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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. 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

  3. Deep coseismic slip of the 2008 Wenchuan earthquake inferred from joint inversion of fault stress changes and GPS surface displacements

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Yang, Yinghui; Luo, Rong; Liu, Guoxiang; Zhang, Kui

    2015-07-01

    Geodetic data are increasingly being used to infer coseismic slip distribution due to its advantages of wide coverage and high accuracy. However, it is difficult to obtain a comprehensive rupture pattern at depth when a source model is only constrained by geodetic surface deformation. In this study, a joint inversion approach incorporating stress changes and GPS surface displacements is explored and applied to characterize the fault slip of the 2008 Mw 7.9 Wenchuan earthquake, China. The earthquake data for the 20-year period before the main quake, which are collected from the background seismicity catalogues, and one month of aftershock data are statistically analysed to determine the fault stress changes based on the Dieterich model. The coseismic surface deformation measurements from 158 GPS surveying sites are jointly used to constrain the solution. Our preferred rupture model reveals four high-slip concentrations on the Yingxiu-Beichuan fault and one on the subparallel PengGuan fault. The spatial distribution suggests that the coseismic slip occurs not only above the hypocentre but also with a significant thrusting motion, with a mean slip of 8.5 m and a maximum of 9.7 m at a depth of 10-16 km. A significant high-slip concentration is found for the first time in this study. The coseismic faulting extends toward ∼16 km southwest of the Yingxiu-Beichuan fault and has a dextral strike-slip with a mean displacement of 4.8 m at a depth of 7-19 km. The joint inversion model misfits (GPS: 1.7 cm, stress change: 0.02 MPa) exhibit a good compatibility between the two types of datasets. The derived slip model, which has an improved resolution at depth, explains 98% of the coseismic surface displacements and 93% of the fault stress changes.

  4. Coseismic Slip Distribution of the 2010 M7.0 Haiti Earthquake and Resulting Stress Changes on Regional Faults

    NASA Astrophysics Data System (ADS)

    Symithe, S. J.

    2012-12-01

    The Mw 7.0 January 12, 2010, Haiti earthquake ruptured the previously unmapped Léogâne Fault, a secondary transpressional fault located close to the Enriquillo Plantain Garden Fault (EPGF), the major fault system assumed to be the primary source of seismic hazard for southern Haiti. In the absence of a precise aftershock catalog, previous estimations of coseismic slip had to infer the rupture geometry from geodetic and/or seismological data. Here we use a catalog of precisely relocated aftershocks covering the 6 months following the event to constrain the rupture geometry, estimate a slip distribution from an inversion of GPS, InSAR and coastal uplift data, and calculate the resulting changes of Coulomb failure stress on neighboring faults. The relocated aftershocks confirm a north dipping structure consistent with the Léogâne fault, as inferred from previous slip inversions. Our updated source model involves two subfaults, each corresponding to a major slip patch. The eastern one combines strike-slip and dip-slip, while the western one is mostly strike-slip. Overall, the event released 68 % of left-lateral strike-slip and 32 % of dip-slip reverse seismic moment, consistent with secular strain accumulation in southern Haiti from regional GPS studies. Coulomb failure stress changes caused by the coseismic rupture show that the cluster of reverse faulting earthquakes, one as large as M 5.9, that were observed to the west of the coseismic rupture coincident with the offshore Trois Baies fault were likely triggered by the main shock. We find increased stresses on the Enriquillo fault to the west of the January 12, 2010 rupture (Miragoâne area, ~3 bars) and to the east near Port-au-Prince (0.3 to ~1 bar). Other regional faults do not show significant increase of static stresses at seismogenic depth. Increased coseismic stress changes on the Trois Baies fault and portions of the Enriquillo fault to the west and east of the Léogâne rupture are a concern as this

  5. Coseismic Coulomb stress changes caused by the Mw6.9 Yutian earthquake in 2014 and its correlation to the 2008 Mw7.2 Yutian earthquake

    NASA Astrophysics Data System (ADS)

    Li, Yujiang; Chen, Lianwang; Liu, Shaofeng; Yang, Shuxin; Yang, Xingyue; Zhang, Guangwei

    2015-06-01

    A three-dimensional viscoelastic finite element model of the Qinghai-Tibet Plateau and its adjacent regions was used to explore the relationship between the Mw7.2 Yutian earthquake in 2008 and the 2014 Mw6.9 Yutian earthquake. We further analyzed the Coulomb failure stress change caused by the Yutian Mw6.9 earthquake on faults surrounding the Bayan Har block and discussed the relationship between the Coulomb stress change and aftershock distribution. The preliminary results showed that: (1) The Coulomb failure stress change caused by the Mw7.2 Yutian earthquake in 2008, which was projected on the slip direction of the 2014 Yutian Mw6.9 earthquake, exceeded the earthquake triggering threshold of 0.01 MPa, implying an apparent triggering effect. Specifically, the coseismic Coulomb failure stress changes were 0.0167 MPa and 0.0170 MPa when assuming apparent friction coefficients of 0.4 and 0.6, respectively. The Coulomb failure stress changes, including viscoelastic relaxation effects, were 0.0187 MPa and 0.0194 MPa respectively. Combined with the tectonic stressing rate, the Mw6.9 Yutian earthquake in 2014 was advanced 21.4-24.9 years by the 2008 Mw7.2 Yutian earthquake; (2) The stress changes derived from the viscoelastic relaxation effect were much less than that from the coseismic effect, which was possibly interpreted as the shorter elapsed time between the two earthquakes relative to the characteristic time; (3) The Coulomb failure stresses increased on the mid-northern segment of the Altyn Tagh fault, the middle segment of the Mani-Yushu fault and the western segment of the eastern Kunlun fault, which demonstrated increasing seismic potential. In particular, the Coulomb failure stress on the middle segment of the Altyn Tagh fault increased by 2.8 × 103 Pa, the most significant increase. In contrast, the Coulomb failure stress decreased on the western segment of the Mani-Yushu and Minjiang faults, with the western segment of the Mani-Yushu fault dropping by 3

  6. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  10. 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.

  11. Renewal models and coseismic stress transfer in the Corinth Gulf, Greece, fault system

    NASA Astrophysics Data System (ADS)

    Console, Rodolfo; Falcone, Giuseppe; Karakostas, Vassilis; Murru, Maura; Papadimitriou, Eleftheria; Rhoades, David

    2013-07-01

    model interevent times and Coulomb static stress transfer on the rupture segments along the Corinth Gulf extension zone, a region with a wealth of observations on strong-earthquake recurrence behavior. From the available information on past seismic activity, we have identified eight segments without significant overlapping that are aligned along the southern boundary of the Corinth rift. We aim to test if strong earthquakes on these segments are characterized by some kind of time-predictable behavior, rather than by complete randomness. The rationale for time-predictable behavior is based on the characteristic earthquake hypothesis, the necessary ingredients of which are a known faulting geometry and slip rate. The tectonic loading rate is characterized by slip of 6 mm/yr on the westernmost fault segment, diminishing to 4 mm/yr on the easternmost segment, based on the most reliable geodetic data. In this study, we employ statistical and physical modeling to account for stress transfer among these fault segments. The statistical modeling is based on the definition of a probability density distribution of the interevent times for each segment. Both the Brownian Passage-Time (BPT) and Weibull distributions are tested. The time-dependent hazard rate thus obtained is then modified by the inclusion of a permanent physical effect due to the Coulomb static stress change caused by failure of neighboring faults since the latest characteristic earthquake on the fault of interest. The validity of the renewal model is assessed retrospectively, using the data of the last 300 years, by comparison with a plain time-independent Poisson model, by means of statistical tools including the Relative Operating Characteristic diagram, the R-score, the probability gain and the log-likelihood ratio. We treat the uncertainties in the parameters of each examined fault source, such as linear dimensions, depth of the fault center, focal mechanism, recurrence time, coseismic slip, and

  12. Coseismic water-level changes in a well induced by teleseismic waves from three large earthquakes

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Fu, Li-Yun; Huang, Fuqiong; Chen, Xuezhong

    2015-05-01

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

  13. Co-seismic and post-seismic gravity change due to the 2004 Sumatra-Andaman earthquake: EOF study

    NASA Astrophysics Data System (ADS)

    Li, Y.; Chao, B. F.

    2009-12-01

    The magnitude 9.3 earthquake in Sumatra-Andaman on December 26, 2004, was the second largest earthquake in the past century. We examine the before-and-after time-variable gravity (TVG) associated with the earthquake using the monthly data from the GRACE satellite mission (launched in 2002). We calculate the EOF (Empirical Orthogonal Function) to analyze the space-time variation of the co-seismic and post-seismic behavior of the epicentral region. In addition to the conspicuous co-seismic, dipolar jump of TVG in the region, we found: (1) no evidence of pre-seismic TVG behavior; (2) a gradual post-seismic appearance of a third decreasing TVG pattern to the southwest of the co-seismic dipole; (3) that the west side of the Sunda Trench sees a post-seismic TVG growth on top of the co-seismic jump; (4) that the east side of the Sunda Trench sees a post-seismic TVG recovery from the co-seismic jump. One can thus infer the post-seismic mass flow across the fault zone. We also analyzed by EOF the sea level change as a proxy for the regional geoid change using radar altimetry data. We could only find a weak signal that appears to be related to the co-seismic dipolar TVG in the form of geoid change, obscured by the presence of various meteorological and oceanographic signals.

  14. Co-seismic Static Stress Drops for Earthquake Ruptures Nucleated on Faults After Progressive Strain Localization

    NASA Astrophysics Data System (ADS)

    Griffith, W. A.; Nielsen, S.; di Toro, G.; Pollard, D. D.; Pennacchioni, G.

    2007-12-01

    We estimate the coseismic static stress drop on small exhumed strike-slip faults in the Mt. Abbot quadrangle of the central Sierra Nevada (California). The sub-vertical strike-slip faults cut ~85 Ma granodiorite, were exhumed from 7-10 km depth, and were chosen because they are exposed along their entire lengths, ranging from 8 to 13 m. Net slip is estimated using offset aplite dikes and shallowly plunging slickenlines on the fault surfaces. The faults show a record of progressive strain localization: slip initially nucleated on joints and accumulated from ductile shearing (quartz-bearing mylonites) to brittle slipping (epidote-bearing cataclasites). Thin (< 1 mm) pseudotachylytes associated with the cataclasites have been identified along some faults, suggesting that brittle slip may have been seismic. The brittle contribution to slip may be distinguished from the ductile shearing because epidote-filled, rhombohedral dilational jogs opened at bends and step-overs during brittle slip, are distributed periodically along the length of the faults. We argue that brittle slip occurred along the measured fault lengths in single slip events based on several pieces of evidence. 1) Epidote crystals are randomly oriented and undeformed within dilational jogs, indicating they did not grow during aseismic slip and were not broken after initial opening and precipitation. 2) Opening-mode splay cracks are concentrated near fault tips rather than the fault center, suggesting that the reactivated faults ruptured all at once rather than in smaller slip patches. 3) The fact that the opening lengths of the dilational jogs vary systematically along the fault traces suggests that brittle reactivation occurred in a single slip event along the entire fault rather than in multiple slip events. This unique combination of factors distinguishes this study from previous attempts to estimate stress drop from exhumed faults because we can constrain the coseismic rupture length and slip. The

  15. Coseismic stresses indicated by pseudotachylytes in the Outer Hebrides Fault Zone, UK.

    NASA Astrophysics Data System (ADS)

    Campbell, Lucy; Lloyd, Geoffrey; Phillips, Richard; Holdsworth, Robert; Walcott, Rachel

    2015-04-01

    During the few seconds of earthquake slip, dynamic behaviour is predicted for stress, slip velocity, friction and temperature, amongst other properties. Fault-derived pseudotachylyte is a coseismic frictional melt and provides a unique snapshot of the rupture environment. Exhumation of ancient fault zones to seismogenic depths can reveal the structure and distribution of seismic slip as pseudotachylyte bearing fault planes. An example lies in NW Scotland along the Outer Hebrides Fault Zone (OHFZ) - this long-lived fault zone displays a suite of fault rocks developed under evolving kinematic regimes, including widespread pseudotachylyte veining which is distributed both on and away from the major faults. This study adds data derived from the OHFZ pseudotachylytes to published datasets from well-constrained fault zones, in order to explore the use of existing methodologies on more complex faults and to compare the calculated results. Temperature, stress and pressure are calculated from individual fault veins and added to existing datasets. The results pose questions on the physical meaning of the derived trends, the distribution of seismic energy release across scattered cm-scale faults and the range of earthquake magnitudes calculated from faults across any given fault zone.

  16. 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

  17. Coseismic and postseismic wave velocity changes caused by large crustal earthquakes in Japan

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Using Passive Image Interferometry (PII), we analyzed coseismic and postseismic changes of seismic wave velocities caused by the following earthquakes which occurred in Japan between 2004 and 2011: The 2005 Fukuoka (MW6.6), 2007 Noto Hant¯o (MW6.6) and 2008 Iwate-Miyagi Nairiku (MW6.9) earthquakes, three earthquakes in Niigata Prefecture (2004 Mid-Niigata, MW6.8; 2007 Ch¯u etsu Offshore, MW6.6; 2011 Nagano/Niigata, MW6.2), as well as the 2011 Tohoku earthquake (MW9.0) in the four regions of the other earthquakes. The time series of ambient noise used for the different earthquakes spanned from at least half a year before the respective earthquake until three months after the Tohoku earthquake. Cross-correlations and single-station cross-correlations of several years of ambient seismic noise, which was recorded mainly by Hi-net sensors in the surrounding areas of the respective earthquakes, are calculated in different frequency ranges between 0.125 and 4.0 Hz. Between 10 and 20 seismometers were used in the different areas. The cross-correlations are calculated for all possible station pairs. Using a simple tomography algorithm, the resulting velocity variations can be reprojected on the actual station locations. The cross-correlation and single-station cross-correlation techniques give compatible results, the former giving more reliable results for frequencies below 0.5 Hz, the latter for higher frequencies. Our analysis yields significant coseismic velocity drops for all analyzed earthquakes, which are strongest close to the fault zones and exceed 1 % for some stations. The coseismic velocity drops are larger at higher frequencies and recover on a time scale of several years, but the coseismic velocity drops do not completely recover during our observation time. Velocity drops are also visible in all areas at the time of the Tohoku earthquake. Furthermore, we measured seasonal velocity variations of the order of 0.1 % in all areas which are, at least for

  18. 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

  19. Coseismic and postseismic velocity changes detected by Passive Image Interferometry: comparison of one great and five strong earthquakes in Japan

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    We present a systematic study of seismic velocity changes associated with a megathrust and five strong crustal earthquakes in Japan. We perform both cross-correlation and single-station cross-correlation analysis for station pairs and stations, respectively. The correlation of ambient seismic noise allows us to reconstruct the Green's functions of the wave propagation. By relating the coda parts of the daily Green's functions with the long-term reference Green's functions, shear wave velocity changes are determined. We analyze data from four areas in Japan where large earthquakes occurred: Iwate-Miyagi (2008 MW 6.9 Iwate-Miyagi Nairiku earthquake), Niigata (2004 MW 6.6 Chūetsu, 2007 MW 6.6 Chūetsu-oki and 2011 MW 6.2 Nagano/Niigata earthquakes), Noto Peninsula (2007 MW 6.7 Noto Hantō earthquake) and Fukuoka (2005 MW 6.6 Fukuoka earthquake). In all areas, we analyze time series which start before the respective earthquakes and last until after the 2011 MW 9.0 Tōhoku-oki earthquake. The analysis in five different frequency ranges between 0.125 and 4.0 Hz yields time series of the velocity changes for the different station pairs or stations. At the time of the respective earthquakes, we observe coseismic velocity drops in all areas which are followed by a partial postseismic recovery process. For the Tōhoku-oki earthquake, coseismic velocity drops can also be observed in all regions. There is a general trend of increasing coseismic velocity drops with frequency in all four areas. The largest coseismic drops are observed close to the fault zones. Over the observed time range, the postseismic recovery is only partial and around half of the coseismic velocity drops do not recover. The characteristic recovery times for the recovering part are similar in all areas and frequency ranges, with an average value of 0.55 years. We model the volumetric strain changes for the different earthquakes and find that the observed pattern of the coseismic velocity drops cannot be

  20. 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.

  1. 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.

  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 and post-seismic velocity changes detected by Passive Image Interferometry: comparison of one great and five strong earthquakes in Japan

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We present a systematic study of seismic velocity changes associated with a megathrust and five strong crustal earthquakes in Japan. We perform both cross-correlation and single-station cross-correlation analysis for station pairs and stations, respectively. The correlation of ambient seismic noise allows us to reconstruct the Green's functions of the wave propagation. By relating the coda parts of the daily Green's functions with the long-term reference Green's functions, shear wave velocity changes are determined. We analyse data from four areas in Japan where large earthquakes occurred: Iwate-Miyagi (2008 MW 6.9 Iwate-Miyagi Nairiku earthquake), Niigata (2004 MW 6.6 Chūetsu, 2007 MW 6.6 Chūetsu-oki and 2011 MW 6.2 Nagano/Niigata earthquakes), Noto Peninsula (2007 MW 6.7 Noto Hantō earthquake) and Fukuoka (2005 MW 6.6 Fukuoka earthquake). In all areas, we analyse time-series which start before the respective earthquakes and last until after the 2011 MW 9.0 Tōhoku-oki earthquake. The analysis in five different frequency ranges between 0.125 and 4.0 Hz yields time-series of the velocity changes for the different station pairs or stations. At the time of the respective earthquakes, we observe coseismic velocity drops in all areas which are followed by a partial post-seismic recovery process. For the Tōhoku-oki earthquake, coseismic velocity drops can also be observed in all regions. There is a general trend of increasing coseismic velocity drops with frequency in all four areas. The largest coseismic drops are observed close to the fault zones. Over the observed time range, the post-seismic recovery is only partial and around half of the coseismic velocity drops do not recover. The characteristic recovery times for the recovering part are similar in all areas and frequency ranges, with an average value of 0.55 yr. We model the volumetric strain changes for the different earthquakes and find that the observed pattern of the coseismic velocity drops cannot be

  4. Long-term changes to river regimes prior to late Holocene coseismic faulting, Canterbury, New Zealand

    NASA Astrophysics Data System (ADS)

    Campbell, Jocelyn K.; Nicol, Andrew; Howard, Matthew E.

    2003-09-01

    Two sites are described from range front faults along the foothills of the Southern Alps of New Zealand, where apparently a period of 200-300 years of accelerated river incision preceded late Holocene coseismic ruptures, each probably in excess of M w 7.5. They relate to separate fault segments and seismic events on a transpressive system associated with fault-driven folding, but both show similar evidence of off-plane aseismic deformation during the downcutting phase. The incision history is documented by the ages, relative elevations and profiles of degradation terraces. The surface dating is largely based on the weathering rind technique of McSaveney (McSaveney, M.J., 1992. A Manual for Weathering-rind Dating of Grey Sandstones of the Torlesse Supergroup, New Zealand. 92/4, Institute of Geological and Nuclear Sciences), supported by some consistent radiocarbon ages. On the Porters Pass Fault, drainage from Red Lakes has incised up to 12 m into late Pleistocene recessional outwash, but the oldest degradation terrace surface T I is dated at only 690±50 years BP. The upper terraces T I and T II converge uniformly downstream right across the fault trace, but by T III the terrace has a reversed gradient upstream. T II and T III break into multiple small terraces on the hanging wall only, close to the fault trace. Continued backtilting during incision caused T IV to diverge downstream relative to the older surfaces. Coseismic faulting displaced T V and all the older terraces by a metre high reverse scarp and an uncertain right lateral component. This event cannot be younger than a nearby ca. 500 year old rock avalanche covering the trace. The second site in the middle reaches of the Waipara River valley involves the interaction of four faults associated with the Doctors Anticline. The main river and tributaries have incised steeply into a 2000 year old mid-Holocene, broad, degradation surface downcutting as much as 55 m. Beginning approximately 600 years ago

  5. 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.

  6. Using ambient noise correlations to monitor coseismic and postseismic velocity changes caused by the 2008 Iwate-Miyagi Nairiku earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Hobiger, M.; Wegler, U.; Shiomi, K.; Nakahara, H.

