摘要:

A method has been devised for direct measurement of the Rn220flux through the ground surface (‘exhalation’), and measurements are reported for six sites. At one site comparisons are made between the measured exhalation and those exhalations deduced from Rn220profiles in the air above the site; agreement is good with low intensity of turbulence. The discrepancies with higher turbulence are discus

ISSN:0148-0227    

DOI:10.1029/JB074i017p04199

年代:1969

数据来源: WILEY

摘要:

A new geyser, having surface and subsurface connections with the Spectacle Pools, Yellowstone National Park, had a remarkably constant initial periodicity. Eruptive play generally occurred every 35–40 minutes and lasted 80–100 seconds. Water levels and temperatures of the associated pools exhibited consistent variations during each cy

ISSN:0148-0227    

DOI:10.1029/JB074i017p04206

年代:1969

数据来源: WILEY

摘要:

Small quantities of brine trapped in ‘negative crystals’ (cavities) exist in most rock salt (halite) and have been found to migrate toward a heat source. The theory of Hoekstra and others on the migration of liquid inclusions in ice crystals was modified for predicting the migration rates of brine cavities in salt. The driving force for the migration is the difference in solubility between the warm and colder sides of the brine cavity. The theoretical model indicates that the migration rate is a function of temperature and is directly proportional to the temperature gradient. Calculated cavity migration rates for a 1°C/cm gradient ranged from about 0 at 20°C to 7.7 cm/yr at 300°C. The theoretical predictions were found to be in reasonable agreement with migration rates measured in the laboratory, although there was considerable spread in the experimental data. Specimens consisted of relatively pure salt crystals from the Hutchinson, Kansas, mine, about 2½ cm on a side, containing brine cavities between 2 and 10 mm in maximum dimension. Thirty‐one rate measurements (on twelve separate cavities) were obtained, covering the temperature range of 75°–244°C, with gradients ranging from 4 to 34°C/cm. Migration periods varied from about 20 to 358 hours, and the observed distances of migration ranged from 0.8 to 8 mm. The theoretical predictions also tended to confirm the approximate (but difficult to measure) rates of brine migration into a number of heated holes (salt wall temperatures up to 200°C) located in

ISSN:0148-0227    

DOI:10.1029/JB074i017p04209

年代:1969

数据来源: WILEY

摘要:

The age, petrography, chemical composition, and structure of the Antipodes Islands volcanics are established as important criteria in deciding the nature of the Antipodes fracture zone, which delineates the eastern margin of the New Zealand plateau, and which separates it from the Southwestern Pacific basin. Reasons are given for preferring tear‐faulting to rifting as the dominant movement along the fracture zone: an important issue in determining the direction of migration of sialic crustal blocks in the southwest Pacific during Cenozoic time

ISSN:0148-0227    

DOI:10.1029/JB074i017p04213

年代:1969

数据来源: WILEY

摘要:

Whitlockite from the St. Severin chondrite, previously shown to contain excess fission tracks, is here shown to have a large concentration of excess neutron‐rich xenon isotopes. The concentration of excess heavy Xe in the whitlockite is about twenty‐five times that calculated from the track density. An isotopic spectrum is deduced that is identical to the spectrum calculated previously for excess heavy xenon in the Pasamonte achondrite. These results uniquely associate this xenon spectrum with in situ fission in meteorites. Chemical arguments support the correlation of this with Pu244. Identification of the fissioning nucleus as Pu244gives Pu244/U238≈ 1/30. Neither ‘sudden’ nor ‘uniform’ nucleosynthetic models give consistent solutions for Pu244/U238

ISSN:0148-0227    

DOI:10.1029/JB074i017p04221

年代:1969

数据来源: WILEY

摘要:

