Study of the effects of ethylene oxide-freon 12 upon properties of polymers and metallic surfaces Final report, 10 Oct. 1964 - 31 Mar. 1966

Physical, mechanical, and electrical tests to determine the effects on polymeric products after exposure to ethylene oxide-Freon 1

Study of the effects of ethylene oxide-freon 12 upon properties of polymers and metallic surfaces interim status report, 1 oct. 1964 - 30 apr. 1965

Compatibility of polymers and metallic materials with ethelyene oxide-Freon 12 gas to be used in combination with dry heat cycling for sterilization of spacecraf

Are Aftershocks of Large Californian Earthquakes Diffusing?

We analyze 21 aftershock sequences of California to test for evidence of space-time diffusion. Aftershock diffusion may result from stress diffusion and is also predicted by any mechanism of stress weakening. Here, we test an alternative mechanism to explain aftershock diffusion, based on multiple cascades of triggering. In order to characterize aftershock diffusion, we develop two methods, one based on a suitable time and space windowing, the other using a wavelet transform adapted to the removal of background seismicity. Both methods confirm that diffusion of seismic activity is very weak, much weaker than reported in previous studies. A possible mechanism explaining the weakness of observed diffusion is the effect of geometry, including the localization of aftershocks on a fractal fault network and the impact of extended rupture lengths which control the typical distances of interaction between earthquakes.Comment: latex file of 34 pages, 15 postscript figures, minor revision. In press in J. Geophys. Re

A finite element analysis of tidal deformation of the entire earth with a discontinuous outer layer

Tidal deformation of the Earth is normally calculated using the analytical solution with some simplified assumptions, such as the Earth is a perfect sphere of continuous media. This paper proposes an alternative way, in which the Earth crust is discontinuous along its boundaries, to calculate the tidal deformation using a finite element method. An in-house finite element code is firstly introduced in brief and then extended here to calculate the tidal deformation. The tidal deformation of the Earth due to the Moon was calculated for an geophysical earth model with the discontinuous outer layer and compared with the continuous case. The preliminary results indicate that the discontinuity could have different effects on the tidal deformation in the local zone around the fault, but almost no effects on both the locations far from the fault and the global deformation amplitude of the Earth. The localized deformation amplitude seems to depend much on the relative orientation between the fault strike direction and the loading direction (i.e. the location of the Moon) and the physical property of the fault

Seismic triggering by rectified diffusion in geothermal systems

Widespread seismicity was triggered by the June 28, 1992, Landers California, earthquake at a rate which was maximum immediately after passage of the exciting seismic waves. Rectified diffusion of vapor from hydrothermal liquids and magma into bubbles oscillating in an earthquake can increase the local pore pressure to seismically significant levels within the duration of the earthquake. In a hydrothermal system modeled as a two-component H_2O-CO_2 fluid in porous rock the pressure initially increases linearly with time. The rate of pressure buildup depends sensitively on the mean bubble radius and is large for small bubbles. The diffusion-induced pressure is relaxed by percolation and resorption of vapor into the liquid solution. The induced seismicity itself also relieves stress. Values of parameters used in the present calculations give results consistent with observations of triggered seismicity at Long Valley caldera after the Landers earthquake. For one representative condition, at 250°C and 5.6 km depth, oscillating strain acting on 10-μm-diameter bubbles increases pore pressure at the rate of 151 Pa/s resulting in a pressure increase of 12 kPa in the 80-s duration of the Landers earthquake. The elevated pressure induced by a single 26-m-diameter cloud of bubbles in saturated rock relaxes by percolation through soil of 0.2-mdarcy permeability in 53.6 hours. Observations of earthquake swarms at other locations suggest that self-induced buildup of pore pressure by rectified diffusion can provide a positive feedback mechanism for amplifying seismicity

