Symposium on Microseisms Held at Arden House, Harriman, N.Y. 4-6 September 1952, Sponsored by the Office of Naval Research, and the Geophysical Research Directorate of the U.S. Air Force. (1953) / Chapter Skim
Currently Skimming:
The Ocean as an Acoustic System
The Ocean as an Acoustic System
Pages 109-113
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 109... ...
The Ocean as an Acoustic System -- Seismic refraction measurements and earthquake surface wave studies (Ewing et al, 1950, Ewing and Press 1950, Ewing et al, 1952, Ewing and Press in press, Officer et al, 1952) indicate that the ocean basins are underlain by about 1 km of mud with acoustic properties much closer to those of sea water than the underlying crystalline rock.
|
From page 110... ...
A simple theory can account for the entire sequence arrivals of first mode Rayleigh waves having oceanic paths in terms of normal mode propagation over long distances in the watercrystalline rock system. Predictions of the water and sediment thickness as well as the nature of the crystalline rock underlying ocean basins have been verified by seismic refraction measurements (Ewing and Press 1850, Ewing and Press in press, Officer et al.
|
From page 111... ...
study of atmospheric pressure oscillations he classifies oscillations of periods less than 1 minute as "large" when the double amplitude is greater than about 2 dynes/cm'. In the illustrations he gives of typical high microbarometric activity immediately following the passage of a cold front the double amplitude appear to run around 6 dynes/cm1.
|
From page 112... ...
I rather doubt that the idea of resonant coupling between elastic waves in>two different media due to coincidence between the phase velocities of different wave types will turn out to have a great deal to do with the coupling of atmospheric pressure oscillations to the ocean bed. Where it has been possible to correlate wave forms of microbarometric waves across a tripartite array, the apparent phase velocity has usually come out to be very much less than sound velocity and comparable with the wind velocity at some moderate altitude.
|
From page 113... ...
Data at present available for the rate of growth of waves under a wind refers to waves growing gradually under a following wind; it is quite conceivable that the rate of growth of waves travelling downwind, but in the presence of an opposing swell, is greater, on account of the roughness of the sea surface. Observations of the rate of growth should be obtained.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.