Component measurement and interpretation are essentially important in areas around the magnetic equator because of the imbalance of the field components and the possible effect of orientation of ore bodies relative to the magnetic N‐S direction. Separation of anomaly components into the induced and permanent magnetization parts involves a knowledge of the absolute components. A method of magnetic field survey that allows for the absolute measurement of all components in low latitude is described, and a computer method for presenting the results is adopted. The technique of interpretation adopted for some of the results of the survey is presented, and the field results agree well with the mathematical derivation of components from the well‐known Poisson's equation. The dependence of the anomaly component inZon its absolute value is well illustrated, and the author's conclusion in this respect is contrary to the views expressed by S. P. Gay (1963). Separation of theZanomaly component into the induced and permanent magnetization parts in magnetic low latitude could result in a paleomagnetic tool for the study of the magnetic equator. The paleomagnetic importance of the negative anomaly inZ, encountered in the survey, is fully discussed by the author, who points out possible evidence of either a northern shift of the magnetic equator in Nigeria or a reversal of the earth's magnetic field from rocks of Precambrian era in s

ISSN:0148-0227    

DOI:10.1029/JB074i017p04233

年代:1969

数据来源: WILEY

摘要:

Repeated geodetic levelings of elevation points were made between 1936 and 1963 by the Israeli Department of Survey in Mt. Carmel and the eastern Galilee of northern Israel. These measurements show vertical movements of order of magnitude of a few millimeters per year. These movements can be correlated with the Plio‐Pleistocene tectonic structures in this regio

ISSN:0148-0227    

DOI:10.1029/JB074i017p04246

年代:1969

数据来源: WILEY

摘要:

Statistical models for vertical deflections in the form of power spectral densities and autocorrelation functions are derived from theoretical gravity‐anomaly models by means of the Vening Meinesz equations. Details are given for homogeneous and isotropic gravity‐anomaly models described by exponential and Bessel autocorrelation functions. The use of these models for evaluation of mean‐squared output errors in an inertial navigation system is desc

ISSN:0148-0227    

DOI:10.1029/JB074i017p04259

年代:1969

数据来源: WILEY

摘要:

A mathematical solution to predict the properties of the strain waves generated when an explosive detonates inside a spherical cavity in an infinite medium is presented. In the case of commercial explosives in rock, the strain pulse is a highly damped oscillating wave train the characteristics of which depend on the properties of the rock (its density, Young's modulus, and Poisson' ratio), on the radius of the cavity, and on the properties of the explosive (its explosion pressure P and the ratio of the specific heats of its explosion gases). The theory is compared with some experimental data; the agreement is fair, if account is taken of charge shape and detonation time effects. Applicability of the theory to prediction of the relative blasting effectiveness of different explosives is briefly discussed.

ISSN:0148-0227    

DOI:10.1029/JB074i017p04267

年代:1969

数据来源: WILEY

摘要:

This paper presents the results of a field‐seismic study of local earthquake activity at the Nevada Test Site, following the Boxcar underground nuclear test (mb= 6.42) on April 26, 1968. Thousands of small aftershocks were recorded in the six‐week period following the explosion, and events selected for focal determination were found to lie in a zone 12 km long, 3–4 km wide, and 6 km deep. There is evidence of migration of this activity with time with earlier earthquakes concentrated in the vicinity of the blast and northeast part of the zone and later activity in an extension of the zone to the southwest. Most of the Boxcar aftershocks had a focal depth of less than about 5½ km, which is shallower than the predominant depths found for natural earthquakes in the Nevada region. Recurrence curves for the Nevada Test Site sequence had ab‐value of 0.62, different from values of 0.79–0.84 for natural earthquakes in the region. The sequence decayed according to the relationshipN(t) = 372t−0.79, withN(t) andtin number of recorded events per hour and hours, respectively. A unique type of seismic event, seemingly related to the blast cavity, was observed following the Boxcar explosion; it is typified by emergentParrivals, poorly defined S waves, low signal frequency, and long‐duration surface waves. Differences between the Boxcar aftershock sequence and natural earthquakes in the Nevada region are significant and suggest that stresses due to the explosion may have been more significant than regional tectonic stresses in the generation of this after

ISSN:0148-0227    

DOI:10.1029/JB074i017p04281

年代:1969

数据来源: WILEY