    2011-12-01

    Passive Image Interferometry is becoming a widely used technique to measure temporal variations of shear wave velocities. This technique correlates the ambient seismic noise recordings of a pair of seismic sensors in order to reconstruct the Green's function for the propagation of seismic waves between the sensors. By correlating the coda parts of stretched versions of the daily Green's functions (or an average Green's functions for several days) with a reference Green's function (the average of all daily Green's functions), small shear wave velocity changes are determined (Coda Wave Interferometry) for the respective sensor pair. We apply this method to 32 months (January 2008 - August 2010) of recordings from inland Northern Honshu, Japan, where the Iwate-Miyagi Nairiku earthquake (MW = 6.9) occurred on June 14, 2008. The three-component data of 17 Hi-Net velocimeters and 3 surface sensors are analyzed in six different frequency ranges between 0.125 and 8 Hz. The preliminary results show coseismic velocity drops of up to 0.5 % for some station pairs, the largest velocity drops occuring for station pairs located in the central part of the rupture zone. Anyhow, station pairs exhibiting a significant coseismic velocity increase cannot be found. Furthermore, we investigate the postseismic recovery of seismic velocities. With the analyzed data length of about two years after the earthquake, typical recovery times from about 1 to 7 years can be resolved, but some station pairs do not exhibit any measurable velocity recovery during the analyzed period of time. Additionally, some station pairs show seasonal velocity changes of less than 0.1 % with a clear period of one year.

  7. Assessing the influence of viscoelastic stress change globally

    NASA Astrophysics Data System (ADS)

    Sunbul, Fatih; Nalbant, Suleyman; Steacy, Sandy; Parsons, Thomas

    2014-05-01

    Long term viscoleastic effects play an important role in stress accumulation along faults. Developing a better understanding of these effects may lead to improve quantification of the seismic hazard in tectonically active areas. Parsons (2002) computed at a global scale, the difference between the rate of earthquakes occurring in regions where shear stress increased and those regions where the shear stress decreased. Looking at the shear component of the stress tensor, he found globally that 61% of the earthquakes occurred in regions where there was a shear stress increase, while 39% occurred in areas of shear stress decrease. However, he considered only the coseismic period of the seismic cycle and very often this produces an incomplete picture of both the regional stress changes around the fault and its interaction with neighbouring faults. By examining both the coseismic and postseismic periods we aim to develop a more complete understanding of these phenomena. We individually study the shear and the normal components of the stress tensor with the objective of making a final comparison between the results for each component. Another extension to Parsons' (2002) work is the inclusion of viscoelastic stress change in the calculations. Although the stress change contribution of the viscoelastic relaxation is small for short post-seismic periods and small number of events, when it is cumulated over long periods of time and for many earthquakes, it can become a major contributor to the total regional stress. We are testing two crustal viscoelastic models, each consisting of three layers. In both cases the thickness for each layer was obtained from CRUST1.0 program. In the first model, the Strong Lower Crust- Weak Mantle (SLC-WM) we treat the upper crust layer as purely elastic, and a strongly viscoelastic lower crust and weakly viscoelastic upper mantle. In the second model, the Weak Lower Crust- Strong Mantle (WLC-SM) the upper crust remains purely elastic but the

  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. Co-seismic and post-seismic effects of the Tohoku-Oki M W 9.0 earthquake in North and Northeast China

    NASA Astrophysics Data System (ADS)

    Feng, Chengjun; Zhang, Peng; Tan, Chengxuan; Qi, Bangshen; Wang, Lianjie

    2016-01-01

    Using the US Geological Survey (USGS) finite fault model, the co-seismic horizontal displacement and horizontal principal stress field in North and Northeast China generated by the Tohoku-Oki M W 9.0 earthquake of March 11th, 2011, were retrieved by linear elastic finite element numerical simulation. On this basis, the static Coulomb failure stress variations of the main active faults and tectonic zones in North and Northeast China were calculated, and the triggering effect of the earthquake on seismicity in North and Northeast China was discussed. Results were as follows: (1) the co-seismic horizontal displacement field caused by the great earthquake was eastward in North China; the maximum value, which occurred in the Shandong Peninsula and north Jiangsu Province, was about 12 mm; and the values gradually decreased from east to west. The co-seismic horizontal displacement field in Northeast China was SE-SEE and the maximum value, which occurred in northeast Jilin Province, was about 30 mm. The simulated results for the co-seismic horizontal displacement field were in good agreement with GPS observational results. (2) The near-surface co-seismic maximum horizontal principal stress (ΔσHmax) was tensile stress ranging from 0 to 2.0 KPa. From Northeast China to North China, the direction gradually altered from NW to NWW to nearly EW to NEE. The co-seismic minimum horizontal principal stress (ΔσHmax) was compressive as well as tensile stress, with a magnitude of 0-0.75 KPa, which is approximately equal to zero. From Northeast China to North China, the direction gradually changed to NNW from NE to NNE to nearly NS. Although the co-seismic stress effect generated by the great earthquake had some effect on the present tectonic stress field of North and Northeast China, its influence was too slight to change the present framework of the regional tectonic stress field. (3) Coulomb failure stress variations on active fault zones in North and Northeast China mainly

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  11. Stress evolution and seismic hazard on the Maqin-Maqu segment of East Kunlun Fault zone from co-, post- and interseismic stress changes

    NASA Astrophysics Data System (ADS)

    Shan, Bin; Xiong, Xiong; Wang, Rongjiang; Zheng, Yong; Yadav, R. B. S.

    2015-01-01

    The East Kunlun Fault zone, striking E-W to WNW-ESE, has been recognized as one of the largest and most active left-lateral strike-slip faults in the China continent. Presently, the Maqin-Maqu segment (MMS) is recognized as a seismic gap on the East Kunlun Fault. Since several highly populated counties are close to this region, understanding stress transfer and accumulation along this segment is important for hazard assessment along the MMS. In this study, we calculated the stress evolution along the MMS of the East Kunlun Fault zone during 1879-2008 by integrating coseismic effects, viscoelastic relaxation and tectonic loading. It is observed that the stress accumulation on the western part of the Maqin segment has been effected by the 1937 Tuosuo Lake earthquake, the stress on the eastern part of the Maqin segment. Also, the western part of the Maqu segment was relaxed by the 1947 Dari earthquake, and the stress loading on the eastern part of Maqu segment was increased by both the 1879 Wudu and 2008 Wenchuan earthquakes. It is observed that, compared to coseismic static stress changes, the post-seismic viscoelastic relaxation process has played a more important role on stress accumulation in the Maqu segment. The increased stress on the Maqin and Maqu segment is consistent with tectonic loading over 160 and 250 yr, respectively, which we expect will lead to future earthquakes and associated seismic hazard on these segments.

  12. [Glucose metabolic changes in stress].

    PubMed

    Foia, L; Costuleanu, N; Trandafirescu, M; Saila, V; Pavel, M

    1999-01-01

    Provision of a better understanding of the pathogenic pathways underlying injured sugar metabolism during stress should ideally translate into a more rational approach to the provision of nutritional support. Patients with burns, trauma, severe injuries or infections commonly develop a hypermetabolic state that is associated with several changes in carbohydrate metabolism. The hypermetabolic state is induced either by the area of injury and by organs involved in the immunologic response to stress; further it determines a glycemic milieu which will be directed toward satisfaction of the requirements for glucose as an energy support. PMID:10756928

  13. The effects of three-dimensional heterogeneous Earth model of coseismic displacement changes of the Sumatra earthquake of 26 December 2004

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The 26 December 2004 Sumatra-Andaman earthquake with moment magnitude (Mw) of 9.1 to 9.3 is the first great earthquake recorded by digital broadband, high-dynamic-range seismometers and global positioning system (GPS) equipment, which recorded many high-quality geophysical data sets. The spherical curvature is not negligible in far field especially for large event and the real Earth is laterally inhomogeneity and the analytical results still are difficult to explain the geodetic measurements. We use equivalent body force finite elements method Zhang et al. (2015) and mesh the whole earth, to compute global co-seismic displacements using four fault slip models of the 2004 Sumatra earthquake provided by different authors. Comparisons of calculated co-seismic displacements and GPS show that the confidences are well in near field for four models, and the confidences are according to different models. In the whole four models, the Chlieh model (Chlieh et al., 2007) is the best as this slip model not only accord well with near field data but also far field data. And then we use the best slip model, Chlieh model to explore influence of three dimensional lateral earth structure on both layered spherically symmetric (PREM) and real 3-D heterogeneous earth model (Crust 1.0 model and GyPSuM). Results show that the effects of 3-D heterogeneous earth model are not negligible and decrease concomitantly with increasing distance from the epicenter. The relative effects of 3-D crust model are 23% and 40% for horizontal and vertical displacements, respectively. The effects of the 3-D mantle model are much smaller than that of 3-D crust model but with wider impacting area.

  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. Possible coseismic laminar and non-laminar flow along subduction megathrusts

    NASA Astrophysics Data System (ADS)

    Ujiie, K.; Noguchi, K.; Saito, T.; Tsutsumi, A.

    2014-12-01

    Coseismic deformation mechanisms during subduction earthquakes remained unclear other than frictional melting recorded in pseudotachylytes. However, the recent mineralogical studies in the shallow plate-boundary thrust in the Nankai subduction zone and the underplating-related duplex-fault zone in the Shimanto accretionary complex exhumed from 4-6 km depth have identified increased heating along the 2 mm-thick, clay-rich fault gouge and the few-centimeters-thick, basalt-derived ultracataclasite, respectively. The microstructures of the fault gouge are characterized by strong preferred orientation of clay particles along the gouge, while those of the ultracataclasite show the random fabric. High-velocity friction experiments were conducted on the disaggregated fault rocks under wet (water-saturated) conditions at different normal stresses, using the rotary shear frictional testing apparatus. The results show the rapid slip weakening with low peak and steady-state shear stress, and a very small slip weakening distance and fracture energy, suggesting the ease of earthquake rupture propagation through the fault materials. The steady-state shear stress is almost independent of normal stress, indicating that the gouge behaved like a fluid during high-velocity shearing. The microstructures after the experiments are marked by the development of foliated zone in the gouge layer, but the random fabric develops in the outermost region of the circular gouge layer. Given the nearly independence of steady-state shear stress on normal stress and the increase in the rotation velocity from the center of the rotation axis during the rotary shear, the change from foliated zone to non-foliated, random fabric in the circular gouge layer could represent the change from laminar to non-laminar (or turbulent) flow associated with the increase in the Reynolds number. The implications for the fault rocks are that the development of foliated and non-foliated zones may represent coseismic

  16. [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. PMID:16539968

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  18. Coseismic damage and softening of fault rocks at seismogenic depths

    NASA Astrophysics Data System (ADS)

    Griffith, W. Ashley; Mitchell, Thomas M.; Renner, Jörg; Di Toro, Giulio

    2012-11-01

    Elastic stiffness, a critical property for stress-orientation, propagation of earthquake ruptures and associated seismic waves, and the capability of crustal rocks to store strain energy, is expected to be highly variable throughout the seismic cycle due to complex sequences of damage and healing. Post-seismic healing and exhumation-related alteration render it impossible to assess how well rock stiffness as measured in the laboratory on samples collected from fault zones represents in situ, coseismic rock stiffness at seismogenic depths. Here we estimate the in situ, coseismic stiffness of fault rocks from the pseudotachylyte-bearing Gole Larghe Fault Zone (Italian Southern Alps), using aspect ratio measurements of pseudotachylyte injection veins and numerical simulations. Aspect ratios of injection veins cutting across tonalite and cataclasite exhibit a maximum vein aperture positively correlating with vein length. To model vein opening, fault and injection veins are assumed to be filled with pressurized melt. Consistent with recent results from studies of melt lubrication we assume that the magnitude of the melt pressure is in equilibrium with the fault-normal stress and the fault vein approximately maintains constant thickness during slip. The numerical simulations of injection vein opening due to pressurized frictional melt indicate that the average in situ coseismic stiffness of the wall rocks is 5-50 times smaller than the stiffness obtained from laboratory measurements on the same rocks in their present-day state. The disagreement between laboratory measurements and simulations brings into question the appropriateness of using laboratory-derived values for rock stiffness to model coseismic processes at depth.

  19. 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.

  20. Estimates of stress changes from the 2010 Maule, Chile earthquake: the influence on crustal faults and volcanos

    NASA Astrophysics Data System (ADS)

    Keiding, M.; Heidbach, O.; Moreno, M.; Baez, J. C.; Melnick, D.; Kukowski, N.

    2012-04-01

    The south-central Chile margin is an active plate boundary where the accumulated stress in the subduction interface is released frequently by megathrust earthquakes (Mw>8.5). The Maule earthquake of February 27 2010 affected about 500 km of the plate boundary producing spectacular tectonic deformation and a devastating tsunami. A compilation of pre-, co-, and post-earthquake geologic and geodetic data offers the opportunity of gain insight into the processes that control strain accumulation and stress changes associated to megathrust events. The fore-arc deformation is primarily controlled by the stresses that are transferred through the locked parts of the plate interface and the release of stresses during megathrust events. During a great interplate faulting event, upper plate faults, rooted in the plate interface, can play a key role in controlling fluid pressurization. Hence, the hydraulic behavior of splay faults may induce variations of shear strength and may promote dynamic slip weakening along a crustal fault. Furthermore, the co-seismic stress transfer from megathrust earthquakes can severely affect nearby volcanos promoting eruptions and local deformation. InSAR and time-series of continuous GPS in the aftermath of the Maule earthquake show evidences of activation of the NW-striking Lanalhue fault system as well as pressure increase at the Antuco volcano. We build a 3D geomechanical-numerical model that consists of 1.8 million finite elements and incorporates realistic geometries adapted from geophysical data sets as well as the major crustal faults in the region. An updated co-seismic slip model is obtained based on a joint inversion of InSAR and GPS data. The model is used to compute stress changes in the upper plate in order to investigate how the Maule earthquake may have affected the crustal faults and volcanoes in the region.

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

    USGS Publications Warehouse

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

    2008-01-01

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

  2. 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.

  3. 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.

  4. Co-seismic dilatational strain in the far field of great earthquakes

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Fu, Li-Yun; Wang, Chi-yuen; Yan, Rui; Zhao, Lian-feng

    2016-04-01

    The mechanism of the coseismic dilatational strain has been a topic of active debate. Recent studies show that the co-seismic change of dilatational strain in the far field of large earthquakes is often far greater than that predicted from static strain theory, but the underlying mechanism is not understood. Here we study this mechanism by comparing the tidal responses of crustal strain and water level documented in the Fuxin well, northeastern China, before and after three great earthquakes (the 2008 Mw 7.9 Wenchuan earthquake, the 2011 Mw 9.1 Tohoku earthquake and the 2012 Mw 8.6 Sumatra earthquake). We show that, before each earthquake, the phase of water-level fluctuation lagged behind that of the dilatational strain, due to the delay of groundwater flow to the well with respect to the tidal strain. Following each earthquake, however, the phase of water-level fluctuations increased and became the same as that of the dilatational strain. In addition, we show that the predicted change in water level from the co-seismic dilatational strain has the same sign, amplitude and time history as those of the observed coseismic change in water level. The similarity between the simulated and observed coseismic water-level change, together with the similarity in phase between the tidal response of water level and that of dilatational strain after the earthquake, suggest that the dominant mechanism for the coseismic dilatational strain in the Fuxin well is the co-seismic change in pore pressure in the vicinity of the well.

  5. 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.

  6. 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

  7. 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.

  8. Coseismic deformation induced by the Sumatra earthquake

    NASA Astrophysics Data System (ADS)

    Boschi, E.; Casarotti, E.; Devoti, R.; Melini, D.; Piersanti, A.; Pietrantonio, G.; Riguzzi, F.

    2006-08-01

    The giant Sumatra-Andaman earthquake of December 26, 2004 caused permanent deformations effects in a region of previously never observed extension. The GPS data from the worldwide network of permanent IGS sites show significant coseismic displacements in an area exceeding 10 7 km 2, reaching most of South-East Asia, besides Indonesia and India. We have analyzed long GPS time series histories in order to characterize the noise type of each site and, consequently, to precisely assess the formal errors of the coseismic offset estimates. The synthetic simulations of the coseismic displacement field obtained by means of a spherical model using different rupture histories indicate that a major part of the energy release took place in a fault plane similar to that obtained by Ammon et al. (2005) and Vigny et al. (2005) but with a larger amount of compressional slip on the northern segment of the fault area.

  9. 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.

  10. ST-segment changes with exercise stress

    PubMed Central

    Lim, Yoke Ching; Teo, Swee-Guan; Poh, Kian-Keong

    2016-01-01

    The treadmill electrocardiogram (ECG) stress test is widely used to screen for obstructive coronary artery disease (CAD). The presence of STsegment changes, either depression or elevation, on the ECG during the treadmill test often suggests presence of CAD and warrants further management. We herein present three cases, with evidence of ischaemia on the treadmill ECG stress test. In addition, we discuss the use of the treadmill ECG stress test, including its indications, contraindications, reasons for termination and interpretation of the ST-segment changes, heart rate, as well as blood pressure responses to exercise. PMID:27440279

  11. 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.

  12. Temporal stress changes associated with the 2008 May 29 MW 6 earthquake doublet in the western South Iceland Seismic Zone

    NASA Astrophysics Data System (ADS)

    Hensch, Martin; Lund, Björn; Árnadóttir, Thóra; Brandsdóttir, Bryndís

    2016-01-01

    On 2008 May 29, two magnitude MW ˜ 6 earthquakes occurred on two adjacent N-S faults in the western South Iceland Seismic Zone. The first main shock was followed approximately 3 s later by the rupture on a parallel fault, about 5 km to the west. An intense aftershock sequence was mostly confined to the western fault and an E-W aligned zone, extending west of the main shock region into the Reykjanes oblique rift. In this study, a total of 325 well-constrained focal mechanisms were obtained using data from the permanent Icelandic SIL seismic network and a temporary network promptly installed in the source region following the main shocks, which allowed a high-resolution stress inversion in short time intervals during the aftershock period. More than 800 additional focal mechanisms for the time period 2001-2009, obtained from the permanent SIL network, were analysed to study stress changes associated with the main shocks. Results reveal a coseismic counter-clockwise rotation of the maximum horizontal stress of 11 ± 10° (95 per cent confidence level) in the main rupture region. From previous fault models obtained by inversion of geodetic data, we estimate a stress drop of about half of the background shear stress on the western fault. With a stress drop of 8-10 MPa, the pre-event shear stress is estimated to 16-20 MPa. The apparent weakness of the western fault may be caused by fault properties, pore fluid pressure and the vicinity of the fault to the western rift zone, but may also be due to the dynamic stress increase on the western fault by the rupture on the eastern fault. Further, a coseismic change of the stress regime-from normal faulting to strike-slip faulting-was observed at the northern end of the western fault. This change could be caused by stress heterogeneities, but may also be due to a southward shift in the location of the aftershocks as compared to prior events.

  13. Estimation of Electro-Magnetic Signals Generated by Stress Changes before the Arrival of Seismic Waves

    NASA Astrophysics Data System (ADS)

    Yamazaki, K.

    2014-12-01

    This work aims to increase the efficiency of earthquake early warning (EEW) systems. Conventional EEW systems detect occurrence of earthquakes by means of detecting seismic P-waves; thus, they cannot make alert before P-waves reach the ground surface in principle. If we desires to break this limitation, we must observe other physical quantities including the electromagnetic (EM) and gravitational fields, variations of which propagate faster than elastic waves. The present study focuses on changes in the magnetic field generated by co-seismic stress changes in the Earth's crust. When magnetic minerals in the Earth's crust are subjected to mechanical forces, increments or decrements of magnetization appear. This is called the piezomagnetic effect. Significant changes in values of the geomagnetic field has frequently observed between before and after major earthquakes or volcanic ground deformation, which is considered to be generated by the piezomagnetic effect. The problem is, however, whether or not co-seismic changes in the stress field generates earlier signals, that is, changes in the magnetic field at observation sites which occur before arrival of seismic waves. To answer the question, a set of equations governing elastodynamics, electromagnetics, and the piezomagnetic effect, are solved for a whole space stuffed with a uniform physical properties. An impulsive double couple is assumed to represent the earthquake source mechanism. A set of solutions is derived in time-domain, and its features are investigated for several sets of parameters including electrical conductivity and seismic velocities. We can confirm that there are certain amount of changes in the EM field, even before arrival of seismic waves. EM signals before arrival of seismic waves (i.e. earlier EM signals) are relatively large in the case that the Earth's crust is conductive (> 0.01 S/m). However, the appearance of relatively large EM signal is not simultaneous to the rupture; instead, it is

  14. Fluid Dynamic Evidence for Extremely Low Viscosity Coseismic Fault Fluids

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Meneghini, F.; Rowe, C. D.; Moore, J. C.

