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Discover the relationship between modes, boundaries, and orthogonal functions on a sphere, similar to sines and cosines on a string. Explore notable milestones in understanding Earth's normal modes, from the mid-1800s to the present.
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The boundaries make the modes! No boundaries, no discrete modes! (an infinitely long string would have continuous modes at all frequencies)
The boundaries make the modes! No boundaries, no discrete modes! (an infinitely long string would have continuous modes at all frequencies)
The boundaries make the modes! No boundaries, no discrete modes! (an infinitely long string would have continuous modes at all frequencies)
The boundaries make the modes! No boundaries, no discrete modes! (an infinitely long string would have continuous modes at all frequencies)
How would you define a set of orthogonal functions on a sphere? (the equivalent of sines and cosines on a string)
Mid-1800’s – music of the spheres – Earth’s revolution is a C#, 33 octaves below middle C# ( breathing mode is an E, 20 octaves below middle E) 1882 – Lamb – fundamental mode of Earth (as steel ball), 78 minutes 1911 – Love – included self-gravitation – fundamental mode period of 60 minutes 1952 – Kamchatka EQ is first to reveal Earth’s normal modes 1960 – Chile earthquake reveals over 40 modes
