succinate Dehydrogenase (SDH), Nicotinamide Adenine Dinucleotide Diaphorase (NADH) and Reactive Oxygen Species (ROS) techniques. Statistical analyses and two-way ANOVA were applied, followed by Tukey-Kramer tests. In the SDH test, the E+C, E+A and NO+A groups showed a decrease in high desidrogenase activities fibers (P < 0.05), compared to the NO+C group. In the NADH test, there was no difference among the different groups. In the ROS test, in contrast, E+A, E+C and NO+A groups showed a decrease in ROS expression, compared to NO+C groups (P < 0.05). Modified dental occlusion and acute stress - which are important and prevalent problems that affect the general population - are important etiologic factors in metabolic plasticity and ROS levels of masseter muscles. PMID:26053038

  11. Co-seismic offsets due to two earthquakes ( M w 6.1) along the Sumatran fault system derived from GNSS measurements

    NASA Astrophysics Data System (ADS)

    Ito, Takeo; Gunawan, Endra; Kimata, Fumiaki; Tabei, Takao; Meilano, Irwan; Agustan; Ohta, Yusaku; Ismail, Nazli; Nurdin, Irwandi; Sugiyanto, Didik

    2016-04-01

    Since the 2004 Sumatra-Andaman earthquake ( M w 9.2), the northwestern part of the Sumatran island has been a high seismicity region. To evaluate the seismic hazard along the Great Sumatran fault (GSF), we installed the Aceh GNSS network for the Sumatran fault system (AGNeSS) in March 2005. The AGNeSS observed co-seismic offsets due to the April 11, 2012 Indian Ocean earthquake ( M w 8.6), which is the largest intraplate earthquake recorded in history. The largest offset at the AGNeSS site was approximately 14.9 cm. Two M w 6.1 earthquakes occurred within AGNeSS in 2013, one on January 21 and the other on July 2. We estimated the fault parameters of the two events using a Markov chain Monte Carlo method. The estimated fault parameter of the first event was a right-lateral strike-slip where the strike was oriented in approximately the same direction as the surface trace of the GSF. The estimated peak value of the probability density function for the static stress drop was approximately 0.7 MPa. On the other hand, the co-seismic displacement fields of the second event from nearby GNSS sites clearly showed a left-lateral motion on a northeast-southwest trending fault plane and supported the contention that the July 2 event broke at the conjugate fault of the GSF. We also calculated the Coulomb failure function ΔCFF caused by the first event to evaluate its effect on the second event. The results showed that the July 2 event was likely brought 0.1 MPa closer to failure by the January 21 event.

  12. Change in Psychopathology in Referred Children: The Role of Life Events and Perceived Stress

    ERIC Educational Resources Information Center

    Willemen, Agnes M.; Koot, Hans M.; Ferdinand, Robert F.; Goossens, Frits A.; Schuengel, Carlo

    2008-01-01

    Background: This study examined the relation between stress and change in emotional and behavioural problems in children and adolescents referred for mental health services. Method: At three waves across four years, children and their parents (N = 310, mean age at the first wave = 11.26 years, SD = 3.18) reported emotional and behavioural…

  13. Genome wide association of changes in feeding behavior due to heat stress in pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heat stress negatively impacts pork production. Grow-finish production losses include decreased growth, reduced feed intake, and mortality. Pigs change their feeding behavior to decrease heat production when temperatures are elevated. Identification of pigs that are more tolerant of warmer temperatu...

  14. Personality Factors and Stress Ratings of Life Changes in a College Population.

    ERIC Educational Resources Information Center

    Morgan, Charles H., Jr.

    Previous research has shown a statistically significant correlation between life change stress and physical illness. To examine the relationship between locus of control and the rating of life events and to examine the relationship between responsiveness to threat and ratings, a sample of 274 college students answered a series of four…

  15. Mind-body response and neurophysiological changes during stress and meditation: central role of homeostasis.

    PubMed

    Jerath, R; Barnes, V A; Crawford, M W

    2014-01-01

    Stress profoundly impacts quality of life and may lead to various diseases and conditions. Understanding the underlying physiological and neurological processes that take place during stress and meditation techniques may be critical for effectively treating stress-related diseases. The article examines a hypothetical physiological homeostatic response that compares and contrasts changes in central and peripheral oscillations during stress and meditation, and relates these to changes in the autonomic system and neurological activity. The authors discuss how cardiorespiratory synchronization, which occurs during the parasympathetic response and meditation, influences and modulates activity and oscillations of the brain and autonomic nervous system. Evidence is presented on how synchronization of cardiac and respiratory rates during meditation may lead to a homeostatic increase in cellular membrane potentials in neurons and other cells throughout the body. These potential membrane changes may underlie the reduced activity in the amygdala, and other cortical areas during meditation, and research examining these changes may foster better understanding of the restorative properties and health benefits of meditation.

  16. Mechanisms of Decreased Plasma Volume During Acute Psychological Stress and Postural Change in Humans

    DTIC Science & Technology

    1993-09-14

    fibrinogen (Jern et aI, 1989), plasma 2 proteins (Patterson, Krantz, Gottdiener, Hecht, Vargot, & Goldstein, under review) , and serum cholesterol ...and a subsequent hemoconcentration of blood cells (Jern et aI, 1991), cholesterol , and plasma proteins in healthy men (Muldoon, Bachen, Manuck...point is of particular interest because gender differences have been observed in stress- induced changes in cholesterol concentrations (Stoney

  17. MONITORING CHANGES IN STRESSED ECOSYSTEMS USING SPATIAL PATTERNS OF ANT COMMUNITIES

    EPA Science Inventory

    We examined the feasibility of using changes in spatial patterns of ants-distribution on experimental plots as an indicator of response to environmental stress. We produced contour maps based on relative abundances of the three most common genera of ants based on pit-fall trap ca...

  18. Spatially heterogeneous stress field in the source area of the 2011 Mw 6.6 Fukushima-Hamadori earthquake, NE Japan, probably caused by static stress change

    NASA Astrophysics Data System (ADS)

    Yoshida, Keisuke; Hasegawa, Akira; Okada, Tomomi

    2015-05-01

    In order to know whether principal stress orientations in the source area rotated after the 2011 April 11 Mw 6.6 Fukushima-Hamadori earthquake in NE Japan, we investigated detailed spatial distributions of stress orientations for both the pre- and post-main shock periods using a large amount of focal mechanism data. We applied stress tensor inversions to focal mechanism data from Japan's National Research Institute for Earth Science and Disaster Prevention's F-net broadband seismic network and the Japan Meteorological Agency (JMA). The σ3-axes estimated for the pre-main shock period are predominantly oriented WSW-ENE, and are relatively homogeneously in space. In contrast, the orientations of the σ3-axes show a significantly heterogeneous distribution in space for the post-main shock period. In the northern subarea of the focal region, the σ3-axes are oriented NW-SE. In the east and west portions of the central subarea, they are oriented NNW-SSE and WNW-ESE, respectively, almost perpendicular to each other. In the southern subarea, the σ3-axes are oriented WSW-ENE. On the whole, the σ3-axis orientations show concentric circle-like distribution surrounding the large slip area of the Mw Mw 6.6 main shock rupture. The change of principal stress axis orientations after the earthquake is not significant because of the sparse data set for the pre-main shock period. We calculated static stress changes from the Mw 6.6 main shock and three Mw > 5.5 earthquakes to compare with the observed stress axis orientations in the post-main shock period. The σ3-axis orientations of the calculated total static stress change show a concentric circle-like distribution surrounding the large slip area of the main shock, similar to that noted above. This observation strongly suggests that the spatially heterogeneous stress orientations in the post-main shock period were caused by the static stress change from the Mw 6.6 main shock and other large earthquakes. In order to estimate the

  19. Distribution Of Seismic Velocity Change Associated With The May 12, 2008 M7.9 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Chen, J.; Froment, B.; Liu, Q.; Campillo, M.

    2009-12-01

    We used continuous recordings in Sichuan, China to track the temporal evolution of the seismic velocity in a 2 year period which includes the great Wenchuan earthquake. The data are recorded by a temporary network of 84 out of 297 broad-band seismometers run by the Institute of Geology of the China Earthquake Administration. We analyzed the data from the stations in a 400*300km2 region that includes the southern 2/3 of the fault system activated during the Wenchuan event. We computed the cross correlation functions of seismic noise in a 30-day moving window for period between 1 and 3 seconds. We interpret them as an approximation of the actual Green function between the recorders. We then performed a doublet analysis to detect temporal changes of velocity with respect to a reference correlation. We deduce a relative average velocity change from the high quality delay measurements obtained for the ensemble of stations pairs. We found clear evidences that the seismic velocity drops after the earthquake by an average amount of about 0.1% in the fault region when measured with waves in the period range 1-3 seconds. We found that, according to our measurements, the velocity fluctuates within 0.02% in the months before the earthquake. The co-seismic variation is therefore well above the resolution of the measurements. We found that the co-seismic variation has similar amplitude for station groups in the Sichuan basin or in the Longmen Shan range, indicating that the co-seismic change is not fully controlled by the non-linear response of the shallow sediments. To investigate the velocity variations for different part in the region, we used a 0.5-degree station searching radius on 0.5°×0.5° grids to define sub-arrays, and measured the velocity variation for station pairs in the sub-arrays. We compared the measurements of velocity changes in different sub-arrays with a map of stress change deduced from a kinematic rupture model (Ji and Shao, personal communication) and

  20. Evidence for static stress changes triggering the 1999 eruption of Cerro Negro Volcano, Nicaragua and regional aftershock sequences

    NASA Astrophysics Data System (ADS)

    Díez, M.; La Femina, P. C.; Connor, C. B.; Strauch, W.; Tenorio, V.

    2005-02-01

    Remarkable evidence of coupling between tectonic and magmatic events emerges from investigation of three tectonic earthquakes, aftershock sequences and eruption of Cerro Negro volcano, Nicaragua in 1999. Here, we explain this coupling through static stress changes following three Mw 5.2 earthquakes. We use focal mechanism solutions to estimate fault system geometry and magnitude of slip from these events, which are then used to calculate the change in minimum horizontal principal stress (σ3) for the region and the change in Coulomb failure stress on optimally oriented fault planes. Results of these simulations indicate that σ3 was reduced by ~0.08 MPa and that Coulomb failure stress was raised by 0.001 to 0.2 MPa in the region. A Kolmogorov-Smirnov test demonstrates spatial correlation of Coulomb failure stress changes and triggered seismicity and volcanism, and suggests that these small changes in static stress can trigger subsequent geophysical events under appropriate circumstances.

  1. Triggering Effect of the Static Stress Transfer in Mining-Induced Seismicity from Rudna Mine in the Legnica-Gogow Copper District, in Poland

    NASA Astrophysics Data System (ADS)

    Orlecka-Sikora, B.; Papadimitriou, E.; Kwiatek, G.

    2008-12-01

    The static stress transfer is often considered as a possible source of earthquake interaction. Some examples from natural seismicity show that even small stress perturbations resulting from the coseismic slip can enhance or prevent future occurrences. In case of the mining-induced seismicity the coseismic stress changes expressed in terms of the Coulomb failure function (CFF) are at least one order smaller than those for earthquakes. Furthermore, they are only a small component of the stress field variations in mines. In order to recognize whether the static stress transfer can influence also the generation process of the mining induced seismicity we analyze seismic data from Rudna Mine in Poland. We consider events of ML>=2.0 occurred in Rudna Mine from 1993-2006. We examine the possible triggering checking correlation between event locations and the stress-increased zones, expressed by the proportion of events consistent with increased CFF areas. We find that more than 50 per-cent of the analyzed events occurred in areas where stress was enhanced due to the occurrence of previous events. In order to recognize the significance of the effect we test the null hypothesis stating that there is no influence of CFF changes due to previous events on the subsequent event. To attain the significance of this null hypothesis we estimate the distribution of the proportion of events located inside positive CFF areas from 2000 results for random permutations of the original series of events. For CFF changes >= 0.02 bar the null hypothesis was rejected at the 95% confidence level. This result indicates that the static CFF triggering in Rudna Mine exists and this effect is statistically significant. This work was prepared within the framework of the research project No. PBS- Grecja/10/2007, financed by the Ministry of Education and Science of Poland during the period 2007 to 2009.

  2. Physiological and biochemical changes of CBF3 transgenic oat in response to salinity stress.

    PubMed

    Oraby, Hesham; Ahmad, Rashid

    2012-04-01

    Salinity is a major abiotic constraint affecting oat productivity. Several physiological and biochemical traits have been found to be related to yield maintenance under salinity. The impact of introducing the Arabidopsis CBF3 gene controlled by the rd29A stress-inducible promoter in T(2) transgenic oat on salinity tolerance and associated physiological changes were studied. Compared with the non-transgenic control, transgenic T(2) plants exhibited greater growth and showed significant maintenance of leaf area, relative water content, chlorophyll content, photosynthetic and transpiration rates as well as increased levels of proline and soluble sugars under high salt stress. These physiological changes delayed leaf-wilting symptoms, increased tolerance and reduced yield loss. At a salinity stress level of 100mM, the CBF3-overexpressing transgenic oat showed a yield loss of 4-11% compared with >56% for the non-transgenic control. These results demonstrate that stress-inducible over-expression of CBF3 may have the potential to enhance abiotic stress tolerance in oat.

  3. Changes in fatty acid composition in the giant clam Tridacna maxima in response to thermal stress

    PubMed Central

    Dubousquet, Vaimiti; Gros, Emmanuelle; Berteaux-Lecellier, Véronique; Viguier, Bruno; Raharivelomanana, Phila; Bertrand, Cédric; Lecellier, Gaël J.

    2016-01-01

    ABSTRACT Temperature can modify membrane fluidity and thus affects cellular functions and physiological activities. This study examines lipid remodelling in the marine symbiotic organism, Tridacna maxima, during a time series of induced thermal stress, with an emphasis on the morphology of their symbiont Symbiodinium. First, we show that the French Polynesian giant clams harbour an important proportion of saturated fatty acids (SFA), which reflects their tropical location. Second, in contrast to most marine organisms, the total lipid content in giant clams remained constant under stress, though some changes in their composition were shown. Third, the stress-induced changes in fatty acid (FA) diversity were accompanied by an upregulation of genes involved in lipids and ROS pathways. Finally, our microscopic analysis revealed that for the giant clam's symbiont, Symbiodinium, thermal stress led to two sequential cell death processes. Our data suggests that the degradation of Symbiodinium cells could provide an additional source of energy to T. maxima in response to heat stress. PMID:27543058

  4. The length change of a dislocation junction in FCC-single crystals under stress

    NASA Astrophysics Data System (ADS)

    Kurinnaya, Raisa; Zgolich, Marina; Starenchenko, Vladimir; Sadritdinova, Gulnora

    2016-01-01

    The product of dislocation reactions among dislocations of non-coplanar slip systems are dislocation junctions. The paper presents the study on the length change of dislocation junctions under stress. It is revealed that dislocation junctions can be destructed by merging of triple dislocation nodes at certain inclination angles of the glide dislocation and the forest dislocation to the junction line and the corresponding lengths of free segments of intersecting dislocations. Dislocation junctions formed at an arbitrary intersection of segments of the reacting dislocation are investigated. The geometry of the intersection of segments of reacting dislocations, at which dislocation junctions are not completely destructed under stress but cease to be an obstacle for further motion of the glide dislocation, is determined. Such junctions remain in the shear zone, presenting an obstacle to other glide dislocations. Conditions under which the length of the dislocation junction increases with an increase in the stress exceeding the original length are found. The formed extended barrier becomes too strong for the acting stress. Higher stresses are required in order to destruct it. The probability of completely destructible junctions under stress, the probability of non-destructible junctions that remain in the shear zone and replenish the density of dislocation debris, as well as the probability of formation of long strong junctions, which are barriers capable of limiting the shear zone, are determined.

  5. Stresses and deformations in cross-ply composite tubes subjected to a uniform temperature change

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Cooper, D. E.; Cohen, D.

    1986-01-01

    This study investigates the effects of a uniform temperature change on the stresses and deformations of composite tubes and determines the accuracy of an approximate solution based on the principle of complementary virtual work. Interest centers on tube response away from the ends and so a planar elasticity approach is used. For the approximate solution a piecewise linear variation of stresses with the radial coordinate is assumed. The results from the approximate solution are compared with the elasticity solution. The stress predictions agree well, particularly peak interlaminar stresses. Surprisingly, the axial deformations also agree well, despite the fact that the deformations predicted by the approximate solution do not satisfy the interface displacement continuity conditions required by the elasticity solution. The study shows that the axial thermal expansion coefficient of tubes with a specific number of axial and circumferential layers depends on the stacking sequence. This is in contrast to classical lamination theory, which predicts that the expansion will be independent of the stacking arrangement. As expected, the sign and magnitude of the peak interlaminar stresses depend on stacking sequence. For tubes with a specific number of axial and circumferential layers, thermally induced interlaminar stresses can be controlled by altering stacking arrangement.

  6. Changes in the transcriptomic profiles of maize roots in response to iron-deficiency stress.

    PubMed

    Li, Yan; Wang, Nian; Zhao, Fengtao; Song, Xuejiao; Yin, Zhaohua; Huang, Rong; Zhang, Chunqing

    2014-07-01

    Plants are often subjected to iron (Fe)-deficiency stress because of its low solubility. Plants have evolved two distinct strategies to solubilize and transport Fe to acclimate to this abiotic stress condition. Transcriptomic profiling analysis was performed using Illumina digital gene expression to understand the mechanism underlying resistance responses of roots to Fe starvation in maize, an important Strategy II plant. A total of 3,427, 4,069, 4,881, and 2,610 genes had significantly changed expression levels after Fe-deficiency treatments of 1, 2, 4 or 7 days, respectively. Genes involved in 2'-deoxymugineic acid (DMA) synthesis, secretion, and Fe(III)-DMA uptake were significantly induced. Many genes related to plant hormones, protein kinases, and protein phosphatases responded to Fe-deficiency stress, suggesting their regulatory roles in response to the Fe-deficiency stress. Functional annotation clustering analysis, using the Database for Annotation, Visualization and Integrated Discovery, revealed maize root responses to Fe starvation. This resulted in 38 functional annotation clusters: 25 for up-regulated genes, and 13 for down-regulated ones. These included genes encoding enzymes involved in the metabolism of carboxylic acids, isoprenoids and aromatic compounds, transporters, and stress response proteins. Our work provides integrated information for understanding maize response to Fe-deficiency stress.

  7. Adaptive changes of the yeast mitochondrial proteome in response to salt stress.

    PubMed

    Martínez-Pastor, Mar; Proft, Markus; Pascual-Ahuir, Amparo

    2010-10-01

    Mitochondria are dynamic organelles with the capacity to adapt to environmental stimuli and stress. Here we use yeast (Saccharomyces cerevisiae) in combination with proteomic approaches to quantify the changes in the protein composition of mitochondria in the presence of salt stress provoked by NaCl. We identified 15 proteins that were more than twofold overrepresented in salt adapted mitochondria. These proteins are mainly involved in the oxidative stress defense, the biosynthesis of amino acids and ubiquinone or in the metabolism of pyruvate and acetate. Loss of function of most of the upregulated proteins did not result in a significant growth phenotype under high salt conditions. However, all identified proteins were necessary to sustain efficient growth under oxidative stress caused by hydrogen peroxide. Additionally, a subset of outer mitochondrial membrane proteins was shown to be upregulated upon salt stress. We furthermore identified nine proteins that were more than threefold underrepresented in salt adapted mitochondria. These proteins were mainly glycolytic enzymes or proteins with a predominant localization at the endoplasmatic reticulum. Our results underline the complex nature of the stress adaptation of mitochondria and identify functional groups of proteins whose specific role in salt resistance should be revealed in the future.

  8. Investigation of changes in psycho-physiological parameters evoked by short duration, intensive physical stress.

    PubMed

    Németh, E; Bretz, K J; Sótonyi, P; Bretz, Károly; Horváth, T; Tihanyi, J; Zima, E; Barna, T

    2013-12-01

    The aim of our study was to investigate changes in psycho-physiological parameters evoked by short duration, intensive physical stress on university students practicing judo at different intensities and timely manner. Stability of posture, muscle strength (hand force exertions), attention concentration (choice reaction time), cardiac parameters, (ECG, heart rate, heart rate variability), and oxygen saturation were measured, cardiac state and stress index were computed before and after the physical stress. The actual psychic state of the subjects was evaluated using the Spielberger's STPI-H Y-1 test which determined anxiety, curiosity, anger and depression level. Analysis of psychometric and physiologic parameters indicated significant correlations, among others, between force and cardiac stress (-), force and depression (-), anxiety and errors in actions (+), cardiac state and errors in action (-), cardiac state and depression (-). Paired samples tests showed the influence of intensive physical stress within groups of students, and independent samples tests made it possible to evaluate the power of medical and sport students, performing physical training at a significantly higher level than it is usual among the medical students. Our results proved that higher level physical training influences the psychic state advantageously, limits increases in cardiac stress level, and decreases susceptibility to anxiety and depression.

  9. Modeling of stress-triggered faulting and displacement magnitude along Agenor Linea, Europa

    NASA Astrophysics Data System (ADS)

    Nahm, A.; Cameron, M. E.; Smith-Konter, B. R.; Pappalardo, R. T.

