1997 JUL04-08 Solid Earth Tide

Superimposed on the tide seismogram are an Mw=6.8 earthquake Near the Coast of Central Chile

and an Mw=5.8 earthquake in the Caribbean Sea

VERTICAL SEISMOGRAM OF EARTH TIDES NEAR LEONARD, OKLAHOMA, 1997 JUL04-08jl


The above seismogram was recorded at one sample per second from a Geotech
KS54000-0103 broadband seismometer at 119 meter depth in the Glastnost 
Borehole near Leonard, Oklahoma. The trace represents vertical ground
acceleration.

The large M shaped curves are the solid earth tide. Like the Ocean tide,
earth tide is caused by the gravitational attraction of the sun and moon.
The curves are a band instead of a line, as the constant rise and fall of
Ocean generated microseisms is superimposed on the M shaped line which
represents earth tide.

The two earthquakes listed in the headings are obvious near 11:00:00
JUL06, and left of 00:00:00 JUL06. A third earthquake, near the rightmost
peak (right of 13:00:00) was an Ms=4.6 off the coast of Oregon, USA.
These earthquakes appear to be spikes because the compressed time scale
has "squeezed" their waves together. On seismic analysis software, a part
of the trace can be expanded to show the earthquake's individual waves.
On this "gif" web image, expansion is not possible.

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