Re-assessment of peak ground accelerations for large magnitude Vrancea intermediate-depth earthquakes

2020 ◽  
Vol 24 (6) ◽  
pp. 1271-1280
Author(s):  
Florin Pavel ◽  
Radu Vacareanu
Keyword(s):  
Large Magnitude ◽  
Intermediate Depth ◽  
Peak Ground Accelerations

scholarly journals Northern Chile intermediate-depth earthquakes controlled by plate hydration

2020 ◽  
Author(s):  
Leoncio Cabrera ◽  
Sergio Ruiz ◽  
Piero Poli ◽  
Eduardo Contreras-Reyes ◽  
Axel Osses ◽  
...  
Keyword(s):  
Template Matching ◽  
Thermal Structure ◽  
Seismic Source ◽  
Northern Chile ◽  
Large Magnitude ◽  
Aftershock Activity ◽  
Dramatic Decrease ◽  
Intermediate Depth ◽  
Subducting Plate

Summary We investigate the variations of the seismic source properties and aftershock activity using kinematic inversions and template-matching, for six large magnitude intermediate-depth earthquakes occurred in northern Chile. Results show similar rupture geometry and stress drop values between 7–30 MPa. Conversely, aftershocks productivity systematically decreases for the deeper events within the slab. Particularly there is a dramatic decrease in aftershock activity below the 400–450°C isotherm-depth, which separates high and low-hydrated zones. The events exhibit tensional focal mechanisms at unexpected depths within the slab, suggesting a deepening of the neutral plane, where the extensional regimen reaches the 700–800°C isotherm-depth. We interpret the reduction of aftershocks in the lower part of the extensional regime as the absence of a hydrated-slab at those depths. Our finding highlights the role of the thermal-structure and fluids in the subducting plate, in controlling the intermediated-depth seismic activity and shed new light in their causative mechanism.

Ground Motions prediction Equations from a stochastic simulation approach for in-slab intermediate-depth earthquakes along the Hellenic subduction zone

2020 ◽  
Author(s):  
Harris Kkallas ◽  
Costas Papazachos ◽  
Dominikos Vamvakaris
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Motion Prediction ◽  
Ground Motion Prediction Equations ◽  
Prediction Equations ◽  
Ground Motion Prediction ◽  
Large Magnitude ◽  
Intermediate Depth ◽  
Back Arc

<p>We have used a stochastic approach to simulate a large number of scenarios for in-slab intermediate-depth earthquakes in the southern Aegean Sea Hellenic subduction region, by applying an extended-source model using the EXSIM code. A large database of synthetic ground motion recordings for events with magnitudes in the range <strong>M</strong>6.0-8.5 has been compiled, covering the whole southern Aegean Benioff zone. For the stochastic simulations, we followed the approach developed in our previous works (Kkallas et al., 2018a,b), where we used the anelastic attenuation from the GMPEs modeling developed by Skarlatoudis et al. (2013) to constrain the different attenuation patterns and properties for the back-arc and fore-arc area. Simulation model parameters, such as stress parameters and attenuation parameters were also adopted from previous works, while for fault parameters we adopted the typical average focal mechanisms proposed by Papazachos et al. (2000), in agreement with the regional subduction tectonics. Estimates of expected ground motion measurements (PGA and PGV values) at different distances from different earthquakes have been employed to generate hybrid Ground-Motion Prediction Equations (GMPE). More specifically, we attempt to modify the existing Ground-Motion Prediction Equations (GMPE) from Skarlatoudis et al. (2013) for intermediate-depth earthquakes along the Hellenic Arc for large magnitude events (<strong>M</strong>>6.5), so that they can be efficiently used for Seismic Hazard assessment, as the original strong-motion dataset used for their development was lacking data in this magnitude range. Peak ground accelerations and velocities predicted by the EXSIM code are generally in very good agreement with the available GMPE results for magnitudes less than <strong>M</strong>7. However, significantly lower ground motions than those predicted by the GMPEs are predicted for large-magnitude events (<strong>M</strong>>7). Using the previous results, we propose a magnitude-dependent correction for the GMPE results both back-arc and along-arc ground motions. Moreover, we demonstrate how the final earthquake ground motion scenarios, as well as the modified GMPEs affect both deterministic and probabilistic seismic hazard analysis. This work has been partly supported by the HELPOS (MIS 5002697) project.</p>

