Upper Plate Response to a Sequential Elastic Rebound and Slab Acceleration During Laboratory‐Scale Subduction Megathrust Earthquakes

An earthquake‐induced stress drop on a megathrust instigates different responses on the upper plate and slab. We mimic homogenous and heterogeneous megathrust interfaces at the laboratory scale to monitor the strain relaxation on two elastically bi‐material plates by establishing analog velocity weakening and neutral materials. A sequential elastic rebound follows the coseismic shear‐stress drop in our elastoplastic‐frictional models: a fast rebound of the upper plate and the delayed and smaller rebound on the elastic belt (model slab). A combination of the rebound of the slab and the rapid relaxation (i.e., elastic restoration) of the upper plate after an elastic overshooting may accelerate the relocking of the megathrust. This acceleration triggers/antedates the failure of a nearby asperity and enhances the early slip reversal in the rupture area. Hence, the trench‐normal landward displacement in the upper plate may reach a significant amount of the entire interseismic slip reversal and speeds up the stress build‐up on the upper plate backthrust that emerges self‐consistently at the downdip end of the seismogenic zones. Moreover, the backthrust switches its kinematic mode from a normal to reverse mechanism during the coseismic and postseismic stages, reflecting the sense of shear on the interface

Unterschätzte Unbekannte - Aktive Störungen in der Oberplatte großer Subduktionssysteme

The Atacama Fault System (AFS) is an active trench-parallel fault system, located in the forearc of N-Chile directly above the subduction zone interface. Due to its well-exposed position in the hyper arid forearc of N-Chile it is the perfect target to investigate the interaction between the deformation cycle in the overriding forearc and the subduction zone seismic cycle of the underlying megathrust. Although the AFS and large parts of the upper crust are devoid of any noteworthy seismicity or historically documented earthquakes, at least three M=7 earthquakes in the past 10 ky have been documented in the paleoseismological record, demonstrating the potential of large events in the future. We apply a two-fold approach to explore fault activation and reactivation patterns through time and to investigate the triggering potential of upper crustal faults. 1) A new methodology using high-resolution topographic data allows us to investigate the number of past earthquakes for any given segment of the fault system as well as the amount of vertical displacement of the last increment. This provides us with a detailed dataset of past earthquake rupture of upper plate faults which is potentially linked to large subduction zone earthquakes. 2) The IPOC Creepmeter array provides us with high-resolution time series of fault displacement accumulation for eleven stations along the four most active branches of the AFS

CANEUS2006-11042 HIGH TEMPERATURE (800°C) MEMS PRESSURE SENSOR DEVELOPMENT INCLUDING REUSABLE PACKAGING FOR ROCKET ENGINE APPLICATIONS

ABSTRACT For aircraft and rocket engines there is a strong need to measure the pressure in the propulsion system at high temperature (HT) with a high local resolution. Miniaturized sensor elements commercially available show decisive disadvantages. With piezoelectric-based sensors working clearly above 500°C static pressures can not be measured. Optical sensors are very expensive and require complex electronics. SiC sensor prototypes are operated up to 650°C, but require high technological efforts. The present approach is based on resistors placed on top of a 2 mm diameter sapphire membrane (8 mm chip diameter). The strain gauges are made either of antimony doped tin oxide (SnO2:Sb) or platinum (Pt). This material combination allows for matching the thermal coefficients of expansion (TCE) of the materials involved. The morphology of the SnO 2 :Sb layer can be optimized to reduce surface roughness on the nanometer scale and hence, gas sensitivity. Antimony doping increases conductivity, but decreases the gauge factor. With this nanotechnological knowledge it is possible to adjust the material properties to the needs of our aerospace applications. Tin oxide was shown to be very stable at HT. We also measured a 2.5% change in electrica

The 4q12 Amplicon in Malignant Peripheral Nerve Sheath Tumors: Consequences on Gene Expression and Implications for Sunitinib Treatment

Malignant peripheral nerve sheath tumors (MPNST) are highly aggressive tumors which originate from Schwann cells and develop in about 10% of neurofibromatosis type 1 (NF1) patients. The five year survival rate is poor and more effective therapies are needed. Sunitinib is a drug targeting receptor tyrosine kinases (RTK) like PDGFRα, c-Kit and VEGFR-2. These genes are structurally related and cluster on chromosomal segment 4q12.) was present in MPNST cell lines suggesting an autocrine loop. We show that VEGF triggered signal transduction via the MAPK pathway, which could be blocked by sunitinib. might serve as predictive markers for efficacy of sunitinib

Upper Plate Response to a Sequential Elastic Rebound and Slab Acceleration During Laboratory‐Scale Subduction Megathrust Earthquakes