    2012-12-01

    We investigate the relationship between shear and normal stresses at Agenor Linea (AL) to better understand the role of tidal stress sources and implications for faulting on Europa. AL is a ~1500 km long, E-W trending, 20-30 km wide zone of geologically young deformation located in the southern hemisphere, and it forks into two branches at its eastern end. Based on photogeological evidence and stress orientation predictions, AL is primarily a right-lateral strike slip fault and may have accommodated up to 20 km of right-lateral slip. We compute tidal shear and normal stresses along present-day AL using SatStress, a numerical code that calculates tidal stresses at any point on the surface of a satellite for both diurnal and non-synchronous rotation (NSR) stresses. We adopt model parameters appropriate for Europa with a spherically symmetric, 20 km thick ice shell underlain by a global subsurface ocean and assume a coefficient of friction μ = 0.6. Along AL, shear stresses are primarily right-lateral (~1.8 MPa), while normal stresses are predominantly compressive along the west side of the structure (~0.7 MPa) and tensile along the east side (~2.9 MPa). Failure along AL is assessed using the Coulomb failure criterion, which states that shear failure occurs when the shear stress exceeds the frictional resistance of the fault. Where fault segments meet these conditions for shear failure, coseismic displacements are determined (assuming complete stress drop). We calculate shallow displacements as large as ~50 m at 1 km depth and ~10 m at 3 km depth. Triggered stresses from coseismic fault slip may also contribute to the total slip. We investigate the role of stress triggering by computing the change in Coulomb failure stress (ΔCFS) along AL. Where slip has occurred, negative ΔCFS is calculated; positive ΔCFS values indicate segments where failure is promoted. Positive ΔCFS is calculated at the western tip and the intersection of the branches with the main fault at a

  10. Stress response in honeybees is associated with changes in task-related physiology and energetic metabolism.

    PubMed

    Bordier, Célia; Suchail, Séverine; Pioz, Maryline; Devaud, Jean Marc; Collet, Claude; Charreton, Mercedes; Le Conte, Yves; Alaux, Cédric

    2017-04-01

    In a rapidly changing environment, honeybee colonies are increasingly exposed to diverse sources of stress (e.g., new parasites, pesticides, climate warming), which represent a challenge to individual and social homeostasis. However, bee physiological responses to stress remain poorly understood. We therefore exposed bees specialised in different tasks (nurses, guards and foragers) to ancient (immune and heat stress) or historically more recent sources of stress (pesticides), and we determined changes in the expression of genes linked to behavioural maturation (vitellogenin - vg and juvenile hormone esterase - jhe) as well as in energetic metabolism (glycogen level, expression level of the receptor to the adipokinetic hormone - akhr, and endothermic performance). While acute exposure to sublethal doses of two pesticides did not affect vg and jhe expression, immune and heat challenges caused a decrease and increase in both genes, respectively, suggesting that bees had responded to ecologically relevant stressors. Since vg and jhe are expressed to a higher level in nurses than in foragers, it is reasonable to assume that an immune challenge stimulated behavioural maturation to decrease potential contamination risk and that a heat challenge promoted a nurse profile for brood thermoregulation. All behavioural castes responded in the same way. Though endothermic performances did not change upon stress exposure, the akhr level dropped in immune and heat-challenged individuals. Similarly, the abdomen glycogen level tended to decline in immune-challenged bees. Altogether, these results suggest that bee responses are stress specific and adaptive but that they tend to entail a reduction of energetic metabolism that needs to be studied on a longer timescale.

  11. Perceived stress and freshman weight change: the moderating role of baseline body mass index.

    PubMed

    Boyce, Jessica A; Kuijer, Roeline G

    2015-02-01

    The transition from high-school to university is a critical period of weight change. Popular media suggest that freshman students gain 15 lb (6.80 kg) of body weight during their first year at university (i.e., the freshman 15). In contrast, a recent meta-analysis calculated freshman weight gain to be 1.75 kg, with statistics suggesting that only a proportion of freshman students are prone to gain weight. Researchers are beginning to investigate how certain variables and interactions between such variables predict freshman weight status. The current study focused on body mass index (BMI) and psychological stress. In isolation, previous research has tested how these two variables predict freshman student's weight status. However, because BMI and stress interact to predict weight gain and weight loss in adult samples, the current study tested the interaction between student's baseline BMI and baseline stress levels to predict weight change in a New Zealand sample of freshman students (N=65). Participants completed two separate online surveys in March and October 2012 (i.e., New Zealand's academic year). Although only three students gained over 6.80 kg (i.e., the freshman 15), participants did gain a statistically significant 1.10 kg of body weight during the year. Consistent with previous research, students with a higher baseline BMI gained a higher amount of body weight. However, this main effect was qualified by an interaction between stress and BMI. Students who entered university with high levels of stress gained weight if they also had high BMIs; if they had lower BMIs then they lost weight. In order to reduce unhealthy levels of freshman weight change, vulnerable students need to be taught stress-reduction techniques and coping strategies early in the academic year.

  12. Learning, memory, and glial cell changes following recovery from chronic unpredictable stress.

    PubMed

    Bian, Yanqing; Pan, Zhuo; Hou, Ziyuan; Huang, Cui; Li, Wei; Zhao, Baohua

    2012-08-01

    Previous research has indicated that chronic stress induces inflammatory responses, cognitive impairments, and changes in microglia and astrocytes. However, whether stress-induced changes following recovery are reversible is unclear. The present study examined the effects of chronic unpredictable stress (CUS) following recovery on spatial learning and memory impairments, changes in microglia and astrocytes, and interleukine-1β (IL-1β) and glial-derived neurotrophic factor (GDNF) levels. Mice were randomly divided into control, stress, and recovery groups, and CUS was applied to mice in the stress and recovery groups for 40 days. Following the application of CUS, the recovery group was allowed 40 days without stress. The results of the Morris water maze illustrated that CUS-induced spatial learning and memory impairments could be reversed or even improved by a period of recovery. Immunohistochemical tests revealed that CUS-induced alterations in microglia could dissipate with time in the CA3 region of the hippocampus and prelimbic areas. However, CUS-induced activation of astrocytes was sustained in the CA3 area following recovery. Western blot analyses revealed that CUS induced a significant increase of GDNF and a significant decrease in IL-1β. Additionally, increased GDNF levels were sustained in the hippocampus during recovery. In conclusion, this study provides evidence that CUS-induced learning and memory impairments could be reversible following recovery. However, activated astrocytes and increased GDNF levels in the hippocampus remained elevated after recovery, suggesting that activated astrocytes and increased GDNF play important roles in the adaptation of the brain to CUS and in repairing CUS-induced impairments during recovery.

  13. Time-dependent evolution of stress over the past 200 years in Southern California

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    Seismic hazard estimates can be refined by examining the current state of stress change in regions prone to earthquakes. Active faults which have not recently failed and lie in regions experiencing high rates of stress increase represent the best candidates for near future earthquakes. Evolution of stress in the crust is influenced by three main factors: interseismic loading, static stress changes from large earthquakes; and postseismic relaxation of a viscous lower crust or upper mantle. Southern California has had more than eighteen large (Mw ≥ 6.5) earthquakes in the past two centuries. Previous research has calculated the evolution of stress in southern California over this period of time due to coseismic slip associated with these events and interseismic loading. Here we extend this analysis to include the effects of viscous relaxation that follows each quake and can significantly alter the stress field. Our approach is to numerically model the evolution of Coulomb stress for southern California due to all the major (Mw ≥ 6.5) earthquakes over the past 200 years using the superposition of a viscoelastic model and the regional stress rate. The regional stress rate is due to the relative motion of the Pacific and North American plates as constrained by the SCEC velocity field map. We plan to present results that discuss where Coulomb stress is currently building the fastest and how these stress changes resolve themselves on major strike-slip faults in the region and thrust faults within the LA Basin. We are particularly interested in how the stress shadows (region of Coulomb stress decrease) cast by the great Fort Tejon earthquake of 1857 and other large historic events have been influenced by the competing role of viscoelastic relaxation, which would tend to prolong the longevity of shadows associated with strike-slip earthquakes, and the build up of regional stresses which work to erase them.

  14. Bedrock temperature as a potential method for monitoring change in crustal stress: Theory, in situ measurement, and a case history

    NASA Astrophysics Data System (ADS)

    Chen, Shunyun; Liu, Peixun; Liu, Liqiang; Ma, Jin

    2016-06-01

    Experimental studies have confirmed that temperature is notably affected by rock deformation; therefore, change in crustal stress should be indicated by measurable changes in bedrock temperature. In this work, we investigated the possibility that the bedrock temperature might be used to explore the state of crustal stress. In situ measurement of bedrock temperature at three stations from 2011 to 2013 was used as the basis for the theoretical analysis of this approach. We began with theoretical analyses of temperature response to change in crustal stress, and of the effect of heat conduction. This allowed distinction between temperature changes produced by crustal stress (stress temperature) from temperature changes caused by conduction from the land surface (conduction temperature). Stress temperature has two properties (synchronous response and a high-frequency feature) that allow it to be distinguished from conduction temperature. The in situ measurements confirmed that apparently synchronous changes in the stress temperature of the bedrock occur and that there exist obvious short-term components of the in situ bedrock temperature, which agrees with theory. On 20 April 2013, an earthquake occurred 95 km away from the stations, fortuitously providing a case study by which to verify our method for obtaining the state of crustal stress using temperature. The results indicated that the level of local or regional seismic activity, representing the level of stress adjustment, largely accords with the stress temperature. This means that the bedrock temperature is a tool that might be applied to understand the state of stress during seismogenic tectonics. Therefore, it is possible to record changes in the state of crustal stress in a typical tectonic position by long-term observation of bedrock temperature. Hereby, the measurement of bedrock temperature has become a new tool for gaining insight into changes in the status of shallow crustal stress.

  15. Changes in seed water status as characterized by NMR in developing soybean seed grown under moisture stress conditions

    SciTech Connect

    Krishnan, P. Singh, Ravender; Verma, A.P.S.; Joshi, D.K.; Singh, Sheoraj

    2014-02-21

    Highlights: • In developing soybean seeds, moisture stress resulted in more proportion of water to bound state. • These changes are further corroborated by concomitant changes in seed metabolites. • Thus there exists a moisture stress and development stage dependence of seed tissue water status. - Abstract: Changes in water status of developing seeds of Soybean (Glycine max L. Merrill.) grown under different moisture stress conditions were characterized by proton nuclear magnetic resonance (NMR)- spin–spin relaxation time (T{sub 2}). A comparison of the seed development characteristics, composition and physical properties indicated that, characteristics like seed weight, seed number/ear, rate of seed filling increased with development stages but decreased with moisture stress conditions. The NMR- spin–spin relaxation (T{sub 2}) component like bound water increased with seed maturation (40–50%) but decreased with moisture stress conditions (30–40%). The changes in seed water status to increasing levels of moisture stress and seed maturity indicates that moisture stress resulted in more proportion of water to bound state and intermediate state and less proportion of water in free-state. These changes are further corroborated by significant changes in protein and starch contents in seeds under high moisture stress treatments. Thus seed water status during its development is not only affected by development processes but also by moisture stress conditions. This study strongly indicated a clear moisture stress and development stage dependence of seed tissue water status in developing soybean seeds.

  16. Mass and stress changes in the Menderes Massif (Western Anatolia, Turkey)

    NASA Astrophysics Data System (ADS)

    Çırmık, Ayça; Pamukçu, Oya; Akçığ, Zafer

    2016-12-01

    Comparing the results of the microgravity and GNSS measurements is useful for understanding the vertical displacements of the plates. In this study, for determining the geodynamical behaviors of seismically active tectonic structures of Gediz and Büyük Menderes grabens which are located in Western Anatolia (Turkey) graben system, the mass changes were examined by processing of GNSS and microgravity data. Besides, after modeling the GNSS velocity by Coulomb stress analysis, the stress distributions were investigated for these models. Therefore, first of all, the changes of gravity and the vertical components of GNSS velocity values were evaluated together with a statistical method. Secondly, GNSS velocities were calculated relative to the main tectonic structures and the stress changes of tectonic structures were obtained at different depths with Coulomb stress analysis by using these velocities and all results were evaluated with the earthquakes that had occurred in the study area. Consequently, the crustal movements of the areas located at the GNSS stations and their surroundings were put forwarded as in compensation or uncompensation concept of surface and subsurface loadings due to the mass or groundwater effects by using both microgravity and GNSS measurements, as an initial study on Western Anatolia graben system.

  17. Glucocorticoid Mechanisms of Functional Connectivity Changes in Stress-Related Neuropsychiatric Disorders.

    PubMed

    Hall, Baila S; Moda, Rachel N; Liston, Conor

    2015-01-01

    Stress-especially chronic, uncontrollable stress-is an important risk factor for many neuropsychiatric disorders. The underlying mechanisms are complex and multifactorial, but they involve correlated changes in structural and functional measures of neuronal connectivity within cortical microcircuits and across neuroanatomically distributed brain networks. Here, we review evidence from animal models and human neuroimaging studies implicating stress-associated changes in functional connectivity in the pathogenesis of PTSD, depression, and other neuropsychiatric conditions. Changes in fMRI measures of corticocortical connectivity across distributed networks may be caused by specific structural alterations that have been observed in the prefrontal cortex, hippocampus, and other vulnerable brain regions. These effects are mediated in part by glucocorticoids, which are released from the adrenal gland in response to a stressor and also oscillate in synchrony with diurnal rhythms. Recent work indicates that circadian glucocorticoid oscillations act to balance synapse formation and pruning after learning and during development, and chronic stress disrupts this balance. We conclude by considering how disrupted glucocorticoid oscillations may contribute to the pathophysiology of depression and PTSD in vulnerable individuals, and how circadian rhythm disturbances may affect non-psychiatric populations, including frequent travelers, shift workers, and patients undergoing treatment for autoimmune disorders.

  18. The two-dimensional magnetic change process of grain-oriented silicon steel under tensile stress

    NASA Astrophysics Data System (ADS)

    Saito, Akihiko; Nakata, Kumi; Murashige, Shinichi

    1996-07-01

    The effect of tensile stress on the magnetization properties of silicon steel samples declined from the rolling direction has been investigated. The locus for the two-dimensional magnetization change was measured. The locus of magnetization due to magnetic field without stress was different from that under tension. The locus of magnetization with tension has two knees which correspond to the two knees of the hysteresis curve with tension. These results indicate the essential importance of investigations of the two-dimensional magnetization process.

  19. Inherited structures impact on co-seismic surface deformation pattern during the 2013 Balochistan, Pakistan, earthquake

    NASA Astrophysics Data System (ADS)

    Vallage, Amaury; Klinger, Yann; Grandin, Raphael; Delorme, Arthur; Pierrot-Deseilligny, Marc

    2016-04-01

    The understanding of earthquake processes and the interaction of earthquake rupture with Earth's free surface relies on the resolution of the observations. Recent and detailed post-earthquake measurements bring new insights on shallow mechanical behavior of rupture processes as it becomes possible to measure and locate surficial deformation distribution. The 2013 Mw 7.7 Balochistan earthquake, Pakistan, offers a nice opportunity to comprehend where and why surficial deformation might differs from at-depth localized slip. This earthquake ruptured the Hoshab fault over 200 km; the motion was mainly left lateral with a small and discontinuous vertical component in the southern part of the rupture. Using images with the finest resolution currently available, we measured the surface displacement amplitude and its orientation at the ground surface (including the numerous tensile cracks). We combined these measurements with the 1:500 scale ground rupture map to focus on the behavior of the frontal rupture in the area where deformation distributes. Comparison with orientations of inherited tectonic structures, visible in older rocks formation surrounding the actual 2013 rupture, shows the control exercised by such structures on co-seismic rupture distribution. Such observation raises the question on how pre-existing tectonic structures in a medium, mapped in several seismically active places around the globe; can control the co-seismic distribution of the deformation during earthquakes.

  20. Coseismic slip distribution of the February 27, 2010 Mw 8.9 Maule, Chile earthquake

    USGS Publications Warehouse

    Pollitz, Fred F.; Brooks, Ben; Tong, Xiaopeng; Bevis, Michael G.; Foster, James H.; Burgmann, Roland

    2011-01-01

    [1] Static offsets produced by the February 27, 2010 Mw = 8.8 Maule, Chile earthquake as measured by GPS and InSAR constrain coseismic slip along a section of the Andean megathrust of dimensions 650 km (in length) × 180 km (in width). GPS data have been collected from both campaign and continuous sites sampling both the near-field and far field. ALOS/PALSAR data from several ascending and descending tracks constrain the near-field crustal deformation. Inversions of the geodetic data for distributed slip on the megathrust reveal a pronounced slip maximum of order 15 m at ∼15–25 km depth on the megathrust offshore Lloca, indicating that seismic slip was greatest north of the epicenter of the bilaterally propagating rupture. A secondary slip maximum appears at depth ∼25 km on the megathrust just west of Concepción. Coseismic slip is negligible below 35 km depth. Estimates of the seismic moment based on different datasets and modeling approaches vary from 1.8 to 2.6 × 1022 N m. Our study is the first to model the static displacement field using a layered spherical Earth model, allowing us to incorporate both near-field and far-field static displacements in a consistent manner. The obtained seismic moment of 1.97 × 1022 N m, corresponding to a moment magnitude of 8.8, is similar to that obtained by previous seismic and geodetic inversions.

  1. Modelling climate change impacts on viticultural yield, phenology and stress conditions in Europe.

    PubMed

    Fraga, Helder; García de Cortázar Atauri, Iñaki; Malheiro, Aureliano C; Santos, João A

    2016-11-01

    Viticulture is a key socio-economic sector in Europe. Owing to the strong sensitivity of grapevines to atmospheric factors, climate change may represent an important challenge for this sector. This study analyses viticultural suitability, yield, phenology, and water and nitrogen stress indices in Europe, for present climates (1980-2005) and future (2041-2070) climate change scenarios (RCP4.5 and 8.5). The STICS crop model is coupled with climate, soil and terrain databases, also taking into account CO2 physiological effects, and simulations are validated against observational data sets. A clear agreement between simulated and observed phenology, leaf area index, yield and water and nitrogen stress indices, including the spatial differences throughout Europe, is shown. The projected changes highlight an extension of the climatic suitability for grapevines up to 55°N, which may represent the emergence of new winemaking regions. Despite strong regional heterogeneity, mean phenological timings (budburst, flowering, veraison and harvest) are projected to undergo significant advancements (e.g. budburst/harvest can be >1 month earlier), with implications also in the corresponding phenophase intervals. Enhanced dryness throughout Europe is also projected, with severe water stress over several regions in southern regions (e.g. southern Iberia and Italy), locally reducing yield and leaf area. Increased atmospheric CO2 partially offsets dryness effects, promoting yield and leaf area index increases in central/northern Europe. Future biomass changes may lead to modifications in nitrogen demands, with higher stress in northern/central Europe and weaker stress in southern Europe. These findings are critical decision support systems for stakeholders from the European winemaking sector.

  2. The rheology of a growing leaf: stress-induced changes in the mechanical properties of leaves

    PubMed Central

    Sahaf, Michal; Sharon, Eran

    2016-01-01

    We study in situ the mechanics and growth of a leaf. Young Nicotiana tabacum leaves respond to applied mechanical stress by altering both their mechanical properties and the characteristics of their growth. We observed two opposite behaviours, each with its own typical magnitude and timescale. On timescales of the order of minutes, the leaf deforms in response to applied tensile stress. During this phase we found a high correlation between the applied stress field and the local strain field throughout the leaf surface. For times over 12 hours the mechanical properties of the leaf become anisotropic, making it more resilient to deformation and restoring a nearly isotropic growth field despite the highly anisotropic load. These observations suggest that remodelling of the tissue allows the leaf to respond to mechanical perturbations by changing its properties. We discuss the relevance of the observed behaviour to the growth regulation that leads to proper leaf shape during growth. PMID:27651350

  3. The stress-buffering effects of hope on changes in adjustment to caregiving in multiple sclerosis.

    PubMed

    Madan, Sindia; Pakenham, Kenneth I

    2015-09-01

    This study examined the direct and stress-buffering effects of global hope and its components (agency and pathways) on changes in adjustment to multiple sclerosis caregiving over 12 months. A total of 140 carers and their care-recipients completed questionnaires at Time 1 and 12 months later, Time 2. Focal predictors were stress, hope, agency and pathways, and the adjustment outcomes were anxiety, depression, positive affect, positive states of mind and life satisfaction. Results showed that as predicted, greater hope was associated with better adjustment after controlling for the effects of initial adjustment and caregiving and care-recipient illness variables. No stress-buffering effects of hope emerged. Regarding hope components, only the agency dimension emerged as a significant predictor of adjustment. Findings highlight hope as an important protective resource for coping with multiple sclerosis caregiving and underscore the role of agency thinking in this process.

  4. Myofibril Changes in the Copepod Pseudodiaptomus marinus Exposed to Haline and Thermal Stresses

    PubMed Central

    Ibrahim, Ali; Souissi, Anissa; Leray, Aymeric; Héliot, Laurent; Vandenbunder, Bernard; Souissi, Sami

    2016-01-01

    Copepods are small crustaceans capable to survive in various aquatic environments. Their responses to changes in different external factors such as salinity and temperature can be observed at different integration levels from copepod genes to copepod communities. Until now, no thorough observation of the temperature or salinity effect stresses on copepods has been done by optical microscopy. In this study, we used autofluorescence to visualize these effects on the morphology of the calanoid copepod Pseudodiaptomus marinus maintained during several generations in the laboratory at favorable and stable conditions of salinity (30 psu) and temperature (18°C). Four different stress experiments were conducted: at a sharp decrease in temperature (18 to 4°C), a moderate decrease in salinity (from 30 to 15 psu), a major decrease in salinity (from 30 to 0 psu), and finally a combined stress with a decrease in both temperature and salinity (from 18°C and 30 psu to 4°C and 0 psu). After these stresses, images acquired by confocal laser scanning microscopy (CLSM) revealed changes in copepod cuticle and muscle structure. Low salinity and/or temperature stresses affected both the detection of fluorescence emitted by muscle sarcomeres and the distance between them. In the remaining paper we will use the term sarcomeres to describe the elements located within sarcomeres and emitted autofluorescence signals. Quantitative study showed an increase in the average distance between two consecutive sarcomeres from 2.06 +/- 0.11 μm to 2.44 +/- 0.42 μm and 2.88 +/- 0.45μm after the exposure to major haline stress (18°C, 0 psu) and the combined stress (4°C, 0 psu), respectively. These stresses also caused cuticle cracks which often occurred at the same location, suggesting the cuticle as a sensitive area for osmoregulation. Our results suggest the use of cuticular and muscle autofluorescence as new biomarkers of stress detectable in formalin-preserved P. marinus individuals. Our

  5. Stress

    MedlinePlus

    ... flu shot, are less effective for them. Some people cope with stress more effectively than others. It's important to know your limits when it comes to stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  6. Moderate stress responses and specific changes in polyamine metabolism characterize Scots pine somatic embryogenesis

    PubMed Central

    Salo, Heikki M.; Sarjala, Tytti; Jokela, Anne; Häggman, Hely; Vuosku, Jaana

    2016-01-01

    Somatic embryogenesis (SE) is one of the methods with the highest potential for the vegetative propagation of commercially important coniferous species. However, many conifers, including Scots pine (Pinus sylvestris L.), are recalcitrant to SE and a better understanding of the mechanisms behind the SE process is needed. In Scots pine SE cultures, embryo production is commonly induced by the removal of auxin, addition of abscisic acid (ABA) and the desiccation of cell masses by polyethylene glycol (PEG). In the present study, we focus on the possible link between the induction of somatic embryo formation and cellular stress responses such as hydrogen peroxide protection, DNA repair, changes in polyamine (PA) metabolism and autophagy. Cellular PA contents and the expression of the PA metabolism genes arginine decarboxylase (ADC), spermidine synthase (SPDS), thermospermine synthase (ACL5) and diamine oxidase (DAO) were analyzed, as well as the expression of catalase (CAT), DNA repair genes (RAD51, KU80) and autophagy-related genes (ATG5, ATG8) throughout the induction of somatic embryo formation in Scots pine SE cultures. Among the embryo-producing SE lines, the expression of ADC, SPDS, ACL5, DAO, CAT, RAD51, KU80 and ATG8 showed consistent profiles. Furthermore, the overall low expression of the stress-related genes suggests that cells in those SE lines were not stressed but recognized the ABA + PEG treatment as a signal to trigger the embryogenic pathway. In those SE lines that were unable to produce embryos, cells seemed to experience the ABA + PEG treatment mostly as osmotic stress and activated a wide range of stress defense mechanisms. Altogether, our results suggest that the direction to the embryogenic pathway is connected with cellular stress responses in Scots pine SE cultures. Thus, the manipulation of stress response pathways may provide a way to enhance somatic embryo production in recalcitrant Scots pine SE lines. PMID:26786537

  7. Changes of subjective stress and stress-related symptoms after a merger announcement: a longitudinal study in a merger-planning company in Japan.