    2007-12-01

    We combine geological observations of fault rock textures with fluid mechanics to constrain the mechanics of a fault zone during a subduction earthquake. We analyze buoyant intrusive features in a fault rock that formed at 12- 14 km depth in a large-scale thrust fault embedded in a paleo-accretionary prism in Kodiak Island, AK. The fault rock can been interpreted as either a pseudotachylyte or fluidized ultracataclasite. The intrusive structures provide new, direct evidence on the coseismic rheology of the fault. The asymmetric buoyant intrusions are most readily understood as Rayleigh-Taylor instabilities with an unusually short wavelengths relative to the thickness of the layer. The geometry requires a moderately high Reynolds number flow (Re~1-10) in order to produce the observed wavelength to thickness ratio. The resulting rise velocity under these conditions is ~40 cm/s. Since the shear strain in the layer is over order 1 and the deformation is continuous, the rise velocity must be comparable to the horizontal shear velocity during emplacement. Thus, the geometry alone requires that the fault rocks were intruded coseismically. Furthermore, the Reynolds number constraint combined with the computed rise velocity provides a maximum bound on the viscosity of the fluid during emplacement. The coseismic fault fluid at this locality must have had a viscosity of \\ll 10 Pa-s. This viscosity constraint is compatible with the viscosity of the silicate melt of the observed composition at 1300-1400°, which is consistent with the temperature constraints imposed by the absence of plagioclase survivor grains. In summary, both the fluid dynamical and geological evidence points to an extraordinarily low viscosity fluid in the fault zone during rupture and hence extremely low local stress in the fault during an earthquake.

  15. WHITE CLOVER MORPHOLOGY CHANGES WITH STRESS TREATMENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The plasticity of white clover (Trifolium repens L.) results in morphological changes in plant habit in response to different environmental stresses. This research characterized morphological changes in white clover clones derived either from two cultivars and a germplasm exposed to treatments in 2-...

  16. Coseismic thermal pressurization can prolong recurrence intervals of earthquake cycle

    NASA Astrophysics Data System (ADS)

    Mitsui, Y.; Hirahara, K.

    2008-12-01

    Earthquake is a short-lived event, while it needs a very long preparation period. The transition is rapid but seamless. We should correlate physics governing during the short-term earthquake period with that governing during the long-term preparation period. Brace and Byerlee [1966] proposed that stick-slip behavior is a mechanism for earthquakes from this standpoint. Following the proposition, lots of researchers have executed numerical simulations of a spring- slider system in order to interpret the earthquake cyclicity (e.g., Gu et al. [1991]). For such researches, it is necessary to use a constitutive law of friction on an interface between a slider and ground. By way of example, a rate- and state- dependent friction law (Dieterich [1979]) has been widely used, because it can represent frictional healing during the interseismic period. Despite the previous extensive studies, there is a dearth of information on roles of pore fluid. The pore fluid existence within a fault zone dramatically changes the frictional property via reduction of normal stress (Brace and Martin [1968]). Further, the pore fluid pressure may evolve and affect every aspect of earthquakes. Here, we try to add a new perspective to the earthquake cyclicity. It is an effect of short-term temporal change of the pore pressure, due to the coseismic thermal pressurization (hereinafter called TP). TP is a short-lived physical mechanism that frictional heating at a fluid-saturated fault pressurizes the pore fluid within the fault zone (Sibson [1973]). It can greatly affect the fault constitutive relation (Andrews [2002]) and the dynamic propagation of the earthquake rupture (Bizzarri and Cocco [2006]). In this presentation, we show that the short-lived TP is again a significant mechanism for the earthquake cyclicity, using the spring-slider system with the rate- and state- dependent law in a 1-D elastic body. If the shear zone thickness is smaller than several decimeters, TP can greatly prolong the

  17. 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

  18. 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.

  19. Environmental Change, the Stress Response, and Neurogenesis.

    PubMed

    LaDage, Lara D

    2015-09-01

    Previous to the 1980's, the prevailing neuroscience dogma held that no new neurons were produced in the brains of adult mammals. Now, we understand that the production of new neurons, or neurogenesis, is a common and plastic process in the adult brain. To date, however, researchers have not come to a unified understanding of the functional significance of neurogenesis. Several factors have been shown to modulate hippocampal neurogenesis including spatial learning, stress, and aspects of environmental change, but questions still remain. How do these modulating factors overlap? Which aspects of environmental change induce a stress response? Is there a relationship between hippocampal neurogenesis, the stress response, and environmental change? Can this relationship be altered when taking into consideration other factors such as perception and predictability of the environment? Finally, do results from neurobiological research on laboratory rodents translate to wild systems? This review attempts to address these questions and synthesize research from the fields of ecology, psychology, and behavioral neuroscience. PMID:25980567

  20. 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.

  1. 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.

  2. Replication Stress: A Lifetime of Epigenetic Change

    PubMed Central

    Khurana, Simran; Oberdoerffer, Philipp

    2015-01-01

    DNA replication is essential for cell division. Challenges to the progression of DNA polymerase can result in replication stress, promoting the stalling and ultimately collapse of replication forks. The latter involves the formation of DNA double-strand breaks (DSBs) and has been linked to both genome instability and irreversible cell cycle arrest (senescence). Recent technological advances have elucidated many of the factors that contribute to the sensing and repair of stalled or broken replication forks. In addition to bona fide repair factors, these efforts highlight a range of chromatin-associated changes at and near sites of replication stress, suggesting defects in epigenome maintenance as a potential outcome of aberrant DNA replication. Here, we will summarize recent insight into replication stress-induced chromatin-reorganization and will speculate on possible adverse effects for gene expression, nuclear integrity and, ultimately, cell function. PMID:26378584

  3. Diatoms confirm coseismic uplift and subsidence along the eastern Alaska-Aleutian megathrust

    NASA Astrophysics Data System (ADS)

    Dura, T.; Briggs, R. W.; Engelhart, S. E.; Nelson, A. R.; Horton, B.

    2013-12-01

    The Alaska-Aleutian subduction zone is the source of a series of Mw 8-9.2 20th century ruptures, including the second largest historical earthquake ever recorded in 1964. Paleoseismic studies, employing coastal stratigraphic sequences, have been successfully applied at sites within the 1964 rupture zone, but geologic records are unstudied west of the 1964 rupture. Understanding the behavior of the megathrust is important because a tsunamigenic rupture could damage the west coast of the United States. Investigations in the tidal marshes of Sitkinak Island, off the southwest coast of Kodiak Island, have uncovered stratigraphic evidence of five apparent coseismic land-level changes. Radiocarbon, 210Pb, and 137Cs dating indicate this record may include the 1964 and 1788 earthquakes and some predecessors. Here, we present new paleoecological evidence that independently confirms the inference that at least four of the abrupt lithologic changes in the stratigraphy of Sitkinak Island record coseismic land-level changes. Sudden and lasting changes in fossil diatom assemblages spanning tidal lithologic contacts reveal both coseismic subsidence (mud over peat) and coseismic uplift (peat over mud) during the last 1000 years. Across the contact that may mark the 1964 earthquake, a shift from a brackish, low-marsh diatom assemblage dominated by Diploneis interrupta and Navicula cincta to a tidal flat assemblage containing Actinocyclus normanii and Synedra tabulata indicates a sudden rise in relative sea-level, which we infer to record coseismic subsidence. In contrast, diatoms show evidence of coseismic uplift across the probable 1788 contact. An abrupt transition from a fully marine assemblage containing coastal planktonic and tychoplanktonic taxa to a freshwater marsh assemblage dominated by the salt-intolerant benthic diatom Eunotia fallax is consistent with a sudden and lasting relative sea-level fall. Abrupt changes in lithology across a contact dated about ~575 cal yr

  4. 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.

  5. Oxidative stress in haemodialysis--intradialytic changes.

    PubMed

    Srinivasa Rao, P V; Dakshinamurty, K V; Saibaba, K S; Raghavan, M S; Vijayabhaskar, M; Sreekrishna, V; Ambekar, J G; Jayaseelan, L

    2001-01-01

    Oxidative stress is likely to be involved in the development of complications due to haemodialysis. Though there is evidence for production of oxygen free radicals during haemodialysis, reports on net oxidative imbalance due to a single dialysis session are conflicting. Hence, a time-course analysis of changes in lipid peroxides (LPO) along with antioxidant enzymes and vitamins was carried out. Hourly changes in LPO and antioxidants were studied during a first-use cuprophan membrane and acetate dialysis in 20 patients on regular haemodialysis treatment. Data were corrected for haemoconcentration and standardised to measure the rate of change before statistical evaluation using analysis of variance for repeated measures. The results of the study showed a net oxidative stress due to a single dialysis session in the form of increased plasma and erythrocyte lipid peroxidation, decrease in plasma vitamin E, slight increase in plasma superoxide dismutase and erythrocyte glutathione peroxidase and no change in plasma glutathione peroxidase. erythrocyte superoxide dismutase and plasma vitamin A levels. The oxygen radical production was found to be maximum in the first hour of dialysis. PMID:11778848

  6. Changes of mental stress biomarkers in ultramarathon.

    PubMed

    Agawa, H; Yamada, N; Enomoto, Y; Suzuki, H; Hosono, A; Arakawa, K; Ghadimi, R; Miyata, M; Maeda, K; Shibata, K; Tokudome, M; Goto, C; Tokudome, Y; Hoshino, H; Imaeda, N; Marumoto, M; Suzuki, S; Kobayashi, M; Tokudome, S

    2008-11-01

    We investigated the possible influence of an exhaustive physical exercise on mental stress biomarkers (serotonin, tryptophan, and beta-endorphin) along with dopamine, noradrenaline and free fatty acids in an ultramarathon race in which 45 km was run on the first day and 90 km on the second. We obtained serum samples at 6 different time points during and after the race from 18 Japanese male runners who completed the marathon. Overall changes of serum serotonin and tryptophan concentrations were statistically significant according to ANOVA for repeated measurements (p < 0.05). Serum serotonin levels elevated rapidly on the first day with the post hoc Tukey's test. Tryptophan concentrations inversely decreased during the race, possibly because of utilization for synthesis of serotonin. Levels of beta-endorphin appeared to increase on the first and second days, but were not statistically significant. In conclusion, serum serotonin, tryptophan and beta-endorphin appeared to be used for mental stress markers in physical exercise. PMID:18418810

  7. Coseismic and aseismic deformations of the rock mass around deep level mining in South Africa - Joint South African and Japanese study

    NASA Astrophysics Data System (ADS)

    Milev, A. M.; Yabe, Y.; Naoi, M. M.; Nakatani, M.; Durrheim, R. J.; Ogasawara, H.; Scholz, C. H.

    2010-12-01

    Two underground sites in a deep level gold mine in South Africa were instrumented by the Council for Scientific and Industrial Research (CSIR) with tilt meters and seismic monitors. One of the sites was also instrumented by JApanese-German Underground Acoustic emission Research in South Africa (JAGUARS) with a small network, approx. 40 m span, of eight Acoustic Emission (AE) sensors. The rate of tilt, defined as quasi-static deformations, and the seismic ground motion, defined as dynamic deformations, were analysed in order to understand the rock mass behavior around deep level mining. In addition the high frequency AE events recorded at hypocentral distances of about 50m were analysed. This was the first implementation of high frequency AE events at such a great depth (3300m below the surface). A good correspondence between the dynamic and quasi-static deformations was found. The rate of coseismic and aseismic tilt, as well as seismicity recorded by the mine seismic network, are approximately constant until the daily blasting time, which takes place from about 19:30 until shortly before 21:00. During the blasting time and the subsequent seismic events the coseismic and aseismic tilt shows a rapid increase indicated by a rapid change of the tilt during the seismic event. Much of the quasi-static deformation, however, occurs independently of the seismic events and was described as ‘slow’ or aseismic events. During the monitoring period a seismic event with MW 1.9 (2.1) occurred in the vicinity of the instrumented site. This event was recorded by both the CSIR integrated monitoring system and JAGUARS acoustic emotion network. The tilt changes associated with this event showed a well pronounced after-tilt. More than 21,000 AE aftershocks were located in the first 150 hours after the main event. Using the distribution of the AE events the position of the fault in the source area was successfully delineated. The distribution of the AE events following the main shock

  8. 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

  9. Coseismic and postseismic slip models of the 2011 Van earthquake, Turkey, from InSAR, offset-tracking, MAI, and GPS observations

    NASA Astrophysics Data System (ADS)

    Wang, Chisheng; Ding, Xiaoli; Li, Qingquan; Shan, Xinjian; Zhu, Wu; Guo, Bo; Liu, Peng

    2015-11-01

    We derived the coseismic and postseismic slip models of the 2011 Van earthquake from multi-source geodetic datasets, including interferometric synthetic aperture radar (InSAR), multi-aperture InSAR (MAI), offset-tracking, and GPS measurements. The constrained least squares algorithm and Laplacian smoothing were used to estimate and regularize the slip distribution. The coseismic slip model suggested two nearly W-E striking segment faults breaking during the Van event. Two main slip concentrations were found to to be located at depths ranging from 7 km to 20 km. The estimated moment reached 6.08 × 1019 Nm (equal to an Mw 7.19 event). A stress change analysis showed that the main shock imposed an up to ∼5 bars stress load on the causative fault of the 9 November aftershock, implying a triggering mechanism between the two events. The postseismic slips of the Van earthquake were dominated by shallow left-lateral and deep thrust components. The slips distributed in most of the unruptured area of the fault plane. The accumulated postseismic moment reached 2.04 × 1019 Nm, which was about 34% of the main shock moment. We conclude that the future seismic hazard will be relatively low in this area.

  10. 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.

  11. Field evidence for a hybrid interfacial-coseismic seismoelectric effect

    NASA Astrophysics Data System (ADS)

    Butler, K. E.; Kulessa, B.; Pugin, A.

    2014-12-01

    In May, 2011, we carried out a field experiment in Leda Clay sediments near Ottawa, Canada to investigate whether seismoelectric conversions might be observed along with the clear P, S and PS converted waves regularly observed during near-surface seismic reflection surveys in that environment. Although high electrical conductivities (~10 Ωm below 6 m depth) were expected to result in weak electrical fields, we were encouraged by the availability of an IVI Minivib 1 vibroseis source, and by the presence of interfacial targets including the top of bedrock at ~23 m depth as well as porosity and textural changes within the overburden revealed by geotechnical logs. Seismic and seismoelectric shot records were acquired separately using both the MiniVib and an in-hole shotgun source. The recording system included 26 grounded dipoles, 4.5 m in length, all equipped with custom-made differential amplifiers. Harmonic subtraction, remote reference subtraction, and stacking of shot records were used to combat electrical noise levels associated with unstable powerline harmonics and apparent AM radio demodulation. Seismic and seismoelectric shot records bear a striking resemblance to each other; direct and refracted P-waves as well as P, S, and PS wave reflections all appear clearly in the seismoelectric records. At first glance, these would appear to be simply co-seismic seismoelectric effects. However, closer inspection reveals that some precede their corresponding seismic arrivals by several milliseconds, and exhibit broader bandwidths (up to 600 Hz) and better coherency. They are inferred to have been generated beneath each dipole receiver by upward travelling P and S-waves arriving at an interface, defined by contrasts in porosity and clay content, 7 m below the surface. These arrivals do not conform to either true co-seismic or true interfacial effects and therefore present a new challenge to our understanding of seismoelectric phenomena.

  12. 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.

  13. Modeling of Kashmir Aftershock Decay Based on Static Coulomb Stress Changes and Laboratory-Derived Rate-and-State Dependent Friction Law

    NASA Astrophysics Data System (ADS)

    Javed, F.; Hainzl, S.; Aoudia, A.; Qaisar, M.

    2016-05-01

    We model the spatial and temporal evolution of October 8, 2005 Kashmir earthquake's aftershock activity using the rate-and-state dependent friction model incorporating uncertainties in computed coseismic stress perturbations. We estimated the best possible value for frictional resistance " Aσ n", background seismicity rate " r" and coefficient of stress variation "CV" using maximum log-likelihood method. For the whole Kashmir earthquake sequence, we measure a frictional resistance Aσ n ~ 0.0185 MPa, r ~ 20 M3.7+ events/year and CV = 0.94 ± 0.01. The spatial and temporal forecasted seismicity rate of modeled aftershocks fits well with the spatial and temporal distribution of observed aftershocks that occurred in the regions with positive static stress changes as well as in the apparent stress shadow region. To quantify the effect of secondary aftershock triggering, we have re-run the estimations for 100 stochastically declustered catalogs showing that the effect of aftershock-induced secondary stress changes is obviously minor compared to the overall uncertainties, and that the stress variability related to uncertain slip model inversions and receiver mechanisms remains the major factor to provide a reasonable data fit.

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

    PubMed

    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

  15. 300-km-long co-seismic surface rupture produced by the 2008 Mw 7.9 Wenchuan earthquake along the active Longmen Shan Thrust Belt, China

    NASA Astrophysics Data System (ADS)

    Lin, A.; Rao, G.; Yan, B.

    2012-12-01

    evidence that the Qingchuan Fault was ruptured by the 2008 Wenchuan earthquake and that the total length of the co-seismic surface rupture zone is up to 285-300 km. Field investigations reveal that the earthquake produced a ≥60-km-long surface rupture zone along the pre-existing Qingchuan Fault, northeastern segment of the LSTB, with the offset being mainly right-lateral strike-slip and a distinct component of vertical slip. Co-seismic surface ruptures are characterized by faults and extensional cracks. Field measurements indicate co-seismic right-lateral strike-slip displacements along the Qingchuan Fault of 0.3-0.6 m and vertical offsets of 0.2-0.5 m, which differs to the displacements observed along the central and southwestern segments of the Wenchuan surface rupture zone in the displacement amount and sense. The change in slip sense from thrust-dominated slip in the central and southwestern segments of the LSTB to right-lateral strike-slip-dominated displacement along the Qingchuan Fault reflects a change in the orientation of compressive stress along the LSTB, associated with eastward extrusion of the Tibetan Plateau as it accommodates the ongoing penetration of the Indian Plate into the Eurasian Plate.

  16. 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

    2016-01-01

    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

  17. 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

  18. 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.

  19. The analysis of observed coseismic deformation and dynamic triggering of Ms 8.0 Wenchuan Earthquake

    NASA Astrophysics Data System (ADS)

    Xiaofan, L.

    2012-04-01

    The cosiesmic deformation of Ms 8.0 Wenchuan Earthquake was observed almost all over China. There are 84 sets of strain instruments in the whole country, and 61 sets of them had obvious coseismic steps. Meanwhile, 757 tilt items of 945 tilt data was observed coseismic changes, among which 179 of them did not have data on May 12, 2008. Because of the difference of selected cell value, the observation step changes can't be used for comparative study. Considering the stability of tidal data, we normalized the strain and tilt data before and after the earthquake and the result showed that the step changes had a good consistency with the epicentral distance. We also analysis the step directions of the coseismic step, the distribution of the directions had a good correlation with the earthquake mechanism. By using the method of high-pass filter, we analyzed the seismic wave of the broadband stations of the whole country, especially the volcanic areas. Some small earthquakes could be picked up after the Ms 8.0 Wenchuan Earthquake.