Strong-axis response of steel I-sections subjected to close-in detonations

2020 ◽  
pp. 204141962098448
Author(s):  
Hezi Y Grisaro ◽  
Michael V Seica ◽  
Jeffrey A Packer ◽  
Wei Li
Keyword(s):  
Computation Time ◽  
Structural Member ◽  
Local Damage ◽  
Structural Members ◽  
Large Magnitude ◽  
Single Degree Of Freedom ◽  
Charge Shape ◽  
Dynamic Scenario ◽  
Detonation Process ◽  
Residual Deformations

The analysis of structural members subjected to close-in detonations involves a complicated dynamic scenario. Since the charge is very close to the structural member, the reflected pressure distribution on the member surface is highly non-uniform. In addition, the level of damage to the structural member may be high because of the large magnitude of the load. Due to these phenomena, the response of a structural member to close-in detonation cannot be accurately modelled by relatively simple methods like single-degree of freedom models, and more complicated models are required. Such models need to include numerical simulation of the detonation process, which produces a non-uniform pressure environment, allowing the pressure to reflect and flow around the member section. The local damage and flow around the section are especially of interest in I-shaped, or wide-flange-section members. Herein, the response of such sections is modelled by numerical simulations using a novel technique, which overcomes the difficulty of computation time, and is validated through various calculations. The model is used to perform a parametric study to investigate the response of I-sections subjected to close-in detonations, in terms of local damage and global behaviour, with scaled distances of 0.15–0.29 m/kg1/3 and loading causing flexure about the strong axis. Various aspects that affect the performance are studied, such as: the effect of scaled distance, the addition of welded stiffening plates between the flanges and web, the effect of boundary conditions and the effect of charge shape. Resulting local damage and residual deformations are assessed for the cases studied.

scholarly journals Perceiving numerosity does not cause automatic shifts of spatial attention

2021 ◽  
Author(s):  
Michele Pellegrino ◽  
Mario Pinto ◽  
Fabio Marson ◽  
Stefano Lasaponara ◽  
Fabrizio Doricchi
Keyword(s):  
Spatial Attention ◽  
Colour Change ◽  
Simultaneous Presentation ◽  
Variable Delay ◽  
Large Magnitude ◽  
Small Magnitude ◽  
Spatial Component ◽  
Speed Up ◽  
The Right

AbstractIt is debated whether the representation of numbers is endowed with a directional-spatial component so that perceiving small-magnitude numbers triggers leftward shifts of attention and perceiving large-magnitude numbers rightward shifts. Contrary to initial findings, recent investigations have demonstrated that centrally presented small-magnitude and large-magnitude Arabic numbers do not cause leftward and rightward shifts of attention, respectively. Here we verified whether perceiving small or large non-symbolic numerosities (i.e., clouds of dots) drives attention to the left or the right side of space, respectively. In experiment 1, participants were presented with central small (1, 2) vs large-numerosity (8, 9) clouds of dots followed by an imperative target in the left or right side of space. In experiment 2, a central cloud of dots (i.e., five dots) was followed by the simultaneous presentation of two identical dot-clouds, one on the left and one on the right side of space. Lateral clouds were both lower (1, 2) or higher in numerosity (8, 9) than the central cloud. After a variable delay, one of the two lateral clouds turned red and participants had to signal the colour change through a unimanual response. We found that (a) in Experiment 1, the small vs large numerosity of the central cloud of dots did not speed up the detection of left vs right targets, respectively, (b) in Experiment 2, the detection of colour change was not faster in the left side of space when lateral clouds were smaller in numerosity than the central reference and in the right side when clouds were larger in numerosity. These findings show that perceiving non-symbolic numerosity does not cause automatic shifts of spatial attention and suggests no inherent association between the representation of numerosity and that of directional space.

Consideration on modeling of Nb sorption onto clay minerals

2020 ◽  
Vol 108 (11) ◽  
pp. 873-877
Author(s):  
Tetsuji Yamaguchi ◽  
Saki Ohira ◽  
Ko Hemmi ◽  
Logan Barr ◽  
Asako Shimada ◽  
...  
Keyword(s):  
Distribution Coefficient ◽  
Clay Minerals ◽  
Safety Assessment ◽  
Distribution Coefficients ◽  
Surface Species ◽  
Complex Species ◽  
Intermediate Depth ◽  
Speciation Model ◽  
Surface Phases ◽  
High Distribution Coefficient