    PubMed

    Haruyama, Yasuo; Muto, Takashi; Ichimura, Kumiko; Yan, Yoko; Fukuda, Hiroshi

    2008-04-01

    To investigate the influences of a merger on employees in a Japanese company, changes of subjective stress and stress-related symptoms after a merger announcement in a major Japanese financial company were explored using longitudinal study surveys. Seventy-one participants responded to the first and second questionnaires, consisting of stress and symptoms, personal characteristics, lifestyle, medical examination, and work-related factors. After the merger announcement, the prevalence of subjective stress, anxiety, and impatience increased significantly from 46.5% to 78.9%, 18.3% to 40.8%, and 15.9% to 29.0%, respectively. The study suggests that subjective stress and stress-related symptoms may increase after a merger announcement. To reduce the negative impact of mergers, employers are expected to provide mental health-promotion programs in a merger-planning company.

  8. Biochemical and molecular changes in rice seedlings (Oryza sativa L.) to cope with chromium stress.

    PubMed

    Kabir, A H

    2016-07-01

    Chromium (Cr) is very toxic to both humans and plants. This investigation aimed to understand the physiological and molecular responses of rice seedlings to Cr stress. Cr toxicity did not significantly affect morphological features and Cr accumulation in roots and shoots in Pokkali but not in BRRI 51, although there was a reduction in chlorophyll concentration in leaves of both genotypes. These results imply that Pokkali has mechanisms to cope with Cr supplementation. We therefore performed quantitative real-time PCR on the expression pattern of two chelator genes, OsPCS1 and OsMT1, but there were no significant changes in expression in roots and shoots of Pokkali and BRRI 51 following Cr stress. This suggests that there was no metal sequestration following heavy metal stress in roots of these genotypes. Moreover, no expression of two heavy metal transporter genes, OsHMA3 and OsNRAMP1, was induced after Cr stress in roots and shoots, suggesting that these transporter genes are not induced by Cr stress or might not be involved in Cr uptake in rice. We also performed a targeted study on the effect of Cr on Fe uptake mechanisms. Our studies showed a consistent reduction in Fe uptake, Fe reductase activity and expression of Fe-related genes (OsFRO1 and OsIRT1) under Cr stress in both roots and leaves of Pokkali. In contrast, these parameters and genes were significantly increased in Cr-sensitive BRRI 51 under Cr stress. The results confirm that limiting Fe uptake through the down-regulation of Fe reductase and Fe transporter genes is the main strategy of Cr-tolerant Pokkali to cope with Cr stress. Finally, increased CAT, POD and GR activity and elevated glutathione and proline synthesis might provide strong antioxidant defence against Cr stress in Pokkali. Taken together, our findings reveal that Cr stress tolerance in rice (Pokkali) is not related to metal sequestration but is associated with reduced Fe transport and increased antioxidant defence.

  9. Coping with a changing environment: the effects of early life stress

    PubMed Central

    Madaro, Angelico; Fraser, Thomas W. K.; Höglund, Erik; Olsen, Rolf E.; Øverli, Øyvind; Kristiansen, Tore S.

    2016-01-01

    Ongoing rapid domestication of Atlantic salmon implies that individuals are subjected to evolutionarily novel stressors encountered under conditions of artificial rearing, requiring new levels and directions of flexibility in physiological and behavioural coping mechanisms. Phenotypic plasticity to environmental changes is particularly evident at early life stages. We investigated the performance of salmon, previously subjected to an unpredictable chronic stress (UCS) treatment at an early age (10 month old parr), over several months and life stages. The UCS fish showed overall higher specific growth rates compared with unstressed controls after smoltification, a particularly challenging life stage, and after seawater transfer. Furthermore, subjecting fish to acute stress at the end of the experiment, we found that UCS groups had an overall lower hypothalamic catecholaminergic and brain stem serotonergic response to stress compared with control groups. In addition, serotonergic activity was negatively correlated with final growth rates, which implies that serotonin responsive individuals have growth disadvantages. Altogether, our results may imply that a subdued monoaminergic response in stressful farming environments may be beneficial, because in such situations individuals may be able to reallocate energy from stress responses into other life processes, such as growth. PMID:27853554

  10. Changes of immunoregulatory cells induced by psychological and physical stress: relationship to plasma catecholamines.

    PubMed Central

    Landmann, R M; Müller, F B; Perini, C; Wesp, M; Erne, P; Bühler, F R

    1984-01-01

    Lymphocyte subpopulations were measured before and after physical and psychological stress in 15 healthy subjects and correlated with plasma catecholamine and cortisol levels. During psychological stress monocytes (P less than 0.05), NK (P less than 0.01), B cells (P less than 0.05) and heart rate (P less than 0.001) increased, while catecholamines remained unchanged. With physical stress granulocytes, monocytes and all lymphocyte subsets increased significantly, although B cells rose more than T cells and T (suppressor) cells more than T (helper) cells. Thus the ratio of T/B cells and of Th/Ts cells decreased (P less than 0.001 and P less than 0.01). Adrenaline and noradrenaline concentrations increased (P less than 0.001), while cortisol remained unchanged. There was a negative relationship between adrenaline and the Th/Ts cell ratio before and after stress (P less than 0.05). Lymphocyte subpopulations from a different group of 4 healthy subjects were analysed before and after isoproterenol infusion. There was a small increase in Ts and B cells only (P less than 0.1) and a decrease of the T/B cell ratio (P less than 0.05). The predominant enrichment of circulating B, Ts and NK cells during short lasting adrenergic activation, as well as the relationship of the T cell changes to plasma adrenaline, suggest an immunoregulatory effect of the sympathetic nervous system in stress. PMID:6478647

  11. Shallow Lunar Seismic Activity and the Current Stress State of the Moon

    NASA Technical Reports Server (NTRS)

    Watters, T. R.; Weber, R. C.; Collins, G. C.; Johnson, C. L.

    2017-01-01

    A vast, global network of more than 3200 lobate thrust fault scarps has been revealed in high resolution Lunar Reconnaissance Orbiter Camera (LROC) images. The fault scarps very young, less than 50 Ma, based on their small scale and crisp appearance, crosscutting relations with small-diameter impact craters, and rates of infilling of associated small, shallow graben and may be actively forming today. The population of young thrust fault scarps provides a window into the recent stress state of the Moon and offers insight into the origin of global lunar stresses. The distribution of orientations of the fault scarps is non-random, inconsistent with isotropic stresses from late-stage global contraction as the sole source of stress Modeling shows that tidal stresses contribute significantly to the current stress state of the lunar crust. Tidal stresses (orbital recession and diurnal tides) superimposed on stresses from global contraction result in non-isotropic compressional stress and thrust faults consistent with lobate scarp orientations. Stresses due to orbital recession do not change with orbital position, thus it is with the addition of diurnal stresses that peak stresses are reached. At apogee, diurnal and recession stresses are most compressive near the tidal axis, while at perigee they are most compressive 90 degrees away from the tidal axis. Coseismic slip events on currently active thrust faults are expected to be triggered when peak stresses are reached. Analysis of the timing of the 28 the shallow moonquakes recorded by the Apollo seismic network shows that 19 indeed occur when the Moon is closer to apogee, while only 9 shallow events occur when the Moon is closer to perigee. Here we show the results of relocating the shallow moonquake using an algorithm designed for sparse networks to better constrain their epicentral locations in order to compare them with stress models. The model for the current stress state of the Moon is refined by investigating the

  12. Time Course Transcriptome Changes in Shewanella algae in Response to Salt Stress

    PubMed Central

    Yin, Xiling; Du, Pengcheng; Kan, Biao

    2014-01-01

    Shewanella algae, which produces tetrodotoxin and exists in various seafoods, can cause human diseases, such as spondylodiscitis and bloody diarrhea. In the present study, we focused on the temporal, dynamic process in salt-stressed S. algae by monitoring the gene transcript levels at different time points after high salt exposure. Transcript changes in amino acid metabolism, carbohydrate metabolism, energy metabolism, membrane transport, regulatory functions, and cellular signaling were found to be important for the high salt response in S. algae. The most common strategies used by bacteria to survive and grow in high salt environments, such as Na+ efflux, K+ uptake, glutamate transport and biosynthesis, and the accumulation of compatible solutes, were also observed in S. algae. In particular, genes involved in peptidoglycan biosynthesis and DNA repair were highly and steadily up-regulated, accompanied by rapid and instantaneous enhancement of the transcription of large- and small-ribosome subunits, which suggested that the structural changes in the cell wall and some stressful responses occurred in S. algae. Furthermore, the transcription of genes involved in the tricarboxylic acid (TCA) cycle and the glycolytic pathway was decreased, whereas the transcription of genes involved in anaerobic respiration was increased. These results, demonstrating the multi-pathway reactions of S. algae in response to salt stress, increase our understanding of the microbial stress response mechanisms. PMID:24789066

  13. Metabolic changes in Citrus leaf volatiles in response to environmental stress.

    PubMed

    Asai, Tomonori; Matsukawa, Tetsuya; Kajiyama, Shin'ichiro

    2016-02-01

    Citrus plants are well known as a rich source of VOCs, and several have important roles in defense responses. However, how VOCs are regulated in response to environmental stress is not yet well understood. In this study, we investigated dynamic changes of VOCs present in leaves of seven Citrus species (Citrus sinensis, C. limon, C. paradisi, C. unshiu, C. kinokuni, C. grandis, and C. hassaku) in response to mechanical wounding, jasmonic acid (JA), and salicylic acid (SA) as determined by gas chromatography/mass spectrometric analysis followed by multivariate analysis (principal component analysis, PCA, and orthogonal partial least squares-discriminant analysis, OPLS-DA). PCA and OPLS-DA suggested that changes in VOC profiles against stress stimuli were much diverse among Citrus species. OPLS-DA showed that C6 volatiles, such as hexanal and trans-2-hexenal, were induced in response to JA and SA stimuli in C. sinensis and C. grandis, while the other VOCs were decreased under all tested stress conditions. α-Farnesene was induced in all species except C. hassaku after wounding or JA treatment. In addition, α-farnesene was also induced in response to SA stimuli in C. unshiu and C. kinokuni. Therefore these volatiles can be candidates of the common stress biomarkers in Citrus. Our results will give a new insight into defense mechanisms in Citrus species.

  14. Modeling stress/strain-dependent permeability changes for deep geoenergy applications

    NASA Astrophysics Data System (ADS)

    Rinaldi, Antonio Pio; Rutqvist, Jonny

    2016-04-01

    Rock permeability is a key parameter in deep geoenergy systems. Stress and strain changes induced at depth by fluid injection or extraction may substantially alter the rock permeability in an irreversible way. With regard to the geoenergies, some applications require the permeability to be enhanced to improve productivity. The rock permeability is generally enhanced by shearing process of faults and fractures (e.g. hydroshearing for Enhanced and Deep Geothermal Systems), or the creation of new fractures (e.g. hydrofracturing for shale gas). However, such processes may, at the same time, produce seismicity that can be felt by the local population. Moreover, the increased permeability due to fault reactivation may pose at risk the sealing capacity of a storage site (e.g. carbon sequestration or nuclear waste disposal), providing then a preferential pathway for the stored fluids to escape at shallow depth. In this work we present a review of some recent applications aimed at understanding the coupling between stress (or strain) and permeability. Examples of geoenergy applications include both EGS and CO2 sequestration. To investigate both "wanted" and "unwanted" effects, THM simulations have been carried out with the TOUGH-FLAC simulator. Our studies include constitutive equations relating the permeability to mean effective stress, effective normal stress, volumetric strain, as well as accounting for permeability variation as related to fault/fracture reactivation. Results show that the geomechanical effects have a large role in changing the permeability, hence affecting fluids leakage, reservoir enhancement, as well as the induced seismicity.

  15. Cognitive Change Predicts Symptom Reduction With Cognitive Therapy for Posttraumatic Stress Disorder

    PubMed Central

    Kleim, Birgit; Grey, Nick; Wild, Jennifer; Nussbeck, Fridtjof W.; Stott, Richard; Hackmann, Ann; Clark, David M.; Ehlers, Anke

    2012-01-01

    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 dysfunctional appraisals of the trauma and its aftermath. If this is the case, then changes in appraisals should predict a change in symptoms. The present study investigated whether cognitive change precedes symptom change in Cognitive Therapy for PTSD, a version of TF-CBT. Method: The study analyzed weekly cognitive and symptom measures from 268 PTSD patients who received a course of Cognitive Therapy for PTSD, using bivariate latent growth modeling. Results: Results showed that (a) dysfunctional trauma-related appraisals and PTSD symptoms both decreased significantly over the course of treatment, (b) changes in appraisals and symptoms were correlated, and (c) weekly change in appraisals significantly predicted subsequent reduction in symptom scores (both corrected for the general decrease over the course of therapy). Changes in PTSD symptom severity did not predict subsequent changes in appraisals. Conclusions: The study provided preliminary evidence for the temporal precedence of a reduction in negative trauma-related appraisals in symptom reduction during trauma-focused CBT for PTSD. This supports the role of change in appraisals as an active therapeutic mechanism. PMID:23276122

  16. Posttraumatic Stress Disorder in the DSM-5: Controversy, Change, and Conceptual Considerations.

    PubMed

    Pai, Anushka; Suris, Alina M; North, Carol S

    2017-02-13

    The criteria for posttraumatic stress disorder PTSD have changed considerably with the newest edition of the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Changes to the diagnostic criteria from the DSM-IV to DSM-5 include: the relocation of PTSD from the anxiety disorders category to a new diagnostic category named "Trauma and Stressor-related Disorders", the elimination of the subjective component to the definition of trauma, the explication and tightening of the definitions of trauma and exposure to it, the increase and rearrangement of the symptoms criteria, and changes in additional criteria and specifiers. This article will explore the nosology of the current diagnosis of PTSD by reviewing the changes made to the diagnostic criteria for PTSD in the DSM-5 and discuss how these changes influence the conceptualization of PTSD.

  17. Posttraumatic Stress Disorder in the DSM-5: Controversy, Change, and Conceptual Considerations

    PubMed Central

    Pai, Anushka; Suris, Alina M.; North, Carol S.

    2017-01-01

    The criteria for posttraumatic stress disorder PTSD have changed considerably with the newest edition of the American Psychiatric Association’s (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Changes to the diagnostic criteria from the DSM-IV to DSM-5 include: the relocation of PTSD from the anxiety disorders category to a new diagnostic category named “Trauma and Stressor-related Disorders”, the elimination of the subjective component to the definition of trauma, the explication and tightening of the definitions of trauma and exposure to it, the increase and rearrangement of the symptoms criteria, and changes in additional criteria and specifiers. This article will explore the nosology of the current diagnosis of PTSD by reviewing the changes made to the diagnostic criteria for PTSD in the DSM-5 and discuss how these changes influence the conceptualization of PTSD. PMID:28208816

  18. Using management to address vegetation stress related to land-use and climate change

    USGS Publications Warehouse

    Middleton, Beth A.; Boudell, Jere; Fisichelli, Nicholas

    2017-01-01

    While disturbances such as fire, cutting, and grazing can be an important part of the conservation of natural lands, some adjustments to management designed to mimic natural disturbance may be necessary with ongoing and projected climate change. Stressed vegetation that is incapable of regeneration will be difficult to maintain if adults are experiencing mortality, and/or if their early life-history stages depend on disturbance. A variety of active management strategies employing disturbance are suggested, including resisting, accommodating, or directing vegetation change by manipulating management intensity and frequency. Particularly if land-use change is the main cause of vegetation stress, amelioration of these problems using management may help vegetation resist change (e.g. strategic timing of water release if a water control structure is available). Managers could direct succession by using management to push vegetation toward a new state. Despite the historical effects of management, some vegetation change will not be controllable as climates shift, and managers may have to accept some of these changes. Nevertheless, proactive measures may help managers achieve important conservation goals in the future.

  19. Changes in permeability caused by transient stresses: field observations, experiments, and mechanisms

    USGS Publications Warehouse

    Manga, Michael; Beresnev, Igor; Brodsky, Emily E.; Elkhoury, Jean E.; Elsworth, Derek; Ingebritsen, Steve E.; Mays, David C.; Wang, Chi-yuen

    2012-01-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10–6 can increase discharge in streams and springs, change the water level in wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to prestimulated values over a period of months to years. Mechanisms that can change permeability at such small stresses include unblocking pores, either by breaking up permeability-limiting colloidal deposits or by mobilizing droplets and bubbles trapped in pores by capillary forces. The recovery time over which permeability returns to the prestimulated value is governed by the time to reblock pores, or for geochemical processes to seal pores. Monitoring permeability in geothermal systems where there is abundant seismicity, and the response of flow to local and regional earthquakes, would help test some of the proposed mechanisms and identify controls on permeability and its evolution.

  20. Structural features and seismotectonic implications of coseismic surface ruptures produced by the 2016 M w 7.1 Kumamoto earthquake

    NASA Astrophysics Data System (ADS)

    Lin, Aiming

    2017-03-01

    Field investigations and analyses of satellite images and aerial photographs reveal that the 2016 M w 7.1 (Mj 7.3) Kumamoto earthquake produced a ˜40-km surface rupture zone striking NE-SW on central Kyushu Island, Japan. Coseismic surface ruptures were characterized by shear faults, extensional cracks, and mole tracks, which mostly occurred along the pre-existing NE-SW-striking Hinagu-Futagawa fault zone in the southwest and central segments, and newly identified faults in the northeast segment. This study shows that (i) the Hinagu-Futagawa fault zone triggered the 2016 Kumamoto earthquake and controlled the spatial distribution of coseismic surface ruptures; (ii) the southwest and central segments were dominated by right-lateral strike-slip movement with a maximum in-site measured displacement of up to 2.5 m, accompanied by a minor vertical component. In contrast, the northeast segment was dominated by normal faulting with a maximum vertical offset of up to 1.75 m with a minor horizontal component that formed graben structures inside Aso caldera; (iii) coseismic rupturing initiated at the jog area between the Hinagu and Futagawa faults, then propagated northeastward into Aso caldera, where it terminated. The 2016 M w 7.1 Kumamoto earthquake therefore offers a rare opportunity to study the relationships between coseismic rupture processes and pre-existing active faults, as well as the seismotectonics of Aso volcano.

  1. Coseismic and postseismic surface displacements of the 10 December 2003 ( M W 6.5) Chengkung, eastern Taiwan, earthquake

    NASA Astrophysics Data System (ADS)

    Chen, Horng-Yue; Yu, Shui-Beih; Kuo, Long-Chen; Liu, Chi-Ching

    2006-01-01

    The MW 6.5 Chengkung earthquake occurred in eastern Taiwan at 04:38 UTC on 10 December 2003. The GPS data from eighteen continuously recording stations (CORS) and 86 campaign-surveyed stations (CSS) collected 18 days to 9 months before and 6 days to 4 months after the main shock are utilized to analyze the coseismic and postseismic deformation associated with the Chengkung earthquake. The earthquake resulted from rupturing of the Chihshang fault, a 25-km-long segment of the Longitudinal Valley Fault (LVF). The coseismic horizontal displacements in the hanging wall showed a fan-shape distribution with vectors towards the west. On the other hand, the movements of the revealed a mirror fan-shape with relatively lesser amounts of displacement. The largest coseismic displacement, which reached 126 mm and 263 mm in the horizontal and vertical components, occurred near the epicenter area in the hanging wall. The largest postseismic displacements in 109 days, which approached 59 mm and 68 mm in the horizontal and vertical components, occurred near the surface trace of the Chihshang fault (TAPO) and near the epicenter area (CHEN), respectively. The stations near the Chihshang fault indicated a more significant postseismic displacement than coseismic one.

  2. Detrital 10Be Response to the 2008 Wenchuan Earthquake and Quantifying Evacuation of Coseismic Landslide Debris

    NASA Astrophysics Data System (ADS)

    Wang, W.; Godard, V.; Liu-Zeng, J.; Scherler, D.; Xu, C.; Xu, Q.; Xie, K.; Bellier, O.; Bourles, D. L.; Ansberque, C.

    2014-12-01

    In reverse fault-bounded high relief mountain ranges, large-magnitude earthquakes contribute to the topographic growth by co- and inter-seismic surface uplift on the hanging wall. Meanwhile, they also trigger widespread landslides along ridge lines or hillslopes. Coseismic landsliding lowers relief and causes a phase of high erosion in the period following the quake. The net effect of large-magnitude earthquakes in topographic evolution of active orogens partially depends on how fast the landslide debris are being evacuated out of the mountain range. The 2008 Mw7.9 Wenchuan earthquake, China activated the Longmen Shan reverse fault system in eastern Tibetan plateau, also induced enormous amount of landslides, volume comparable to the coseismic uplift, providing an excellent opportunity to address the question. We use cosmogenic 10Be concentration in river sand as a tracer to study the sediment routing process of coseismic landslide debris, because landslide debris contains low 10Be concentration. We sampling annually during 2008-2013, at 19 locations along the rivers that traverse the fault ruptures, with upstream catchment area varying between 4.4 km2 and 21775 km2, including 10 catchments sampled before Wenchuan earthquake in 2004 and 2005. A comparison with pre-earthquake measurements show reduced 10Be concentration at all sites. This dilution is more significant for small catchments on short range-front rivers: mostly half to one-fourth, and down to one-fifth in some cases. Multi-year time series of 10Be concentration at single sites show roughly constant level of dilution six years after the quake, with moderate temporal fluctuations, which may be related to the variation in precipitation and storm intensity. Under the assumption of constant dilution rate and a depth-mixing of 10Be concentration for landslide input, a simple calculation indicates it would take ~ 200 to 3000 years to completely evacuate the landslides debris within range-front transverse rivers

  3. Beyond Adapting to Climate Change: Embedding Adaptation in Responses to Multiple Threats and Stresses

    SciTech Connect

    Wilbanks, Thomas J; Kates, Dr. Robert W.

    2010-01-01

    Climate change impacts are already being experienced in every region of the United States and every part of the world most severely in Arctic regions and adaptation is needed now. Although climate change adaptation research is still in its infancy, significant adaptation planning in the United States has already begun in a number of localities. This article seeks to broaden the adaptation effort by integrating it with broader frameworks of hazards research, sustainability science, and community and regional resilience. To extend the range of experience, we draw from ongoing case studies in the Southeastern United States and the environmental history of New Orleans to consider the multiple threats and stresses that all communities and regions experience. Embedding climate adaptation in responses to multiple threats and stresses helps us to understand climate change impacts, themselves often products of multiple stresses, to achieve community acceptance of needed adaptations as co-benefits of addressing multiple threats, and to mainstream the process of climate adaptation through the larger envelope of social relationships, communication channels, and broad-based awareness of needs for risk management that accompany community resilience.