  20. Strain localization driven by co-seismic pore fluid pressurization

    NASA Astrophysics Data System (ADS)

    Rice, James; Platt, John; Brantut, Nicolas; Rudnicki, John

    2015-04-01

    The absence of a thermal anomaly associated with the San Andreas fault, and low driving stress resolved on it, suggest that such mature faults weaken dramatically during seismic slip. Thermal pressurization (TP) and thermal decomposition (TD) are two mechanisms to explain this co-seismic weakening. Both rely on elevated pore pressures in a fluid-saturated gouge, with TP achieving this through thermal expansion of native pore fluid and TD by releasing additional pore fluid (e.g., H2O or CO2) during a reaction. We use a one-dimensional model for a fluid-saturated gouge layer sheared between two undeforming half-spaces to study how TP (Rice et al., Platt et al., JGR-B, 2014) and TD (Platt et al., submitted JGR-B) drive seismic strain localization. A linear stability analysis is first used to predict the localized zone thickness for each of the weakening mechanisms. Using representative parameters for fault gouge we predict localized zone thicknesses of a few tens of microns, in line with laboratory (Kitajima et al., 2010) and field (Chester and Chester, 1998) observations. Next we use numerical simulations to study how the localized zone develops once nonlinear effects become important. These show that the final localized zone thickness is very similar to the linear stability prediction. In the simulations, the onset of localization accelerates fault weakening, making co-seismic strain localization an important consideration, apparently neglected in all current earthquake simulations. Finally we show how a secondary instability can lead to migration of the deforming zone across the gouge layer. This instability is driven by hydrothermal diffusion for TP, and by reactant depletion for TD. Our results show that migration must be taken into account when inferring the width of the deforming zone from field observations. Even when the zone of localized straining is only a few tens of microns wide, migration can lead to a final strain profile with a zone of roughly uniform

  1. Strain localization driven by co-seismic pore fluid pressurization

    NASA Astrophysics Data System (ADS)

    Platt, J. D.; Brantut, N.; Rice, J. R.; Rudnicki, J. W.

    2014-12-01

    The absence of a thermal anomaly associated with the San Andreas fault, and low driving stress resolved on it, suggest that such mature faults weaken dramatically during seismic slip. Thermal pressurization (TP) and thermal decomposition (TD) are two mechanisms to explain this co-seismic weakening. Both rely on elevated pore pressures in a fluid-saturated gouge, with TP achieving this through thermal expansion of native pore fluid and TD by releasing additional pore fluid (e.g., H2O or CO2) during a reaction. We use a one-dimensional model for a fluid-saturated gouge layer sheared between two undeforming half-spaces to study how TP (Rice et al., Platt et al., JGR-B, 2014) and TD (Platt et al., submitted JGR-B) drive seismic strain localization. A linear stability analysis is first used to predict the localized zone thickness for each of the weakening mechanisms. Using representative parameters for fault gouge we predict localized zone thicknesses of a few tens of microns, in line with laboratory (Kitajima et al., 2010) and field (Chester and Chester, 1998) observations. Next we use numerical simulations to study how the localized zone develops once nonlinear effects become important. These show that the final localized zone thickness is very similar to the linear stability prediction. In the simulations, the onset of localization accelerates fault weakening, making co-seismic strain localization an important consideration, apparently neglected in all current earthquake simulations. Finally we show how a secondary instability can lead to migration of the deforming zone across the gouge layer. This instability is driven by hydrothermal diffusion for TP, and by reactant depletion for TD. Our results show that migration must be taken into account when inferring the width of the deforming zone from field observations. Even when the zone of localized straining is only a few tens of microns wide, migration can lead to a final strain profile with a zone of roughly uniform

  2. 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)

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

    NASA Astrophysics Data System (ADS)

    Eddo, J.; Olsen, K.

    2007-12-01

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

  4. 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.

  5. Stress reduction correlates with structural changes in the amygdala

    PubMed Central

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

    2010-01-01

    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. PMID:19776221

  6. 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. PMID:26042538

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  8. 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

  9. 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.

  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. PMID:22605683

  11. Divorce Matters: Coping with Stress and Change

    MedlinePlus

    ... familiar with your sources of stress and your style of coping. Take time to think about ways ... Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) ...

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  13. 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.

  14. 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

  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. 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. PMID:24171155

  17. Coseismic Strengthening of the Shallow Portion of the Subduction Fault and Effects on Frontal Prism Taper

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Wang, K.; He, J.

    2007-12-01

    Ample evidence suggests that the shallowest segment of subduction interface, down to a few km depth and updip of the megathrust seismogenic zone, exhibits a velocity-strengthening (aseismic) behavior. According to the dynamic Coulomb wedge model, it is mainly this coseismic strengthening that is responsible for the growth and permanent deformation of the overlying frontal prism (Wang and Hu, 2006). However, the degree of the strengthening as controlled by earthquake size and the location of the seismogenic zone has not been investigated. In this work, we use numerical models to study how the stress is coseismically transferred from the velocity-weakening seismogenic zone to the velocity-strengthening shallow segment. The model is a hybrid of the frictional contact model and the classic crack model. An earthquake is simulated using a decrease in the effective friction coefficient μ' (i.e., weakening) along the seismogenic zone, producing a few MPa stress drop. The simultaneous strengthening of the aseismic updip and downdip segments is simulated using an increase in their μ'. Only the net effect of the coseismic weakening/strengthening is modeled in this work; the dynamic evolution of the friction and post-seismic stress relaxation are not included. We demonstrate how the slip distribution along the subduction fault is controlled by the degree of coseismic strengthening of the updip segment. The minimum level of strengthening required to prevent the rupture from breaking the trench depends on the force drop along the seismogenic zone, defined as the product of the average shear stress drop along the seismogenic zone and its area. For a fault geometry similar to that of Nankai Trough with about 3 MPa stress drop along a seismogenic zone of 120 km downdip width, an increase of μ' by 0.055 along the 30 km wide updip segment will render the segment on the verge of breaking the trench. This level of stress increase may readily push the outer wedge into a critical

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  19. Stress causes tissue-specific changes in the sialyltransferase activity.

    PubMed

    Dabelic, Sanja; Flögel, Mirna; Maravić, Gordana; Lauc, Gordan

    2004-01-01

    Numerous pathological conditions are associated with specific changes in glycosylation. Recent studies clearly demonstrated a link between stress and the development and course of many diseases. Biochemical mechanisms that link stress and diseases are still not fully understood, but there are some indications that changes in glycosylation are involved in this process. Influence of acute and chronic psychological stress on protein sialylation as well as the activity of sialyltransferases, enzymes that synthesize sialoglycoproteins, has been studied on Fischer rats. Liver, spleen, kidney, skeletal muscle, heart, adrenal gland, serum, cerebellum, hippocampus, medulla oblongata and cortex have been analyzed. Statistically significant tissue- and type of stress-specific changes in total sialyltransferase (ST) activity were observed. Acute stress resulted in 39% increase of ST activity in liver and spleen, while at the same time there was 43% decrease in ST activity in cerebellum. In chronic stress, ST activity increased in spleen (93%) and decreased in liver (17%), cerebellum (38%) and hippocampus (64%). Western-blot analysis using Maackia amurensis and Sambucus nigra lectins did not reveal any difference in protein sialylation. The results of serum corticosterone analysis indicate that showed increase in acute stress and decrease in chronic stress are in good accordance with the hypothesis that corticosterone has a role in the regulation of liver ST activity. PMID:15241940

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

    PubMed

    Spector, June T; Sheffield, Perry E

    2014-10-01

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

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

    PubMed Central

    Spector, June T.; Sheffield, Perry E.

    2014-01-01

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

  2. Monitoring Stress Changes in a Concrete Bridge with Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Stähler, S.; Sens-Schönfelder, C.; Niederleithinger, E.; Pirskawetz, S.

    2009-12-01

    The sensitivity of coda waves for material changes has been demonstrated in various environments ranging form laboratory scale to regional seismology. Here we present a test for monitoring stress induced velocity variations in a concrete construction. The construction is a bridge made of reinforced concrete in Germany that is build in incremental launching method (Taktschiebe-Mode). This means that construction takes place at one end of the bridge from which the bridge is successively pushed over the pillars as the constructions continues. During the movement of the construction over the pillars the stress in the girder and the deck slab undergoes changes between 0 and 14 MPa in horizontal direction. We used seismic equipment to induce elastic waves in the deck slab of the bridge at different position of the array relative to the supporting pillars. Comparing reverberating waves in slab recorded at different stress states we can infer changes in the propagation velocity. The observed velocity change is compared to modeled stress variations in the slab. Comparison is difficult due to imprecise positioning of the array and the spatially periodic stress variations. But we can show that the observed velocity variation is in agreement with the predictions from the stress model. Samples of the concrete used in the bridge are tested under different loads in the laboratory to infer the stress-velocity relation. The experiments show that the acousto-elastic effect in the specific concrete can account for the observed velocity variations.

  3. 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.

  4. 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.

  5. 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.

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

    ERIC Educational Resources Information Center

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

    2008-01-01

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

  7. 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

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

    PubMed

    Amat, Marta; Camps, Tomàs; Manteca, Xavier

    2016-08-01

    Domestic cats are exposed to a variety of stressful stimuli, which may have a negative effect on the cats' welfare and trigger a number of behavioural changes. Some of the stressors most commonly encountered by cats include changes in environment, inter-cat conflict, a poor human-cat relationship and the cat's inability to perform highly motivated behaviour patterns. Stress is very likely to reduce feed intake, and stress-related anorexia may contribute to the development of potentially serious medical conditions. Stress also increases the risk of cats showing urine marking and some forms of aggression, including redirected aggression. A number of compulsive disorders such as over-grooming may also develop as a consequence of stressful environments. Some of the main strategies to prevent or reduce stress-related behavioural problems in cats are environmental enrichment, appropriate management techniques to introduce unfamiliar cats to each other and the use of the synthetic analogue of the feline facial pheromone. As the stress response in cats depends, to a large extent, on the temperament of the animal, breeding and husbandry strategies that contribute to the cat developing a well-balanced temperament are also very useful. PMID:26101238

  9. 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.

  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

    2016-01-01

    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

  12. Coulomb stress change on surrounding faults by the January 12, 2010, Haiti earthquake

    NASA Astrophysics Data System (ADS)

    Symithe, S. J.; Calais, E.; Freed, A. M.; Haase, J. S.

    2011-12-01

    The M7 January 12, 2010, Haiti earthquake occurred on the previously unmapped Léogâne Fault, a transpressional fault located very close to the Enriquillo Plantain Garden Fault (EPGF), the major fault system and primary seismic hazard in southern Haiti. How the rupture of the Léogâne fault influenced stresses on the Enriquillo Fault - especially toward Port-au-Prince - as well as on other regional faults is critical to understanding how seismic hazard in this heavily populated region has been altered as a result of the devastating 2010 earthquake. We calculated Coulomb Failure Stress (CFS) changes in the region surrounding the M7 January 12, 2010, Haiti earthquake using dislocation theory, assuming elastic properties for the region. We considered two possible slip models, the simple single-fault slip model proposed by Calais et al. (2010) and the more complex model by Hayes et al. (2010), which involves three subfaults. We resolve CFS changes on the Léogâne rupture plane itself, as well as on regional faults such as the Enriquillo, Neiba-Matheux, and Trois Baies faults. We find that the aftershock distribution is well explained by CFS changes caused by the coseismic rupture, in particular the cluster of reverse faulting events to the west of the rupture, offshore, coincident with the Trois Baies fault. This fault therefore appears to have been triggered by the January 2010 event. The aftershock distribution in the rupture area clearly outlines the Léogâne fault (see Douilly et al., this meeting) but shows no clear evidence of activity on the other subfaults suggested by Hayes et al. (2010). Both slip models imply a ~1 bar increase of CFS bar on the Enriquillo fault to the west and east of the January 2010 rupture. For the Calais et al. (2010) model, CFS changes are higher to the east if the Enriquillo Fault is modeled with a dip of 65° and a rake 20°, as suggested by some geological observations, compared to a purely strike-slip vertical fault, as often

  13. Global perceived stress predicts cognitive change among older adults.

    PubMed

    Munoz, Elizabeth; Sliwinski, Martin J; Scott, Stacey B; Hofer, Scott

    2015-09-01

    Research on stress and cognitive aging has primarily focused on examining the effects of biological and psychosocial indicators of stress, with little attention provided to examining the association between perceived stress and cognitive aging. We examined the longitudinal association between global perceived stress (GPS) and cognitive change among 116 older adults (M(age) = 80, SD = 6.40, range = 67-96) in a repeated measurement burst design. Bursts of 6 daily cognitive assessments were repeated every 6 months over a 2-year period, with self-reported GPS assessed at the start of every burst. Using a double-exponential learning model, 2 parameters were estimated: (a) asymptotic level (peak performance), and (b) asymptotic change (the rate at which peak performance changed across bursts). We hypothesized that greater GPS would predict slowed performance in tasks of attention, working memory, and speed of processing and that increases in GPS across time would predict cognitive slowing. Results from latent growth curve analyses were consistent with our first hypothesis and indicated that level of GPS predicted cognitive slowing across time. Changes in GPS did not predict cognitive slowing. This study extends previous findings by demonstrating a prospective association between level of GPS and cognitive slowing across a 2-year period, highlighting the role of psychological stress as a risk factor for poor cognitive function. PMID:26121285

  14. Coseismic vertical deformation during the great 2007 Solomon Islands megathrust rupture

    NASA Astrophysics Data System (ADS)

    Briggs, R.; Taylor, F. W.; Frohlich, C.; Papabatu, A. K.; Billy, D.; Brown, A.; Meltzner, A. J.

    2007-12-01

    A joint US-Solomon Islands team visited the epicentral area of the 1 April 2007 Mw 8.1 Solomon Islands earthquake a few weeks after the event. We used coral microatolls, satellite imagery, and displaced geomorphic and cultural features to map the coseismic deformation pattern in the region directly above and adjacent to the subduction megathrust rupture. Among our main findings is that most slip occurred on the shallow portion of the megathrust and that slip appears to have reached the deformation front at Ranongga island, which was uplifted as much as ~2.5 m when the rupture propagated across the subducting Simbo ridge transform. Simbo island, which sits on the downgoing Australian plate and lies only 8 km across the plate boundary from uplifted Ranongga, subsided ~0.7 m coseismically and experienced only subdued ground motions. The line of zero vertical displacement (hingeline) runs closely along the southwestern coasts of Vella Lavella, Ghizo, and Parara islands, implying a persistent structural relationship between the downdip limit of coseismic slip and these coastlines. A broad, asymmetrical subsidence trough as deep as ~0.7 m extends across Vella Lavella, Kolombangara, Parara, and New Georgia. Uplift of ~0.35 m on the westermost tip of Rendova, along with overall subsidence of Rendova and Tetepare, place a firm limit on the southeastern extent of rupture. Uplift of Mono and subsidence of Fauro and the Shortlands, and no resolvable vertical change on Bougainville, define a rupture length of nearly 250 km between Rendova and the Woodlark rise.

  15. Oxidative stress involving changes in Nrf2 and ER stress in early stages of Alzheimer's disease.

    PubMed

    Mota, Sandra I; Costa, Rui O; Ferreira, Ildete L; Santana, Isabel; Caldeira, Gladys L; Padovano, Carmela; Fonseca, Ana C; Baldeiras, Inês; Cunha, Catarina; Letra, Liliana; Oliveira, Catarina R; Pereira, Cláudia M F; Rego, Ana Cristina

    2015-07-01

    Oxidative stress and endoplasmic reticulum (ER) stress have been associated with Alzheimer's disease (AD) progression. In this study we analyzed whether oxidative stress involving changes in Nrf2 and ER stress may constitute early events in AD pathogenesis by using human peripheral blood cells and an AD transgenic mouse model at different disease stages. Increased oxidative stress and increased phosphorylated Nrf2 (p(Ser40)Nrf2) were observed in human peripheral blood mononuclear cells (PBMCs) isolated from individuals with mild cognitive impairment (MCI). Moreover, we observed impaired ER Ca2+ homeostasis and increased ER stress markers in PBMCs from MCI individuals and mild AD patients. Evidence of early oxidative stress defense mechanisms in AD was substantiated by increased p(Ser40)Nrf2 in 3month-old 3xTg-AD male mice PBMCs, and also with increased nuclear Nrf2 levels in brain cortex. However, SOD1 protein levels were decreased in human MCI PBMCs and in 3xTg-AD mice brain cortex; the latter further correlated with reduced SOD1 mRNA levels. Increased ER stress was also detected in the brain cortex of young female and old male 3xTg-AD mice. We demonstrate oxidative stress and early Nrf2 activation in AD human and mouse models, which fails to regulate some of its targets, leading to repressed expression of antioxidant defenses (e.g., SOD-1), and extending to ER stress. Results suggest markers of prodromal AD linked to oxidative stress associated with Nrf2 activation and ER stress that may be followed in human peripheral blood mononuclear cells. PMID:25857617

  16. Stress-induced core temperature changes in pigeons (Columba livia).

    PubMed

    Bittencourt, Myla de Aguiar; Melleu, Fernando Falkenburger; Marino-Neto, José

    2015-02-01

    Changes in body temperature are significant physiological consequences of stressful stimuli in mammals and birds. Pigeons (Columba livia) prosper in (potentially) stressful urban environments and are common subjects in neurobehavioral studies; however, the thermal responses to stress stimuli by pigeons are poorly known. Here, we describe acute changes in the telemetrically recorded celomatic (core) temperature (Tc) in pigeons given a variety of potentially stressful stimuli, including transfer to a novel cage (ExC) leading to visual isolation from conspecifics, the presence of the experimenter (ExpR), gentle handling (H), sham intracelomatic injections (SI), and the induction of the tonic immobility (TI) response. Transfer to the ExC cage provoked short-lived hyperthermia (10-20 min) followed by a long-lasting and substantial decrease in Tc, which returned to baseline levels 2 h after the start of the test. After a 2-hour stay in the ExC, the other potentially stressful stimuli evoked only weak, marginally significant hyperthermic (ExpR, IT) or hypothermic (SI) responses. Stimuli delivered 26 h after transfer to the ExC induced definite and intense increases in Tc (ExpR, H) or hypothermic responses (SI). These Tc changes appear to be unrelated to modifications in general activity (as measured via telemetrically recorded actimetric data). Repeated testing failed to affect the hypothermic responses to the transference to the ExC, even after nine trials and at 1- or 8-day intervals, suggesting that the social (visual) isolation from conspecifics may be a strong and poorly controllable stimulus in this species. The present data indicated that stress-induced changes in Tc may be a consistent and reliable physiological parameter of stress but that they may also show stressor type-, direction- and species-specific attributes. PMID:25479572

  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. 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

  19. Stress

    MedlinePlus

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

  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 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.

  1. 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.

  2. 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.

  3. 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.

  4. Transcript changes in Vibrio cholerae in response to salt stress.

    PubMed

    Fu, Xiuping; Liang, Weili; Du, Pengcheng; Yan, Meiying; Kan, Biao

    2014-01-01

    Vibrio cholerae, which is a serious human intestinal pathogen, often resides and thrives in estuaries but requires major self-regulation to overcome intestinal hyperosmotic stress or high salt stress in water and food. In the present study, we selected multiple O1 and O139 group V. cholerae strains that were isolated from different regions and during different years to study their salt tolerance. Based on the mechanisms that other bacteria use to respond to high salt stress, we selected salt stress-response related genes to study the mechanisms which V. cholerae responds to high salt stress. V. cholerae strains showed salt-resistance characteristics that varied in salt concentrations from 4% to 6%. However, group O1 and group O139 showed no significant difference in the degree of salt tolerance. The primary responses of bacteria to salt stress, including Na(+) exclusion, K(+) uptake and glutamate biosynthesis, were observed in V. cholerae strains. In addition, some sigma factors were up-regulated in V. cholerae strains, suggesting that V. cholerae may recruit common sigma factors to achieve an active salt stress response. However, some changes in gene transcript levels in response to salt stress in V. cholerae were strain-specific. In particular, hierarchical clustering of differentially expressed genes indicated that transcript levels of these genes were correlated with the degree of salt tolerance. Therefore, elevated transcript levels of some genes, including sigma factors and genes involved in peptidoglycan biosynthesis, may be due to the salt tolerance of strains. In addition, high salt-tolerant strains may recruit common as well as additional sigma factors to activate the salt stress response. PMID:25589902

  5. 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. PMID:17749731

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    We present an analytical approach to compute the curvature effect by the new analytical solutions of co-seismic deformation derived for the homogeneous sphere model. We consider two spheres with different radii: one is the same as earth, the other with a larger radius can approximate a half-space model. Then, we calculate the co-seismic 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 co-seismic displacement. The results show that the maximum curvature effect is about 4% for source depths of less than 100 km, and about 30% 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%. 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.

  7. 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.

  8. Mode of Strong Earthquake Recurrence In Central Ionian Islands (greece). Possible Triggering Due To Coulomb Stress Changes Generated By The Occurrence of Previous Strong Shocks

    NASA Astrophysics Data System (ADS)

    Papadimitriou, E.