An earthquake‐induced stress drop on a megathrust instigates different responses on the upper plate and slab. We mimic homogenous and heterogeneous megathrust interfaces at the laboratory scale to monitor the strain relaxation on two elastically bi‐material plates by establishing analog velocity weakening and neutral materials. A sequential elastic rebound follows the coseismic shear‐stress drop in our elastoplastic‐frictional models: a fast rebound of the upper plate and the delayed and smaller rebound on the elastic belt (model slab). A combination of the rebound of the slab and the rapid relaxation (i.e., elastic restoration) of the upper plate after an elastic overshooting may accelerate the relocking of the megathrust. This acceleration triggers/antedates the failure of a nearby asperity and enhances the early slip reversal in the rupture area. Hence, the trench‐normal landward displacement in the upper plate may reach a significant amount of the entire interseismic slip reversal and speeds up the stress build‐up on the upper plate backthrust that emerges self‐consistently at the downdip end of the seismogenic zones. Moreover, the backthrust switches its kinematic mode from a normal to reverse mechanism during the coseismic and postseismic stages, reflecting the sense of shear on the interface.Plain Language Summary: Subduction zones, where one tectonic plate slides underneath the other, host the largest earthquakes on earth. Two plates with different physical properties define the upper and lower plates in the subduction zones. A frictional interaction at the interface between these plates prevents them from sliding and builds up elastic strain energy until the stress exceeds their strength and releases accumulated energy as an earthquake. The source of the earthquake is located offshore; hence illuminating the plates' reactions to the earthquakes is not as straightforward as the earthquakes that occur inland. Here we mimic the subduction zone at the scale of an analog model in the laboratory to generate analog earthquakes and carefully monitor our simplified model by employing a high‐resolution monitoring technique. We evaluate the models to examine the feedback relationship between upper and lower plates during and shortly after the earthquakes. We demonstrate that the plates respond differently and sequentially to the elastic strain release: a seaward‐landward motion of the upper plate and an acceleration in the lower plate sliding underneath the upper plate. Our results suggest that these responses may trigger another earthquake in the nearby region and speed up the stress build‐up on other faults.Key Points: Seismotectonic scale models provide high‐resolution observations to study the surface deformation signals from shallow megathrust earthquakes. Surface displacement time‐series suggest a sequential elastic rebound of the upper plate and slab during great subduction megathrust earthquakes. Slip reversal may be caused by rapid restoration of the upper plate after overshooting and amplified upper plate motion.SUBITOP Marie Sklodowska‐Curie Action project from the European Union's EU Framework ProgrammeDeutsche Forschungsgemeinschafthttps://doi.org/10.5880/fidgeo.2022.02

Upper plate dynamic response to a sequential elastic rebound and slab acceleration in laboratory-scale subduction megathrust

An earthquake-induced stress drop on a megathrust instigates different responses on the upper plate and slab. We mimic homogenous and heterogeneous megathrust interfaces at the laboratory scale to monitor the strain relaxation on the two elastically bi-material plates by establishing analog velocity weakening and neutral materials. A sequential elastic rebound follows the coseismic shear-stress drop in our elastic-frictional models: a fast rebound of the upper plate and the delayed and smaller rebound on the slab. A combination of the rebound of the slab and the rapid relaxation (i.e., elastic restoration) of the upper plate after an elastic overshooting may accelerate the relocking of the megathrust. This acceleration triggers/antedates the failure of a nearby asperity and enhances the early slip reversal in the rupture area. Hence, the trench-normal rearward displacement in the upper plate may reach a significant amount of the entire interseismic slip reversal and speeds up the stress build-up on upper plate backthrust. Moreover, the backthrust switches its kinematic mode from a normal to reverse mechanism reflecting the sense of shear on the interface during coseismic and postseismic stages

Main effects of species, soil moisture and soil composition on the survival rate (living cuttings) and growth performance (n° of sprouts, longest sprouts, shoot biomass, root biomass) after 84 days (three-way ANOVAs; response variables were square-root-transformed to improve the diagnostic plots) and general linear mixed models of the number of sprouts and the longest sprout over time.

<p>Values are F-values. Levels of significance (p) are denoted with *p<0.05, **p<0.01 and ***p<0.001.</p

(a–h) Growth performance over time.

<p>Growth performance over time of the four species investigated under different soil moisture conditions. (a–d): effects on the number of sprouts (means±SE) after 18, 29, 40, 62 and 84 days; (e–h): effects on the longest sprout (means±SE) after 29, 40, 62 and 84 days. Different letters indicate differences (p<0.05) after Tukey’s all-pairwise comparisons.</p

Effects of species and soil moisture.

<p>Effects of species and soil moisture on a) number of living cuttings, b) number of sprouts, c) longest sprout, d) shoot biomass and e) root biomass (means±SE) after 84 days. Different letters indicate Tukey’s HSD between the species (p<0.05).</p