  4. Urodynamic Changes Associated with Successful Stress Urinary Incontinence Surgery: Is a Little Tension a Good Thing?

    PubMed Central

    Kraus, Stephen R.; Lemack, Gary E.; Sirls, Larry; Chai, Toby C.; Brubaker, Linda; Albo, Michael; Leng, Wendy W.; Lloyd, L. Keith; Norton, Peggy; Litman, Heather

    2011-01-01

    Objectives The aim of this study is to identify urodynamic changes that correlate with successful outcomes after stress urinary incontinence (SUI) surgery. Methods 655 women were randomized to Burch colposuspension or autologous fascial sling as part of the multi-center Stress Incontinence Surgical Treatment Efficacy Trial. Preoperatively and 24 months after surgery, participants underwent standardized urodynamic testing which included non-invasive uroflowmetry, cystometrogram and pressure flow studies. Changes in urodynamic parameters were correlated to a successful outcome, defined a priori as: 1) negative pad test, 2) no urinary incontinence on 3-day diary, 3) negative cough and valsalva stress test, 4) no self-reported SUI symptoms on the Medical, Epidemiological and Social Aspects of Aging Questionnaire and 5) no retreatment for SUI. Results Subjects who met criteria for surgical success showed a greater relative increase in mean Pdet@Qmax (baseline vs 24 months) than women who were considered surgical failures (p = 0.008). While a trend suggested an association between greater increases in bladder outlet obstruction index and outcome success, this was not statistically significant. Other urodynamic variables such as maximum uroflow, bladder compliance, and the presence of preoperative or de novo detrusor overactivity did not differ with respect to outcome status. Conclusions Successful outcomes in both surgical groups (Burch and sling) were associated with higher voiding pressures relative to preoperative baseline values. However, concomitant changes in other urodynamic voiding parameters were not significantly associated with outcome. PMID:21996108

  5. Investigation of coseismic displacements and ionospheric disturbances in the Far East of Russia generated by the Great 2011 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Shestakov, Nikolai; Perevalova, Natalia; Voeykov, Sergey; Ishin, Artem; Yasyukevich, Yury; Bykov, Victor; Gerasimenko, Mikhail

    2013-04-01

    The 2011 Great Tohoku earthquake struck and generated a huge tsunami along the Pacific coast of Honshu Island, Japan, almost two years ago. The near-field crustal displacements and deformations, propagation of surface waves and ionospheric disturbances were carefully investigated in a number of recent publications. However, the far-field coseismic displacements and ionospheric disturbances have not so far been completely investigated. In this study we determine and analyze the far-field coseismic crustal displacements, deformations and ionospheric disturbances induced by the 2011 Great Tohoku earthquake using different GPS data sources (IGS data, continuously and periodically observed regional geodynamic GNSS networks and other GNSS observations applicable for this study). We combined our coseismic offset estimates with the analogous results already published for the Korean Peninsula and China through the six-parameter transformation method using coseismic shifts at a set of common GPS sites. Our analysis shows that the most intense coseismic offsets exceeding 50 mm were localized in the south of the Russian Far East and propagated westward from the earthquake source. We modeled the observed far-field coseismic displacements using different source models developed based on our far-field GPS data and other sources. Quite good agreement between the calculated and observed offsets was found for a simple one-plane rectangular fault model of 200×100 km size with a homogeneous slip value of about 33 m. The total electron content (TEC) data extracted from the original GPS observations were used to study the ionospheric response to this seismic event in the far-field zone. The initial slant TEC series Io(t) were converted into the equivalent vertical values I(t) to normalize the amplitude of TEC disturbances. The I(t) series were smoothed with 2-min time window, to remove high-frequency oscillations, and detrended. The TEC disturbances with periods of 5-15 min propagated

  6. Emotions and eating. Self-reported and experimentally induced changes in food intake under stress.

    PubMed

    Wallis, D J; Hetherington, M M

    2009-04-01

    Two studies investigated the stress-eating relationship. The first examined self-reported changes in intake of snack foods, whilst the second investigated stress-induced overconsumption in a laboratory setting comparing high (HF) and low-fat (LF) snacks. Eighty-nine females completed the Dutch Eating Behaviour Questionnaire (DEBQ) [Van Strien, T., Fritjers, J. E. R., Bergers, G. P. A., & Defares, P. B. (1986). Dutch Eating Behaviour Questionnaire for assessment of restrained, emotional and external eating behaviour. International Journal of Eating Disorders, 5, 295-315] and a self-report measure designed to evaluate changes in eating in response to stress. Increased intake of HF snacks was associated with high emotional eating but not with restraint. A laboratory-based experiment compared intake of HF and LF snacks after ego-threatening and neutral Stroop colour-naming tasks. Intake was suppressed by 31.8% in restrained compared to unrestrained eaters across tasks. Restrained eaters consumed significantly less after ego-threat than after the neutral manipulation, but this was associated only with intake of the LF snack. Restrained eaters' intake of dried fruit was suppressed by 33.2% after ego-threat relative to the neutral task, despite a significant increase in hunger for this group following ego-threat. These results suggest that the type and variety of foods offered influences the link between stress and eating in laboratory settings. Further research should aim to replicate and extend these findings, with a view to informing potential interventions for stress-related eating.

  7. A damage mechanics approach for quantifying stress changes due to brittle failure of porous rocks

    NASA Astrophysics Data System (ADS)

    Jacquey, Antoine B.; Cacace, Mauro; Blöcher, Guido; Milsch, Harald; Scheck-Wenderoth, Magdalena

    2016-04-01

    Natural fault zones or man-made injection or production of fluid impact the regional stress distribution in Earth's crust and can be responsible for localized stress discontinuities. Understanding the processes controlling fracturing of the porous rocks and mechanical behaviour of fault zones is therefore of interest for several applications including geothermal energy production. In this contribution, we will present a thermodynamically consistent visco-poroelastic damage model which can deal with the multi-scale and multi-physics nature of the physical processes controlling the deformation of porous rocks during and after brittle failure. Deformation of a porous medium is crucially influenced by the changes in the effective stress. Considering a strain-formulated yield cap and the compaction-dilation transition, three different regimes can be identified: quasi-elastic deformation, cataclastic compaction with microcracking (damage accumulation) and macroscopic brittle failure with dilation. The governing equations for deformation, damage accumulation/healing and fluid flow have been implemented in a fully-coupled finite-element-method based framework (MOOSE). The MOOSE framework provides a powerful and flexible platform to solve multiphysics problems implicitly and in a tightly coupled manner on unstructured meshes which is of interest for such non-linear context. To illustrate the model, simulation of a compaction experiment of a sandstone leading to shear failure will be presented which allows to quantify the stress drop accompanying the failure. Finally, we will demonstrate that this approach can also be used at the field scale to simulate hydraulic fracturing and assess the resulting changes in the stress field.

  8. A microfluidic cell culture system for monitoring of sequential changes in endothelial cells after heat stress.

    PubMed

    Tazawa, Hidekatsu; Sato, Kenjiro; Tsutiya, Atsuhiro; Tokeshi, Manabu; Ohtani-Kaneko, Ritsuko

    2015-08-01

    Endothelial damage induced by a highly elevated body temperature is crucial in some diseases including viral hemorrhagic fevers. Here, we report the heat-induced sequential changes of endothelial cells under shear stress, which were determined with a microfluidic culture system. Although live cell imaging showed only minor changes in the appearance of heat-treated cells, Hsp70 mRNA expression analysis demonstrated that the endothelial cells in channels of the system responded well to heat treatment. F-actin staining also revealed clear changes in the bundles of actin filaments after heat treatment. Well-organized bundles of actin filaments in control cells disappeared in heat-treated cells cultured in the channel. Furthermore, the system enabled detection of sequential changes in plasminogen activator inhibitor-1 (PAI-1) secretion from endothelial cells. PAI-1 concentration in the effluent solution was significantly elevated for the first 15min after initiation of heat treatment, and then decreased subsequently. This study provides fundamental information on heat-induced endothelial changes under shear stress and introduces a potent tool for analyzing endothelial secretions.

  9. Stress evolution in southern California and triggering of moderate-, small-, and micro-size earthquakes

    NASA Astrophysics Data System (ADS)

    Deng, Jishu; Sykes, Lynn R.

    1997-11-01

    We calculate the evolution of stresses in southern California, extending the study of Deng and Sykes [1997] by increasing from 6 to 36 the number of earthquakes for which coseismic changes in stress are computed and by expanding from M≥6 to M≥1.8 the range of magnitudes M of events whose focal mechanism solutions are examined in the context of the evolving stress field. The cumulative stress on a given date is calculated with respect to an arbitrary zero baseline just before the 1812 Wrightwood earthquake. By taking into account the long-term stress loading associated with 98 fault segments and coseismic stress changes for 36 significant earthquakes, our calculations indicate that more than 85% of M≥5 earthquakes from 1932-1995 occurred in regions of positive change in Coulomb failure function (ΔCFF). Most of the remaining about 15% earthquakes that occurred in areas of negative ΔCFF fall very close to boundaries between positive and negative ΔCFF, some of which are sensitive to the less well controlled slip distributions of the earliest historic events. Calculations also show that from 1981 until just before the 1992 Landers earthquake more than 85% of small- (M≥3) and micro-size (M≥1.8) shocks in the Seeber and Armbruster [1995] catalog with mechanisms involving either NW trending right-lateral or NE trending left-lateral strike-slip faulting occurred in regions of positive ΔCFF. The ratio of encouraged to all small- and micro-size events reaches a high value of about 88% if an apparent coefficient of friction μ between 0.0 and 0.6 is used. The highest percentage of earthquakes occurred in areas where stress is about 1 MPa above the 1812 baseline. Most (66%) events occurred in regions of ΔCFF between 0.0 and 2.0 MPa. The upper limit indicates that the approximate range of stress variation in the earthquake cycle is of the order of 2.0 MPa. The fact that the locations of most moderate-, small-, and micro-size earthquakes are still related to stress

  10. Coseismic and postseismic displacements from the 1978 Mw 7.3 Tabas-e-Golshan earthquake in eastern Iran

    NASA Astrophysics Data System (ADS)

    Zhou, Yu; Walker, Richard T.; Hollingsworth, James; Talebian, Morteza; Song, Xiaogang; Parsons, Barry

    2016-10-01

    We use optical image correlation of historical aerial photographs, and modern satellite images to investigate the 1978 Mw 7.3 Tabas-e-Golshan thrust earthquake in eastern Iran. Correlation of images between 1974 and 1991 reveals a near-surface shortening component of ∼2.9 m across the margin of the Tabas fold, which is a combination of coseismic and postseismic deformation. Correlation of images between 1991 and 2013 shows a further ∼0.3 m of postseismic shortening. Using six pre-earthquake aerial photographs acquired in 1956 and stereo SPOT-6 imagery from 2013, we also generate pre- and post-earthquake digital elevation models (DEMs) for one of the main fold segments. Differencing of the two DEMs reveals a height change of ∼4.7 m. Elastic dislocation modelling of the 1974-2013 displacement field requires 7 m slip on a 50° dipping fault, extending from a depth of 0.1 km to 6 km at its base (the majority of slip, ∼6.5 m, occurred prior to 1991). Our results, combined with previous InSAR observations, indicate time-decaying shallow postseismic afterslip. It is likely that most of the afterslip occurred prior to 1991. The slip appears to dissipate in the near surface, and is accommodated as a narrow band of flexural slip on bedding planes. Comparison of the fault slip model with terrace heights measured from the SPOT-6 DEM suggests that the Tabas fold system may exhibit characteristic slip behaviour. Such behaviour would require a magnitude Mw 7.3 earthquake every ∼3500 years, based on the previously estimated shortening rate of ∼1.0 mm/yr. This study highlights the usefulness of historical imagery in investigating past earthquakes, thus providing new information about historical faulting in continental regions.

  11. Late Quaternary coseismic uplift events on the Huon Peninsula, Papua New Guinea, deduced from coral terrace data

    NASA Astrophysics Data System (ADS)

    Ota, Yoko; Chappell, John

    1996-03-01

    Up to six regressive terraces occur on the Holocene raised reef tract and up to 15 occur on late Pleistocene raised reef tracts along 40 km of coastline at Huon Peninsula, Papua New Guinea. We suggest that the regressive terraces represent repeated episodic uplift caused by great earthquakes. Ages of Holocene coseismic uplift events are established by radiocarbon dating; the late Pleistocene events are bracketed by U series ages of the raised reef tracts on which they occur. The mean recurrence interval of great earthquakes that caused the uplift events is 970 to 1165 years in the Holocene and probably the same in the late Pleistocene; the interval ranged from about 200 to 1900 years. The uplift rate increases parallel to the coast from northwest to southeast, and the amplitude of coseismic uplifts generally increases similarly, although some events produced uplift with little shore-parallel tilting. The mean amplitude of coseismic uplifts throughout the study area is ˜3 m in for both Holocene and late Pleistocene sequences. Large, late Quaternary landslides are numerous, and some probably were triggered by the great earthquakes that caused coseismic uplift. There appears to be no continuum between historical large earthquakes at Huon Peninsula of magnitudes >7 that produced no or only minor uplift, and the great earthquakes represented by meter-scale coseismic uplifts and very large landslides. Two tectonic subregions are recognized, which were uplifted together by some Holocene events but not by others. There is no surface trace of Holocene faulting between the subregions, and a buried fault is thought to separate them.

  12. Stress coupling in the seismic cycle indicated from geodetic measurements

    NASA Astrophysics Data System (ADS)

    Wang, L.; Hainzl, S.; Zoeller, G.; Holschneider, M.

    2012-12-01

    The seismic cycle includes several phases, the interseismic, coseismic and postseismic phase. In the interseismic phase, strain gradually builds up around the overall locked fault in tens to thousands of years, while it is coseismically released in seconds. In the postseismic interval, stress relaxation lasts months to years, indicated by evident aseismic deformations which have been indicated to release comparable or even higher strain energy than the main shocks themselves. Benefiting from the development of geodetic observatory, e.g., Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) in the last two decades, the measurements of surface deformation have been significantly improved and become valuable information for understanding the stress evolution on the large fault plane. In this study, we utilize the GPS/InSAR data to investigate the slip deficit during the interseismic phase, the coseismic slip and the early postseismic creep on the fault plane. However, it is already well-known that slip inversions based only on the surface measurements are typically non-unique and subject to large uncertainties. To reduce the ambiguity, we utilize the assumption of stress coupling between interseismic and coseismic phases, and between coseismic and postseismic phases. We use a stress constrained joint inversion in Bayesian approach (Wang et al., 2012) to invert simultaneously for (1) interseismic slip deficit and coseismic slip, and (2) coseismic slip and postseismic creep. As case studies, we analyze earthquakes occurred in well-instrumented regions such as the 2004 M6.0 Parkfield earthquake, the 2010 M8.7 earthquake and the 2011 M9.1 Tohoku-Oki earthquake. We show that the inversion with the stress-coupling constraint leads to better constrained slip distributions. Meanwhile, the results also indicate that the assumed stress coupling is reasonable and can be well reflected from the available geodetic measurements. Reference: Lifeng

  13. Earthquake Source Mechanisms, Coseismic Costal Uplifts and Tsunamigenesis in the Eastern Hellenic Arc and Trench

    NASA Astrophysics Data System (ADS)

    Triantafyllou, Ioanna; Papadopoulos, Gerassimos

    2015-04-01

    The eastern segment of the Hellenic Arc and Trench (HA-T) is tectonically characterized by interplate seismic activity with mainly thrust mechanism. Large earthquakes and tsunamis are known from both the historical and geological record particularly in Rhodes Isl. (Greece). Geological observations have indicated that eastern Rhodes has systematically uplifted during the Holocene with uplift amplitude increasing from S to N with average velocity ranging from 0 at south to 1 mm/yr at the NE side of the island. In order to better understand why some large earthquakes caused tsunamis while others did not, we examined the source mechanisms and the submarine setting of historical and instrumental earthquakes occurring in the area of Rhodes. Historical sources maintain direct evidence that three, large earthquakes caused coseismic uplift with permanent sea retreat in the city of Rhodes at the NE side of the island at 227 BC, AD 142 and 12 October 1856. The average historical coseismic uplift was found around 0.7 mm/yr which is close to the geological average. We examined original documentary sources and found that these earthquakes were non-tsunamigenic, thus revising previous thoughts. We suggested that the ones of 227 BC and AD 142, both with magnitude M~7, were crustal earthquakes having their epicenters offshore but close to Rhodes city, that is in shallow water domain. The 1856 earthquake of M~7.5 very likely was of intermediate focal depth, quite similar to that of 26 June 1926, therefore it was not capable to produce a tsunami. Another set of earthquakes includes the large events of AD 1303, 1481, 1609 and 1741. It is documented from historical sources and/or geological observations that all of them caused powerful tsunamis. However, no evidence for coseismic uplift was found in Rhodes Isl. Therefore, we suggested that these earthquakes had their epicenters offshore away from the island. The 1303 earthquake was a very large event (M~8) that ruptured under deep

  14. Bootheel lineament: A possible coseismic fault of the great New Madrid earthquakes

    SciTech Connect

    Schweig, E.S. III; Marple, R.T. )

    1991-10-01

    A remote sensing examination of the New Madrid seismic zone has revealed a feature, the Bootheel lineament, that may be the surface expression of one of the coseismic faults of the great New Madrid earthquakes of 1811 and 1812. The lineament extends about 135 km in a north-northeast direction through northeastern Arkansas and southeastern Missouri. The morphology and pattern of the lineament suggest that it reflects a fault with strike-slip displacement. Field data indicate that liquefied sand was injected along the lineament, probably in 1811 and 1812. The Bootheel lineament does not coincide with any of the major arms of New Madrid seismicity, possibly indicating that the current seismicity does not precisely reflect the faults that ruptured in 1811 and 1812.

  15. Calculation of coseismic displacement from lidar data in the 2016 Kumamoto, Japan, earthquake

    NASA Astrophysics Data System (ADS)

    Moya, Luis; Yamazaki, Fumio; Liu, Wen; Chiba, Tatsuro

    2017-02-01

    The spatial distribution of the coseismic displacements that occurred along the Futagawa fault during the 2016 Kumamoto earthquake of Mw 7.0 was estimated using airborne light detection and ranging (lidar) data. In this study, a pair of digital surface models (DSMs) obtained from the high-density lidar data before and after the mainshock on 16 April 2016 were used. A window matching search approach based on the correlation coefficient between the two DSMs was used to estimate the geodetic displacement in the near-field region. The results showed good agreements with the geodetic displacements calculated from strong-motion acceleration records and coincided with the fault line surveyed by the Geological Survey of Japan.

  16. Coseismic landslide reactivation characteristics determined from dynamic ring-shear testing

    USGS Publications Warehouse

    Schulz, William H.; Wang, Gonghui; Zhang, Fanyu

    2012-01-01

    Large earthquakes often cause widespread landsliding that alters landscapes and presents significant hazards to human safety and the built environment. For example, the 2008, Mw 7.9 Wenchuan, China earthquake triggered more than 56,000 landslides that killed about 20,000 people. Predicting the occurrence and nature of coseismic landslides remains elusive largely because limitations on laboratory apparatus and a lack of instrumental field observations have precluded understanding the basic response of geologic materials to seismically induced shearing. Coastal Oregon, USA is a region of numerous landslides and great subduction-zone earthquakes that recur every 300-500 yrs, the most recent of which occurred during January 1700. Reactivation of existing landslides during future great earthquakes could threaten human safety because many of these slides potentially impact tsunami evacuation and emergency response routes.

  17. The 3-D surface deformation, coseismic fault slip and after-slip of the 2010 Mw6.9 Yushu earthquake, Tibet, China

    NASA Astrophysics Data System (ADS)

    Zhang, Guohong; Shan, Xinjian; Feng, Guangcai

    2016-07-01

    Using SAR interferometry on C band Envisat descending track and L band ALOS ascending track SAR images, respectively, we firstly obtain two coseismic deformation fields and one postseismic deformation of the 2010 Yushu earthquake, Tibet, China. In the meanwhile, we also obtain the azimuthal coseismic deformation of the Yushu event by Multi Aperture Interferometry (MAI) technique. With the 3 components of one-dimensional coseismic InSAR measurements, we resolve the complete 3-dimensional deformation of the 2010 Yushu event, which shows conformity and complexity to left lateral slip mechanism. The horizontal deformation is basically consistent with a sinistral slip event; whereas the vertical displacement does show certain level of complexity, which we argue is indicative of local fault geometry variation. Based on the InSAR data and elastic dislocation assumption, we invert for coseismic fault slip and early after-slip of the Yushu event. Our inversion results show major coseismic left lateral strike slip with only minor thrust component. The after-slip model fills most of the slip gaps left by the coseismic fault slip and finds a complementary slip distribution to the coseismic fault slip, which is a good indicator that future earthquake potential on the Yushu segment has been significantly reduced.

  18. Water stress as a trigger of demand change: exploring the implications for drought planning

    NASA Astrophysics Data System (ADS)

    Garcia, M. E.; Islam, S.; Portney, K. E.

    2015-12-01

    Drought in the Anthropocene is a function of both supply and demand. Despite its importance, demand is typically incorporated into planning models exogenously using a single scenario of demand change over time. Alternatively, demand is incorporated endogenously in hydro-economic models based on the assumption of rationality. However, actors are constrained by limited information and information processing capabilities, casting doubt on the rationality assumption. Though the risk of water shortage changes incrementally with demand growth and hydrologic change, significant shifts in management are punctuated and often linked to periods of stress. The observation of lasting decreases in per capita demands in a number of cities during periods of water stress prompts an alternate hypothesis: the occurrence of water stress increases the tendency of cities to promote and enforce efficient technologies and behaviors and the tendency of users to adopt them. We show the relevance of this hypothesis by building a model of a hypothetical surface water system to answer the following question: what is the impact of reservoir operation policy on the reliability of water supply for a growing city? The model links the rate of demand decreases to the past reliability to compare standard operating policy (SOP) with hedging policy (HP). Under SOP, demand is fulfilled unless available supply drops below demand; under HP, water releases are reduced in anticipation of a deficit to decrease the risk of a large shortfall. The model shows that reservoir storage acts both as a buffer for variability and as a delay triggering oscillations around a sustainable level of demand. HP reduces the threshold for action thereby decreasing the delay and the oscillation effect. As a result per capita demand decrease during periods of water stress are more frequent but less drastic and the additive effect of small adjustments decreases the tendency of the system to overshoot available supplies.