    The spatial-temporal distribution of shallow strong (M>6.3) earthquakes occurring in the area of central Ionian Islands is analyzed. These shocks generated on two adja- cent fault segments with different strike, but both associated with strike-slip faulting, constituting the boundary between continental collision to the north and oceanic sub- duction to the south. Seismic activity is confined in short time intervals alternating by much longer relatively quiescent periods. Each active period consists of a relatively large event or series (two to four) of events occurring closely both in space and time. This alteration was observed to happen four times since 1867, from when complete data exist for the study area. Since the phenomenon is not strictly periodic and during each active period multiple events occurred, it is attempted to interpret the seismic behavior on the basis of possible triggering. It is then investigated how changes in Coulomb Failure Function (DCFF) associated with one or more earthquakes may trig- ger subsequent events. Both the coseismic slip due to the generation of the strong earthquakes and stress build up associated with the two major fault segments were taken into account for the DCFF calculation. Earthquakes can be modeled as static dislocations in elastic half-space, and the stress pattern has been inverted according to the geometry and slip of each of the faults that ruptured in the chain of events. These calculations show that 13 out of 14 earthquakes with M>6.3 were preceded by a static stress change that encouraged failure. The magnitude of the stress increases transferred from one earthquake to another ranged from 0.01 MPa (0.1 bar) to over 0.1 MPa (1 bar). Maps of current DCFF provide additional information to long-term earthquake prediction. Areas of positive DCFF have been identified at two sites in Ke- falonia and Lefkada faults, respectively, where the next strong events are expected to occur.

  9. Changes in ventricular function during emotional stress and cold exposure

    SciTech Connect

    Kiess, M.C.; Moore, R.A.; Dimsdale, J.; Alpert, N.M.; Boucher, C.A.; Strauss, H.W.

    1984-01-01

    Patients with cardiac disease frequently develop symptoms with emotional stress or cold exposure. To investigate the effects of these stresses in normal subjects, an ambulatory ventricular function monitor (VEST) (previously reported to measure EFs which correlate well with gamma camera measurements) was employed to record sequential 2 minute time activity curves from the left ventricles of 6 healthy men (ages 19-24) during a control period and during a 30 minute stress interview with a psychiatrist. Four of the subjects were also monitored in a cold room (1/sup 0/C) for 20 min. In addition to the left ventricular time-activity curve, heart rate (HR), and BP (cuff) were recorded. All subjects had increases in HR, BP and EF during the stress interview. Cold, however, produced decreases in HR and EF and an increase in BP. The results (mean +- SD) are tabulated. End-systolic and end-diastolic counts and hence volume decreased during the interview and increased during cold exposure. The results suggest that (1) ambulatory changes in ventricular function can be measured with the VEST, and (2) significant changes in cardiovascular physiology are seen in normal subjects during a stress interview and exposure to cold.

  10. Optical changes in unilamellar vesicles experiencing osmotic stress.

    PubMed Central

    White, G; Pencer, J; Nickel, B G; Wood, J M; Hallett, F R

    1996-01-01

    Membrane properties that vary as a result of isotropic and transmembrane osmolality variations (osmotic stress) are of considerable relevance to mechanisms such as osmoregulation, in which a biological system "senses" and responds to changes in the osmotic environment. In this paper the light-scattering behavior of a model system consisting of large unilamellar vesicles of dioleoyl phosphatidyl glycerol (DOPG) is examined as a function of their osmotic environment. Osmotic downshifts lead to marked reductions in the scattered intensity, whereas osmotic upshifts lead to strong intensity increases. It is shown that these changes in the scattering intensity involve changes in the refractive index of the membrane bilayer that result from an alteration in the extent of hydration and/or the phospholipid packing density. By considering the energetics of osmotically stressed vesicles, and from explicit analysis of the Rayleigh-Gans-Debye scattering factors for spherical and ellipsoidal shells, we quantitatively demonstrate that although changes in vesicle volume and shape can arise in response to the imposition of osmotic stress, these factors alone cannot account for the observed changes in scattered intensity. PMID:8913607

  11. Reynolds stress under a change of frame of reference.

    PubMed

    Huang, Y N; Durst, F

    2001-05-01

    In this paper, we study the characteristics of the Reynolds stress under a change of frame, as defined by the Euclidean group of transformation. We show that being subject to the dynamical processes induced from the mean Navier-Stokes equations, the invariance group of the fluctuating velocity and the Reynolds stress is no longer the Euclidean group of transformation, which is merely a kinematical aspect, but reduces to the extended Galilean group of transformation. As a consequence, in contrast to developing the constitutive equations for the Cauchy stress in continuum mechanics, wherein the principle of material frame-indifference is a guiding principle, the frame-dependent kinematical quantities, e.g., the mean spin tensor, may be allowed to play an effective role as the constitutive variable in turbulence modeling. PMID:11415004

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  14. 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…

  15. 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

  16. 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.

  17. 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

  18. 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. PMID:23537434

  19. Modeling Stress Changes Following the 2004-2005 Sumatra Earthquake Sequence: Exploring Triggering of the 2007 Rupture and its Relationship to the 1797 and 1833 Events

    NASA Astrophysics Data System (ADS)

    Grijalva, K. A.; Apel, E. V.; Bürgmann, R.

    2007-12-01

    The September 2007 Sumatra M8.4 earthquake initiated in the southern section of the 1833 rupture segment. Twelve hours later a deeper M7.9 aftershock ruptured further to the north. Their occurrence, close in time and space to the 2004 M9.2 and 2005 M8.7 Sumatra earthquakes, suggest the possibility of these being triggered events. Earlier studies of vertical motion, derived from coral growth histories, suggest that interseismic strain accumulated along the 1833 segment has approached levels relieved in the historic earthquake. Along the 1797 segment the accumulated interseismic strain appears to have exceeded previously relieved levels. Following the 2004 and 2005 events, investigations of coseismic and viscoelastic deformation show that the 1797 segment had higher Coulomb failure stress changes than the 1833 segment. Therefore, it is puzzling that the 1797 and northern 1833 rupture zones did not recur before the southern 1833 segment. We model additional postseismic processes, including afterslip and poroelastic rebound, in an attempt to find scenarios that can explain why the southern 1833 segment was triggered prior to the 1797 segment.

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

    PubMed

    Sherwood, Steven C; Huber, Matthew

    2010-05-25

    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 T(W), is surprisingly similar across diverse climates today. T(W) never exceeds 31 degrees C. Any exceedence of 35 degrees 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 degrees C, calling the habitability of some regions into question. With 11-12 degrees C warming, such regions would spread to encompass the majority of the human population as currently distributed. Eventual warmings of 12 degrees 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

  1. 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

  2. Quantitative monitoring of the coseismic seismoelectric field relatively to salinity and saturation variation

    NASA Astrophysics Data System (ADS)

    Brito, D.; Holzhauer, J.; Bordes, C.; Guatarbes, B.; Callot, J. P.

    2014-12-01

    Resulting from an electrokinetic coupling generated under seismic excitation, the seismoelectric (SE) effect appears as a promising tool for porous media characterization. However, due to the incomplete understanding of the underlying physics, observations remained strictly qualitative for a long time. Eventually in the 1990's, Pride's robust explanation for the SE effect opened new prospects. Within a decade, a dynamic formulation of the coseismic transfer function had been given, that expresses the coseismic electric field E relatively to the acceleration ü.Our purpose is to confront this model to measurements carried out on a simple porous medium at lab scale. In this experiment, a seismic wave propagates within a 120l-sandbox, filled with unconsolidated monodisperse quartz sand, for varying water contents and fluid conductivities. The seismic wave is generated by a pneumatic source of wide frequency spectrum allowing for measurements at the kilohertz range. The sandbox is equipped with 20 accelerometers, 5 water-sensors and a 30 rods electrode array. All captors are placed with a maximum offset of 30cm to the source.By changing salinity in the range [2-8mS/m] at constant saturation, we observed a decrease in the |E/ü| transfer function proportional to the salinity increase, as expected by Pride and already reported in literature. This proved the experimental setup to be suitable for further quantitative measuring, being in our case a SE monitoring under saturation variations. After a relaxation time, a dramatic increase in seismic velocities attested full saturation. The ensuing SE monitoring while draining, going from 100 to 35% water-content, showed a change in the sign of the E/ü ratio consistent with Pride's predictions. In the meanwhile, seismic records exhibited velocity changes in agreement with a patchy evolution of the saturation

  3. Experimental evidence for seismically initiated gas bubble nucleation and growth in groundwater as a mechanism for coseismic borehole water level rise and remotely triggered seismicity

    NASA Astrophysics Data System (ADS)

    Crews, Jackson B.; Cooper, Clay A.

    2014-09-01

    Changes in borehole water levels and remotely triggered seismicity occur in response to near and distant earthquakes at locations around the globe, but the mechanisms for these phenomena are not well understood. Experiments were conducted to show that seismically initiated gas bubble growth in groundwater can trigger a sustained increase in pore fluid pressure consistent in magnitude with observed coseismic borehole water level rise, constituting a physically plausible mechanism for remote triggering of secondary earthquakes through the reduction of effective stress in critically loaded geologic faults. A portion of the CO2 degassing from the Earth's crust dissolves in groundwater where seismic Rayleigh and P waves cause dilational strain, which can reduce pore fluid pressure to or below the bubble pressure, triggering CO2 gas bubble growth in the saturated zone, indicated by a spontaneous buildup of pore fluid pressure. Excess pore fluid pressure was measured in response to the application of 0.1-1.0 MPa, 0.01-0.30 Hz confining stress oscillations to a Berea sandstone core flooded with initially subsaturated aqueous CO2, under conditions representative of a confined aquifer. Confining stress oscillations equivalent to the dynamic stress of the 28 June 1992 Mw 7.3 Landers, California, earthquake Rayleigh wave as it traveled through the Long Valley caldera, and Parkfield, California, increased the pore fluid pressure in the Berea core by an average of 36 ± 15 cm and 23 ± 15 cm of equivalent freshwater head, respectively, in agreement with 41.8 cm and 34 cm rises recorded in wells at those locations.

  4. Menstrual cycle-related changes in amygdala morphology are associated with changes in stress sensitivity.

    PubMed

    Ossewaarde, Lindsey; van Wingen, Guido A; Rijpkema, Mark; Bäckström, Torbjörn; Hermans, Erno J; Fernández, Guillén

    2013-05-01

    Premenstrual increases in negative mood are thought to arise from changes in gonadal hormone levels, presumably by influencing mood regulation and stress sensitivity. The amygdala plays a major role in this context, and animal studies suggest that gonadal hormones influence its morphology. Here, we investigated whether amygdala morphology changes over the menstrual cycle and whether this change explains differences in stress sensitivity. Twenty-eight young healthy women were investigated once during the premenstrual phase and once during the late follicular phase. T1-weighted anatomical images of the brain were acquired using magnetic resonance imaging and analyzed with optimized voxel-based morphometry. To measure mood regulation and stress sensitivity, negative affect was assessed after viewing strongly aversive as well as neutral movie clips. Our results show increased gray matter volume in the dorsal part of the left amygdala during the premenstrual phase when compared with the late follicular phase. This volume increase was positively correlated with the premenstrual increase in stress-induced negative affect. This is the first study showing structural plasticity of the amygdala in humans at the macroscopic level that is associated with both endogenous gonadal hormone fluctuations and stress sensitivity. These results correspond with animal findings of gonadal hormone-mediated neural plasticity in the amygdala and have implications for understanding the pathogenesis of specific mood disorders associated with hormonal fluctuations. PMID:22162177

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

    SciTech Connect

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

    2005-06-15

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

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

    SciTech Connect

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

    2005-06-15

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

  7. Mechanical and Microphysical Constraints on Co-seismic Rupture into the Creeping Segment of the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    French, M. E.; Chester, F. M.; Chester, J. S.

    2014-12-01

    Experimentally-determined mechanical properties of clay-rich fault rock, and the associated micromechanical processes, are used to constrain the conditions of slip instability along the San Andreas Fault (SAF). Using smectite-rich fault gouge collected from the Central Deforming Zone (CDZ) of the SAF in the San Andreas Fault Observatory at Depth (SAFOD), rotary and triaxial shear deformation experiments were conducted at rates that correspond to co-seismic slip (1 m/s) and in-situ creep (~10-10 s-1). Frictional strength depends on rate, temperature, availability of pore water, and fabric development, all of which reflect operation of different microscopic mechanisms at high and low shear rates. On the basis of the results, we use an energy balance for a propagating rupture to evaluate the potential for seismic slip along the CDZ. Appropriate scaling of the gouge strength from experimental to in-situ conditions, particularly for seismic slip rates, is critical to evaluating seismic hazards. Accordingly, the micromechanical processes identified from results of the deformation experiments are used to constrain and evaluate several different scaling relations between strength, critical displacement, and normal stress for the CDZ gouge. Experiments show that, at in situ creep rates, dislocation glide in clay is the rate-controlling mechanism and is responsible for the low strength (μ = 0.11), which limits the potential energy available for sustaining co-seismic frictional slip. As a consequence, microseismic patches within the CDZ are predicted to arrest for all scaling relationships under in-situ deformation conditions. Dynamic weakening at co-seismic rates involves thermal fluid pressurization, and for some scaling relations may be sufficient to sustain propagation of a rupture that nucleates within the adjacent locked segment into the CDZ

  8. Early life stress increases stress vulnerability through BDNF gene epigenetic changes in the rat hippocampus.

    PubMed

    Seo, Mi Kyoung; Ly, Nguyen Ngoc; Lee, Chan Hong; Cho, Hye Yeon; Choi, Cheol Min; Nhu, Le Hoa; Lee, Jung Goo; Lee, Bong Ju; Kim, Gyung-Mee; Yoon, Bong June; Park, Sung Woo; Kim, Young Hoon

    2016-06-01

    Early life stress (ELS) exerts long-lasting epigenetic influences on the brain and makes an individual susceptible to later depression. It is poorly understood whether ELS and subsequent adult chronic stress modulate epigenetic mechanisms. We examined the epigenetic mechanisms of the BDNF gene in the hippocampus, which may underlie stress vulnerability to postnatal maternal separation (MS) and adult restraint stress (RS). Rat pups were separated from their dams (3 h/day from P1-P21). When the pups reached adulthood (8 weeks old), we introduced RS (2 h/day for 3 weeks) followed by escitalopram treatment. We showed that both the MS and RS groups expressed reduced levels of total and exon IV BDNF mRNA. Furthermore, RS potentiated MS-induced decreases in these expression levels. Similarly, both the MS and RS groups showed decreased levels of acetylated histone H3 and H4 at BDNF promoter IV, and RS exacerbated MS-induced decreases of H3 and H4 acetylation. Both the MS and RS groups had increased MeCP2 levels at BDNF promoter IV, as well as increased HDAC5 mRNA, and the combination of MS and RS exerted a greater effect on these parameters than did RS alone. In the forced swimming test, the immobility time of the MS + RS group was significantly higher than that of the RS group. Additionally, chronic escitalopram treatment recovered these alterations. Our results suggest that postnatal MS and subsequent adult RS modulate epigenetic changes in the BDNF gene, and that these changes may be related to behavioral phenotype. These epigenetic mechanisms are involved in escitalopram action. PMID:26877199

  9. 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.

  10. Volcanoes triggered by dynamic and static stress changes in Chile: Observations, stress field changes and physical modelling

    NASA Astrophysics Data System (ADS)

    Gaete, Ayleen; Walter, Thomas

    2015-04-01

    Evidence is increasing that subduction zone earthquakes may influence the volcanic activity along a volcanic arc. The processes of triggering, however, are not clear. In a commonly discussed concept, changes of the crustal stress field may affect intrusive bodies under volcano, open magma pathways and faults, and decompress a magma-fluid system. Other concepts focus on the dynamic passage of seismic waves, inducing bubble growth and ascent as well as fluid migration. Volcanoes in the south and central Andes have a century long documented history of earthquake - eruption interactions. Numerous subduction earthquakes were followed by more and unexpected volcano eruptions, which is why we here concentrate our research on this particular area. The most recent major subduction earthquake occurred on April 1st, 2014, close to the coast of northern Chile. During this event we had volcano monitoring stations located at several active volcanoes and fumarole sites, as well as at on of the largest geyser fields of the world, all located within 500 km distance to the earthquake epicenter. Here we present preliminary results describing if and how those monitored volcano sites showed activity level changes, which is an opportunity to study the influence of earthquakes over active and dormant volcanoes. After analysis of the date we computed the static strain and stress field in the overriding plate and at the sites of the volcanoes. In addition we design physical models that allow to study not only the effects of static stress changes and dilatation on fluid paths, but also the effect of dynamic processes. To this aim we simulate real seismic waveforms on a shaking table hosting an analogue volcano, and discuss under which situations magma paths and ascent rates are augmented and hindered by the subduction earthquake. Results are transferrable to other subduction related volcano-earthquake interactions and may allow better understanding of the processes of static and dynamic

  11. "Coseismic foliations" in gouge and cataclasite: experimental observations and consequences for interpreting the fault rock record

    NASA Astrophysics Data System (ADS)

    Smith, Steven; Griffiths, James; Fondriest, Michele; Di Toro, Giulio; Demurtas, Matteo

    2016-04-01

    Foliated gouges and cataclasites are commonly interpreted as the product of distributed (aseismic) fault creep. However, foliated fault rocks are often associated with localized slip surfaces, the latter indicating potentially unstable (seismic) behavior. One possibility is that such fault zones preserve the effects of both seismic slip and slower aseismic creep. An alternative possibility explored here is that some foliated fault rocks and localized slip surfaces develop contemporaneously during seismic slip. We studied the microstructural evolution of calcite-dolomite gouges deformed experimentally at slip velocities <1.13 m/s and for total displacements of 0.03 - 1 m, in the range expected for the average coseismic slip during earthquakes of Mw 3-7. As strain progressively localized in the gouge layers at the onset of high-velocity shearing, an initial mixed assemblage of calcite and dolomite grains evolved quickly to an organized, foliated fabric. The foliation was defined mainly by compositional layering and grain size variations that formed by cataclasis and shearing of individual foliation domains. Quantitative image analysis (e.g. grain size, strain) showed that the most significant microstructural changes in the bulk gouge occurred before and during dynamic weakening (<0.08 m displacement). Strain was localized to a bounding slip surface by the end of dynamic weakening and thus microstructural evolution in the bulk gouge ceased. Our experiments suggest that certain types of foliated gouge and cataclasite can form by distributed brittle "flow" as strain localizes to a bounding slip surface during coseismic shearing. We will also present preliminary observations of natural calcite-dolomite foliated cataclasites from the Campo Imperatore normal fault, central Italy, which bear striking resemblance to our well-characterized experimental examples.

  12. Inversion for coseismic slip distribution of the 2010 Mw 6.9 Yushu Earthquake from InSAR data using angular dislocations

    NASA Astrophysics Data System (ADS)

    Jiang, Guoyan; Xu, Caijun; Wen, Yangmao; Liu, Yang; Yin, Zhi; Wang, Jianjun

    2013-08-01

    We used interferometric SAR (InSAR) crustal deformation data sets to explore the fault slip involved in the 2010 April 14 (Mw = 6.9) Yushu earthquake modelled using angular dislocations. A refined rupture trace of the Yushu fault was extracted from two InSAR coseismic interferograms and field investigation results. We present a new method to discretize the fault geometry using triangular dislocation elements (TDEs), which are able to maintain consistency with the fault geometry modelled using rectangular dislocation elements (RDEs) and to avoid dislocation gaps and overlaps. Comprehensive comparisons between RDE and TDE models indicate that the classic Laplacian operator, which has not been carefully explored in many published studies, minimizes the slip on the boundary RDEs of the fault. A modification is proposed for the development of reasonable RDE models. The inversion shows that there were two larger concentrated slip zones during the Yushu earthquake. The largest was southeast of the hypocentre, near Luorongda, with a maximum slip of ˜1.6 m at the surface. The smaller slip patch was in the middle of the fault at a depth of ˜6 km, near the hypocentre. To improve the computational efficiency, we re-derived the analytic expressions for the strains associated with angular dislocations in an elastic half-space. The Coulomb stress changes increase at the northwestern and southeastern ends of the fault, and the small number of aftershocks in the southeast indicates that the seismic risk may be elevated in this area.