AbstractSorption distribution coefficient (Kd) of niobium-94 on minerals are an important parameter in safety assessment of intermediate-depth disposal of waste from core internals etc. The Kd of Nb on clay minerals in Ca(ClO4)2 solutions were, however, not successfully modeled in a previous study. The high distribution coefficients of Nb on illite in Ca(ClO4)2 solutions were successfully reproduced by taking Ca–Nb–OH surface species into account. Solubility of Nb was studied in Ca(ClO4)2 solutions and the results were reproduced by taking an aqueous Ca–Nb–OH complex species, CaNb(OH)6+, into account in addition to previously reported Nb(OH)6− and Nb(OH)72−. Based on this aqueous speciation model, the Ca–Nb–OH surface species responsible for the sorption of Nb on illite in Ca(ClO4)2 solutions was presumed to be X_OCaNb(OH)6. Although uncertainties exist in the speciation of aqueous Ca–Nb–OH species, the result of this study proposed a possible mechanism for high distribution coefficient of Nb on illite in Ca(ClO4)2 solutions. The mechanism includes Ca–Nb–OH complex formation in aqueous, solid and surface phases.

scholarly journals Use of Pediatric Injectable Medicines Guidelines and Associated Medication Administration Errors: A Human Reliability Analysis

2021 ◽  
pp. 106002802199964
Author(s):  
Matthew D. Jones ◽  
Jonathan Clarke ◽  
Calandra Feather ◽  
Bryony Dean Franklin ◽  
Ruchi Sinha ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Medication Administration ◽  
Original Study ◽  
Human Reliability ◽  
Large Magnitude ◽  
Human Reliability Analysis ◽  
Video Recordings ◽  
Medication Administration Errors ◽  
Key Factor ◽  
Clinically Significant

Background: In a recent human reliability analysis (HRA) of simulated pediatric resuscitations, ineffective retrieval of preparation and administration instructions from online injectable medicines guidelines was a key factor contributing to medication administration errors (MAEs). Objective: The aim of the present study was to use a specific HRA to understand where intravenous medicines guidelines are vulnerable to misinterpretation, focusing on deviations from expected practice ( discrepancies) that contributed to large-magnitude and/or clinically significant MAEs. Methods: Video recordings from the original study were reanalyzed to identify discrepancies in the steps required to find and extract information from the NHS Injectable Medicines Guide (IMG) website. These data were combined with MAE data from the same original study. Results: In total, 44 discrepancies during use of the IMG were observed across 180 medication administrations. Of these discrepancies, 21 (48%) were associated with an MAE, 16 of which (36% of 44 discrepancies) made a major contribution to that error. There were more discrepancies (31 in total, 70%) during the steps required to access the correct drug webpage than there were in the steps required to read this information (13 in total, 30%). Discrepancies when using injectable medicines guidelines made a major contribution to 6 (27%) of 22 clinically significant and 4 (15%) of 27 large-magnitude MAEs. Conclusion and Relevance: Discrepancies during the use of an online injectable medicines guideline were often associated with subsequent MAEs, including those with potentially significant consequences. This highlights the need to test the usability of guidelines before clinical use.

scholarly journals A revised position for the primary strand of the Pleistocene-Holocene San Andreas fault in southern California

2021 ◽  
Vol 7 (13) ◽  
pp. eaaz5691
Author(s):  
Kimberly Blisniuk ◽  
Katherine Scharer ◽  
Warren D. Sharp ◽  
Roland Burgmann ◽  
Colin Amos ◽  
...  
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
San Andreas Fault ◽  
Slip Rate ◽  
Large Magnitude ◽  
Slip Rates ◽  
San Andreas ◽  
The Pacific ◽  
Large Earthquakes ◽  
Dependent Probability

The San Andreas fault has the highest calculated time-dependent probability for large-magnitude earthquakes in southern California. However, where the fault is multistranded east of the Los Angeles metropolitan area, it has been uncertain which strand has the fastest slip rate and, therefore, which has the highest probability of a destructive earthquake. Reconstruction of offset Pleistocene-Holocene landforms dated using the uranium-thorium soil carbonate and beryllium-10 surface exposure techniques indicates slip rates of 24.1 ± 3 millimeter per year for the San Andreas fault, with 21.6 ± 2 and 2.5 ± 1 millimeters per year for the Mission Creek and Banning strands, respectively. These data establish the Mission Creek strand as the primary fault bounding the Pacific and North American plates at this latitude and imply that 6 to 9 meters of elastic strain has accumulated along the fault since the most recent surface-rupturing earthquake, highlighting the potential for large earthquakes along this strand.

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