摘要:

The electrical resistivity of a saturated granite during frictional sliding showed clear variations premonitory to the occurrence of stick‐slip: Resistivity decreased by a few percent with increasing shear stress; the minimum coincided with a sudden release of shear stress of a few bars, accompanied by an immediate return of resistivity. This sequence of changes of resistivity bears some similarity to those observed in the field prior to the occurrence of some earthquakes and suggests that the causative mechanisms for both the field and the laboratory phenomena might be closely related. Further field application of the electrical method for earthquake prediction seems desirabl

ISSN:0094-8276    

DOI:10.1029/GL002i012p00525

年代:1975

数据来源: WILEY

摘要:

The water content of synthetic amphibole (richterite50+ tremolite50solid solution) markedly increases with increase in the vapor pressure in the range from 5 to 20 kb at fixed temperatures. Temperature change from 750°C to 900°C at fixed pressures does not affect the water content of synthetic amphiboles. The water content of common hornblende from ultramafic‐mafic rocks is found to be always higher than that from granitic rocks. This difference indicates a difference in the confining pressure of formation of two rock ty

ISSN:0094-8276    

DOI:10.1029/GL002i012p00529

年代:1975

数据来源: WILEY

摘要:

Precise interlaboratory measurements of various physical properties of synthetic crystals of major mantle minerals will contribute to solving current controversies in solid earth geophysics. For this purpose, high quality crystals of orthoenstatite, MgSiO3, up to 5×2×1 mm size, were obtained by the primary crystallization of a melt in the system MgO‐SiO2‐lithiumvanadomolybdate. The growth was effected by slow cooling of the melt from 930°C to 650°C at 1.5° per hour. The temperature coefficient of solubility of MgSiO3in this solvent is 0.023 (6.5wt%/280°C). The crystals are stoichiometric, transparent, and often euhedral, elongated parallel tocwithout parting or cleavage. Unit‐cell dimensions area=18.212(4),b=8. 818(2),c=5.177(2)Åwith space groupPbca. Superheating of the melt before cooling induced metastable nucleation and growth of protoenstatite which readily transformed to clinoenstatite on cooling, while rapid cooling of the melt resulted in metastable forsteri

ISSN:0094-8276    

DOI:10.1029/GL002i012p00533

年代:1975

数据来源: WILEY

摘要:

The direction of the apparent polar motion relative to Laurentia for the interval 2.2 to 1.9 b.y. ago is the subject of a controversy owing to difficulties in determining the age relationships and age of the complex magnetization of those very old rocks. Three cleaning treatments (thermal, chemical and alternating field) were used to study the fossil magnetization of 104 specimens (8 sites) of 2.3 b.y. old red argillites of the Huronian Supergroup. The results indicate that the magnetization was acquired during the initial process of magnetization. The mean direction 337°, +52° (N=8; α95=8°) yields a pole at 158°E, 67°N (δp=8°; δm=11°). This and other recently published results indicate that the apparent polar motion relative to Laurentia for the 2.3 to 1.9 b.y. ago was mainly latitudinal and from north

ISSN:0094-8276    

DOI:10.1029/GL002i012p00537

年代:1975

数据来源: WILEY

摘要:

Statistical time series modeling was applied to the monthly average total ozone data taken at Arosa, Switzerland over the period 1932–74. The analysis led to a model that provided a significantly good representation of the Arosa data, and indicated that a much discussed decline in ozone for the first half of the 1970's is a predictable phenomenon from historical patterns in the Arosa data prior to 1970. If historical patterns persist, such as a clearly identified 133 month cycle, a return or upward trend could be expected in the late 1970's. No significant phase lag relationship could be detected between solar sunspot data and the Arosa data, nor did the sunspot periodicity seem to explain the 133 month cycle. The modeling approach is proposed as a tool for atmospheric scientists when evaluating the significance of future trends in ozone from one or a multiple of ozone recording centers around the worl