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

    PubMed Central

    Landis, Gary; Tower, John

    2012-01-01

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

  14. 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

  15. Social stress at work and change in women's body weight.

    PubMed

    Kottwitz, Maria U; Grebner, Simone; Semmer, Norbert K; Tschan, Franziska; Elfering, Achim

    2014-01-01

    Social stressors at work (such as conflict or animosities) imply disrespect or a lack of appreciation and thus a threat to self. Stress induced by this offence to self might result, over time, in a change in body weight. The current study investigated the impact of changing working conditions--specifically social stressors, demands, and control at work--on women's change in weighted Body-Mass-Index over the course of a year. Fifty-seven women in their first year of occupational life participated at baseline and thirty-eight at follow-up. Working conditions were assessed by self-reports and observer-ratings. Body-Mass-Index at baseline and change in Body-Mass-Index one year later were regressed on self-reported social stressors as well as observed work stressors, observed job control, and their interaction. Seen individually, social stressors at work predicted Body-Mass-Index. Moreover, increase in social stressors and decrease of job control during the first year of occupational life predicted increase in Body-Mass-Index. Work redesign that reduces social stressors at work and increases job control could help to prevent obesity epidemic. PMID:24429516

  16. Coseismic Offsets on PBO Borehole Strainmeters: Real, or Spurious?

    NASA Astrophysics Data System (ADS)

    Barbour, A. J.; Agnew, D. C.

    2010-12-01

    We have observed coseismic strain offsets during many significant earthquakes, at all locations in the 74-instrument PBO borehole strainmeter (BSM) network. The M7.2 El Mayor-Cucapah earthquake of April 4, 2010 induced the largest offsets thus far, on BSMs located within the San Jacinto fault zone - the "Anza cluster". Here we present analyses of trends in the observed offsets for the Anza cluster, as well as inspection of their inferred borehole lithology. We find that offsets rarely agree with elastic dislocation theory in magnitude and sign, and speculate that they are controlled more by localized geologic constraints than by triggered fault slip, as has been suggested in previous studies (e.g. Linde and Johnson, 1989).

  17. 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…

  18. 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.

  19. Thermobarometry of metamorphosed pseudotachylyte and associated mylonite: Constraints on dynamic Co-seismic rupture depth attending Caledonian extension, North Norway

    NASA Astrophysics Data System (ADS)

    Leib, S. E.; Moecher, D. P.; Steltenpohl, M. G.; Andresen, Arild

    2016-07-01

    The exhumed post-Caledonian Eidsfjord and Fiskfjord extensional shear zones of northern Norway exhibit evidence of coseismic rupture propagating into the ductile crust as evidenced by the presence of mylonitic and metamorphosed pseudotachylyte. Geothermobarometric calculations on garnet-bearing mineral assemblages in mylonitic gneisses associated with mylonitic pseudotachylyte and in metamorphosed pseudotachylyte permit determination of the depth and ambient temperature of seismogenic low-angle ductile extension. Average pressures from Eidsfjord (570 ± 115 MPa at ca. 650 °C) and Fiskfjord (1120 ± 220 MPa at ca. 650 °C) correspond to faulting depths of 21 ± 4 km and 41 ± 9 km, respectively. The Fiskfjord results agree with previous thermobarometric calculations on mylonitic Cpx + Grt-bearing pseudotachylyte at Fiskfjord. The calculated depths are 5-25 km below the depth of the standard seismogenic zone. These results demonstrate that low angle normal faults may cut through a large portion of continental crust. This occurrence of mylonitic pseudotachylyte in an extensional crustal setting is most easily explained by dynamic downward rupture into the ductile regime and/or unusually high shear stresses to account for coseismic rupture at such depths, implying a direct connection with a seismogenic normal fault in the upper crust.

  20. Distributed Coseismic and Early Postseismic Dip-Slip from the 1 April 2007 Solomon Islands Earthquake: A Unique Image of Near-Trench Rupture

    NASA Astrophysics Data System (ADS)

    Chen, T.; Newman, A. V.; Fritz, H.

    2008-12-01

    We estimate the spatial distribution of dip-slip in the 1 April 2007 magnitude MW=8.1 Solomon earthquake, which created a locally large tsunami with runup heights up to 12 m. The event is unique in that involved the rupture of at least two subducting plates, and that land occurs very close to the trench on the hanging wall side. The occurrence of islands extremely proximal to the trench allowed for the collection of near-shore uplift and subsidence information from costal areas (including the exposure and subsidence of corals), hence giving a unique well-resolved image of the near-trench geodetically derived slip. Two surveys, taken between 1 week and 1 month after the event primarily across the southern portion of the slip zone, comprise a dataset of approximately 100 measurements of between +3.6 and -1.5 m of vertical displacements [Fritz and Kalligeris, 2008; Taylor et al., 2008]. We use the Okada [1992] elastic dislocation model, to explore the distribution of dip-slip on discrete patches. To maintain a realistic distribution of slip we smooth the solution by attempting to minimize the second-order spatial derivative of slip, hence minimizing the stress change across the system. Because data are only vertical in nature and the expected strike-slip component of the thrust is small, only the dip-slip component of rupture was considered. Early results show highly variable dip-slip both along-strike and down- dip, with a significant focus of slip in the shallow near trench area. If real, this near-trench focusing may explain the locally high runup on portions of Simbo Island. Because it is not certain how much of the modeled slip occurred due to coseismic versus post-seismic recovery and afterslip, we explore the variability of solutions between the two surveys and compare results with the available spatial distribution of co-seismic finite-slip model of C. Ji [unpublished, 2007].

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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

  6. Coseismic response of water level in Changping well, China, to the Mw 9.0 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Sun, Xiaolong; Wang, Guangcai; Yang, Xuanhui

    2015-12-01

    A water-level meter installed in Changping well, China, recorded coseismic fluctuations and a step change induced by the Mw 9.0 Tohoku earthquake of 11 March 2011. Here we analyse the correlation between water level in the well and vertical ground motions recorded at a nearby surface site, and we examine the relationship between the characteristics of these two datasets and the well-aquifer system parameters. During the arrival period of P- and S-waves, the water level provides information about the intensification of high-frequency ground motions. During the arrival period of the surface waves, the amplitude of water-level fluctuations was closely related to the velocity of vertical-component surface motions. The fluctuation periods of these two parameters are in the range 15-35 s, and the period of oscillation displays a large-to-small characteristic behaviour. The amplification effect on the water level in Changping well, driven by the pressure fluctuation induced by the surface wave, was relatively small, but a low-to-high characteristic is apparent during the coseismic period, related to the gradual enhancement of aquifer permeability due to the action of seismic waves. The coseismic step increase in water level was related to the enhancement of aquifer permeability under the action of seismic waves, and the results of an inversion of water-level tidal-response characteristics show that permeability increased by ∼6.56 × 10-14 m2 in the vicinity of Changping well in response to the action of seismic waves emanating from the Tohoku earthquake.

  7. Near-field and far-field effects of elastic structure on coseismic deformation of the 2011 Tohoku earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Hashima, Akinori; Becker, Thorsten; Freed, Andy; Sato, Hiroshi; Okaya, David; Suito, Hisashi; Yarai, Hiroshi; Ishiyama, Tatsuya; Iwasaki, Takaya

    2016-04-01

    Coseismic deformation due to the 2011 Tohoku earthquake, Japan, was detected by dense GPS network of over 1200 stations and several seafloor stations. Using these observations, we investigated effects of elastic structure on coseismic deformation with a 3-D finite element model incorporating geometry of the regional plate boundaries and elastic structures. First, we computed displacement fields for different elastic models with the same coseismic slip distribution to understand the effect of elastic structures. We assumed the three structure models: (a) Homogeneous model, (b) two-layered model considering crust-mantle structure (rigidity of 35 and 65 GPa, respectively) (Layered model), (c) crust-mantle model with cold subducting slab (85 GPa) (Slab model). We found the two contradicting effects: (1) In the far field (mostly at onshore stations), the amount of displacement decreases with the increase of the average rigidity. (2) In the near field at offshore stations, the amount of surface displacement increases with the increase of rigidity across the faults. This is because the stiffer (less deformable) footwall requires more movement of the hanging wall to accommodate the slip. Next, we inverted the observed displacements to obtain slip distribution for three elastic structures. The patterns of inverted slip distribution are basically similar for all three models but the amount of maximum slip is not simply related to average rigidity of structure models. The maximum slip increases from 39 m in Homogeneous model to 40 m in Layered model and then falls to 38 m in Slab model. These changes show that crust-mantle layering is more effective on far field while slab effect is more important in the near field.

  8. Monitoring in situ stress changes in a mining environment with coda wave interferometry

    NASA Astrophysics Data System (ADS)

    Grêt, Alexandre; Snieder, Roel; Özbay, Uḡur

    2006-11-01

    Coda waves are highly sensitive to changes in the subsurface; we use this sensitivity to monitor small stress changes in an underground mine. We apply coda wave interferometry to seismic data excited by a hammer source, collected at an experimental hard rock mine in Idaho Springs, CO. We carried out a controlled stress-change experiment in a mine pillar and we show how coda wave interferometry can be used to monitor the in situ stress change with modest hardware requirements.

  9. Rate of environmental change determines stress response specificity

    PubMed Central

    Young, Jonathan W.; Locke, James C. W.; Elowitz, Michael B.

    2013-01-01

    Cells use general stress response pathways to activate diverse target genes in response to a variety of stresses. However, general stress responses coexist with more specific pathways that are activated by individual stresses, provoking the fundamental question of whether and how cells control the generality or specificity of their response to a particular stress. Here we address this issue using quantitative time-lapse microscopy of the Bacillus subtilis environmental stress response, mediated by σB. We analyzed σB activation in response to stresses such as salt and ethanol imposed at varying rates of increase. Dynamically, σB responded to these stresses with a single adaptive activity pulse, whose amplitude depended on the rate at which the stress increased. This rate-responsive behavior can be understood from mathematical modeling of a key negative feedback loop in the underlying regulatory circuit. Using RNAseq we analyzed the effects of both rapid and gradual increases of ethanol and salt stress across the genome. Because of the rate responsiveness of σB activation, salt and ethanol regulons overlap under rapid, but not gradual, increases in stress. Thus, the cell responds specifically to individual stresses that appear gradually, while using σB to broaden the cellular response under more rapidly deteriorating conditions. Such dynamic control of specificity could be a critical function of other general stress response pathways. PMID:23407164

  10. Analysis of the Far-Field Co-seismic and Post-seismic Responses Caused by the 2011 M W 9.0 Tohoku-Oki Earthquake

    NASA Astrophysics Data System (ADS)

    Shao, Zhigang; Zhan, Wei; Zhang, Langping; Xu, Jing

    2016-02-01

    We analyzed the far-field co-seismic response of the M W 9.0 Tohoku-Oki earthquake, which occurred on March 11th 2011 at the Japan Trench plate boundary. Our analysis indicates that the far-field co-seismic displacement was very sensitive to the magnitude of this event, and that a significant co-seismic surface displacement from earthquakes in the Japan Trench region can be observed in Eurasia only for events of M W ≥ 8.0. We also analyzed the temporal characteristics of the near-field post-seismic deformation caused by the afterslip and the viscoelastic relaxation following the Japan earthquake. Next, we performed a simulation to analyze the influence of the two post-seismic effects previously mentioned on the far-field post-seismic crustal deformation. The simulation results help explain the post-seismic crustal deformation observed on the Chinese mainland 1.5 years after the event. Fitting results revealed that after the M W 9.0 Tohoku-Oki earthquake, the afterslip decayed exponentially, and may eventually disappear after 4 years. The far-field post-seismic displacement in Eurasia caused by the viscoelastic relaxation following this earthquake will reach the same magnitude as the co-seismic displacement in approximately 10 years. In addition, the co- and post-seismic Coulomb stress on several NE-trending faults in the northeastern and northern regions of the Chinese mainland were significantly enhanced because of the M W 9.0 earthquake, especially on the Yilan-Yitong and the Dunhua-Mishan faults (the northern section of the Tan-Lu fault zone) as well as the Yalujiang and the Fuyu-Zhaodong faults.

  11. Coulomb stress evolution over the past 200 years and seismic hazard along the Xianshuihe fault zone of Sichuan, China

    NASA Astrophysics Data System (ADS)

    Shao, Zhigang; Xu, Jing; Ma, Hongsheng; Zhang, Langping

    2016-02-01

    This study focuses on the M ≥ 6.7 earthquakes that have occurred since 1816 on the Xianshuihe fault zone in southwest China. The interseismic Coulomb stress accumulation and the Coulomb stress changes caused by coseismic dislocation and postseismic viscoelastic relaxation of the previous shocks were computed for different periods on the relevant fault segments. Based on these results, we analyzed the relationship between time-adjacent strong shocks and the Coulomb stress evolution before every earthquake. The analysis suggests that strong earthquakes mostly occurred in the Coulomb stress enhancement region caused by coseismic dislocation and postseismic viscoelastic relaxation of the last earthquake. Considering the Coulomb stress evolution at the fault planes of the epicentral area before earthquakes, we found that the Coulomb stress accumulation caused by the interseismic tectonic loading was dominant for most strong earthquakes. For some other earthquakes the stress changes caused by coseismic dislocation and postseismic viscoelastic relaxation of surrounding earthquakes were very significant, which may be equivalent to the effect of interseismic tectonic loading lasting hundreds of years. Based on the time-dependent probabilistic risk model and the Dieterich (1994) model, we estimate the background seismic activity and the future earthquake probability for different fault segments, using long term seismic activity and strong earthquake recurrence cycles. It is shown that the Bamei, Selaha, and Kangding segments of the Xianshuihe fault zone have high earthquake probability, and are likely to have strong earthquakes. If energy is accumulated up to the year 2050, the magnitude of an event on these three segments could reach Mw 7.2, Mw 7.0, and Mw 7.1 respectively, while if the S7 and S8 cascades rupture, the event on these segments could reach a magnitude of up to Mw 7.2.

  12. 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.

  13. 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

  14. Pernicious progressive coseismic rock-mass degradation and rock-avalanche volume

    NASA Astrophysics Data System (ADS)

    McSaveney, M. J.; Massey, C. I.

    2013-12-01

    Some effects of the 2010/11 Canterbury earthquake sequence provide new insights into processes leading to rock slides and rock avalanches. These processes are, as yet, part way through defining a mass that will fall. They are causing deep-seated gravitational slope deformation, but they have much relevance to predicting the reach of rock slides and rock avalanches because they are defining a future landslide volume. The phenomenon can be called pernicious, progressive, coseismic rock-mass degradation: pernicious because it will eventually destroy an affected portion of a mountain edifice, given time and enough shaking. In a series of severe aftershocks in 2011, small co-seismic ground movements opened cracks for 300 m along a hillside, some 50 m back from an 80-m-high former coastal cliff in an extinct (Miocene) basalt volcano. Investigations to determine the significance of the movement involved measuring displacement, crack widths and orientations, terrestrial laser scans of the cliff face, a geological log of the cliff, drilling with core recovery into the hill top to below the cliff base, and downhole logging of seismic velocities. The core revealed a scoriaceous basalt flow at depth containing non-cooling related fractures, some of which were fresh, but unrelated to drilling. The flow corresponded to a prominent down-hole logged seismic velocity contrast. We do not discuss details of this site, but discuss the insight it gave us into the wider problem of rock-mass degradation to become a rock slide or rock avalanche. A key to the process is the presence in a brittle rock mass of a large seismic velocity contrast to slow input elastic body waves, and thereby amplify seismic stress fluctuations, sometimes out of the elastic response range. With time and mountain erosion, the position of the velocity contrast is advected higher into the edifice. There, the rock mass is subject to high static shear stresses induced by the mass and the edifice shape. During some

  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. 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. PMID:23442135

  18. A Renewed Look at the Coseismic Surface Deformation and Fault Slip of the 1994 Northridge Earthquake Using Space Geodesy

    NASA Astrophysics Data System (ADS)

    Severson, Chad M.

    The January 17, 1994 M6.7 Northridge earthquake occurred in the densely populated suburbs northwest of Los Angeles, California, causing 33 deaths and ˜$20 billion in damage. To quantify the influence, in terms of stress changes, of the Northridge event on surrounding faults, detailed knowledge of the location, orientation and amount of fault slip is important. Existing InSAR models of this earthquake typically were developed by fitting the pattern of displacements by trial and error, and were therefore somewhat subjective. In the 15 years since the original studies were published a number of new modeling tools and community data products have been developed that should enable us to produce more detailed, objective and robust results. We measure the coseismic deformation of this earthquake using InSAR data from the ERS-1 and JERS-1 satellites, combined with GPS measurements (Hudnut et al., 1996) that together show uplift of ˜42 cm. Using these data, we first employ a nonlinear inversion to determine the parameters of a best-fitting model using rectangular, uniform slip dislocations. Our best-fitting fault solution contains two faults, a main fault with 2.3 m of slip and a secondary fault to the northwest with 0.8 m. In detail, however, the deformation pattern of the Northridge event is more complex than can be described by rectangular dislocations. To investigate this, we solve for a detailed slip distribution for the event using a non-planar triangular element fault mesh modified from the SCEC Community Fault Model (Plesch et al.,2007). This model shows a main asperity on a protrusion on the fault, with peak slip of ˜2.7m, bounded at its western edge by a geometrical barrier, a steep down-dip parallel lateral ramp in the fault. Secondary slip of about 0.6m to the northwest of this feature is also present. These two slip patches together shows that the geometry of the fault strongly influences the slip pattern of the event.

  19. 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...

  20. Regional coseismic landslide hazard assessment without historical landslide inventories: A new approach

    NASA Astrophysics Data System (ADS)

    Kritikos, Theodosios; Robinson, Tom R.; Davies, Tim R. H.

    2015-04-01

    Currently, regional coseismic landslide hazard analyses require comprehensive historical landslide inventories as well as detailed geotechnical data. Consequently, such analyses have not been possible where these data are not available. A new approach is proposed herein to assess coseismic landslide hazard at regional scale for specific earthquake scenarios in areas without historical landslide inventories. The proposed model employs fuzzy logic and geographic information systems to establish relationships between causative factors and coseismic slope failures in regions with well-documented and substantially complete coseismic landslide inventories. These relationships are then utilized to estimate the relative probability of landslide occurrence in regions with neither historical landslide inventories nor detailed geotechnical data. Statistical analyses of inventories from the 1994 Northridge and 2008 Wenchuan earthquakes reveal that shaking intensity, topography, and distance from active faults and streams are the main controls on the spatial distribution of coseismic landslides. Average fuzzy memberships for each factor are developed and aggregated to model the relative coseismic landslide hazard for both earthquakes. The predictive capabilities of the models are assessed and show good-to-excellent model performance for both events. These memberships are then applied to the 1999 Chi-Chi earthquake, using only a digital elevation model, active fault map, and isoseismal data, replicating prediction of a future event in a region lacking historic inventories and/or geotechnical data. This similarly results in excellent model performance, demonstrating the model's predictive potential and confirming it can be meaningfully applied in regions where previous methods could not. For such regions, this method may enable a greater ability to analyze coseismic landslide hazard from specific earthquake scenarios, allowing for mitigation measures and emergency response plans

  1. 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.

  2. 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

  3. Stress-corrosion-induced property changes in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bankston, B. F.; Clotfelter, W. N.

    1968-01-01

    Measurements of electrical conductivity, ultrasonic surface wave attenuation, and internal friction loss were made on aluminum alloys 7079-T6, 2219-T31, and 2219-T81 as a function of the onset of stress corrosion.

  4. 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.

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

    PubMed

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

    2015-11-01

    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

  6. 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

  7. Chromatin changes in response to drought, salinity, heat, and cold stresses in plants

    PubMed Central

    Kim, Jong-Myong; Sasaki, Taku; Ueda, Minoru; Sako, Kaori; Seki, Motoaki

    2015-01-01

    Chromatin regulation is essential to regulate genes and genome activities. In plants, the alteration of histone modification and DNA methylation are coordinated with changes in the expression of stress-responsive genes to adapt to environmental changes. Several chromatin regulators have been shown to be involved in the regulation of stress-responsive gene networks under abiotic stress conditions. Specific histone modification sites and the histone modifiers that regulate key stress-responsive genes have been identified by genetic and biochemical approaches, revealing the importance of chromatin regulation in plant stress responses. Recent studies have also suggested that histone modification plays an important role in plant stress memory. In this review, we summarize recent progress on the regulation and alteration of histone modification (acetylation, methylation, phosphorylation, and SUMOylation) in response to the abiotic stresses, drought, high-salinity, heat, and cold in plants. PMID:25784920

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

    SciTech Connect

    Teufel, L.W.

