Dr. Randall Peters talked about
"New Window on the Solid Earth."
W 1/20/00, 4:45pm, WSC 109

A 1959 March Scientific American article titled "Long earthquake waves", contains the following statement: "Though experimental data are scanty, the earth's free oscillations have intrigued mathematicians since the early 19th century. As a result, a considerable body of theory is ready for the test of observation when that becomes possible." Data to assist the indicated theory have remained scanty for the four decades since this article was written. Although long-lived, but infrequent eigenmodes of the free earth have been studied and catalogued since then; the much more common short-lived modes remained without notice until studies with an instrument invented by Dr. Peters (http://physics.mercer.edu/petepag/pend.htm#tiltmeter). The tiltmeter which uses his patented symmetric differential capacitive (SDC) sensor is less an accelerometer and more of an earth shape sensor than the conventional geoscience instrument. By monitoring the tiltmeter simultaneously with an SDC modified vertical seismometer (WWSN Sprengnether), interesting new earth motions have been discovered just in the month since these studies started (http://physics.mercer.edu/earthwaves/instr.html). A description of the instrument will be provided, including the contrast between it and conventional instruments; and some results will be provided--including material to be presented at the fall 2000 American Geophysical Union conference under the title: "Autocorrelation analysis of data from a novel tiltmeter".