  19. Paroxetine ameliorates changes in hippocampal energy metabolism in chronic mild stress-exposed rats

    PubMed Central

    Khedr, Lobna H; Nassar, Noha N; El-Denshary, Ezzeldin S; Abdel-tawab, Ahmed M

    2015-01-01

    The molecular mechanisms underlying stress-induced depression have not been fully outlined. Hence, the current study aimed at testing the link between behavioral changes in chronic mild stress (CMS) model and changes in hippocampal energy metabolism and the role of paroxetine (PAROX) in ameliorating these changes. Male Wistar rats were divided into three groups: vehicle control, CMS-exposed rats, and CMS-exposed rats receiving PAROX (10 mg/kg/day intraperitoneally). Sucrose preference, open-field, and forced swimming tests were carried out. Corticosterone (CORT) was measured in serum, while adenosine triphosphate and its metabolites, cytosolic cytochrome-c (Cyt-c), caspase-3 (Casp-3), as well as nitric oxide metabolites (NOx) were measured in hippocampal tissue homogenates. CMS-exposed rats showed a decrease in sucrose preference as well as body weight compared to control, which was reversed by PAROX. The latter further ameliorated the CMS-induced elevation of CORT in serum (91.71±1.77 ng/mL vs 124.5±4.44 ng/mL, P<0.001) as well as the changes in adenos-ine triphosphate/adenosine diphosphate (3.76±0.02 nmol/mg protein vs 1.07±0.01 nmol/mg protein, P<0.001). Furthermore, PAROX reduced the expression of Cyt-c and Casp-3, as well as restoring NOx levels. This study highlights the role of PAROX in reversing depressive behavior associated with stress-induced apoptosis and changes in hippocampal energy metabolism in the CMS model of depression. PMID:26622178

  20. Response of a subcritically growing macrocrack in the mining environment to induced stress changes

    NASA Astrophysics Data System (ADS)

    Becker, Dirk; Cailleau, Beatrice; Kaiser, Diethelm; Dahm, Torsten

    2013-04-01

    Microcrack activity observed in underground mines may indicate regions prone to future rock burst and rockfall events and may help mitigating risks in the mining environment. We use observed microcrack activity as recorded in a catalog of acoustic emission (AE) events in combination with calculated stress gradients and transients to test physical seismicity models and their forecast potential in mines. The study deals with the response of the rock mass in an abandoned rock salt mine to stress changes induced by backfilling of an old cavity. The high spatial-temporal resolution of our dataset allows the study of slowly growing fractures and the development of microcrack activity in the fracture damage zone of a growing macrockrack. The physical insights we obtain are important to understand the development of possible sudden rockfall events, but may also be useful to better understand the nucleation of earthquakes. A pre-existing fracture of about 15 m length within the hanging wall about 15-20 m above the backfilled cavity was identified by careful analysis of the pre-filling AE activity. This fracture was found to be very responsive to small changes in the traction like terms of the stress field transferred instantaneously after backfilling started. This behaviour was indicated by a slowly spreading front of AE activity migrating at a rate of up to about 1 m/month. The recorded AE events likely occur in the fracture damage zone during its outward growth. Their temporal event rate evolution correlates very well with the forecast of stress-based seismicity models suggesting that concepts like the Coulomb failure model are also applicable on the micro scale. This observation is supported by the response of the microcracking activity of the damage zone to the initiation of a second macrocrack occurring in close proximity. The initiation of this new macrocrack temporally corresponds with a clear break-down of the high positive correlation between AE activity on and the

  1. Feather corticosterone reveals stress associated with dietary changes in a breeding seabird.

    PubMed

    Will, Alexis; Watanuki, Yutaka; Kikuchi, Dale M; Sato, Nobuhiko; Ito, Motohiro; Callahan, Matt; Wynne-Edwards, Katherine; Hatch, Scott; Elliott, Kyle; Slater, Leslie; Takahashi, Akinori; Kitaysky, Alexander

    2015-10-01

    Changes in climate and anthropogenic pressures might affect the composition and abundance of forage fish in the world's oceans. The junk-food hypothesis posits that dietary shifts that affect the quality (e.g., energy content) of food available to marine predators may impact their physiological state and consequently affect their fitness. Previously, we experimentally validated that deposition of the adrenocortical hormone, corticosterone, in feathers is a sensitive measure of nutritional stress in seabirds. Here, we use this method to examine how changes in diet composition and prey quality affect the nutritional status of free-living rhinoceros auklets (Cerorhinca monocerata). Our study sites included the following: Teuri Is. Japan, Middleton Is. central Gulf of Alaska, and St. Lazaria Is. Southeast Alaska. In 2012 and 2013, we collected "bill loads" delivered by parents to feed their chicks (n = 758) to document dietary changes. We deployed time-depth-temperature recorders on breeding adults (n = 47) to evaluate whether changes in prey coincided with changes in foraging behavior. We measured concentrations of corticosterone in fledgling (n = 71) and adult breeders' (n = 82) feathers to determine how birds were affected by foraging conditions. We found that seasonal changes in diet composition occurred on each colony, adults dove deeper and engaged in longer foraging bouts when capturing larger prey and that chicks had higher concentrations of corticosterone in their feathers when adults brought back smaller and/or lower energy prey. Corticosterone levels in feathers of fledglings (grown during the breeding season) and those in feathers of adult breeders (grown during the postbreeding season) were positively correlated, indicating possible carryover effects. These results suggest that seabirds might experience increased levels of nutritional stress associated with moderate dietary changes and that physiological responses to changes in prey composition

  2. Correlation of rock dehydration and dynamic micro state-rate friction law to coseismic fault

    NASA Astrophysics Data System (ADS)

    Zhu, B.; Shi, Y.

    2011-12-01

    In this paper, the relationship between the coseismic fault rock dehydration and micro state-rate friction law have been explored at multi temporal scales level by using hybrid hypersingular integral equation & Lattice Boltzmann method (HHIE-LBM) under parallel CPU and GPU platform. First, seven standard rock specimens from Continental Scientific Drilling Project in China were studied. Based on the micro tomography technology, digital restructure technology and first principle, molecular scale (10nm) virtual modules, micro crystal scale (30~50nm) and meso crystals scale (2um~10um) were established, respectively. The mechanism of structural OH and molecular H2O translate through internal crystal structure, the mechanism of molecular H2O translate through crystal spaces and the supercritical water through crystal spaces and dislocations were explored and the relatively critical temperature and pressure to these specimens were obtained. The simulation results show that the diffusion, transport and dehydration energy of structural OH is two orders of magnitude than molecular H2O, and the diffusion, transport and dehydration energy of molecular H2O is one order of magnitude than supercritical water. Second, the diffusion, transport and dehydration process of structural OH, molecular H2O and supercritical water on the coseismic fault is studied and the relationship between micro dynamics friction coefficient, dehydration process and ultra temperature and pressure is presentation. The classical state and rate friction law is revised and extended micro state and rate friction law which consider the effect of fault interface rock dehydration and thermal diffusion is obtained, and these formulation will helpful understand the earthquake triggering mechanism and provide theoretical suggestion for earthquake early warning system. Key words Structural HO, molecular H2O and supercritical water, Diffusion transport and dehydration; Ultra high temperature and pressure; Developed

  3. Changing emotion dynamics: individual differences in the effect of anticipatory social stress on emotional inertia.

    PubMed

    Koval, Peter; Kuppens, Peter

    2012-04-01

    Emotional inertia-the degree to which people's feelings carry over from one moment to the next-is an important property of the temporal dynamics of emotions. Thus far, emotional inertia has only been examined as a stable, trait-like characteristic. However, internal or external events (e.g., stress) may trigger changes in people's emotion dynamics, particularly among individuals with heightened sensitivity to such events. The current study investigated how emotional inertia is influenced by the anticipation of social stress, and how this effect is moderated by individual differences in depression, self-esteem, and fear of negative evaluation. We measured participants' (n = 71) emotional inertia in daily life using experience sampling before and after experimentally manipulating anticipatory social stress. Consistent with previous research, psychological maladjustment was associated with higher emotional inertia during "normal" daily life. However, when anticipating a socially stressful event, levels of emotional inertia dropped, particularly among participants scoring high on depression and fear of negative evaluation and low on self-esteem. These results demonstrate that emotion dynamics can vary as a function of contextual factors and identify moderators of such variation.

  4. Explosion-induced stress changes estimated from vibrating-wire stressmeter measurements near the Mighty Epic event, Nevada Test Site

    USGS Publications Warehouse

    Ellis, William L.; Kibler, J.D.

    1983-01-01

    Explosion-induced compressive stress increases near an underground nuclear explosion are believed to contribute significantly to the containment of high-pressure gases within the explosion-produced cavity. These induced compressive stresses are predicted by computer calculations, but have never been adequately confirmed by field measurements, owing primarily to the unique difficulties of obtaining such field data. Vibrating-wire stressmeter measurements made near the Mighty Epic nuclear detonation, however, qualitatively indicate that within 150 meters of the working point, permanent compressive stress increases of several megapascals were present 15 weeks after the event. Additionally, stress-change magnitudes interpreted from the stressmeter data between the 75- and 260-meter range from the working point compare favorably with calculational predictions of the stress changes believed to be present shortly after detonation of the event. The measurements and calculations differ, however, with regard to the pattern of stress change radial and transverse to the explosion source. For the range of the field measurements from the working point, computer models predict the largest compressive-stress increase to be radial to the explosion source, while the field data indicate the transverse component of. stress change to be the most compressive. The significance of time-dependent modification of the initial explosion-induced stress distribution is, however, uncertain with regard to the comparison of the field measurements and theoretical predictions.

  5. Coulomb-Rate-and-State models with time dependent stresses: the role of afterslip and secondary triggering

    NASA Astrophysics Data System (ADS)

    Cattania, C.; Hainzl, S.; Roth, F.; Wang, L.

    2013-12-01

    Large earthquakes are known to trigger aftershocks by redistributing stresses in the crust, and a correlation between the location of aftershocks and positive Coulomb stress changes has been repeatedly observed. Mainshocks also trigger aseismic phenomena which can in turn modify the stress field, such as afterslip, viscoelastic and poroelastic response of the crust; moreover, aftershocks themselves contribute to the a relocalization of stresses. These processes have the potential to trigger seismicity; and while most physics based forecasting models neglect postseismic stresses, several lines of evidence suggest that both processes play a role in triggering earthquakes. The cumulative moment of afterslip can be a significant fraction of the mainshock moment, producing comparable stress changes; and while stress changes induced by individual aftershocks are orders of magnitude smaller than those due to the mainshocks, they can still be large in the near field, and the cumulative contribution of small events can be significant. The clustering of aftershocks, and the success of statistical models with cascade triggering (such as ETAS) suggest that secondary triggering may be an important aspect to model. Our goal is to study the impact of afterslip and secondary triggering in models based on Coulomb stresses. We model the seismic response to stress changes following the Dieterich constitutive law, derived from Rate and State frictional behavior on an infinite population of faults. We focus on the first 250 days from the mainshock, for two case studies: the Parkfield, Mw=6.0 and the Tohoku, Mw=9.0 earthquakes. For each case, we consider a starting model with only coseismic stresses; a model with afterslip; a model with secondary triggering; and a model with both processes. Model parameters (ta and Aσ) are inverted separately for each model. We find that in both cases, the treating aftershocks as stress sources leads to a significant improvement in model performance

  6. Persistent water level changes in a well near Parkfield, California, due to local and distant earthquakes

    USGS Publications Warehouse

    Roeloffs, E.A.

    1998-01-01

    Coseismic water level rises in the 30-m deep Bourdieu Valley (BV) well near Parkfield, California, have occurred in response to three local and five distant earthquakes. Coseismic changes in static strain cannot explain these water level rises because (1) the well is insensitive to strain at tidal periods; (2) for the distant earthquakes, the expected coseismic static strain is extremely small; and (3) the water level response is of the incorrect sign for the local earthquakes. These water level changes must therefore be caused by seismic waves, but unlike seismic water level oscillations, they are monotonic, persist for days or weeks, and seem to be caused by waves with periods of several seconds rather than long-period surface waves. Other investigators have reported a similar phenomenon in Japan. Certain wells consistently exhibit this type of coseismic water level change, which is always in the same direction, regardless of the earthquake's azimuth or focal mechanism, and approximately proportional to the inverse square of hypocentral distance. To date, the coseismic water level rises in the BV well have never exceeded the seasonal water level maximum, although their sizes are relatively well correlated with earthquake magnitude and distance. The frequency independence of the well's response to barometric pressure in the frequency band 0.1 to 0.7 cpd implies that the aquifer is fairly well confined. High aquifer compressibility, probably due to a gas phase in the pore space, is the most likely reason why the well does not respond to Earth tides. The phase and amplitude relationships between the seasonal water level and precipitation cycles constrain the horizontal hydraulic diffusivity to within a factor of 4.5, bounding hypothetical earthquake-induced changes in aquifer hydraulic properties. Moreover, changes of hydraulic conductivity and/or diffusivity throughout the aquifer would not be expected to change the water level in the same direction at every time

  7. Contemporary deformation and stressing rates in Southern Alaska

    NASA Astrophysics Data System (ADS)

    Ali, Syed Tabrez; Freed, Andrew M.

    2010-11-01

    the width of the locked plate interface. Calculations show that post-seismic relaxation following the large strike-slip events serves to reload these rupture surfaces while relieving stress on the eastern Denali Fault. Post-seismic relaxation following the 1964 earthquake combined with coseismic stress changes, promoted the triggering of the 2002 Denali quake. Calculations also suggest that over the past 50 years high stress has accumulated on part of the thrust interface to the west and east of the 1964 rupture surface and along the Queen-Charlotte Fault to the south of the 1949 rupture surface.

  8. Stress memory induced transcriptional and metabolic changes of perennial ryegrass (Lolium perenne) in response to salt stress.

    PubMed

    Hu, Tao; Jin, Yupei; Li, Huiying; Amombo, Erick; Fu, Jinmin

    2016-01-01

    Preexposure to a stress could induce stable signals and reactions on plant physiology and gene expression during future encounters as a 'stress memory'. In this study, we found that two trainable genes, BPSP encoding putative brown plant hopper susceptibility protein and sucs encoding sucrose synthase displayed transcriptional memory for their considerably higher transcript levels during two or more subsequent stresses (S3, S4) relative to the initial stress (S0), and their expression returning to basal transcript levels (non-stressed) during the recovery states (R1, R2 and R3). Removing the repetitive stress/recovery exercise, activated transcriptional memory from two trainable genes persisted for at least 4 days in perennial ryegrass. The pretrainable genes with stress memory effort had higher response to the subsequent elevated NaCl concentration treatment than the non-trainable plants, which was confirmed by lower electrolyte leakage and minimum H2 O2 and O2 (-) accumulation. Salt stress elevated the content of 41 metabolites in perennial ryegrass leaves, and sugars and sugar alcohol accounted for more than 74.1% of the total metabolite content. The salt stress memory was associated with higher contents of 11 sugars and 1 sugar alcohol in the pretrainable grass leaves. Similarly, six sugars showed greater content in the pretrainable grass roots. These novel phenomena associated with transcriptional memory and metabolite profiles could lead to new insights into improving plant salinity acclimation process.

  9. Hepatic and cardiac oxidative stress and other metabolic changes in broilers with the ascites syndrome.

    PubMed

    Díaz-Cruz, A; Nava, C; Villanueva, R; Serret, M; Guinzberg, R; Piña, E

    1996-07-01

    The objective of this study was to evaluate the gluconeogenic response of in vitro stimulated hepatocytes from control broilers and broilers with clinical manifestations of the ascites syndrome. The basal rate of glucose synthesis from lactate was found to be threefold greater in sick birds than in the control group and stimulation obtained with epinephrine was found to be quantitatively similar in both groups. Under basal conditions, the hepatocytes from the sick broilers exhibited 60% more ammonium than the control birds. In addition, the quantification of thiobarbituric acid reactive substances, as indicators of cellular lipoperoxidation, showed an increase of over 100% in heart and liver of sick broilers fowl. In conclusion, the complex integrated response of gluconeogenesis to epinephrine is maintained in broilers with ascites, although their hepatocytes present changes compatible with those observed in cases of oxidative stress. It is not known whether this stress is a cause or a consequence of the ascites syndrome.

  10. Thermoelastic investigation of residual stress: plastic deformation and the change in thermoelastic constant

    NASA Astrophysics Data System (ADS)

    Robinson, A. F.; Dulieu-Barton, J. M.; Quinn, S.; Burguete, R. L.

    2010-06-01

    Plastic deformation causes very small changes in the thermoelastic response of metallic materials; this variation of the thermoelastic constant has the potential to form the basis of a new non-destructive, non-contact, full-field technique for residual stress assessment that is quicker and cheaper than existing methods. The effect of plastic strain on the thermoelastic constant is presented as a potential basis for a calibration methodology that reveals areas of a component that have experienced plastic strain. Establishing this basis provides the initial step in identifying a new approach to residual stress analysis using the thermoelastic response. An evaluation of initial calibration results is presented and the feasibility of applying the methodology to actual components is assessed. As the response to plastic strain is likely to be small it is necessary to identify the effects of the paint coating; experimental work is presented that highlights the importance of repeatable coating approaches.

  11. Athletic performance and recovery-stress factors in cycling: An ever changing balance.

    PubMed

    Filho, Edson; di Fronso, Selenia; Forzini, Fabio; Murgia, Mauro; Agostini, Tiziano; Bortoli, Laura; Robazza, Claudio; Bertollo, Maurizio

    2015-01-01

    We sought to examine whether the relationship between recovery-stress factors and performance would differ at the beginning (Stage 1) and the end (Final Stage) of a multi-stage cycling competition. Sixty-seven cyclists with a mean age of 21.90 years (SD = 1.60) and extensive international experience participated in the study. The cyclists responded to the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) and rated their performance (1 = extremely poor to 10 = excellent) in respect to the first and last stage. Two step-down multiple regression models were used to estimate the relationship among recovery (nine factors; e.g. Physical Recovery, Sleep Quality) and stress factors (10 factors; e.g. Lack of Energy, Physical Complaints), as assessed by the RESTQ-Sport and in relation to performance. Model 1 pertained to Stage 1, whereas Model 2 used data from the Final Stage. The final Model 1 revealed that Physical Recovery (β = .46, p = .01), Injury (β = -.31, p = .01) and General Well-being (β = -.26, p = .04) predicted performance in Stage 1 (R(2) = .21). The final Model 2 revealed a different relationship between recovery-stress factors and performance. Specifically, being a climber (β = .28, p = .01), Conflicts/Pressure (β = .33, p = .01), and Lack of Energy (β = -.37, p = .01) were associated with performance at the Final Stage (R(2) = .19). Collectively, these results suggest that the relationship among recovery and stress factors changes greatly over a relatively short period of time, and dynamically influences performance in multi-stage competitions.

  12. Differential stress response in rats subjected to chronic mild stress is accompanied by changes in CRH-family gene expression at the pituitary level.

    PubMed

    Kolasa, Magdalena; Faron-Górecka, Agata; Kuśmider, Maciej; Szafran-Pilch, Kinga; Solich, Joanna; Żurawek, Dariusz; Gruca, Piotr; Papp, Mariusz; Dziedzicka-Wasylewska, Marta

    2014-11-01

    The purpose of this study was to examine molecular markers of the stress response at the pituitary and peripheral levels in animals that responded differently to chronic mild stress (CMS). Rats were subjected to 2-weeks CMS and symptoms of anhedonia was measured by the consumption of 1% sucrose solution. mRNA levels of CRH-family neuropeptides (Crh-corticotropin-releasing hormone, Ucn1-urocortin 1, Ucn2-urocortin 2, Ucn3-urocortin 3), CRH receptors (Crhr1-corticotropin-releasing hormone receptor 1, Crhr2-corticotropin-releasing hormone receptor 2) and Crhbp (corticotropin-releasing factor binding protein) in the pituitaries of rats were determined with real-time PCR. Plasma levels of ACTH (adrenocorticotropin), CRH and urocortins were measured with ELISA assays. CMS procedure led to the development of anhedonia manifested by the decreased sucrose consumption (stress-reactive, SR, stress-susceptible group). Additionally, the group of animals not exhibiting any signs of anhedonia (stress non-reactive, SNR, stress-resilient group) and the group characterized by the increased sucrose consumption (stress invert-reactive group SIR) were selected. The significant increases in ACTH plasma level accompanied by the decreases in the pituitary gene expression of the Crh, Ucn2 and Ucn3 in both stress non-reactive and stress invert-reactive groups were observed. The only molecular change observed in stress-reactive group was the increase in UCN2 plasma level. The differentiated behavioral stress responses were reflected by gene expression changes in the pituitary. Alterations in the mRNA levels of Crh, Ucn2 and Ucn3 in the pituitary might confirm the paracrine and/or autocrine effects of these peptides in stress response. The opposite behavioral effect between SNR vs. SIR groups and the surprising similarity at gene expression and plasma ACTH levels in these two groups may suggest the discrepancy between molecular and behavioral stress responses; however, there results might

  13. Hydrological response to earthquakes in the Haibara well, central Japan - I. Groundwater level changes revealed using state space decomposition of atmospheric pressure, rainfall and tidal responses

    USGS Publications Warehouse

    Matsumoto, N.; Kitagawa, G.; Roeloffs, E.A.

    2003-01-01

    For the groundwater level observed at the Haibara well, Shizuoka Prefecture, central Japan, time series analysis using state-space modelling is applied to extract hydrological anomalies related to earthquakes. This method can decompose observed groundwater level time series into five components: atmospheric pressure, tidal, and precipitation responses, observation noise, and residual water level. The decomposed responses to atmospheric pressure and precipitation are independently determined and are consistent with the expected response to surface loading. In the groundwater level at the Haibara well, 28 coseismic changes can be discerned during the period from 1981 April to 1997 December. There is a threshold in the relationship between earthquake magnitude and the well-hypocentre distance, above which earthquakes cause coseismic changes in the residual water level. All of the coseismic water level changes at the Haibara well are decreases, although 33 per cent of the estimated coseismic volumetric strain steps are contraction, which would be expected to cause water level increases. The coseismic changes in groundwater level are more closely proportional to the estimated ground motion than to coseismic volumetric strain steps, suggesting that ground motion due to earthquakes is the major cause of the coseismic water level drops and that the contribution from static strain is rather small. Possible pre- or inter-earthquake water level changes have occurred at the Haibara well and may have been caused by local aseismic crustal deformation.

