9 Matching Results

Search Results

Advanced search parameters have been applied.

Propagation of near-infrasound over long ranges

Description: This paper describes the results of basic research on the physics of infrasonic propagation, both for predictive purposes and signal interpretation. The following aspects were considered: (1) attenuation, (2) seasonal effects, (3) wave effects, (4) average velocity, (5) azimuth deviations, (6) coherence, and (7) surface effects. The primary region of interest was approximately 0.1 to Hz with corresponding wavelengths of 3000 to 30 meters. (ACR)
Date: January 1, 1986
Creator: Mutschlecner, J.P. & Whitaker, R.W.
Partner: UNT Libraries Government Documents Department

Infrasonic observation of earthquakes

Description: Infrasound signals generated by earthquakes have been detected at arrays operated by the Los Alamos National Laboratory. Three modes of propagation are possible and all have been observed by the authors. The observations suggest that regions remote from the epicenters are excited and may serve as secondary source regions. A relation is found between the normalized peak amplitudes and the seismic magnitudes.
Date: December 31, 1998
Creator: Mutschlecner, J.P. & Whitaker, R.W.
Partner: UNT Libraries Government Documents Department

Infrasonic signals from an accidental chemical explosion

Description: A series of large accidental explosions occurred at a chemical plant in Henderson, Nevada on May 4, 1988. The explosions were produced by the ignition of stores of ammonium perchlorate produced for solid rocket fuel at the Pacific Engineering and Production Co. This material, prior to the incident, had been believed to be non- explosive. The blasts destroyed the plant and caused one death. There was a series of explosions over a period of time with two major explosions which we will identify as A at 18:53:34 (all times herein will be given in C.U.T.) and B at 18:57:35. Signals from events A and B as well as smaller events were detected by the infrasound arrays operated by the Los Alamos National Laboratory at St. George, Utah (distance 159 km) and at Los Alamos, N.M. (distance 774 km). The Henderson explosions present an interesting and challenging set of infrasound observations. The case may be unique in providing two very large sources separated in time by only four minutes. To fully understand the propagation details will require further analysis and probably a modeling effort. The understanding of the St. George signals in the context of Lamb waves would be valuable for a better understanding of this mode of propagation. The improved understanding of long range infrasonic propagation is now especially important in the context of the Comprehensive Test Ban Treaty (CTBT). A portion of the plan for CTBT monitoring includes a global distribution of sixty infrasound arrays to provide for the monitoring of signals in as uniform a way as possible. It is expected that under this global network many signals and interpretation questions of the type described here will be encountered. Investigations of propagation over the ranges of hundreds to thousands of kilometers will be highly desired.
Date: December 31, 1996
Creator: Mutschlecner, J.P. & Whitaker, R.W.
Partner: UNT Libraries Government Documents Department

The design and operation of infrasonic microphones

Description: This report is intended as a guide to the design and operation of infrasonic microphones. It will emphasize general principles and the effects of parameter choices upon performance but will not provide details of design for specific microphones. The report will consider primarily the mechanical aspects that control the acoustic properties; it will not discuss the features of electronic design, which vary greatly among microphones. Here the authors define infrasonic microphones as sensors capable of detecting pressure variations in the period range of about 0.1 s to 1000 s with changes from about 0.1 {mu}bar (microbar = 1 dyne cm{sup {minus}2}) to about 1 mbar.
Date: May 1, 1997
Creator: Mutschlecner, J.P. & Whitaker, R.W.
Partner: UNT Libraries Government Documents Department

Visibility issue in the Rocky Mountain West. [Relation to energy facility siting]

Description: Clear, clean air is one of the natural resources of the Rocky Mountain West. The visibility provisions of the Clean Air Act of 1977 were intended to protect this natural resource in certain Federal class I areas, for example, national parks and wilderness areas. There are a number of potential issues which arise due to the possible reduction of visibility caused by emissions from energy facilities. A number of these issues are briefly discussed. The issues are highlighted by computer generated color photographs showing the effects on a clean landscape of several coal-fired power plant scenarios discussed in the text. The study suggests that visibility may be the limiting factor in energy facility siting in clean air areas. The unique method of displaying the results makes the visibility calculations comprehensible to general audiences.
Date: January 1, 1977
Creator: Leonard, E.M.; Williams, M.D. & Mutschlecner, J.P.
Partner: UNT Libraries Government Documents Department