ISSN:0094-8276    

DOI:10.1029/GL002i012p00541

年代:1975

数据来源: WILEY

摘要:

Although the assumption of complete and immediate recombination of atmospheric atomic oxygen at the surfaces of the open ion source of the AEROS‐A mass spectrometer is reasonable below 300 km, application of this assumption at higher altitudes results in a substantial underestimation of the ambient density of atomic oxygen. A two layer surface model seems necessary to explain the observations. Parameters for several surface reaction processes are estimate

ISSN:0094-8276    

DOI:10.1029/GL002i012p00545

年代:1975

数据来源: WILEY

摘要:

A re‐investigation of the ultraviolet absorption spectrum of nitrous oxide (N2O) agrees with previous results in the range 210 to 235 nm, but contrary to previous results it indicates a vanishingly small cross section above 260 nm. The absence of the relatively long wave length absorption implies a negligible rate of photolysis of nitrous oxide in the troposphere. These results plus the previously estimated atmospheric mean residence times of N2O indicate that there is a large, unknown tropospheric sink for nitrous oxid

ISSN:0094-8276    

DOI:10.1029/GL002i012p00549

年代:1975

数据来源: WILEY

摘要:

Electron density irregularity in the scale size of 4 to 100 m was observed in altitude between 90 and 120 km from rocket measurements over Japan. Analysis of the data makes clear that the spectral index of irregularities is 2 to 4 and that the irregularity amplitude is smaller than 5%. Strong irregularities exist at 92 to 95 km. The generation mechanism of these irregularities is explained by the theories of the cross field instability or the neutral turbulence.

ISSN:0094-8276    

DOI:10.1029/GL002i012p00553

年代:1975

数据来源: WILEY

摘要:

Pulsating aurora has been identified in DMSP photographs. Its unique zebra‐stripe appearance is due to the interaction of the aurora pulsation period with the imaging device's raster scan period. It most commonly, but not exclusively, occurs on the equatorward edge of the auroral oval after midnight and is positively correlated with global magnetic activity. Pulsating aurora also occurs on the poleward leading edge of midnight sector surge

ISSN:0094-8276    

DOI:10.1029/GL002i012p00557

年代:1975

数据来源: WILEY

摘要:

A number of quiet‐time enhancements in the intensity of interplanetary electrons over the range 0.22 ≲ E ≲ 2.5 MeV have been observed with the JHU/APL experiment on the earth orbiting near‐circular (∼ 32 by 38 Re) Explorer 47 (IMP‐7) spacecraft during 1973 and 1974. These quiet‐time increases last from ∼ 3 to ∼ 20 days and are observed both in the interplanetary medium and inside the magnetotail. The main features of the observations are as follows: (a) The increases occur during the first 200 days of 1973 and from day ∼ 20 to ∼ 230 in 1974. (b) The intensity onset is relatively slow (1 to 2 days) when compared to either solar electron events or magnetospheric electron bursts, (c) The electron energy spectrum is quite distinct from that of solar or magnetospheric electrons and is consistent with γ = 1.3±0.3 in a differential power law spectrum. (d) Significant anisotropies are present, several days after the onset of the increase. (e) Some distinct fluctuations appear in some of the intensity profiles, suggesting the presence of a modulated source. The appearance of these enhancements occurs during times when the earth could be magnetically connected to the magnetosphere of Jupiter, assuming typical solar wind velocities. Further, the energy spectrum is not unlike that observed by instrumentation on Pioneer 10 in the vicinity of Jupiter. On the basis of the above it is reasonable to suggest that the observed electrons may be of Jovian origin. The implications of these results are discussed, and it is suggested that interconnection between the interplanetary and Jovian magnetic field takes place. Using this concept, a length of the Jovian magnetotail

ISSN:0094-8276    

DOI:10.1029/GL002i012p00561

年代:1975

数据来源: WILEY