Mathematical problems in seismology

Blake, Archie

doi:10.1029/tr021i004p01094

Cited by 3 publications

(2 citation statements)

References 48 publications

(58 reference statements)

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“…The increase in the epicentral angle A spanned by the ray will be obtained by adding to (6) the angle through which the core turns while the wave is passing through it dA (BJ To proceed from (7) to the differential of the time for the whole ray, we adopt the nota tions (^Jsm and ^d t^A t0 demote the differentials respectively for fixed parameter sm and for fixed A; they are related by (9) (dt)A -(dt)g at 3A dA…”

Section: Ds"mentioning

confidence: 99%

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The possibility of seiemic measurement of the rotation of the Earth's core

Blake

1941

Eos Trans. AGU

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The calculations of Inglis show that the rate of transfer of angular momentum to the Earth's (liquid) core may be small enough to permit the axis of rotation of the core to lag about 2° behind that of the rock‐mantle in the precessional motion of the Earth. The travel‐time of P′ would be altered by about one‐fifth of a second, which is too small to be detected by a single observation made with even the best instrument, but can be brought out statistically when we have accumulated about three thousand clear measurements, on sensitive vertical‐component seismographs, of the P′‐waves from accurately located earthquakes.

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Section: Ds"mentioning

confidence: 99%

“…It seems very desirable that the installation of the best seismo graphs should become considerably more wide-spread (cf. [7], section 2).…”

Section: Ds"mentioning

confidence: 99%

The possibility of seiemic measurement of the rotation of the Earth's core

Blake

1941

Eos Trans. AGU

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New service of geodetic survey

Shneiderov

1944

Eos Trans. AGU

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In the introduction to the Transactions of 1943 of the American Geophysical Union, the following statements are made by J. A. FLEMING: “Now, as never before, scientists in general of the Western Hemisphere need to affiliate and play their part not only in the immediate problems of application to the war effort—to which the geophysicist is contributing effectively—but in the rehabilitation of international relations and endeavors particularly necessary to investigation of earth physics;” “The Nation needs more, not less, scientific endeavor.”

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The density variation of the earth's central core*

Bullen

1942

Bulletin of the Seismological Society of America

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A detailed analysis of the problem of the earth's density variation has been extended to the earth's central core. It is shown that in the region between the outer boundary of the core and a distance of about 1400 km. from the earth's center the density ranges from 9.4 gm/cm.3 to 11.5 gm/cm.3 within an uncertainty which, if certain general assumptions are true, does not exceed 3 per cent. The density and pressure figures are, moreover, compatible with the existence of fairly pure iron in this part of the earth. The result for the earth's outer mantle as given in a previously published paper, together with those in the present paper, are found to give with good precision the density distribution in a region occupying 99 per cent of the earth's volume. Values of the density within 1400 km. of the earth's center are subject, however, to a wide margin of uncertainty, and there appears to be no means of resolving this uncertainty for the present. The most that can be said is that the mean density in the latter region is greater than 12.3 gm/cm.3 and may quite possibly be several gm/cm.3 in excess of this figure. In the present paper figures are also included for the variation of gravity and the distribution of pressure within the central core. The gravity results are shown to be subject to an appreciable uncertainty except within about 1000 km. of the outer boundary of the core, but the pressure results are expected to be closely accurate at all depths.

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Mathematical problems in seismology

Cited by 3 publications

References 48 publications

The possibility of seiemic measurement of the rotation of the Earth's core

The possibility of seiemic measurement of the rotation of the Earth's core

New service of geodetic survey

The density variation of the earth's central core*

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