  14. Global crop yield response to extreme heat stress under multiple climate change futures

    NASA Astrophysics Data System (ADS)

    Deryng, Delphine; Conway, Declan; Ramankutty, Navin; Price, Jeff; Warren, Rachel

    2014-03-01

    Extreme heat stress during the crop reproductive period can be critical for crop productivity. Projected changes in the frequency and severity of extreme climatic events are expected to negatively impact crop yields and global food production. This study applies the global crop model PEGASUS to quantify, for the first time at the global scale, impacts of extreme heat stress on maize, spring wheat and soybean yields resulting from 72 climate change scenarios for the 21st century. Our results project maize to face progressively worse impacts under a range of RCPs but spring wheat and soybean to improve globally through to the 2080s due to CO2 fertilization effects, even though parts of the tropic and sub-tropic regions could face substantial yield declines. We find extreme heat stress at anthesis (HSA) by the 2080s (relative to the 1980s) under RCP 8.5, taking into account CO2 fertilization effects, could double global losses of maize yield (ΔY = -12.8 ± 6.7% versus - 7.0 ± 5.3% without HSA), reduce projected gains in spring wheat yield by half (ΔY = 34.3 ± 13.5% versus 72.0 ± 10.9% without HSA) and in soybean yield by a quarter (ΔY = 15.3 ± 26.5% versus 20.4 ± 22.1% without HSA). The range reflects uncertainty due to differences between climate model scenarios; soybean exhibits both positive and negative impacts, maize is generally negative and spring wheat generally positive. Furthermore, when assuming CO2 fertilization effects to be negligible, we observe drastic climate mitigation policy as in RCP 2.6 could avoid more than 80% of the global average yield losses otherwise expected by the 2080s under RCP 8.5. We show large disparities in climate impacts across regions and find extreme heat stress adversely affects major producing regions and lower income countries.

  15. Global crop yield response to extreme heat stress under multiple climate change futures

    NASA Astrophysics Data System (ADS)

    Deryng, D.; Conway, D.; Ramankutty, N.; Price, J.; Warren, R.

    2014-12-01

    Extreme heat stress during the crop reproductive period can be critical for crop productivity. Projected changes in the frequency and severity of extreme climatic events are expected to negatively impact crop yields and global food production. This study applies the global crop model PEGASUS to quantify, for the first time at the global scale, impacts of extreme heat stress on maize, spring wheat and soybean yields resulting from 72 climate change scenarios for the 21st century. Our results project maize to face progressively worse impacts under a range of RCPs but spring wheat and soybean to improve globally through to the 2080s due to CO2 fertilization effects, even though parts of the tropic and sub-tropic regions could face substantial yield declines. We find extreme heat stress at anthesis (HSA) by the 2080s (relative to the 1980s) under RCP 8.5, taking into account CO2 fertilization effects, could double global losses of maize yield (dY = -12.8 ± 6.7% versus -7.0 ± 5.3% without HSA), reduce projected gains in spring wheat yield by half (dY = 34.3 ± 13.5% versus 72.0 ± 10.9% without HSA) and in soybean yield by a quarter (dY = 15.3 ± 26.5% versus 20.4 ± 22.1% without HSA). The range reflects uncertainty due to differences between climate model scenarios; soybean exhibits both positive and negative impacts, maize is generally negative and spring wheat generally positive. Furthermore, when assuming CO2 fertilization effects to be negligible, we observe drastic climate mitigation policy as in RCP 2.6 could avoid more than 80% of the global average yield losses otherwise expected by the 2080s under RCP 8.5. We show large disparities in climate impacts across regions and find extreme heat stress adversely affects major producing regions and lower income countries.

  16. S-Nitrosylated proteins in pea (Pisum sativum L.) leaf peroxisomes: changes under abiotic stress

    PubMed Central

    Ortega-Galisteo, Ana P.; Rodríguez-Serrano, María; Pazmiño, Diana M.; Gupta, Dharmendra K.; Sandalio, Luisa M.; Romero-Puertas, María C.

    2012-01-01

    Peroxisomes, single-membrane-bounded organelles with essentially oxidative metabolism, are key in plant responses to abiotic and biotic stresses. Recently, the presence of nitric oxide (NO) described in peroxisomes opened the possibility of new cellular functions, as NO regulates diverse biological processes by directly modifying proteins. However, this mechanism has not yet been analysed in peroxisomes. This study assessed the presence of S-nitrosylation in pea-leaf peroxisomes, purified S-nitrosylated peroxisome proteins by immunoprecipitation, and identified the purified proteins by two different mass-spectrometry techniques (matrix-assisted laser desorption/ionization tandem time-of-flight and two-dimensional nano-liquid chromatography coupled to ion-trap tandem mass spectrometry). Six peroxisomal proteins were identified as putative targets of S-nitrosylation involved in photorespiration, β-oxidation, and reactive oxygen species detoxification. The activity of three of these proteins (catalase, glycolate oxidase, and malate dehydrogenase) is inhibited by NO donors. NO metabolism/S-nitrosylation and peroxisomes were analysed under two different types of abiotic stress, i.e. cadmium and 2,4-dichlorophenoxy acetic acid (2,4-D). Both types of stress reduced NO production in pea plants, and an increase in S-nitrosylation was observed in pea extracts under 2,4-D treatment while no total changes were observed in peroxisomes. However, the S-nitrosylation levels of catalase and glycolate oxidase changed under cadmium and 2,4-D treatments, suggesting that this post-translational modification could be involved in the regulation of H2O2 level under abiotic stress. PMID:22213812

  17. Plant physiological models of heat, water and photoinhibition stress for climate change modelling and agricultural prediction

    NASA Astrophysics Data System (ADS)

    Nicolas, B.; Gilbert, M. E.; Paw U, K. T.

    2015-12-01

    Soil-Vegetation-Atmosphere Transfer (SVAT) models are based upon well understood steady state photosynthetic physiology - the Farquhar-von Caemmerer-Berry model (FvCB). However, representations of physiological stress and damage have not been successfully integrated into SVAT models. Generally, it has been assumed that plants will strive to conserve water at higher temperatures by reducing stomatal conductance or adjusting osmotic balance, until potentially damaging temperatures and the need for evaporative cooling become more important than water conservation. A key point is that damage is the result of combined stresses: drought leads to stomatal closure, less evaporative cooling, high leaf temperature, less photosynthetic dissipation of absorbed energy, all coupled with high light (photosynthetic photon flux density; PPFD). This leads to excess absorbed energy by Photosystem II (PSII) and results in photoinhibition and damage, neither are included in SVAT models. Current representations of photoinhibition are treated as a function of PPFD, not as a function of constrained photosynthesis under heat or water. Thus, it seems unlikely that current models can predict responses of vegetation to climate variability and change. We propose a dynamic model of damage to Rubisco and RuBP-regeneration that accounts, mechanistically, for the interactions between high temperature, light, and constrained photosynthesis under drought. Further, these predictions are illustrated by key experiments allowing model validation. We also integrated this new framework within the Advanced Canopy-Atmosphere-Soil Algorithm (ACASA). Preliminary results show that our approach can be used to predict reasonable photosynthetic dynamics. For instances, a leaf undergoing one day of drought stress will quickly decrease its maximum quantum yield of PSII (Fv/Fm), but it won't recover to unstressed levels for several days. Consequently, cumulative effect of photoinhibition on photosynthesis can cause

  18. Changes in crested wheatgrass root exudation caused by flood, drought, and nutrient stress.

    PubMed

    Henry, Amelia; Doucette, William; Norton, Jeanette; Bugbee, Bruce

    2007-01-01

    Root exudates can chelate inorganic soil contaminants, change rhizosphere pH, and may increase degradation of organic contaminants by microbial cometabolism. Root-zone stress may increase exudation and enhance phytoremediation. We studied the effects of low K+, high NH4+/NO3- ratio, drought, and flooding on the quantity and composition of exudates. Crested wheatgrass (Agropyron cristatum) was grown in Ottawa sand in sealed, flow-through glass columns under axenic conditions for 70 d. Root exudates were collected and analyzed for total organic carbon (TOC) and organic acid content to compare treatment effects. Plants in the low K+ treatment exuded 60% more TOC per plant per day (p = 0.01) than the unstressed control. Drought stress increased cumulative TOC exuded per gram dry plant by 71% (p = 0.05). The flooded treatment increased TOC exuded per gram dry plant by 45%, although this was not statistically significant based on the two replicate plants in this treatment. Exudation from the high NH4+/NO3- ratio treatment was 10% less than the control. Exudation rates in this study ranged from 8 to 50% of rates in four other published studies. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that malic acid was the predominant organic acid exuded. Fumaric, malonic, succinic, and oxalic acids were also detected in the exudates of all treatments. These results demonstrate that nutrient and water stress have significant effects on the quantity and composition of root exudates. Cultural manipulations to induce stress may change the quantity of root exudates and thus increase the effectiveness of phytoremediation.

  19. Quantification of cell volume changes upon hyperosmotic stress in Saccharomyces cerevisiae.

    PubMed

    Petelenz-Kurdziel, Elzbieta; Eriksson, Emma; Smedh, Maria; Beck, Caroline; Hohmann, Stefan; Goksör, Mattias

    2011-11-01

    Cell volume is a biophysical property, which is of great importance for quantitative characterisations of biological processes, such as osmotic adaptation. It also is a crucial parameter in the most common type of mathematical description of cellular behaviour-ordinary differential equation (ODE) models, e.g. the integrative model of the osmotic stress response in baker's yeast (E. Klipp, B. Nordlander, R. Kruger, P. Gennemark and S. Hohmann, Nat. Biotechnol., 2005, 23, 975-982). Until recently only rough estimates of this value were available. In this study we measured the mean volume of more than 300 individual yeast cells (Saccharomyces cerevisiae). We quantitatively characterised the dependence between the relative cell volume and the concentration of osmoticum in the cell surrounding. We also followed the recovery of the cellular volume over time, as well as the influence of increased external osmolarity on the nuclear volume. We found that cell shrinkage caused by shifts in the external osmolarity is proportional to the stress intensity only up to 1000 mM NaCl. At this concentration the yeast cells shrink to approximately 55% of their unstressed volume and this volume is maintained even in the case of further osmolarity increase. We observed that returning to the initial, unstressed volume takes more than 45 minutes for stress concentrations exceeding 100 mM NaCl and that only cells treated with the latter concentration are able to fully regain their initial size within the course of the experiment. We postulate that the cytoplasm plays a protective role for the nucleus by buffering the changes in volume caused by external osmolarity shifts. In conclusion, we quantitatively characterised the dynamics of cell volume changes caused by hyperosmotic stress, providing an accurate description of a biophysical cell property, which is crucial for precise mathematical simulations of cellular processes.

  20. Stress Management Apps With Regard to Emotion-Focused Coping and Behavior Change Techniques: A Content Analysis

    PubMed Central

    Hoffmann, Alexandra; Bleser, Gabriele

    2017-01-01

    Background Chronic stress has been shown to be associated with disease. This link is not only direct but also indirect through harmful health behavior such as smoking or changing eating habits. The recent mHealth trend offers a new and promising approach to support the adoption and maintenance of appropriate stress management techniques. However, only few studies have dealt with the inclusion of evidence-based content within stress management apps for mobile phones. Objective The aim of this study was to evaluate stress management apps on the basis of a new taxonomy of effective emotion-focused stress management techniques and an established taxonomy of behavior change techniques. Methods Two trained and independent raters evaluated 62 free apps found in Google Play with regard to 26 behavior change and 15 emotion-focused stress management techniques in October 2015. Results The apps included an average of 4.3 behavior change techniques (SD 4.2) and 2.8 emotion-focused stress management techniques (SD 2.6). The behavior change technique score and stress management technique score were highly correlated (r=.82, P=.01). Conclusions The broad variation of different stress management strategies found in this sample of apps goes in line with those found in conventional stress management interventions and self-help literature. Moreover, this study provided a first step toward more detailed and standardized taxonomies, which can be used to investigate evidence-based content in stress management interventions and enable greater comparability between different intervention types. PMID:28232299

  1. Colloid Mobilization and Porous Media Permeability Changes by Dynamic Stress Stimulations

    SciTech Connect

    Abdel-Fattah, Amr I.; Roberts, Peter M; Tarimala, Sowmitri; Ibrahim, Reem; Beckham, Richard

    2010-12-10

    Laboratory experiments on porous rock cores have shown that seismic-band (100 Hz or less) mechanical stress/strain cycling of the rock matrix can mobilize sub-pore-size particles (colloids) trapped in the pore space and allow them to be expelled during steady-state water flow. This coupling of dynamic stress to colloid mobility is a potential key mechanism whereby seismic waves may alter formation permeability and porous mass transport in Earth's crust. Experiments where colloid suspensions were injected into Fontainebleau sandstone cores demonstrated that colloid size and the ionic strength of the suspending fluid are major parameters that will control the ability of the colloids to attach to pore walls or to form particle bridges at pore throats. Both effects can lead to significant changes in permeability. A unique core-holder apparatus that applies low-frequency mechanical stress/strain to 2.54-cm-diameter porous rock samples during constant-rate fluid flow was used for those experiments. Microsphere injection caused the core's permeability to decline due to colloid bridging at pore throats. It was found that dynamic stress at 25 to 50 Hz mobilized these trapped colloids mainly when the ionic strength is low, and thereby partially restored the permeability of the sample. These earlier experiments on natural rocks were difficult to interpret in terms of how the colloids distributed themselves throughout the heterogeneous pore space and what interactions were occurring between the colloids and the solid matrix. Observed permeability changes appeared to be confined to the first 5-10 cm of the rock where the colloids were injected, yet significant transport of colloids was observed along the entire length of the sample. The 'natural rock' system is too complex geometrically at the pore scale to allow quantification of mass transport properties along its entire length. To remedy this problem, new colloid transport experiments were performed with a synthetic glass

  2. Forensic implications of changes in DSM-5 criteria for responses to trauma and stress.

    PubMed

    Milchman, Madelyn Simring

    DSM-5 significantly changed the diagnostic criteria for Posttraumatic Stress Disorder (PTSD) relative to DSM-IV/DSM-IV-TR. These changes do not alter its basic approach to diagnosing mental disorders, which treats each disorder as a separate category. This article analyzes the strengths and weaknesses of the categorical approach, and reviews empirical evidence regarding the impact of changes within it on the ease or difficulty of receiving the PTSD diagnosis. It especially analyzes the impact of newly included symptoms that are meant to identify cases in which trauma exposure was associated with changes in more serious PTSD cases, known as Complex PTSD (C-PTSD). It proposes some effects that the changes could have on psychological injury claims. Many changes could support plaintiffs' claims while others could support defense claims. Some changes could support either. Overall, DSM-5 PTSD diagnosis is more responsive to individual differences in symptom presentations and appears able to diagnose some C-PTSD cases. The thesis throughout the article is that PTSD diagnostic accuracy could be improved further, especially for C-PTSD cases, by complementing its current exclusive reliance on behavioral symptoms that are characteristic of victims in general with assessment of the meaning that the symptoms have for individual victims. The article proposes some principles to guide interpretation of the individualized meaning of victims' symptoms, which help make the reasoning behind the interpretations explicit.

  3. The temporal order of change in daily mindfulness and affect during mindfulness-based stress reduction.

    PubMed

    Snippe, Evelien; Nyklíček, Ivan; Schroevers, Maya J; Bos, Elisabeth H

    2015-04-01

    Increases in mindfulness are assumed to lead to improvements in psychological well-being during mindfulness-based treatments. However, the temporal order of this association has received little attention. This intensive longitudinal study examines whether within-person changes in mindfulness precede or follow changes in negative affect (NA) and positive affect (PA) during a mindfulness based stress reduction (MBSR) program. This study also examines interindividual differences in the association between mindfulness and affect and possible predictors of these differences. Mindfulness, NA, and PA were assessed on a daily basis in 83 individuals from the general population who participated in an MBSR program. Multilevel autoregressive models were used to investigate the temporal order of changes in mindfulness and affect. Day-to-day changes in mindfulness predicted subsequent day-to-day changes in both NA and PA, but reverse associations did not emerge. Thus, changes in mindfulness seem to precede rather than to follow changes in affect during MBSR. The magnitude of the effects differed substantially between individuals, showing that the strength of the relationship between mindfulness and affect is not the same for all participants. These between-subjects differences could not be explained by gender, age, level of education, average level of mindfulness home practice, or baseline levels of mindfulness and affect. Mindfulness home practice during the day did predict subsequent increases in mindfulness. The findings suggest that increasing mindfulness on a daily basis can be a beneficial means to improve daily psychological well-being.

  4. The Evolving Construct of Posttraumatic Stress Disorder (PTSD): DSM-5 Criteria Changes and Legal Implications

    PubMed Central

    Zoellner, Lori A.; Bedard-Gilligan, Michele A.; Jun, Janie J.; Marks, Libby H.; Garcia, Natalia M.

    2014-01-01

    In the DSM-5, the diagnosis of posttraumatic stress disorder (PTSD) has undergone multiple, albeit minor, changes. These changes include shifting PTSD placement from within the anxiety disorders into a new category of traumatic and stressor-related disorders, alterations in the definition of a traumatic event, shifting of the symptom cluster structure from three to four clusters, the addition of new symptoms including persistent negative beliefs and expectations about oneself or the world, persistent distorted blame of self or others, persistent negative trauma-related emotions, and risky or reckless behaviors, and the addition of a dissociative specifier. The evidence or lack thereof behind each of these changes is briefly reviewed. These changes, although not likely to change overall prevalence, have the potential to increase the heterogeneity of individuals receiving a PTSD diagnosis both by altering what qualifies as a traumatic event and by adding symptoms commonly occurring in other disorders such as depression, borderline personality disorder, and dissociative disorders. Legal implications of these changes include continued confusion regarding what constitutes a traumatic stressor, difficulties with differential diagnosis, increased ease in malingering, and improper linking of symptoms to causes of behavior. These PTSD changes are discussed within the broader context of DSM reliability and validity concerns. PMID:24470838

  5. Examining Stress Changes Due to Subducting Topography and Variable Rheology in the Middle America Trench at Nicoya Gulf, Costa Rica

    NASA Astrophysics Data System (ADS)

    Elliott, C. E.; Bilek, S. L.; Lithgow-Bertelloni, C.

    2007-05-01

    Offshore of the Nicoya Gulf at the Middle America Trench, the Cocos Plate is subducting beneath the Caribbean plate at about 84 mm per year. A line of seamounts are entering the trench in this region, causing dramatic deformation of the seafloor landward of the thrust. It has been suggested that these seamounts are being subducted, causing coastal uplift and seismicity. The March 25, 1990 Mw 7.0 Nicoya Gulf earthquake is thought to have occurred as one of these seamounts ruptured. How do these seamounts affect the rupture process? Are they behaving as patches of increased or decreased friction along the seismic interface? How does the subducting topography change the stress field after an earthquake? Can triggered events be explained by static stress changes, or does the rheology down dip from the seismogenic zone influence subsequent events in the region? Using a three dimensional model with patches of variable friction to simulate the seamounts as asperities, we compare the location of aftershocks to the stress changes associated with increased and decreased friction. We compare this to a model of Coulomb static stress change, which displays lobes of static stress increase and decrease due to slip on the fault plane, and the distribution of aftershocks within these lobes. To examine the stress changes associated with a set of delayed inland triggered events, we also vary the rheology of our model, using a linear elastic half space for the seismogenic zone, and viscous creep along the lower, aseismic portion of the fault below 40 kilometers. These models allow us to examine the spatial and temporal relationship of seismicity associated with stress changes due to variable friction and rheology. Our results indicate that stresses increase away from the fault with time if viscous creep is included in the model. These stress increases roughly correspond to inland areas of noted increase in seismicity, suggesting that creep along the down dip, aseismic portion of the

  6. New Insights into the Coulomb Stress and Seismicity Rate Changes Induced by the 2008 Mw 7.9 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Hu, J., Jr.; Fu, L. Y.; Zhang, Y.

    2015-12-01

    Some new insights into the relationship between the Coulomb stress and seismicity rate changes after the Wenchuan earthquake are gained. Three improvements are made in the calculation including employing a new triangular dislocation element method,setting up a much more realistic model and resolving stress change on variable focal mechanisms. The calculated Coulomb stress changes indicate that not only the three major faults systems including east Kunlun,southern part of Xianshuihe and Northern Min Jiang, but southern rim of Qinling, parts of the Tazang and Pingwu-Qinchuan faults were encouraged by the Wenchuan earthquake. Eastern segment of Longriba are shown to be quite dangerous due to dramatic stress increase. Ya'an was rightly located in the southwestern triggering lobe of the main rupture.Spatial distribution patterns of events before and after the Wenchuan mainshock are shown to be quite different . The observed seismicity rate changes were also calculated and compared with the Coulomb stress changes. We found that besides the three major faults systems mentioned above, east Longriba, Daliangshan, Zemuhe ,two ends of the main rupture,and some cities including Ya'an , Chengdu,Chongqing underwent a seismicity rate increase. It is in agreement with positive coulomb stress changes in these regions. The results also indicate that high background seismicity rate will amplify the effect of static coulomb stress increase. It is noticeable that a burst of seismicity near the main rupture with stress drop clearly confirmed the existence of the dynamic waves which were induced by the earthquake and lasted for the first 1-3 months after the mainshock.To check whether an event is responsive to the Wenchuan earthquake, we resolved coulomb stress changes on the focal mechanisms after the Wenchuan earthquakes. We found that only some events with long distance from the main rupture were brought closer to failure. The events with no stress change near the main rupture are

  7. Changes in seed water status as characterized by NMR in developing soybean seed grown under moisture stress conditions.

    PubMed

    Krishnan, P; Singh, Ravender; Verma, A P S; Joshi, D K; Singh, Sheoraj

    2014-02-21

    Changes in water status of developing seeds of Soybean (Glycine max L. Merrill.) grown under different moisture stress conditions were characterized by proton nuclear magnetic resonance (NMR)- spin-spin relaxation time (T2). A comparison of the seed development characteristics, composition and physical properties indicated that, characteristics like seed weight, seed number/ear, rate of seed filling increased with development stages but decreased with moisture stress conditions. The NMR- spin-spin relaxation (T2) component like bound water increased with seed maturation (40-50%) but decreased with moisture stress conditions (30-40%). The changes in seed water status to increasing levels of moisture stress and seed maturity indicates that moisture stress resulted in more proportion of water to bound state and intermediate state and less proportion of water in free-state. These changes are further corroborated by significant changes in protein and starch contents in seeds under high moisture stress treatments. Thus seed water status during its development is not only affected by development processes but also by moisture stress conditions. This study strongly indicated a clear moisture stress and development stage dependence of seed tissue water status in developing soybean seeds.

  8. Reactivity of seismicity rate to static Coulomb stress changes of two consecutive large earthquakes in the central Philippines

    NASA Astrophysics Data System (ADS)

    Dianala, J. D. B.; Aurelio, M.; Rimando, J. M.; Taguibao, K.

