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Surface ages and resurfacing rates of the Polar Layered Deposits on Mars Surface ages and resurfacing rates of the Polar Layered Deposits on Mars

Interpretation of the polar stratigraphy of Mars in terms of global climate changes is complicated by the significant difference in surface ages between the north and south polar layered terrains inferred from crater statistics. We have reassessed the cratering record in both polar regions using Viking Orbiter and Mariner 9 images. No craters have been found in the north polar layered...
Authors
Kenneth E. Herkenhoff, Jeffrey J. Plaut

Hydrogen defects in α-Al2O3 and water weakening of sapphire and alumina ceramics between 600°C and 1000°C: II. Mechanical properties Hydrogen defects in α-Al2O3 and water weakening of sapphire and alumina ceramics between 600°C and 1000°C: II. Mechanical properties

Hydrogen impurities in alumina have been introduced by hydrothermal annealing (see part I). In this paper, we report on reductions in the flow strength of α-Al2O3 single crystals and polycrystals associated with hydrogen incorporation. Prior to deformation, α-Al2O3 single crystal and ceramic specimens were annealed in the presence of supercritical water at 850° or 900°C, under 1500 MPa...
Authors
J. Castaing, A. K. Kronenberg, S. H. Kirby, T. E. Mitchell

A seismic landslide susceptibility rating of geologic units based on analysis of characterstics of landslides triggered by the 17 January, 1994 Northridge, California earthquake A seismic landslide susceptibility rating of geologic units based on analysis of characterstics of landslides triggered by the 17 January, 1994 Northridge, California earthquake

One of the most significant effects of the 17 January, 1994 Northridge, California earthquake (M=6.7) was the triggering of thousands of landslides over a broad area. Some of these landslides damaged and destroyed homes and other structures, blocked roads, disrupted pipelines, and caused other serious damage. Analysis of the distribution and characteristics of these landslides is...
Authors
M. Parise, Randall W. Jibson

Topography and Stratigraphy of the Northern Martian Polar Layered Deposits Using Photoclinometry, Stereogrammetry, and MOLA Altimetry Topography and Stratigraphy of the Northern Martian Polar Layered Deposits Using Photoclinometry, Stereogrammetry, and MOLA Altimetry

We present two photoclinometric profiles across a trough in the martian northern polar layered terrain. Complications caused by albedo variations were avoided by using an early springtime Viking image with a thin cover of seasonal CO2 frost. The topographic profiles were constrained with stereogrammetric elevations derived from summertime Viking images of the same region. We find that...
Authors
Lori K. Fenton, Kenneth E. Herkenhoff

A filter circuit board for the Earthworm Seismic Data Acquisition System A filter circuit board for the Earthworm Seismic Data Acquisition System

The Earthworm system is a seismic network data acquisition and processing system used by the Northern California Seismic Network as well as many other seismic networks. The input to the system is comprised of many realtime electronic waveforms fed to a multi-channel digitizer on a PC platform. The digitizer consists of one or more National Instruments Corp. AMUX–64T multiplexer boards...
Authors
Edward Gray Jensen

Three-month performance evaluation of the Nanometrics, Inc., Libra Satellite Seismograph System in the northern California Seismic Network Three-month performance evaluation of the Nanometrics, Inc., Libra Satellite Seismograph System in the northern California Seismic Network

In 1999 the Northern California Seismic Network (NCSN) purchased a Libra satellite seismograph system from Nanometrics, Inc to assess whether this technology was a cost-effective and robust replacement for their analog microwave system. The system was purchased subject to it meeting the requirements, criteria and tests described in Appendix A. In early 2000, Nanometrics began delivery of...
Authors
David H. Oppenheimer

Towards policy relevant environmental modeling: contextual validity and pragmatic models Towards policy relevant environmental modeling: contextual validity and pragmatic models

"What makes for a good model?" In various forms, this question is a question that, undoubtedly, many people, businesses, and institutions ponder with regards to their particular domain of modeling. One particular domain that is wrestling with this question is the multidisciplinary field of environmental modeling. Examples of environmental models range from models of contaminated ground...
Authors
Scott B. Miles

Origin of the 17 July 1998 Papua New Guinea tsunami: Earthquake or landslide Origin of the 17 July 1998 Papua New Guinea tsunami: Earthquake or landslide

The tsunami that struck Papua New Guinea on 17 July 1998 shortly after a Mw 7.0 earthquake (Figure 1) was one of the deadliest tsunamis in this century. At least 2,200 people died from this event, essentially destroying an entire generation in some communities. In the months following the tsunami, several international survey teams collected data in an attempt to better understand the...
Authors
E.L. Geist

Statiscal analysis of an earthquake-induced landslide distribution - The 1989 Loma Prieta, California event Statiscal analysis of an earthquake-induced landslide distribution - The 1989 Loma Prieta, California event

The 1989 Loma Prieta, California earthquake (moment magnitude, M=6.9) generated landslides throughout an area of about 15,000 km2 in central California. Most of these landslides occurred in an area of about 2000 km2 in the mountainous terrain around the epicenter, where they were mapped during field investigations immediately following the earthquake. The distribution of these landslides...
Authors
D. K. Keefer
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