    1996-02-01

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

  9. Global coseismic deformations, GNSS time series analysis, and earthquake scaling laws

    NASA Astrophysics Data System (ADS)

    Métivier, Laurent; Collilieux, Xavier; Lercier, Daphné; Altamimi, Zuheir; Beauducel, François

    2014-12-01

    We investigate how two decades of coseismic deformations affect time series of GPS station coordinates (Global Navigation Satellite System) and what constraints geodetic observations give on earthquake scaling laws. We developed a simple but rapid model for coseismic deformations, assuming different earthquake scaling relations, that we systematically applied on earthquakes with magnitude larger than 4. We found that coseismic displacements accumulated during the last two decades can be larger than 10 m locally and that the cumulative displacement is not only due to large earthquakes but also to the accumulation of many small motions induced by smaller earthquakes. Then, investigating a global network of GPS stations, we demonstrate that a systematic global modeling of coseismic deformations helps greatly to detect discontinuities in GPS coordinate time series, which are still today one of the major sources of error in terrestrial reference frame construction (e.g., the International Terrestrial Reference Frame). We show that numerous discontinuities induced by earthquakes are too small to be visually detected because of seasonal variations and GPS noise that disturb their identification. However, not taking these discontinuities into account has a large impact on the station velocity estimation, considering today's precision requirements. Finally, six groups of earthquake scaling laws were tested. Comparisons with our GPS time series analysis on dedicated earthquakes give insights on the consistency of these scaling laws with geodetic observations and Okada coseismic approach.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  12. 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

  13. 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

    2016-01-01

    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

  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. Implications of Financial Changes in Education on Teacher Stress: A Study of Teacher Perceptions.

    ERIC Educational Resources Information Center

    Hurley, Noel P.

    Educators in Ontario, Canada, have been subjected to a barrage of changes in the last decade. Many of these changes have had direct or indirect financial implications for teachers. These changes can be organized as "curriculum" and "school governance." In an effort to understand the effect of educational change on teacher stress, this paper…

  16. 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. PMID:26151391

  17. Academic Stress and Health Changes in Female College Students.

    ERIC Educational Resources Information Center

    Lesko, Wayne A.; Summerfield, Liane

    1989-01-01

    Results are reported from a study, involving 35 female undergraduates, which examined the correlation between the health of the students, as measured by self-reported incidence of illness and directly observable physiological (blood pressure) measures, and the frequency and perceived stress of examinations and assignments. (IAH)

  18. Modeling of the coseismic electromagnetic fields observed during the 2004 Mw 6.0 Parkfield earthquake

    NASA Astrophysics Data System (ADS)

    Gao, Yongxin; Harris, Jerry M.; Wen, Jian; Huang, Yihe; Twardzik, Cedric; Chen, Xiaofei; Hu, Hengshan

    2016-01-01

    The coseismic electromagnetic signals observed during the 2004 Mw 6 Parkfield earthquake are simulated using electrokinetic theory. By using a finite fault source model obtained via kinematic inversion, we calculate the electric and magnetic responses to the earthquake rupture. The result shows that the synthetic electric signals agree with the observed data for both amplitude and wave shape, especially for early portions of the records (first 9 s) after the earthquake, supporting the electrokinetic effect as the reasonable mechanism for the generation of the coseismic electric fields. More work is needed to explain the magnetic fields and the later portions of the electric fields. Analysis shows that the coseismic electromagnetic (EM) signals are sensitive to both the material properties at the location of the EM sensors and the electrochemical heterogeneity in the vicinity of the EM sensors and can be used to characterize the underground electrochemical properties.

  19. 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.

  20. Laboratory measurements and theoretical modeling of seismoelectric interface response and coseismic wave fields

    SciTech Connect

    Schakel, M. D.; Slob, E. C.; Heller, H. K. J.; Smeulders, D. M. J.

    2011-04-01

    A full-waveform seismoelectric numerical model incorporating the directivity pattern of a pressure source is developed. This model provides predictions of coseismic electric fields and the electromagnetic waves that originate from a fluid/porous-medium interface. An experimental setup in which coseismic electric fields and interface responses are measured is constructed. The seismo-electric origin of the signals is confirmed. The numerically predicted polarity reversal of the interfacial signal and seismoelectric effects due to multiple scattering are detected in the measurements. Both the simulated coseismic electric fields and the electromagnetic waves originating from interfaces agree with the measurements in terms of travel times, waveform, polarity, amplitude, and spatial amplitude decay, demonstrating that seismoelectric effects are comprehensively described by theory.

  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

  2. In vitro and in vivo Phase Changes of the Mouse Circadian Clock by Oxidative Stress

    PubMed Central

    Tahara, Yu; Yokota, Aya; Shiraishi, Takuya; Yamada, Shunya; Haraguchi, Atsushi; Shinozaki, Ayako

    2016-01-01

    Mammalian circadian rhythms are governed by an endogenous circadian clock system, including the molecular clock works in each cell and tissue. Adaptation of the circadian clock to different environmental stimuli such as light, food, and stress is essential for homeostasis maintenance. However, the influence of oxidative stress on the circadian clock phase is not fully understood in vitro and in vivo. Here, we examined the effects of hydrogen peroxide (H2O2)-induced oxidative stress on the PERIOD2::LUCIFERASE bioluminescence rhythm in mouse embryonic fibroblasts in vitro and in mouse peripheral tissues in vivo. The circadian clock phase changed with the dose of H2O2 and time of day in vitro; similar phase changes were observed in vivo in the circadian clocks of the peripheral tissues. In addition, mice treated with hemin-induced oxidative stress also showed phase changes of peripheral clocks, similarly as H2O2 treatment. Thus, oxidative stress can entrain circadian clock systems.

  3. Field and stress dependence of the irreversible magnetization changes in pure iron

    NASA Astrophysics Data System (ADS)

    Pearson, J.; Squire, P. T.

    1998-06-01

    Measurements of the irreversible magnetization changes accompanying the application and removal of stress to a sample of 99.99% pure iron have been made as a function of applied field and stress magnitude for both compressive and tensile stress. The fields for peak change have been compared with those for the peak difference MAN-MINI between the anhysteretic and initial magnetization curves and the field derivative of the magnetostriction. It is shown that at low tensile stress the magnetostrictive contribution is dominant, as found by Pravdin. At higher stress the wall pinning term is dominant, and the magnetization changes are proportional to MAN-MINI, in accordance with the Jiles-Atherton model.

  4. 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.

  5. Proteome changes induced by aluminium stress in tomato roots.

    PubMed

    Zhou, Suping; Sauvé, Roger; Thannhauser, Theodore W

    2009-01-01

    Growth inhibition in acid soils due to Al stress affects crop production worldwide. To understand mechanisms in sensitive crops that are affected by Al stress, a proteomic analysis of primary tomato root tissue, grown in Al-amended and non-amended liquid cultures, was performed. DIGE-SDS-MALDI-TOF-TOF analysis of these tissues resulted in the identification of 49 proteins that were differentially accumulated. Dehydroascorbate reductase, glutathione reductase, and catalase enzymes associated with antioxidant activities were induced in Al-treated roots. Induced enzyme proteins associated with detoxification were mitochondrial aldehyde dehydrogenase, catechol oxidase, quinone reductase, and lactoylglutathione lyase. The germin-like (oxalate oxidase) proteins, the malate dehydrogenase, wali7 and heavy-metal associated domain-containing proteins were suppressed. VHA-ATP that encodes for the catalytic subunit A of the vacuolar ATP synthase was induced and two ATPase subunit 1 isoforms were suppressed. Several proteins in the active methyl cycle, including SAMS, quercetin 3-O-methyltransferase and AdoHcyase, were induced by Al stress. Other induced proteins were isovaleryl-CoA dehydrogenase and the GDSL-motif lipase hydrolase family protein. NADPH-dependent flavin reductase and beta-hydroxyacyl-ACP dehydratase were suppressed. PMID:19336389

  6. 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

  7. Control when it counts: Change in executive control under stress predicts depression symptoms.

    PubMed

    Quinn, Meghan E; Joormann, Jutta

    2015-08-01

    Individual differences in the ability to regulate affect following stressful life events have been associated with an increased risk for experiencing depression symptoms. Research further suggests that emotion regulation may depend on executive control which, in turn, has been shown to decline following stress exposure. Whether individual differences in stress-induced change in executive control predict depression symptoms, however, remains unknown. The current study examined whether trait executive control as well as stress-induced change in executive control predicts depression symptoms during a stressful time of life. The current study recruited 43 individuals during their first year of college. Participants completed an executive control task before and after a laboratory stress induction. Participants reported baseline depression symptoms during the laboratory session and follow-up depression symptoms during the final weeks of the semester. Results demonstrate that stress-induced change in executive control predicted an increase in depression symptoms at the end of the semester. The findings suggest that individual differences in the degree of decline in executive control following stress exposure may be a key factor in explaining why some individuals are vulnerable to depression during a stressful time of life. PMID:26098731

  8. 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.

  9. Co-seismic EM signals in magnetotelluric measurement -- a case study during Bhuj earthquake (26th January 2001), India

    NASA Astrophysics Data System (ADS)

    Abdul Azeez, K. K.; Manoj, C.; Veeraswamy, K.; Harinarayana, T.

    2009-08-01

    Significant changes in amplitude and frequency characteristics were observed in the magnetotelluric (MT) time series recorded during Bhuj earthquake (˜7.6 Mw), at a site ˜350 km from the epicenter. The telluric and magnetic signals recorded in the frequency range (10-1-101 Hz) of MT spectrum show considerable variations in their spectral characteristics during the earthquake event compared to the data recorded before and after the earthquake. The spectral analysis brings out sharp changes in amplitude of low-frequency signals during the earthquake as compared to the typical flat spectrum observed before and after the earthquake. The wavelet analysis of the electric and magnetic field data reveals two different spectral regimes; (1) the flat spectrum related to the natural MT signals, and (2) localized, high amplitude signals (in time and frequency) related to the onset of main shock. Three more high amplitude events are noted in the wavelet spectrum, after the main shock event, and can be speculated to be associated with the after-shock events. The MT impedance estimates clearly show scattered apparent resistivity and phase values during the earthquake suggesting that the high amplitude electric and magnetic signals were not related by an MT transfer function. The MT impedance estimates made before and after the earthquake are strikingly normal and smooth. The Pearson's correlation coefficients between the orthogonal electric and magnetic fields show a drastic drop for the data measured during earthquake, while the MT fields recorded before and after the earthquake are well correlated. The observed MT signals during the seismic activity do not show any external geomagnetic origin and may be attributed to co-seismic EM phenomena. The probable mechanisms responsible for the co-seismic EM phenomena could be electro-kinetic and seismic dynamo effects.

  10. Lessons on the calculation of static stress loading from the 2003 Bingol, Turkey earthquake [rapid communication

    NASA Astrophysics Data System (ADS)

    Nalbant, Suleyman S.; McCloskey, John; Steacy, Sandy

    2005-07-01

    The 2003 Bingol earthquake ( Mw = 6.4) occurred very close to a region along the east Anatolian fault zone which was identified in 2002 as posing a particularly high seismic risk. This damaging earthquake occurred on a conjugate right-lateral blind fault that was inconsistent with the stress-change field calculated for preceding large earthquakes in the region. In this paper, four reasons which might be responsible for this stress discrepancy are identified and investigated individually. Firstly, co-seismic stress changes are considered. The time frame of the previous stress calculations is extended to include the large earthquakes in the 1780s which were not included in the earlier study. A sensitivity analysis is then conducted on the more recent events since 1822 to examine the effect of errors in their location and sizes. The possibility of the occurrence of a small magnitude event close to the 2003 epicentre is considered. We argue that, barring the occurrence of a low-probability, unmodelled local event, the Bingol earthquake was unlikely to have been triggered by co-seismic stress transfer from any known sequence of previous earthquakes. Finally we examine and modify the secular loading model used in the 2002 study and show that loading which is properly constrained by regional GPS data produces a positive stress change on the 2003 rupture. As a result of our examination of the stressing history of the Bingol hypocentre we argue that it is through a combination of historical seismology, guided and constrained by structural geology, directed paleoseismology in which the locations and extent of historical events are confirmed, and stress modelling which has been informed by detailed GPS data, that an integrated seismic hazard program might have the best chance of success.

  11. Change and Stress in the Modern Office. FEU/PICKUP. An Occasional Paper.

    ERIC Educational Resources Information Center

    Cox, Sue

    This report summarizes the findings of a study on stress management training in the modern office. It identifies the training needs arising from the modernization of the office environment and the consequent stress experienced by staff, reflecting both the experience of change and the demands of the information technology (IT) environment. The…

  12. Organizational Decision-Making and the Change Agent: The Controlled Use of Stress.

    ERIC Educational Resources Information Center

    Hanson, Mark

    This document asks whether a stress situation created in an organization could be controlled and used to influence the decisionmaking process. The hypothesis tested was that stress induced intentionally by a change agent in a target agency, with consequent generation of strain between the actors of the organizational, would result in the…

  13. Effect of prior drought and pathogen stress on Arabidopsis transcriptome changes to caterpillar herbivory.

    PubMed

    Davila Olivas, Nelson H; Coolen, Silvia; Huang, Pingping; Severing, Edouard; van Verk, Marcel C; Hickman, Richard; Wittenberg, Alexander H J; de Vos, Martin; Prins, Marcel; van Loon, Joop J A; Aarts, Mark G M; van Wees, Saskia C M; Pieterse, Corné M J; Dicke, Marcel

    2016-06-01

    In nature, plants are exposed to biotic and abiotic stresses that often occur simultaneously. Therefore, plant responses to combinations of stresses are most representative of how plants respond to stresses. We used RNAseq to assess temporal changes in the transcriptome of Arabidopsis thaliana to herbivory by Pieris rapae caterpillars, either alone or in combination with prior exposure to drought or infection with the necrotrophic fungus Botrytis cinerea. Pre-exposure to drought stress or Botrytis infection resulted in a significantly different timing of the caterpillar-induced transcriptional changes. Additionally, the combination of drought and P. rapae induced an extensive downregulation of A. thaliana genes involved in defence against pathogens. Despite a more substantial growth reduction observed for plants exposed to drought plus P. rapae feeding compared with P. rapae feeding alone, this did not affect weight increase of this specialist caterpillar. Plants respond to combined stresses with phenotypic and transcriptional changes that differ from the single stress situation. The effect of a previous exposure to drought or B. cinerea infection on transcriptional changes to caterpillars is largely overridden by the stress imposed by caterpillars, indicating that plants shift their response to the most recent stress applied. PMID:26847575

  14. Climate change hampers endangered species through intensified moisture-related plant stresses (Invited)

    NASA Astrophysics Data System (ADS)

    Bartholomeus, R.; Witte, J.; van Bodegom, P.; Dam, J. V.; Aerts, R.

    2010-12-01

    With recent climate change, extremes in meteorological conditions are forecast and observed to increase globally, and to affect vegetation composition. More prolonged dry periods will alternate with more intensive rainfall events, both within and between years, which will change soil moisture dynamics. In temperate climates, soil moisture, in concert with nutrient availability and soil acidity, is the most important environmental filter in determining local plant species composition, as it determines the availability of both oxygen and water to plant roots. These resources are indispensable for meeting the physiological demands of plants. The consequences of climate change for our natural environment are among the most pressing issues of our time. The international research community is beginning to realise that climate extremes may be more powerful drivers of vegetation change and species extinctions than slow-and-steady climatic changes, but the causal mechanisms of such changes are presently unknown. The roles of amplitudes in water availability as drivers of vegetation change have been particularly elusive owing to the lack of integration of the key variables involved. Here we show that the combined effect of increased rainfall variability, temperature and atmospheric CO2-concentration will lead to an increased variability in both wet and dry extremes in stresses faced by plants (oxygen and water stress, respectively). We simulated these plant stresses with a novel, process-based approach, incorporating in detail the interacting processes in the soil-plant-atmosphere interface. In order to quantify oxygen and water stress with causal measures, we focused on interacting meteorological, soil physical, microbial, and plant physiological processes in the soil-plant-atmosphere system. As both the supply and demand of oxygen and water depend strongly on the prevailing meteorological conditions, both oxygen and water stress were calculated dynamically in time to

  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. Psychosocial stress and changes in estimated glomerular filtration rate among adults with diabetes mellitus

    PubMed Central

    Annor, Francis B.; Masyn, Katherine E.; Okosun, Ike S.; Roblin, Douglas W.; Goodman, Michael

    2015-01-01

    Background Psychosocial stress has been hypothesized to impact renal changes, but this hypothesis has not been adequately tested. The aim of this study was to examine the relationship between psychosocial stress and estimated glomerular filtration rate (eGFR) and to examine other predictors of eGFR changes among persons with diabetes mellitus (DM). Methods Data from a survey conducted in 2005 by a major health maintenance organization located in the southeastern part of the United States, linked to patients’ clinical and pharmacy records (n=575) from 2005 to 2008, was used. Study participants were working adults aged 25–59 years, diagnosed with DM but without advanced microvascular or macrovascular complications. eGFR was estimated using the Modification of Diet in Renal Disease equation. A latent psychosocial stress variable was created from five psychosocial stress subscales. Using a growth factor model in a structural equation framework, we estimated the association between psychosocial stress and eGFR while controlling for important covariates. Results The psychosocial stress variable was not directly associated with eGFR in the final model. Factors found to be associated with changes in eGFR were age, race, insulin use, and mean arterial pressure. Conclusion Among fairly healthy DM patients, we did not find any evidence of a direct association between psychosocial stress and eGFR changes after controlling for important covariates. Predictors of eGFR change in our population included age, race, insulin use, and mean arterial pressure. PMID:26484039

  17. Stress-Induced Chromatin Changes: A Critical View on Their Heritability

    PubMed Central

    Pecinka, Ales; Mittelsten Scheid, Ortrun

    2012-01-01

    The investigation of stress responses has been a focus of plant research, breeding and biotechnology for a long time. Insight into stress perception, signaling and genetic determinants of resistance has recently been complemented by growing evidence for substantial stress-induced changes at the chromatin level. These affect specific sequences or occur genome-wide and are often correlated with transcriptional regulation. The majority of these changes only occur during stress exposure, and both expression and chromatin states typically revert to the pre-stress state shortly thereafter. Other changes result in the maintenance of new chromatin states and modified gene expression for a longer time after stress exposure, preparing an individual for developmental decisions or more effective defence. Beyond this, there are claims for stress-induced heritable chromatin modifications that are transmitted to progeny, thereby improving their characteristics. These effects resemble the concept of Lamarckian inheritance of acquired characters and represent a challenge to the uniqueness of DNA sequence-based inheritance. However, with the growing insight into epigenetic regulation and transmission of chromatin states, it is worth investigating these phenomena carefully. While genetic changes (mainly transposon mobility) in response to stress-induced interference with chromatin are well documented and heritable, in our view there is no unambiguous evidence for transmission of exclusively chromatin-controlled stress effects to progeny. We propose a set of criteria that should be applied to substantiate the data for stress-induced, chromatin-encoded new traits. Well-controlled stress treatments, thorough phenotyping and application of refined genome-wide epigenetic analysis tools should be helpful in moving from interesting observations towards robust evidence. PMID:22457398

  18. Stress-induced adaptive islet cell identity changes.

    PubMed

    Cigliola, V; Thorel, F; Chera, S; Herrera, P L

    2016-09-01

    The different forms of diabetes mellitus differ in their pathogenesis but, ultimately, they are all characterized by progressive islet β-cell loss. Restoring the β-cell mass is therefore a major goal for future therapeutic approaches. The number of β-cells found at birth is determined by proliferation and differentiation of pancreatic progenitor cells, and it has been considered to remain mostly unchanged throughout adult life. Recent studies in mice have revealed an unexpected plasticity in islet endocrine cells in response to stress; under certain conditions, islet non-β-cells have the potential to reprogram into insulin producers, thus contributing to restore the β-cell mass. Here, we discuss the latest findings on pancreas and islet cell plasticity upon physiological, pathological and experimental conditions of stress. Understanding the mechanisms involved in cell reprogramming in these models will allow the development of new strategies for the treatment of diabetes, by exploiting the intrinsic regeneration capacity of the pancreas. PMID:27615136

  19. 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

  20. Transcriptome Changes for Arabidopsis in Response to Salt, Osmotic, and Cold Stress1[w

    PubMed Central

    Kreps, Joel A.; Wu, Yajun; Chang, Hur-Song; Zhu, Tong; Wang, Xun; Harper, Jeff F.

