Modeling of postseismic deformation following great earthquakes has revealed the viscous structure of the mantle and the frictional properties of the fault interface. However, for giant megathrust events, viscoelastic flow and afterslip mechanically interplay with each other during the postseismic period. We explore the role of afterslip and viscoelastic relaxation and their interaction in the aftermath of the 2011 Mw (moment magnitude) 9.0 Tohoku earthquake based on a detailed model analysis of the postseismic deformation with laterally varying, experimentally constrained, rock rheology. Mechanical coupling between viscoelastic relaxation and afterslip notably modifies both the afterslip distribution and surface deformation. Thus, we highlight the importance of addressing mechanical coupling for long-term studies of postseismic relaxation, especially in the context of the geodynamics of the Japan trench across the seismic cycle.

N-myristoylation and S-acylation promote protein membrane association, allowing regulation of membrane proteins. However, how widespread this targeting mechanism is in plant signaling processes remains unknown. Through bioinformatics analyses, we determined that among plant protein kinase families, the occurrence of motifs indicative for dual lipidation by N-myristoylation and S-acylation is restricted to only five kinase families, including the Ca -regulated CDPK-SnRK and CBL protein families. We demonstrated N-myristoylation of CDPK-SnRKs and CBLs by incorporation of radiolabeled myristic acid. We focused on CPK6 and CBL5 as model cases and examined the impact of dual lipidation on their function by fluorescence microscopy, electrophysiology and functional complementation of Arabidopsis mutants. We found that both lipid modifications were required for proper targeting of CBL5 and CPK6 to the plasma membrane. Moreover, we identified CBL5-CIPK11 complexes as phosphorylating and activating the guard cell anion channel SLAC1. SLAC1 activation by CPK6 or CBL5-CIPK11 was strictly dependent on dual lipid modification, and loss of CPK6 lipid modification prevented functional complementation of cpk3 cpk6 guard cell mutant phenotypes. Our findings establish the general importance of dual lipid modification for Ca signaling processes, and demonstrate their requirement for guard cell anion channel regulation.

[1] The effect of a lattice preferred orientation on the flow strength of quartz aggregates dynamically recrystallized from single crystals of synthetic quartz was investigated using general shear experiments in a Griggs apparatus. Experiments were conducted at shear strains (g) up to 5 at a temperature of 900°C, confining pressure of 1.5 GPa, and shear strain rate of 10 −5 s −1 . Three starting orientations of crystal were used, to activate three slip systems: basal hai, prism [c], and prism hai, although slip-induced rotation of the crystal axes in the first two orientations led to the activation of additional slip systems. For crystals with higher water contents, basal hai and prism hai orientations are relatively weak and prism [c] orientations are stronger. All three initial crystal orientations undergo dynamic recrystallization with increasing shear strain, although the strain required for 100% recrystallization varies: g ≈ 2 for prism [c] slip, g ≈ 3.8 for basal hai slip, and g ≈ 5 for prism hai slip. For all three starting orientations, distinct domains of recrystallized grains develop with c axes parallel to Y of the strain ellipsoid (Ymax), replacing recrystallized grains of other orientations; the Ymax domains increase in size with increasing strain. In addition, strain markers show that strain is highly localized within the Ymax domains, indicating geometrical softening of up to an order of magnitude in effective viscosity.Citation: Muto, J., G. Hirth, R. Heilbronner, and J. Tullis (2011), Plastic anisotropy and fabric evolution in sheared and recrystallized quartz single crystals,

Using two‐dimensional finite element modeling, we reproduced the observed postseismic deformation of the 2011 Tohoku‐Oki earthquake. Our model, which accounts for the lithosphere‐asthenosphere boundary and weak zones beneath volcanoes, was able to reproduce small‐scale (<20 km) perturbations in postseismic deformation observed by the dense geodetic network, such as local subsidence around Quaternary volcanoes. The inverted afterslip has a peak at the downdip limit of the main rupture region on the subducting plate interface, consistent with physical predictions. The combination of afterslip and viscoelastic relaxation in a heterogeneous rheology model explains the observations well, even on small scales.

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Two‐dimensional viscosity profiles were constructed for the northeastern Japan islands arc‐trench system covering the source area of the 2011 Tohoku‐Oki earthquake. From seismologically determined models of lithospheric structure, experimentally derived constitutive laws of various rocks, and densely measured geothermal gradient data, we have predicted the steady state effective viscosity across the subduction zone. The profile reveals strong lateral viscosity gradients both parallel and normal to the trench axis. The detailed viscosity structures presented here contribute to accurate evaluation of viscoelastic relaxation components when modeling geodetically measured postseismic deformation at high spatial and temporal resolution.

The size distributions of particle in pulverized rocks from the San Andreas fault and the Arima‐Takatsuki Tectonic Line were measured. The rocks are characterized by the development of opening mode fractures with an apparent lack of shear. Fragments in the rocks in both fault zones show a fractal size distribution down to the micron scale. Fractal dimensions, dependent on mineral type, decrease from 2.92 to 1.97 with increasing distance normal to the fault core. The fractal dimensions of the rocks are higher than those of both natural and experimentally created fault gouges measured in previous studies. Moreover, the dimensions are higher than the theoretically estimated upper fractal limit under confined comminution. Dimensions close to 3.0 have been reported in impact loading experiments. The observed characteristics indicate that pulverization is likely to have occurred by a dynamic stress pulse with instantaneous volumetric expansion, possibly during seismic rupture propagation similar to impact loading.

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