Earthquakes: from chemical alteration to mechanical rupture

In the standard rebound theory of earthquakes, elastic deformation energy is progressively stored in the crust until a threshold is reached at which it is suddenly released in an earthquake. We review three important paradoxes, the strain paradox, the stress paradox and the heat flow paradox, that are difficult to account for in this picture, either individually or when taken together. Resolutions of these paradoxes usually call for additional assumptions on the nature of the rupture process (such as novel modes of deformations and ruptures) prior to and/or during an earthquake, on the nature of the fault and on the effect of trapped fluids within the crust at seismogenic depths. We review the evidence for the essential importance of water and its interaction with the modes of deformations. Water is usually seen to have mainly the mechanical effect of decreasing the normal lithostatic stress in the fault core on one hand and to weaken rock materials via hydrolytic weakening and stress corrosion on the other hand. We also review the evidences that water plays a major role in the alteration of minerals subjected to finite strains into other structures in out-of-equilibrium conditions. This suggests novel exciting routes to understand what is an earthquake, that requires to develop a truly multidisciplinary approach involving mineral chemistry, geology, rupture mechanics and statistical physics.Comment: 44 pages, 1 figures, submitted to Physics Report

A simple method to retrieve the complex eigenfrequency of the Earth's nearly diurnal-free wobble; application to the Strasbourg superconducting gravimeter data

International audienceWe have analysed more than four years of data from the Strasbourg superconducting gravimeter to retrieve the period and damping of the nearly diurnal-free wobble (NDFW). The removal of noise spikes is found to be crucial for an accurate determination of tidal-wave amplitudes and phases. A new simple algorithm is derived which allows an analytical solution for the NDFW pertod and damping using the complex gravimetric factors of three resonant diurnal waves. The results show a huge reduction of the confidence intervals when compared with a previous investigation from a Lacoste Romberg spring meter operated at the same station. Our results are in close agreement with values obtained from two other European superconducting gravimeters. The results are also compared with respect to values inferred from very long baseline interferometry (VLBI) measurements

Analysis of seafloor seismograms of the 2003 Tokachi-Oki earthquake sequence for earthquake early warning

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L14310, doi:10.1029/2008GL033986.Earthquake Early Warning (EEW) algorithms estimate the magnitude of an underway rupture from the first few seconds of the P-wave to allow hazard assessment and mitigation before the S-wave arrival. Many large subduction-zone earthquakes initiate 50–150 km offshore, potentially allowing seafloor instruments sufficient time to identify large ruptures before the S-waves reach land. We tested an EEW algorithm using accelerograms recorded offshore Hokkaido in the region of the 2003 Mw 8.1 Tokachi-Oki earthquake and its aftershocks. A wavelet transform of the first ∼4 s of the P-wave concentrates information about earthquake magnitude from both waveform amplitude and frequency content. We find that wavelets with support of a few seconds provide discriminants for EEW that are both accurate enough to be useful and superior to peak acceleration or peak velocity. Additionally, we observe a scaling of wavelet coefficient magnitude above Mw 6.0 indicating that, at least for the mainshock (Mw 8.1) and largest aftershock (Mw 7.1), the final size of a rupture could have been estimated from the initial portion of the seismogram.This work was supported by the Deep Ocean Exploration Institute at WHOI

Indonesian earthquake: Earthquake risk from co-seismic stress.

Following the massive loss of life caused by the Sumatra-Andaman earthquake in Indonesia and its tsunami, the possibility of a triggered earthquake on the contiguous Sunda trench subduction zone is a real concern. We have calculated the distributions of co-seismic stress on this zone, as well as on the neighbouring, vertical strike-slip Sumatra fault, and find an increase in stress on both structures that significantly boosts the already considerable earthquake hazard posed by them. In particular, the increased potential for a large subduction-zone event in this region, with the concomitant risk of another tsunami, makes the need for a tsunami warning system in the Indian Ocean all the more urgent.John McCloskey, Suleyman S.Nalbant, Sandy Steac