Infrasonic observations of the Northridge, California, earthquake

Description: Infrasonic waves from the Northridge, California, earthquake of 17 January 1994 were observed at the St. George, Utah, infrasound array of the Los Alamos National Laboratory. The distance to the epicenter was 543 kilometers. The signal shows a complex character with many peaks and a long duration. An interpretation is given in terms of several modes of signal propagation and generation including a seismic-acoustic secondary source mechanism. A number of signals from aftershocks are also observed.
Date: September 1, 1994
Creator: Mutschlecner, J. P. & Whitaker, R. W.
Partner: UNT Libraries Government Documents Department

The Correction of Infrasound Signals for Upper Atmospheric Winds

Description: Infrasound waves propagate in the atmosphere by a well known mechanism produced by refraction of the waves, return to earth, and reflection at the surface into the atmosphere for subsequent bounces. In this instance three rays are returned to earth from a region centered at about 50 kilometers in altitude and two from a region near 110 kilometers in altitude. The control of the wave refraction is largely dominated by the temperature-height profile and inversions; however, a major influence is also produced by the atmospheric wind profile. It obviously can be expected that infrasonic signal amplitudes will be greatly influenced by the winds in the atmosphere. The seasonal variation of the high altitude atmospheric winds is well documented. The very strong seasonal variation has the ability to exert a major seasonal influence on infrasonic signals. It is our purpose to obtain a method for the correction of this effect.
Date: January 1, 1990
Creator: Mutschlecner, J. P. & Whitaker, R. W.
Partner: UNT Libraries Government Documents Department

Drainage flow over complex terrain

Description: Model calculations even carried in order to simulate tracer release experiments at the Geysers Area. Comparisons with the experimental data provide a test of current ability to model pollutant transport. The calculations were carried out with a windfield code (ATMOS1) and an advection-diffusion code (ATMOS2). The resulting concentrations permit prediction of tracer particle collections at the measurement stations. Comparison of the observations and predictions of sequential and integrated counts shows generally good agreement, but with discrepancies in some instances. The method appears to be a useful one for pollutant transport predictions and for parametric studies.
Date: January 1, 1981
Creator: Davis, C.G.; Bunker, S.S.; King, D.S.; Mutschlecner, J.P.; Barr, S. & Clements, W.E.
Partner: UNT Libraries Government Documents Department

Infrasonic observations of large scale HE events

Description: The Los Alamos Infrasound Program has been operating since about mid-1982, making routine measurements of low frequency atmospheric acoustic propagation. Generally, we work between 0.1 Hz to 10 Hz; however, much of our work is concerned with the narrower range of 0.5 to 5.0 Hz. Two permanent stations, St. George, UT, and Los Alamos, NM, have been operational since 1983, collecting data 24 hours a day. This discussion will concentrate on measurements of large, high explosive (HE) events at ranges of 250 km to 5330 km. Because the equipment is well suited for mobile deployments, it can easily establish temporary observing sites for special events. The measurements in this report are from our permanent sites, as well as from various temporary sites. In this short report will not give detailed data from all sites for all events, but rather will present a few observations that are typical of the full data set. The Defense Nuclear Agency sponsors these large explosive tests as part of their program to study airblast effects. A wide variety of experiments are fielded near the explosive by numerous Department of Defense (DOD) services and agencies. This measurement program is independent of this work; use is made of these tests as energetic known sources, which can be measured at large distances. Ammonium nitrate and fuel oil (ANFO) is the specific explosive used by DNA in these tests. 6 refs., 6 figs.
Date: January 1, 1990
Creator: Whitaker, R.W.; Mutschlecner, J.P.; Davidson, M.B. & Noel, S.D.
Partner: UNT Libraries Government Documents Department