    2015-12-01

    In a region with little understanding in terms of active faults and seismicity, two large-magnitude reverse-fault related earthquakes occurred within 100km of each other in separate islands of the Central Philippines—the Mw=6.7 February 2012 Negros earthquake and the Mw=7.2 October 2013 Bohol earthquake. Based on source faults that were defined using onshore, offshore seismic reflection, and seismicity data, stress transfer models for both earthquakes were calculated using the software Coulomb. Coulomb stress triggering between the two main shocks is unlikely as the stress change caused by Negros earthquake on the Bohol fault was -0.03 bars. Correlating the stress changes on optimally-oriented reverse faults with seismicity rate changes shows that areas that decreased both in static stress and seismicity rate after the first earthquake were then areas with increased static stress and increased seismicity rate caused by the second earthquake. These areas with now increased stress, especially those with seismicity showing reactivity to static stress changes caused by the two earthquakes, indicate the presence of active structures in the island of Cebu. Comparing the history of instrumentally recorded seismicity and the recent large earthquakes of Negros and Bohol, these structures in Cebu have the potential to generate large earthquakes. Given that the Philippines' second largest metropolitan area (Metro Cebu) is in close proximity, detailed analysis of the earthquake potential and seismic hazards in these areas should be undertaken.

  9. The coseismic slip of the 2011 Tarlay earthquake in eastern Myanmar: constraints from InSAR and field investigations

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Lin, Y. N.; Tun, S.; Khaing, S.; Simons, M.; Sieh, K. E.

    2012-12-01

    Field investigations and InSAR analyses confirm the Mw 6.8 March 24, 2011 Tarlay earthquake occurred on the westernmost segment of the Nam Ma fault. This 30-km-long segment is structurally separated from the main trace of the Nam Ma fault by a dilatational stepover. Field measurements show a 1.25-m peak surface offset in the central part of the fault which gradually decreases toward the northeast. The coseismic slip distribution inverted from InSAR and pixel tracking results yields a narrow and shallow slip patch. Most of the slip occurred at the depth between 3 and 9 km on the sub-vertical fault, with the peak slip of ~4 m at the depth of 3-6 km. The Nam Ma fault transects through the cold Paleozoic continental crust and is away from any region of anomalously high geothermal gradient. Thus we believe that rather than the result of a shallow brittle-ductile transition depth, this narrow rupture patch may reflect either the past slip history or the state of stress before the 2011 earthquake. A similar example may be the earthquake sequence on the Rokko-Nojima fault system in Japan, where a shallow patch that ruptured on the Rokko fault in 1596 occurred above (at shallower depths) of the fault slip during the 1995 Kobe earthquake. This analog suggests that a deeper event may have happened prior to the 2011 Tarlay earthquake or may happen in the future. With an average slip rate of 0.6-2.4 mm/yr from late-Miocene to present [Lacassin et al., 1998], we estimate the recurrence interval for moderate events like the Mw 6.8 Tarlay earthquake to be 230 to 930 years at the Nam Ma fault. If the entire 215-km long Nam Ma fault ruptures all at once, it could generate an earthquake of Mw 7.7 with an average recurrence interval of 2200 to 9000 years.

  10. Effects of L-theanine on posttraumatic stress disorder induced changes in rat brain gene expression.

    PubMed

    Ceremuga, Tomás Eduardo; Martinson, Stephanie; Washington, Jason; Revels, Robert; Wojcicki, Jessica; Crawford, Damali; Edwards, Robert; Kemper, Joshua Luke; Townsend, William Luke; Herron, Geno M; Ceremuga, George Allen; Padron, Gina; Bentley, Michael

    2014-01-01

    Posttraumatic stress disorder (PTSD) is characterized by the occurrence of a traumatic event that is beyond the normal range of human experience. The future of PTSD treatment may specifically target the molecular mechanisms of PTSD. In the US, approximately 20% of adults report taking herbal products to treat medical illnesses. L-theanine is the amino acid in green tea primarily responsible for relaxation effects. No studies have evaluated the potential therapeutic properties of herbal medications on gene expression in PTSD. We evaluated gene expression in PTSD-induced changes in the amygdala and hippocampus of Sprague-Dawley rats. The rats were assigned to PTSD-stressed and nonstressed groups that received either saline, midazolam, L-theanine, or L-theanine + midazolam. Amygdala and hippocampus tissue samples were analyzed for changes in gene expression. One-way ANOVA was used to detect significant difference between groups in the amygdala and hippocampus. Of 88 genes examined, 17 had a large effect size greater than 0.138. Of these, 3 genes in the hippocampus and 5 genes in the amygdala were considered significant (P < 0.05) between the groups. RT-PCR analysis revealed significant changes between groups in several genes implicated in a variety of disorders ranging from PTSD, anxiety, mood disorders, and substance dependence.

  11. Effects of L-Theanine on Posttraumatic Stress Disorder Induced Changes in Rat Brain Gene Expression

    PubMed Central

    Ceremuga, Tomás Eduardo; Martinson, Stephanie; Washington, Jason; Revels, Robert; Kemper, Joshua Luke; Townsend, William Luke; Herron, Geno M.; Ceremuga, George Allen; Bentley, Michael

    2014-01-01

    Posttraumatic stress disorder (PTSD) is characterized by the occurrence of a traumatic event that is beyond the normal range of human experience. The future of PTSD treatment may specifically target the molecular mechanisms of PTSD. In the US, approximately 20% of adults report taking herbal products to treat medical illnesses. L-theanine is the amino acid in green tea primarily responsible for relaxation effects. No studies have evaluated the potential therapeutic properties of herbal medications on gene expression in PTSD. We evaluated gene expression in PTSD-induced changes in the amygdala and hippocampus of Sprague-Dawley rats. The rats were assigned to PTSD-stressed and nonstressed groups that received either saline, midazolam, L-theanine, or L-theanine + midazolam. Amygdala and hippocampus tissue samples were analyzed for changes in gene expression. One-way ANOVA was used to detect significant difference between groups in the amygdala and hippocampus. Of 88 genes examined, 17 had a large effect size greater than 0.138. Of these, 3 genes in the hippocampus and 5 genes in the amygdala were considered significant (P < 0.05) between the groups. RT-PCR analysis revealed significant changes between groups in several genes implicated in a variety of disorders ranging from PTSD, anxiety, mood disorders, and substance dependence. PMID:25165739

  12. Response of vegetation indices to changes in three measures of leaf water stress

    NASA Technical Reports Server (NTRS)

    Cohen, Warren B.

    1991-01-01

    The responses of vegetation indices to changes in water stress were evaluated in two separate laboratory experiments. In one experiment the normalized difference vegetation index (NDVI), the near-IR to red ratio (near-IR/red), the Infrared Index (II), and the Moisture Stress Index (MSI) were more highly correlated to leaf water potential in lodgepole pine branches than were the Leaf Water Content Index (LWCI), the mid-IR ratio (Mid-IR), or any of the single Thematic Mapper (TM) bands. In the other experiment, these six indices and the TM Tasseled Cap brightness, greenness, and wetness indices responded to changes in leaf relative water content (RWC) differently than they responded to changes in leaf water content (WC) of three plant species, and the responses were dependent on how experimental replicates were pooled. With no pooling, the LWCI was the most highly correlated index to both RWC and WC among replications, followed by the II, MSI, and wetness. Only the LWCI was highly correlated to RWC and WC when replications were pooled within species. With among species pooling the LWCI was the only index highly correlated with RWC, while the II, MSI, Mid-IR, and wetness were most highly correlated with WC.

  13. Changes in Stomatal Behavior and Guard Cell Cytosolic Free Calcium in Response to Oxidative Stress.

    PubMed Central

    McAinsh, M. R.; Clayton, H.; Mansfield, T. A.; Hetherington, A. M.

    1996-01-01

    We have investigated the cellular basis for the effects of oxidative stress on stomatal behavior using stomatal bioassay and ratio photometric techniques. Two oxidative treatments were employed in this study: (a) methyl viologen, which generates superoxide radicals, and (b) H2O2. Both methyl viologen and H2O2 inhibited stomatal opening and promoted stomatal closure. At concentrations [less than or equal to]10-5 M, the effects of methyl viologen and H2O2 on stomatal behavior were reversible and were abolished by 2 mM EGTA or 10 [mu]M verapamil. In addition, at 10-5 M, i.e. the maximum concentration at which the effects of the treatments were prevented by EGTA or verapamil, methyl viologen and H2O2 caused an increase in guard cell cytosolic free Ca2+ ([Ca2+]i), which was abolished in the presence of EGTA. Therefore, at low concentrations of methyl viologen and H2O2, removal of extracellular Ca2+ prevented both the oxidative stress-induced changes in stomatal aperture and the associated increases in [Ca2+]i. This suggests that in this concentration range the effects of the treatments are Ca2+-dependent and are mediated by changes in [Ca2+]i. In contrast, at concentrations of methyl viologan and H2O2 > 10-5 M, EGTA and verapamil had no effect. However, in this concentration range the effects of the treatments were irreversible and correlated with a marked reduction in membrane integrity and guard cell viability. This suggests that at high concentrations the effects of methyl viologen and H2O2 may be due to changes in membrane integrity. The implications of oxidative stress-induced increases in [Ca2+]i and the possible disruption of guard-cell Ca2+ homeostasis are discussed in relation to the processes of Ca2+-based signal transduction in stomatal guard cells and the control of stomatal aperture. PMID:12226345

  14. Stress-sensitive arterial hypertension, hemodynamic changes and brain metabolites in hypertensive ISIAH rats: MRI investigation.

    PubMed

    Seryapina, A A; Shevelev, O B; Moshkin, M P; Markel, A L; Akulov, A E

    2017-03-08

    The study of early development of the arterial hypertension in association with emotional stress is of great importance for better understanding of etiolody and pathogenesis of the hypertensive disease. MRI technique was applied to evaluate the hemodynamic and brain metabolites changes in 1- and 3-Mo-old ISIAH rats (10 male rats) with stress-sensitive arterial hypertension and in control normotensive WAG rats (8 male rats). In the 3-Mo-old ISIAH rats, age-dependent increase in the blood pressure was associated with increased blood flow through the renal arteries and decreased blood flow in the lower part of abdominal aorta. The renal vascular resistance in the ISIAH rats decreased while aging, though, at both ages it remained higher than the renal vascular resistance in WAG rats. Integral metabolome portrait demonstrated that hypertension development in the ISIAH rats was associated with attenuation of excitatory and energetic activity in the prefrontal cortex, whereas in the WAG rats, the opposite age-dependent changes were observed. In contrast, in hypothalamus of 3-Mo-old ISIAH rats, an increase in energetic activity and prevalence of excitatory neurotransmitters over inhibitory was noticed. The blood flow through the main arteries showed positive correlation with glutamate and glutamine levels in hypothalamus, and negative one - with hypothalamic GABA level. The blood pressure values positively correlated with hypothalamic choline levels. Thus, the early development of the stress-sensitive hypertension in the ISIAH rats is accompanied by considerable changes both in brain metabolite ratios and in the parameters of blood flow through the main arteries. This article is protected by copyright. All rights reserved.

  15. Oxidative stress induced by cumene hydroperoxide evokes changes in neuronal excitability of rat motor cortex neurons.

    PubMed

    Pardillo-Díaz, R; Carrascal, L; Ayala, A; Nunez-Abades, P

    2015-03-19

    Oxidative stress and the production of reactive oxygen radicals play a key role in neuronal cell damage. This paper describes an in vitro study that explores the neuronal responses to oxidative stress focusing on changes in neuronal excitability and functional membrane properties. This study was carried out in pyramidal cells of the motor cortex by applying whole-cell patch-clamp techniques on brain slices from young adult rats. Oxygen-derived free radical formation was induced by bath application of 10μM cumene hydroperoxide (CH) for 30min. CH produced marked changes in the electrophysiological properties of neurons (n=30). Resting membrane potential became progressively depolarized, as well as depolarization voltage, with no variations in voltage threshold. Membrane resistance showed a biphasic behavior, increasing after 5min of drug exposure and then it started to decrease, even under control values, after 15 and 30min. At the same time, changes in membrane resistance produced compensatory variations in the rheobase. The amplitude of the action potentials diminished and the duration increased progressively over time. Some of the neurons under study also lost their ability to discharge action potentials in a repetitive way. Most of the neurons, however, kept their repetitive discharge even though their maximum frequency and gain decreased. Furthermore, cancelation of the repetitive firing discharge took place at intensities that decreased with time of exposure to CH, which resulted in a narrower working range. We can conclude that oxidative stress compromises both neuronal excitability and the capability of generating action potentials, and so this type of neuronal functional failure could precede the neuronal death characteristics of many neurodegenerative diseases.

  16. Sertraline and curcumin prevent stress-induced morphological changes of dendrites and neurons in the medial prefrontal cortex of rats.

    PubMed

    Noorafshan, A; Abdollahifar, M-A; Karbalay-Doust, S; Asadi-Golshan, R; Rashidian-Rashidabadi, A

    2015-01-01

    Stress induces structural and behavioral impairments. The changes in dendrites and neurons are accompanied by impairments in the tasks mediated by the medial prefrontal cortex (mPFC). The present study was conducted to evaluate the structural changes of the dendrites and neurons of the mPFC after stress using stereological methods. In addition, the effects of a natural and a synthetic substance, i.e., curcumin and sertraline, were evaluated. The rats were divided into 7 groups: stress + distilled water, stress + olive oil, curcumin (100 mg/kg/day), sertraline (10 mg/kg/day), stress + curcumin, stress + sertraline, and control groups. The animals were submitted to chronic variable stress for 56 days. The results showed an average 15% reduction in the length of the dendrites per neuron in the mPFC after stress (p < 0.004). The total spine density was reduced by 50% in the stress (+ olive oil or + distilled water) groups in comparison with the control group (p < 0.01). The main reduction was seen in the thin and mushroom spines, while the stubby spines remained unchanged. Mean volume and surface area of the neurons were decreased by 14% and 10% on average in the stress (+ distilled water or + olive oil) rats in comparison to the control rats, respectively (p < 0.01). The data revealed that treatment of stressed rats with curcumin or sertraline can prevent the loss of spines and reduction of dendrite length, volume and surface area of the neurons. Sertraline and curcumin can prevent structural changes of the neurons and dendrites induced by stress in the mPFC of rats.

  17. Regulating the Flow of Change to Reduce Fontline Nurse Stress and Burnout.

    PubMed

    Koppel, Jenna; Virkstis, Katherine; Strumwasser, Sarah; Katz, Marie; Boston-Fleischhauer, Carol

    2015-11-01

    The nursing workforce is at the center of many changes associated with care delivery transformation. To achieve this transformation, frontline nursing staff must be engaged in their work, committed to their organization's mission, and capable of delivering high-quality care. To identify top opportunities for driving nursing engagement, researchers from The Advisory Board Company analyzed engagement survey responses from more than 343 000 employees at 575 healthcare organizations. In this article, the authors describe 3 strategies for addressing 1 of the greatest opportunities for improving nurse engagement: ensuring nurses feel their organization helps them reduce stress and burnout.

  18. Power Relative to Body Mass Best Predicts Change in Core Temperature During Exercise-Heat Stress.

    PubMed

    Gibson, Oliver R; Willmott, Ashley G B; James, Carl A; Hayes, Mark; Maxwell, Neil S

    2017-02-01

    Gibson, OR, Willmott, AGB, James, CA, Hayes, M, and Maxwell, NS. Power relative to body mass best predicts change in core temperature during exercise-heat stress. J Strength Cond Res 31(2): 403-414, 2017-Controlling internal temperature is crucial when prescribing exercise-heat stress, particularly during interventions designed to induce thermoregulatory adaptations. This study aimed to determine the relationship between the rate of rectal temperature (Trec) increase, and various methods for prescribing exercise-heat stress, to identify the most efficient method of prescribing isothermic heat acclimation (HA) training. Thirty-five men cycled in hot conditions (40° C, 39% R.H.) for 29 ± 2 minutes. Subjects exercised at 60 ± 9% V[Combining Dot Above]O2peak, with methods for prescribing exercise retrospectively observed for each participant. Pearson product moment correlations were calculated for each prescriptive variable against the rate of change in Trec (° C·h), with stepwise multiple regressions performed on statistically significant variables (p ≤ 0.05). Linear regression identified the predicted intensity required to increase Trec by 1.0-2.0° C between 20- and 45-minute periods and the duration taken to increase Trec by 1.5° C in response to incremental intensities to guide prescription. Significant (p ≤ 0.05) relationships with the rate of change in Trec were observed for prescriptions based on relative power (W·kg; r = 0.764), power (%Powermax; r = 0.679), rating of perceived exertion (RPE) (r = 0.577), V[Combining Dot Above]O2 (%V[Combining Dot Above]O2peak; r = 0.562), heart rate (HR) (%HRmax; r = 0.534), and thermal sensation (r = 0.311). Stepwise multiple regressions observed relative power and RPE as variables to improve the model (r = 0.791), with no improvement after inclusion of any anthropometric variable. Prescription of exercise under heat stress using power (W·kg or %Powermax) has the strongest relationship with the rate of change in

  19. Catecholamines of the adrenal medula and their morphological changes during adaptation to repeated immobilization stress

    NASA Technical Reports Server (NTRS)

    Kvetnansky, R.; Mitro, A.; Mikulaj, L.; Hocman, G.

    1980-01-01

    Changes of the adrenal medulla of rats were studied in the course of adaptation to repeated immobilization stress. An increase in the number of cells in the adrenal medulla was found in the adapted animals; this increase was confirmed by weight indices of the medulla and by cell counts per surface unit. Simultaneous karyometric measurements of the nuclei of adrenal medulla cells and an analysis of the catecholamine contents in the adrenals explain the increased activity of the adrenal medulla in the course of adaptation.

  20. The Southern Ocean ecosystem under multiple climate change stresses--an integrated circumpolar assessment.

    PubMed

    Gutt, Julian; Bertler, Nancy; Bracegirdle, Thomas J; Buschmann, Alexander; Comiso, Josefino; Hosie, Graham; Isla, Enrique; Schloss, Irene R; Smith, Craig R; Tournadre, Jean; Xavier, José C

    2015-04-01

    A quantitative assessment of observed and projected environmental changes in the Southern Ocean (SO) with a potential impact on the marine ecosystem shows: (i) large proportions of the SO are and will be affected by one or more climate change processes; areas projected to be affected in the future are larger than areas that are already under environmental stress, (ii) areas affected by changes in sea-ice in the past and likely in the future are much larger than areas affected by ocean warming. The smallest areas (<1% area of the SO) are affected by glacier retreat and warming in the deeper euphotic layer. In the future, decrease in the sea-ice is expected to be widespread. Changes in iceberg impact resulting from further collapse of ice-shelves can potentially affect large parts of shelf and ephemerally in the off-shore regions. However, aragonite undersaturation (acidification) might become one of the biggest problems for the Antarctic marine ecosystem by affecting almost the entire SO. Direct and indirect impacts of various environmental changes to the three major habitats, sea-ice, pelagic and benthos and their biota are complex. The areas affected by environmental stressors range from 33% of the SO for a single stressor, 11% for two and 2% for three, to <1% for four and five overlapping factors. In the future, areas expected to be affected by 2 and 3 overlapping factors are equally large, including potential iceberg changes, and together cover almost 86% of the SO ecosystem.

  1. Changes in the protein patterns in pea (Pisum sativum L.) roots under the influence of long- and short-term chilling stress and post-stress recovery.

    PubMed

    Badowiec, Anna; Swigonska, Sylwia; Weidner, Stanisław

    2013-10-01

    Amongst many factors restricting geographical distribution of plants and crop productivity, low temperature is one of the most important. To gain better understanding of the molecular response of germinating pea (Pisum sativum L.) to low temperature, we investigated the influence of long and short chilling stress as well as post-stress recovery on the alterations in the root proteomes. The impact of long stress was examined on the pea seeds germinating in the continuous chilling conditions of 10 °C for 8 days (LS). To examine the impact of short stress, pea seeds germinating for 72 h in the optimal temperature of 20 °C were subjected to 24-h chilling (SS). Additionally, both stress treatments were followed by 24 h of recovery in the optimal conditions (accordingly LSR and SR). Using the 2D gel electrophoresis and MALDI-TOF MS protein identification, it was revealed, that most of the proteins undergoing regulation under the applied conditions were implicated in metabolism, protection against stress, cell cycle regulation, cell structure maintenance and hormone synthesis, which altogether may influence root growth and development in the early stages of plant life. The obtained results have shown that most of detected alterations in the proteome patterns of pea roots are dependent on stress duration. However, there are some analogical response pathways which are triggered regardless of stress length. The functions of proteins which accumulation has been changed by chilling stress and post-stress recovery are discussed here in relation to their impact on pea roots development.

  2. Silibinin mitigates zidovudine-induced hepatocellular degenerative changes, oxidative stress and hyperlipidaemia in rats.

    PubMed

    Raghu, R; Jesudas, B; Bhavani, G; Ezhilarasan, D; Karthikeyan, S

    2015-11-01

    Prolonged zidovudine (AZT) treatment in HIV-infected and AIDS patients is shown to induce liver toxicity leading to complications. Therapeutic regimen that could encounter this adverse effect is unavailable and management of toxicity is often symptomatic or is limited to withdrawal of therapy. In the present investigation, we evaluated the alleviating properties of silibinin (SBN), a flavanolignan obtained from Silybum marianum against subacute AZT-induced hepatotoxicity and oxidative stress in rats. AZT treatment (50 mg/kg body weight (b.w.) periorally (p.o.), daily for 45 days) caused highly significant increases in alanine transaminase, alkaline phosphatase, argininosuccinic acid lyase and bilirubin in serum. Oxidative stress is shown by a highly significant increase in lipid peroxidase and total carbonyl content and decrease in catalase and protein thiols in the liver tissue. Hyperlipidaemia is indicated by highly significant increase in total lipids and free fatty acid in serum. Evaluation of liver by haematoxylin and eosin staining shows parenchymal cell enlargement, inflammatory changes and increase in sinusoidal spaces. Simultaneous treatment of SBN (100 mg/kg b.w. p.o., daily for 45 days) significantly protected the liver against hepatotoxicity, oxidative stress and hyperlipidaemia induced by AZT, and this alleviating property is attributed to hepatoprotective, membrane-stabilizing, antioxidant and free radical scavenging properties of SBN.

  3. Proteomic Analyses of Changes in Synechococcus sp. PCC7942 Following UV-C Stress.

    PubMed

    Peng, Xi; Yang, Jie; Gao, Yang

    2017-01-25

    UV-C's effects on the physiological and biochemical processes of cyanobacteria have been well characterized. However, the molecular mechanisms of cyanobacteria's tolerance to UV-C still needs further investigation. This research attempts to decode the variation in protein abundances in cyanobacteria after UV-C stress. Different expression levels of proteins in the cytoplasm of Synechococcus sp. PCC7942 under UV-C stress were investigated by using a comparative proteomic approach. Forty-seven UV-C-regulated proteins were identified by MALDI-TOF analysis and classified by Gene Ontology (GO). After studying their pathways, the proteins were mainly enriched in the groups of protein folding, inorganic ion transport, and energy production. By focusing on these areas, this study reveals the correlation between UV-C stress-responsive proteins and the physiological changes of Synechococcus sp. PCC7942 under UV-C radiation. These findings may open up new areas for further exploration in the homeostatic mechanisms associated with cyanobacteria responses to UV-C radiation. This article is protected by copyright. All rights reserved.