    2002-01-01

    To identify genes of potential importance to cold, salt, and drought tolerance, global expression profiling was performed on Arabidopsis plants subjected to stress treatments of 4°C, 100 mm NaCl, or 200 mm mannitol, respectively. RNA samples were collected separately from leaves and roots after 3- and 27-h stress treatments. Profiling was conducted with a GeneChip microarray with probe sets for approximately 8,100 genes. Combined results from all three stresses identified 2,409 genes with a greater than 2-fold change over control. This suggests that about 30% of the transcriptome is sensitive to regulation by common stress conditions. The majority of changes were stimulus specific. At the 3-h time point, less than 5% (118 genes) of the changes were observed as shared by all three stress responses. By 27 h, the number of shared responses was reduced more than 10-fold (< 0.5%), consistent with a progression toward more stimulus-specific responses. Roots and leaves displayed very different changes. For example, less than 14% of the cold-specific changes were shared between root and leaves at both 3 and 27 h. The gene with the largest induction under all three stress treatments was At5g52310 (LTI/COR78), with induction levels in roots greater than 250-fold for cold, 40-fold for mannitol, and 57-fold for NaCl. A stress response was observed for 306 (68%) of the known circadian controlled genes, supporting the hypothesis that an important function of the circadian clock is to “anticipate” predictable stresses such as cold nights. Although these results identify hundreds of potentially important transcriptome changes, the biochemical functions of many stress-regulated genes remain unknown. PMID:12481097

  1. 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

  2. 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. PMID:23852614

  3. 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.

  4. Is co-seismic landslide clustering due to topographic site effects?

    NASA Astrophysics Data System (ADS)

    Rault, Claire; Meunier, Patrick; Marc, Odin; Hovius, Neils

    2016-04-01

    We have documented the spatial and time variation of co-seismic landslides position along topographic hillslopes within six strong shallow earthquakes (M w >6): the 1993 Finisterre, the 1994 Northridge, the 1999 Chichi, the 2004 Niigata, the 2008 Wenchuan, and the 2008 Iwate-Miyagi earthquakes. Landslides rate increases with the duration and level of ground motion. In a mountain area in most of the case the highest ground motion amplification occurs near or at the top of the crest due to the interaction of upcoming wave with topography. As a consequence, co-seismic landslides should tend to occur near or at the top of the ridge. The landslides where localized along slope using GIS mapping. We compare lo- cation of co-seismic landslides to the one of pre- and post-seismic landslides catalogues, when available. We show that a co-seismic signature of landslides position (i.e. crest clustering) is not systematically obvious, we identified crest clustering pattern in only three epicentral areas. Clustering patterns show no clear relation with lithology, topographic, or ground motion parameters. Hence earthquake-triggered landslides in some cases, may be the results of complex combination of predispose (lithology, slope, etc) and triggered (rainfall and earthquakes) parameters.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Coseismic Coastal Movements Associated with Strong Submarine Paleoearthquakes in the Eastern Segment of the Hellenic Arc: Observations from Rhodes Isl. (Greece)

    NASA Astrophysics Data System (ADS)

    Triantafyllou, I.; Papadopoulos, G. A.

    2014-12-01

    The eastern segment of the Hellenic Arc and Trench system is characterized by the occurrence of large earthquakes and tsunamis known from both the historical and geological record particularly in Rhodes Isl. (Greece). Historical sources maintain direct evidence of coseismic uplift in the eastern coast of Rhodes, e.g. the very large earthquake of 12 October 1856 (M~7.5), caused ground uplift while the sea receded permanently. Similar observations have been made regarding the earthquake of c. 227 BC who caused the collapse of Colossus in Rhodes and the tsunamigenic earthquake of c. AD 142. Such observations, supported by the instrumental record of seismicity, make realistic the suggestion that the historical earthquakes had their epicenters offshore but close to Rhodes city. However, in SW Asia Minor at the opposite side of Rhodes, coastal subsidence was reported as a result of the strong earthquake sequence of February-April 1851. The occurrence of strong tsunamis after some earthquakes is an independent evidence for significant, submarine coseismic fault displacement very likely in the Rhodes Abyssal Plain of water depth up to 3 km. On the other hand, geological observations have indicated that the eastern side of Rhodes has systematically uplifted during the Holocene with uplift amplitude increasing from S to N with average velocity ranging from 0 in Prasonisi at south to 1 mm/yr at the NE side of the island where coseismic uplift was reported historically. We compare the historical rate of uplift with the geologically estimated rate. To this aim we compiled a new catalogue of historical earthquakes that caused coseismic uplift in the coastal zone of Rhodes city and adopted that they had their epicenters offshore but very close to the city. From damage descriptions maximum macroseismic intensity was assigned to each one of the earthquakes. Then intensity was converted to earthquake magnitude from empirical relationships found for instrumental Greek earthquakes

  12. 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

  13. 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

  14. 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. PMID:25668390

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  16. Metabolite profiling and network analysis reveal coordinated changes in grapevine water stress response

    PubMed Central

    2013-01-01

    Background Grapevine metabolism in response to water deficit was studied in two cultivars, Shiraz and Cabernet Sauvignon, which were shown to have different hydraulic behaviors (Hochberg et al. Physiol. Plant. 147:443–453, 2012). Results Progressive water deficit was found to effect changes in leaf water potentials accompanied by metabolic changes. In both cultivars, but more intensively in Shiraz than Cabernet Sauvignon, water deficit caused a shift to higher osmolality and lower C/N ratios, the latter of which was also reflected in marked increases in amino acids, e.g., Pro, Val, Leu, Thr and Trp, reductions of most organic acids, and changes in the phenylpropanoid pathway. PCA analysis showed that changes in primary metabolism were mostly associated with water stress, while diversification of specialized metabolism was mostly linked to the cultivars. In the phloem sap, drought was characterized by higher ABA concentration and major changes in benzoate levels coinciding with lower stomatal conductance and suberinization of vascular bundles. Enhanced suberin biosynthesis in Shiraz was reflected by the higher abundance of sap hydroxybenzoate derivatives. Correlation-based network analysis revealed that compared to Cabernet Sauvignon, Shiraz had considerably larger and highly coordinated stress-related changes, reflected in its increased metabolic network connectivity under stress. Network analysis also highlighted the structural role of major stress related metabolites, e.g., Pro, quercetin and ascorbate, which drastically altered their connectedness in the Shiraz network under water deficit. Conclusions Taken together, the results showed that Vitis vinifera cultivars possess a common metabolic response to water deficit. Central metabolism, and specifically N metabolism, plays a significant role in stress response in vine. At the cultivar level, Cabernet Sauvignon was characterized by milder metabolic perturbations, likely due to a tighter regulation of stomata

  17. Signals for Change: Stress Indicators for Colleges and Universities.

    ERIC Educational Resources Information Center

    Glenny, Lyman A.; Bowen, Frank M.

    Thirty-five indicators of the need for change in a higher education institution are outlined. They are divided into two large categories: those over which the institution has little or no control, and those over which it has some or total control. Within those categories are subcategories: indicators for short-range planning, and those for…

  18. Behavioral changes over time in post-traumatic stress disorder: Insights from a rat model of single prolonged stress.

    PubMed

    Wu, Zhuoyun; Tian, Qing; Li, Feng; Gao, Junqiao; Liu, Yan; Mao, Meng; Liu, Jing; Wang, Shuyan; Li, Genmao; Ge, Dongyu; Mao, Yingqiu; Zhang, Wei; Liu, Zhaolan; Song, Yuehan

    2016-03-01

    Post-traumatic stress disorder (PTSD) is manifested as a persistent mental and emotional condition after potentially life-threatening events. Different animal models of PTSD have been developed for neuro-pathophysiology and pharmacological evaluations. A single prolonged stress (SPS) induced animal model has demonstrated to result in specific neuro-endocrinological dysregulation, and behavior abnormalities observed in PTSD. However, animal studies of PTSD have mostly been performed at one time point after SPS exposure. To better understand the development of PTSD-like behaviors in the SPS animal model, and to identify an optimal period of study, we examined depressive behavior, anxiety-like behavior, physical activity and body weight in SPS model rats for two weeks. Our results confirmed the SPS-induced PTSD-like behavior and physical activity observed in previous studies, and indicated that the most pronounced symptomatic behavior changes were observed on day 1 and 7 after SPS exposure, which may involve stress-induced acute hormone changes and unclear secondary neurobiological changes, respectively. These results provide a solid basis for further investigation into the neuro-pathophysiology of or neuropharmacology for PTSD using the SPS rat model. However, for chronic (pharmacological) studies longer than 7 days, a prolonged PTSD animal model should be developed, perhaps using enhanced stimulation. PMID:26772783

  19. Fragility of Forearc Stresses as a Consequence of Extreme Weakness of Megathrust Faults

    NASA Astrophysics Data System (ADS)

    Wang, K.; Brown, L. N.; He, J.; Sun, T.

    2015-12-01

    There is mounting evidence that subduction megathrusts are extremely weak. The weakness is based on a spatial and temporal average. Spatially, a seismogenic megathrust may host interspersed stronger and weaker patches due to variations in pore fluid pressure, gouge properties, and fault zone structure. In the 2011 M=9 Tohoku-oki earthquake, one strong patch underwent a local stress drop of several tens of MPa, although the rupture-zone average of the stress drop is less than 5 MPa on the basis of all the (> 20) published rupture models for this earthquake that we have examined. Temporally, megathrust strength fluctuates in earthquake cycles, punctuated by coseismic weakening or strengthening of different patches. Using finite element modeling, we demonstrate that the weakness of the megathrust leads to a fragile state of stress in the overlying forearc wedge, where compression due to plate coupling and tension due to gravity are in a subtle balance that can be tipped by small perturbations. Prior to the Tohoku-oki earthquake, the Japan Trench forearc was predominantly under margin-normal compression, a state that can be modeled using an effective friction coefficient of 0.032 for the megathrust. In a coseismic deformation model, an average stress drop of about 4 MPa on the megathrust changes the offshore forearc into tension. This is consistent with the observed stress reversal in this region as a result of the Tohoku-oki earthquake. The same level of coseismic stress drop would not cause the observed forearc stress reversal if the megathrust was assumed to have a higher strength such as 0.045. The state of stress in the offshore forearc is so fragile that large changes can be caused by other seemingly benign perturbing factors. For example, without the ocean water compressing the continental slope, much of the offshore forearc would no longer be in compression even if the megathrust strength were twice the value of 0.032. If the slope angle of the continental

  20. 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. PMID:24513700

  1. Rapid stress-induced transcriptomic changes in the brain depend on beta-adrenergic signaling.

    PubMed

    Roszkowski, Martin; Manuella, Francesca; von Ziegler, Lukas; Durán-Pacheco, Gonzalo; Moreau, Jean-Luc; Mansuy, Isabelle M; Bohacek, Johannes

    2016-08-01

    Acute exposure to stressful experiences can rapidly increase anxiety and cause neuropsychiatric disorders. The effects of stress result in part from the release of neurotransmitters and hormones, which regulate gene expression in different brain regions. The fast neuroendocrine response to stress is largely mediated by norepinephrine (NE) and corticotropin releasing hormone (CRH), followed by a slower and more sustained release of corticosterone. While corticosterone is an important regulator of gene expression, it is not clear which stress-signals contribute to the rapid regulation of gene expression observed immediately after stress exposure. Here, we demonstrate in mice that 45 min after an acute swim stress challenge, large changes in gene expression occur across the transcriptome in the hippocampus, a region sensitive to the effects of stress. We identify multiple candidate genes that are rapidly and transiently altered in both males and females. Using a pharmacological approach, we show that most of these rapidly induced genes are regulated by NE through β-adrenergic receptor signaling. We find that CRH and corticosterone can also contribute to rapid changes in gene expression, although these effects appear to be restricted to fewer genes. These results newly reveal a widespread impact of NE on the transcriptome and identify novel genes associated with stress and adrenergic signaling. PMID:27026109

  2. Evaluation of in situ stress changes with gas depletion of coalbed methane reservoirs

    NASA Astrophysics Data System (ADS)

    Liu, Shimin; Harpalani, Satya

    2014-08-01

    A sound knowledge of the stress path for coalbed methane (CBM) reservoirs is critical for a variety of applications, including dynamic formation stability evaluation, long-term gas production management, and carbon sequestration in coals. Although this problem has been extensively studied for traditional oil and gas reservoirs, it is somewhat unclear for CBM reservoirs. The difference between the stress paths followed in the two reservoir types is expected to be significant given the unique sorption-induced deformation phenomenon associated with gas production from coal. This results in an additional reservoir volumetric strain, which induces a rather "abnormal" loss of horizontal stress with depletion, leading to continuous changes in the subsurface formation stresses, both effective as well as total. It is suspected that stress changes within the reservoir triggers formation failure after significant depletion. This paper describes an experimental study, carried out to measure the horizontal stress under in situ depletion conditions. The results show that the horizontal stress decreases linearly with depletion under in situ conditions. The dynamic stress evolution is theoretically analyzed, based on modified poroelasticity associated with sorption-induced strain effect. Additionally, the failure tendency of the reservoir under in situ conditions is analyzed using the traditional Mohr-Coulomb failure criterion. The results indicate that depletion may lead to coal failure, particularly in deeper coalbeds and ones exhibiting large matrix shrinkage.

  3. Increased glutathione contributes to stress tolerance and global translational changes in Arabidopsis.

    PubMed

    Cheng, Mei-Chun; Ko, Ko; Chang, Wan-Ling; Kuo, Wen-Chieh; Chen, Guan-Hong; Lin, Tsan-Piao

    2015-09-01

    Although glutathione is well known for its reactive oxygen species (ROS) scavenging function and plays a protective role in biotic stress, its regulatory function in abiotic stress still remains to be elucidated. Our previous study showed that exogenously applied reduced glutathione (GSH) could improve abiotic stress tolerance in Arabidopsis. Here, we report that endogenously increased GSH also conferred tolerance to drought and salt stress in Arabidopsis. Moreover, both exogenous and endogenous GSH delayed senescence and flowering time. Polysomal profiling results showed that global translation was enhanced after GSH treatment and by the induced increase of GSH level by salt stress. By performing transcriptomic analyses of steady-state and polysome-bound mRNAs in GSH-treated plants, we reveal that GSH has a substantial impact on translation. Translational changes induced by GSH treatment target numerous hormones and stress signaling molecules, which might contribute to the enhanced stress tolerance in GSH-treated plants. Our translatome analysis also revealed that abscisic acid (ABA), auxin and jasmonic acid (JA) biosynthesis, as well as signaling genes, were activated during GSH treatment, which has not been reported in previously published transcriptomic data. Together, our data suggest that the increased glutathione level results in stress tolerance and global translational changes. PMID:26213235

  4. Stress inducible proteomic changes in Capsicum annuum leaves.

    PubMed

    Mahajan, Neha S; Mishra, Manasi; Tamhane, Vaijayanti A; Gupta, Vidya S; Giri, Ashok P

    2014-01-01

    Herbivore attack induces defense responses in plants, activating several signaling cascades. As a result, molecules deterrent to the herbivores are produced and accumulated in plants. Expression of defense mechanism/traits requires reorganization of the plant metabolism, redirecting the resources otherwise meant for growth. In the present work, protein profile of Capsicum annuum leaves was examined after herbivore attack/induction. Majority of proteins identified as differentially accumulated, were having roles in redox metabolism and photosynthesis. For example, superoxide dismutase and NADP oxidoreductase were upregulated by 10- and 6-fold while carbonic anhydrase and fructose-1,6-bisphosphatase were downregulated by 9- and 4-fold, respectively. Also, superoxide dismutase, NADPH quinone oxidoreductase and NADP dependent isocitrate dehydrogenase transcripts showed a higher accumulation in induced leaf tissues at early time points. In general, proteins having role in defense and damage repair were upregulated while those involved in photosynthesis appeared downregulated. Thus metabolic reconfiguration to balance defense and tolerance was evident in the stress-induced leaves. PMID:24316010

  5. Behavioural and biochemical changes in maternally separated Sprague-Dawley rats exposed to restraint stress.

    PubMed

    van Zyl, P J; Dimatelis, J J; Russell, V A

    2016-02-01

    Early life adversity has been associated with the development of various neuropsychiatric disorders in adulthood such as depression and anxiety. The aim of this study was to determine if stress during adulthood can exaggerate the depression-/anxiety-like behaviour observed in the widely accepted maternally separated (MS) Sprague-Dawley (SD) rat model of depression. A further aim was to determine whether the behavioural changes were accompanied by changes in hippocampal brain-derived neurotrophic factor (BDNF) and the protein profile of the prefrontal cortex (PFC). Depression-/anxiety-like behaviour was measured in the elevated plus maze, open field and forced swim test (FST) in the MS SD rats exposed to chronic restraint stress in adulthood. As expected, MS increased immobility of SD rats in the FST but restraint stress did not enhance this effect of MS on SD rats. A proteomic analysis of the PFC revealed a decrease in actin-related proteins in MS and non-separated rats subjected to restraint stress as well as a decrease in mitochondrial energy-related proteins in the stressed rat groups. Since MS during early development causes a disruption in the hypothalamic-pituitary-adrenal axis and long-term changes in the response to subsequent stress, it may have prevented restraint stress from exerting its effects on behaviour. Moreover, the decrease in proteins related to mitochondrial energy metabolism in MS rats with or without subsequent restraint stress may be related to stress per se and not depression-like behaviour, because rats subjected to restraint stress displayed similar decreases in energy-related proteins and spent less time immobile in the FST than control rats. PMID:26555398

  6. 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.

  7. 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

  8. Stress-induced changes in skin barrier function in healthy women.

    PubMed

    Altemus, M; Rao, B; Dhabhar, F S; Ding, W; Granstein, R D

    2001-08-01

    Despite clear exacerbation of several skin disorders by stress, the effect of psychologic or exertional stress on human skin has not been well studied. We investigated the effect of three different stressors, psychologic interview stress, sleep deprivation, and exercise, on several dermatologic measures: transepidermal water loss, recovery of skin barrier function after tape stripping, and stratum corneum water content (skin conductance). We simultaneously measured the effects of stress on plasma levels of several stress-response hormones and cytokines, natural killer cell activity, and absolute numbers of peripheral blood leukocytes. Twenty-five women participated in a laboratory psychologic interview stress, 11 women participated in one night of sleep deprivation, and 10 women participated in a 3 d exercise protocol. The interview stress caused a delay in the recovery of skin barrier function, as well as increases in plasma cortisol, norepinephrine, interleukin-1beta and interleukin-10, tumor necrosis factor-alpha, and an increase in circulating natural killer cell activity and natural killer cell number. Sleep deprivation also decreased skin barrier function recovery and increased plasma interleukin-1beta, tumor necrosis factor-alpha, and natural killer cell activity. The exercise stress did not affect skin barrier function recovery, but caused an increase in natural killer cell activity and circulating numbers of both cytolytic T lymphocytes and helper T cells. In addition, cytokine responses to the interview stress were inversely correlated with changes in barrier function recovery. These results suggest that acute psychosocial and sleep deprivation stress disrupts skin barrier function homeostasis in women, and that this disruption may be related to stress-induced changes in cytokine secretion. PMID:11511309

  9. 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.

  10. Changes in static stress on southern California faults after the 1992 Landers earthquake

    USGS Publications Warehouse

    Harris, R.A.; Simpson, R.W.

    1992-01-01

    THE magnitude 7.5 Landers earthquake of 28 June 1992 was the largest earthquake to strike California in 40 years. The slip that occurs in such an earthquake would be expected to induce large changes in the static stress on neighbouring faults; these changes in stress should in turn affect the likelihood of future earthquakes. Stress changes that load faults towards failure have been cited as the cause of small1-5, moderate6 and large7 earthquakes; conversely, those that relax neighbouring faults have been related to a decrease in seismicity5. Here we use an elastic half-space model8 to estimate the stress changes produced by the Landers earthquake on selected southern California faults, including the San Andreas. We find that the estimated stress changes are consistent with the triggering of four out of the five aftershocks with magnitude greater than 4.5, and that the largest changes (1-10 bar), occurring on part of the San Bernardino segment of the San Andreas fault, may have decreased the time to the next magnitude 8 earthquake by about 14 years.