We present a growth tectonic model of Earth's inner core and the resulting model of the seismic anisotropy. The inner core grows anisotropically if the convection in the outer core is of Taylor column type. The anisotropic growth produces a flow field of the poloidal zonal order 2 type as a result of the isostatic adjustment of the viscous inner core. Crystals in the inner core align themselves under the stress field produced by the flow. We model the anisotropic structure of the inner core, using the theory of Kamb [1959] and elastic constants of Stixrude and Cohen [1995b]. We consider models for both hcp iron and fcc iron, which are the probable crystal structures for the inner core iron according to Stixrude and Cohen [1995a]. We have found that the c axis for hcp iron and [111] direction for fcc iron align in the polar direction. The alignment is consistent with seismic observations, which have revealed that the P wave velocity is faster in the polar direction. Our model predicts that the degree of the alignment decreases near the inner core boundary in accord with recent body wave observations. The radial dependence of the alignment would result from the following three effects: (1) crystals near the surface have not undergone stressed state long enough to acquire anisotropy after precipitation, (2) stress near the surface is different from that in the interior of the inner core due to shear stress free boundary condition, and (3) partially molten structure results in transversely isotropic stress condition near the inner core surface due to compaction. Thus the application of Kamb's theory successfully explains the seismic anisotropy in the inner core provided that the crystals have been subjected under the same stress condition for the timescale of the order of 109 years.

A new crystal modification was found in poly(ethylene oxide) stretched about two‐fold after necking at room temperature. An x‐ray diffraction analysis indicated that the planar zigzag molecule passes through a triclinic unit cell with parameters α = 4.71 Å, b = 4.44 Å, c (fiber axis) = 7.12 Å, α = 62.8°, β = 93.2°, and γ = 111.4°. The space group is P1−Ci1. Packing of the molecule is very similar to that of monoclinic polyethylene.

Lava flows present a recurring threat to communities on active volcanoes, and volumetric eruption rate is one of the primary factors controlling flow behavior and hazard. The time scales and driving forces of eruption rate variability, however, remain poorly understood. In 2018, a highly destructive eruption occurred on the lower flank of Kīlauea Volcano, Hawai‘i, where the primary vent exhibited substantial cyclic eruption rates on both short (minutes) and long (tens of hours) time scales. We used multiparameter data to show that the short cycles were driven by shallow outgassing, whereas longer cycles were pressure-driven surges in magma supply triggered by summit caldera collapse events 40 kilometers upslope. The results provide a clear link between eruption rate fluctuations and their driving processes in the magmatic system.

S U M M A R YA detailed study of the physics of a 1-D sedimentary compaction of a viscous medium was carried out both numerically and analytically for columnar and self-gravitating spherical cases, in view of applying it to the inner-core growth process of the Earth. The effects of sedimentation rate and surface porosity upon the porosity profile were investigated. It was found that the porosity profile differs depending on whether or not the sedimentation rate is larger than the Darcy velocity (velocity of the solid matrix when the fluid flows by buoyancy alone). When the sedimentation rate is larger than the Darcy velocity, a thick, constant-porosity layer develops at the surface, and below it, the porosity decreases gradually towards the bottom. When the sedimentation rate is smaller than the Darcy velocity, the porosity profile is characterized by a mushy layer at the top, where the fluid is expelled by the deformation of the solid, underlain by a thick layer of constant porosity, termed the residual porosity. Such a porosity profile can be understood as the propagation of a half-sided solitary wave. The study was extended further for the self-gravitating spherical case. Formation of an unstable porosity structure and the appearance of solitary waves were discovered for the case of monotonically decreasing sedimentation rate. Given the size of the sphere formed by sedimentary compaction, according to the magnitude of the ratio of sedimentation rate to Darcy velocity, three types of porosity structure, which differ in force balance and the typical length scale required for porosity decrease, were discovered. One such structure is where a low-porosity layer forms at the top, accompanied by solitary waves beneath it, indicating that a crust-like region can develop at the surface of the inner core.