  4. Protein expression changes during cotton fiber elongation in response to drought stress and recovery.

    PubMed

    Zheng, Mi; Meng, Yali; Yang, Changqin; Zhou, Zhiguo; Wang, Youhua; Chen, Binglin

    2014-08-01

    An investigation to better understand the molecular mechanism of cotton (Gossypium hirsutum L.) fiber elongation in response to drought stress and recovery was conducted using a comparative proteomics analysis. Cotton plants (cv. NuCOTN 33B) were subjected to water deprivation for 10 days followed by a recovery period (with watering) of 5 days. The temporal changes in total proteins in cotton fibers were examined using 2DE. The results revealed that 163 proteins are significantly drought responsive. MS analysis led to the identification of 132 differentially expressed proteins that include some known as well as some novel drought-responsive proteins. These drought responsive fiber proteins in NuCOTN 33B are associated with a variety of cellular functions, i.e. signal transduction, protein processing, redox homeostasis, cell wall modification, metabolisms of carbon, energy, lipid, lignin, and flavonoid. The results suggest that the enhancement of the perception of drought stress, a new balance of the metabolism of the biosynthesis of cell wall components and cytoskeleton homeostasis plays an important role in the response of cotton fibers to drought stress. Overall, the current study provides an overview of the molecular mechanism of drought response in cotton fiber cells.

  5. Changes in Transcript Related to Osmosis and Intracellular Ion Homeostasis in Paulownia tomentosa under Salt Stress

    PubMed Central

    Fan, Guoqiang; Wang, Limin; Deng, Minjie; Zhao, Zhenli; Dong, Yanpeng; Zhang, Xiaoshen; Li, Yongsheng

    2016-01-01

    Paulownia tomentosa is an important economic and greening tree species that is cultivated widely, including salt environment. Our previous studies indicated its autotetraploid induced by colchicine showed better stress tolerance, but the underlying molecular mechanism related to ploidy and salt stress is still unclear. To investigate this issue, physiological measurements and transcriptome profiling of diploid and autotetraploid plants untreated and treated with NaCl were performed. Through the comparisons among four accessions, for one thing, we found different physiological changes between diploid and autotetraploid P. tomentosa; for another, and we detected many differentially expressed unigenes involved in salt stress response. These differentially expressed unigenes were assigned to several metabolic pathways, including “plant hormone signal transduction,” “RNA transporter,” “protein processing in endoplasmic reticulum,” and “plant-pathogen interaction,” which constructed the complex regulatory network to maintain osmotic and intracellular ion homeostasis. Quantitative real-time polymerase chain reaction was used to confirm the expression patterns of 20 unigenes. The results establish the foundation for the genetic basis of salt tolerance in P. tomentosa, which in turn accelerates Paulownia breeding and expands available arable land. PMID:27066034

  6. Edaravone leads to proteome changes indicative of neuronal cell protection in response to oxidative stress

    PubMed Central

    Jami, Mohammad-Saeid; Salehi-Najafabadi, Zahra; Ahmadinejad, Fereshteh; Hoedt, Esthelle; Chaleshtori, Morteza Hashemzadeh; Neubert, Thomas A.; Larsen, Jan Petter; Møller, Simon Geir

    2015-01-01

    Neuronal cell death, in neurodegenerative disorders, is mediated through a spectrum of biological processes. Excessive amounts of free radicals, such as reactive oxygen species (ROS), has detrimental effects on neurons leading to cell damage via peroxidation of unsaturated fatty acids in the cell membrane. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) has been used for neurological recovery in several countries, including Japan and China, and it has been suggested that Edaravone may have cytoprotective effects in neurodegeneration. Edaravone protects nerve cells in the brain by reducing ROS and inhibiting apoptosis. To gain further insight into the cytoprotective effects of Edaravone against oxidative stress condition we have performed comparative two-dimensional gel electrophoresis (2DE)-based proteomic analyses on SH-SY5Y neuroblastoma cells exposed to oxidative stress and in combination with Edaravone. We showed that Edaravone can reverse the cytotoxic effects of H2O2 through its specific mechanism. We observed that oxidative stress changes metabolic pathways and cytoskeletal integrity. Edaravone seems to reverse the H2O2-mediated effects at both the cellular and protein level via induction of Peroxiredoxin-2. PMID:26232623

  7. Changes in carbohydrate content in zucchini fruit (Cucurbita pepo L.) under low temperature stress.

    PubMed

    Palma, Francisco; Carvajal, Fátima; Lluch, Carmen; Jamilena, Manuel; Garrido, Dolores

    2014-03-01

    The postharvest handling of zucchini fruit includes low-temperature storage, making cold stress unavoidable. We have investigated the changes of soluble carbohydrates under this stress and its relation with weight loss and chilling injury in zucchini fruit during postharvest storage at 4 °C and 20 °C for up to 14 days. Two varieties with different degrees of chilling tolerance were compared: Natura, the more tolerant variety, and Sinatra, the variety that suffered more severe chilling-injury symptoms and weight loss. In both varieties, total soluble carbohydrates, reducing soluble carbohydrates and polyols content was generally higher during storage at 4 °C than at 20 °C, thus these parameters are related to the physiological response of zucchini fruit to cold stress. However, the raffinose content increased in Natura and Sinatra fruits during storage at 4 °C and 20 °C, although at 20 °C the increase in raffinose was more remarkable than at 4 °C in both varieties, so that the role of raffinose could be more likely related to dehydration than to chilling susceptibility of zucchini fruit. Glucose, fructose, pinitol, and acid invertase activity registered opposite trends in both varieties against chilling, increasing in Natura and decreasing in Sinatra. The increase in acid invertase activity in Natura fruit during cold storage could contribute in part to the increase of these reducing sugars, whose metabolism could be involved in the adaptation to postharvest cold storage.

  8. Dissecting DNA damage response pathways by analyzing protein localization and abundance changes during DNA replication stress

    PubMed Central

    Tkach, Johnny M.; Yimit, Askar; Lee, Anna Y.; Riffle, Michael; Costanzo, Michael; Jaschob, Daniel; Hendry, Jason A.; Ou, Jiongwen; Moffat, Jason; Boone, Charles; Davis, Trisha N.; Nislow, Corey; Brown, Grant W.

    2012-01-01

    Re-localization of proteins is a hallmark of the DNA damage response. We use high-throughput microscopic screening of the yeast GFP fusion collection to develop a systems-level view of protein re-organization following drug-induced DNA replication stress. Changes in protein localization and abundance reveal drug-specific patterns of functional enrichments. Classification of proteins by sub-cellular destination allows the identification of pathways that respond to replication stress. We analyzed pairwise combinations of GFP fusions and gene deletion mutants to define and order two novel DNA damage responses. In the first, Cmr1 forms subnuclear foci that are regulated by the histone deacetylase Hos2 and are distinct from the typical Rad52 repair foci. In a second example, we find that the checkpoint kinases Mec1/Tel1 and the translation regulator Asc1 regulate P-body formation. This method identifies response pathways that were not detected in genetic and protein interaction screens, and can be readily applied to any form of chemical or genetic stress to reveal cellular response pathways. PMID:22842922

  9. Subcellular distribution of glutathione and its dynamic changes under oxidative stress in the yeast Saccharomyces cerevisiae.

    PubMed

    Zechmann, Bernd; Liou, Liang-Chun; Koffler, Barbara E; Horvat, Lucija; Tomašić, Ana; Fulgosi, Hrvoje; Zhang, Zhaojie

    2011-12-01

    Glutathione is an important antioxidant in most prokaryotes and eukaryotes. It detoxifies reactive oxygen species and is also involved in the modulation of gene expression, in redox signaling, and in the regulation of enzymatic activities. In this study, the subcellular distribution of glutathione was studied in Saccharomyces cerevisiae by quantitative immunoelectron microscopy. Highest glutathione contents were detected in mitochondria and subsequently in the cytosol, nuclei, cell walls, and vacuoles. The induction of oxidative stress by hydrogen peroxide (H(2) O(2) ) led to changes in glutathione-specific labeling. Three cell types were identified. Cell types I and II contained more glutathione than control cells. Cell type II differed from cell type I in showing a decrease in glutathione-specific labeling solely in mitochondria. Cell type III contained much less glutathione contents than the control and showed the strongest decrease in mitochondria, suggesting that high and stable levels of glutathione in mitochondria are important for the protection and survival of the cells during oxidative stress. Additionally, large amounts of glutathione were relocated and stored in vacuoles in cell type III, suggesting the importance of the sequestration of glutathione in vacuoles under oxidative stress.

  10. Changes in Transcript Related to Osmosis and Intracellular Ion Homeostasis in Paulownia tomentosa under Salt Stress.

    PubMed

    Fan, Guoqiang; Wang, Limin; Deng, Minjie; Zhao, Zhenli; Dong, Yanpeng; Zhang, Xiaoshen; Li, Yongsheng

    2016-01-01

    Paulownia tomentosa is an important economic and greening tree species that is cultivated widely, including salt environment. Our previous studies indicated its autotetraploid induced by colchicine showed better stress tolerance, but the underlying molecular mechanism related to ploidy and salt stress is still unclear. To investigate this issue, physiological measurements and transcriptome profiling of diploid and autotetraploid plants untreated and treated with NaCl were performed. Through the comparisons among four accessions, for one thing, we found different physiological changes between diploid and autotetraploid P. tomentosa; for another, and we detected many differentially expressed unigenes involved in salt stress response. These differentially expressed unigenes were assigned to several metabolic pathways, including "plant hormone signal transduction," "RNA transporter," "protein processing in endoplasmic reticulum," and "plant-pathogen interaction," which constructed the complex regulatory network to maintain osmotic and intracellular ion homeostasis. Quantitative real-time polymerase chain reaction was used to confirm the expression patterns of 20 unigenes. The results establish the foundation for the genetic basis of salt tolerance in P. tomentosa, which in turn accelerates Paulownia breeding and expands available arable land.

  11. Water-deficit stress-induced anatomical changes in higher plants.

    PubMed

    Shao, Hong-Bo; Chu, Li-Ye; Jaleel, Cheruth Abdul; Zhao, Chang-Xing

    2008-03-01

    Water is vital for plant growth and development. Water-deficit stress, permanent or temporary, limits the growth and the distribution of natural vegetation and the performance of cultivated plants more than any other environmental factors do. Although research and practices aimed at improving water-stress resistance and water-use efficiency have been carried out for many years, the mechanism involved is still not clear. Further understanding and manipulating plant-water relations and water-stress tolerance at the scale of physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important to explore anti-drought gene resource in different life forms, but modern agricultural sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics will have further a practical prospect. In this review, we discussed the anatomical changes and drought-tolerance strategies under drought condition in higher plants.

  12. Dynamic changes in the sperm quality of Mytilus galloprovincialis under continuous thermal stress.

    PubMed

    Boni, Raffaele; Gallo, Alessandra; Montanino, Melania; Macina, Alberto; Tosti, Elisabetta

    2016-02-01

    Global warming is an increasingly serious problem underlying ecological change in marine flora and fauna. Mytilus galloprovincialis is an intertidal species that colonizes coasts in moderate and warm climates, and can thus withstand extreme climatic conditions; however, it successfully reproduces only within a certain temperature range. The effects of prolonged exposure to 28 °C, a temperature unsuitable for breeding activity, on sperm quality were evaluated in this study. Such heat stress induced the following: a significant reduction in concentration; a biphasic pattern of motility and mitochondrial membrane potential that first increased, and then collapsed; a decrease in the intracellular calcium concentration; a rapid increase in lipid peroxidation that was normalized after the third week of heat stress; an increase in DNA fragmentation after the third week of heat stress; and atypical morphology (i.e., sperm with a globular head, asymmetrical tail, and acrosome loss). Currently, these elevated-temperature conditions are achieved along the Mediterranean coast during the late summer, when the reproductive activity of M. galloprovincialis is suspended after massive spawning in the spring. The increasing global temperature, however, may shift their breeding season, thus significantly impacting marine ecosystems and mussel production.

  13. A New Mechanism for Pore Pressure Changes Induced by Distant Earthquakes

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Roeloffs, E.; Woodcock, D.; Gall, I.; Manga, M.

    2001-12-01

    Observations during the Mw=7.3 1992 Landers earthquake, Mw=7.4 Izmit earthquake and Mw=7.2 Hector Mine earthquake suggest that seismicity is triggered hundreds of kilometers from a mainshock epicenter. This puzzling phenomenon is not explained by traditional elastic models of seismic stresses. The fact that the triggered sites are often geothermal or magmatic suggests that fluids may be an important part of the triggering process. Rapid changes in pore pressure either reduce the effective stress on faults locally or prompt hydrofracturing to initiate local earthquakes. The challenge is to discover how the seismic waves generate a change in pore fluid pressure. We constrain a mechanism for seismically-induced pore pressure changes by studying coseismic water level drops at a well in Grants Pass, Oregon. Water level drops at the site have been associated with earthquakes for nearly 20 years. High-sample rate (up to 1 Hz) digital water level data is available for the two coseismic drops that have occurred since 1994. The approach of this study is to use the amplification of the seismic waves in the well to constrain variations of the aquifer properties during the water level drops. We find that the amplification of the seismic waves in the well is consistent with standard theory for 7 digitally recorded events without drops, but during an earthquake with a drop a dramatic change in amplification occurs during the passage of the Rayleigh waves. The change in amplification indicates that the transmissivity increases by a factor of 50 during the 11 cm coseismic water level drop accompanying the 1999 Mw=7.5 1999 Oaxaca, Mexico earthquake. Based on these observations, we propose a new model for coseismic pore pressure changes. Drops occur if an earthquake occurs when the well has become temporarily clogged by a solid precipitate or sediment. The seismic shaking induces a flow which removes the obstruction. Once a barrier is removed, water flows rapidly to generate dramatic

  14. Temporal changes of the adrenal endocrine system in a restraint stressed mouse and possibility of postmortem indicators of prolonged psychological stress.

    PubMed

    Hayashi, Takahito; Ikematsu, Kazuya; Abe, Yuki; Ihama, Yoko; Ago, Kazutoshi; Ago, Mihoko; Miyazaki, Tetsuji; Ogata, Mamoru

    2014-07-01

    We investigated temporal changes of adrenal endocrine systems through the hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenomedullary (SA) axis in restraint stressed mice. Restraint stress for 1 day to 3 weeks caused a significant increase in serum levels of ACTH and glucocorticoids accompanied with an increase in adrenal weights, indicating activation of the HPA axis. Reflecting the overproduction of glucocorticoids, adrenal cholesterol content decreased. Moreover, adrenal gene expression involved in cholesterol supply, including scavenger receptor-class B type I, HMG-CoA reductase, and hormone-sensitive lipase, was increased over the same period. After 4 weeks stress, all of these changes returned to control levels. In contrast, adrenal gene expression of chromogranin A, which is cosecreted with catecholamine via the SA axis, was increased with 1 day to 2 weeks of stress, and decreased with 3-4 weeks of stress. Our results suggest that analyses of adrenal endocrine systems based on the combination of several markers examined here would be useful for not only proving prolonged psychological stress experience but also determining its duration.

  15. Volcanism and related Environmental changes linked to Late Maastrichtian High Stress and KT Mass Extinction

    NASA Astrophysics Data System (ADS)

    Keller, Gerta; Adatte, Thierry

    2010-05-01

    Near the end of the Maastrichtian Earth was hit by a confluence of catastrophes ranging from impacts to some of the most devastating volcanic eruptions coupled with major changes in climate, sea level and ocean chemistry that ultimately led to the Cretaceous-Tertiary boundary (KTB) mass extinction. For three decades this mass extinction has been commonly attributed to the sole kill-effect of the Chicxulub impact on Yucatan. Multi-disciplinary evidence (paleontologic, stratigraphic, sedimentologic geochemical) from the Yucatan impact crater to sections in Mexico and Texas revealed that this impact predates the KTB and caused no mass extinction. Recent studies reveal that the most devastating Deccan volcanic eruptions in India occurred near the end of the Maastrichtian and ended coincident with the KT mass extinction (Keller et al., 2008). Examination of biotic stress in the marine realm leading up to the KT mass extinction reveals times of environmental stresses associated with volcanism, greenhouse warming, mesotrophic basins and shallow marginal settings from the Tethys Ocean to the South Atlantic and Indian Oceans (Keller and Abramovich, 2009). Biotic stress conditions vary with the degree of environmental change and range from intraspecies size reduction, to loss of diversity and ultimately mass extinction. No significant biotic stress was observed in assemblages before and after the Chicxulub impact identified by a layer of impact spherules in late Maastrichtian sediments of zone CF1 predating the KTB in Mexico and Texas (Keller et al., 2009b,c). Maximum biotic stress leading to the KT mass extinction is associated with Deccan volcanism in India near the end of the Maastrichtian. This suggests that the mass extinction was likely a direct cause of Deccan volcanism, although the presence of a major Ir anomaly at the KTB does not rule out the possibility of a second major bolide impact exacerbating already catastrophic conditions. Keller, G., Adatte, T., Gardin, S

  16. Systemic inflammatory changes and increased oxidative stress in rural Indian women cooking with biomass fuels

    SciTech Connect

    Dutta, Anindita; Ray, Manas Ranjan; Banerjee, Anirban

    2012-06-15

    cardiovascular health was investigated. ► Serum markers of systemic inflammation and oxidative stress were studied. ► Biomass using women had increased systemic inflammation and oxidative stress. ► Indoor air pollution and observed changes were positively associated.

  17. Early changes in oxidative stress markers in a rat model of acute stress: effect of l-carnitine on the striatum.

    PubMed

    Méndez-Cuesta, Luis A; Márquez-Valadez, Berenice; Pérez-De la Cruz, Verónica; Maldonado, Perla D; Santana, Ricardo A; Escobar-Briones, Carolina; Galván-Arzate, Sonia; Carrillo-Mora, Paul; Santamaría, Abel

    2011-08-01

    This work focuses on the effect of acute stress on different markers of oxidative stress and mitochondrial dysfunction in the rat striatum. In addition, the effect of a single dose of l-carnitine (l-CAR, 300 mg/kg, i.p.) was evaluated in these animals. Immobilization (restraint) stress was induced to rats for 24 hr. The levels of lipid peroxidation (LP) and mitochondrial function (MF), as well as the superoxide dismutase (SOD) activity and content and reduced glutathione (GSH) levels, were all measured in striatal samples of animals subjected to stress. Our results indicate that acute stress is able to increase the striatal LP and reduced the levels of MF, while significantly lowered the manganese superoxide dismutase (Mn-SOD) activity. No changes were observed in the total striatal content of SOD, nor in GSH levels, but serum corticosterone content was increased by stress. l-CAR exhibited partial protective effects on the immobilized group, reducing the striatal LP and recovering the striatal MF and Mn-SOD activity. Our results suggest that acute restraint stress brings an accurate model for early pro-oxidant responses that can be targeted by broad-spectrum antioxidants like l-CAR.

  18. Progressive rock slope failure resulting from fluvial incision and far-field stress changes in alpine landscapes

    NASA Astrophysics Data System (ADS)

    Leith, K.; Moore, J. R.; Loew, S.; Krautblatter, M.

    2013-12-01

    Modifications to rock slope morphology are commonly associated with the destabilization of local rock masses where shear, normal, or tensile stress changes cause in situ stresses to exceed intact or rock mass failure envelopes. Such destabilization is most commonly attributed to ';debuttressing' causing a loss of support from adjacent bodies, or a reduction in effective rock mass strength as critical planes of weakness are ';undercut' by erosional processes. Lower magnitude stress changes which approach the brittle failure envelopes are often implicated in progressive rock slope failure, as local stress concentrations propagate existing fractures or weaken existing joints. We model the development of long-term in situ stresses within an alpine valley affected by ongoing tectonic and erosional processes. We allow for the mechanical effects of long-term bedrock strength limits, and analyze the magnitude of far-field stress changes associated with 100 m of fluvial incision at the axis of a 3000 m wide, 2500 m deep alpine valley. Our model configuration mirrors the erosional history of the Matter Valley (southern Swiss Alps) at the location of the 30 x 106 m3 Randa rock slope failure. We find that incision focuses stresses at the valley floor, reducing stress magnitudes throughout the remainder of the landscape. This effect is particularly strong near the valley shoulder, where decreases in shear stress are approximately half those of normal stresses. Although the magnitude of changes are relatively low (10's to 100's of kPa), we find incision may have had a negative impact on the stability of rock slopes over 1000 m from the valley axis, perhaps initiating progressive failure of the Randa rock slope. Such progressive failure is particularly important in alpine regions, as its initiation requires relatively minor morphological change, and the resulting strength degradation modulates temporal increases in rock slope sensitivity. Our proposition is supported by the

  19. Stress changes, focal mechanisms, and earthquake scaling laws for the 2000 dike at Miyakejima (Japan)

    NASA Astrophysics Data System (ADS)

    Passarelli, Luigi; Rivalta, Eleonora; Cesca, Simone; Aoki, Yosuke

    2015-06-01

    Faulting processes in volcanic areas result from a complex interaction of pressurized fluid-filled cracks and conduits with the host rock and local and regional tectonic setting. Often, volcanic seismicity is difficult to decipher in terms of the physical processes involved, and there is a need for models relating the mechanics of volcanic sources to observations. Here we use focal mechanism data of the energetic swarm induced by the 2000 dike intrusion at Miyakejima (Izu Archipelago, Japan), to study the relation between the 3-D dike-induced stresses and the characteristics of the seismicity. We perform a clustering analysis on the focal mechanism (FM) solutions and relate them to the dike stress field and to the scaling relationships of the earthquakes. We find that the strike and rake angles of the FMs are strongly correlated and cluster on bands in a strike-rake plot. We suggest that this is consistent with optimally oriented faults according to the expected pattern of Coulomb stress changes. We calculate the frequency-size distribution of the clustered sets finding that focal mechanisms with a large strike-slip component are consistent with the Gutenberg-Richter relation with a b value of about 1. Conversely, events with large normal faulting components deviate from the Gutenberg-Richter distribution with a marked roll-off on its right-hand tail, suggesting a lack of large-magnitude events (Mw > 5.5). This may result from the interplay of the limited thickness and lower rock strength of the layer of rock above the dike, where normal faulting is expected, and lower stress levels linked to the faulting style and low confining pressure.

  20. Physico-chemical changes in karkade (Hibiscus sabdariffa L.) seedlings responding to salt stress.

    PubMed

    Galal, Abdelnasser

    2017-03-01

    Salinity is one of the major abiotic stress factors affecting series of morphological, physiological, metabolic and molecular changes in plant growth. The effect of different concentrations (0, 25, 50, 100 and 150 mM) of NaCl on the vegetative growth and some physiological parameters of karkade (Hibiscus sabdariffa var. sabdariffa) seedling were investigated. NaCl affected the germination rate, delayed emergence and retarded vegetative growth of seedlings. The length of seedling as well as the leaf area was significantly reduced