| 摘要 |
<p>To locate potentially hydrocarbon-bearing subsurface formations or other subsurface anomalies, tiltmeters (TI-TS) measure the time of arrival, apparent direction and magnitude of a lunar-induced earth tide at an array of points on the earth"s surface. The measurements are combined to determine the shape of the tidal wave in a region of interest. The shape is indicative of subsurface anomalies in the region. The tiltmeter is mounted on adjustable support legs (188) and includes fluidcarrying cups (168, 170) in which the fluid level changes relative to the cup with the rise and fall of the earth"s surface. An optical array including a monochromatic light source (62) causes interferometric bands to be generated as the distance between the fluid surface and a fixed mirror (65) varies. The fixed mirror (65) is closely spaced from the fluid surface to produce multiple reflection (67) therebetween which significantly increases measurement sensitivity and logic circuitry (72-90) is provided for determining the number of bands and their direction of movement in order to establish the time and magnitude of the peak movements of the crust. A thermostatically controlled heating system (226) maintains both the fluid within the cups and the adjustable support legs at a constant temperature to eliminate measurement error due to the effects of thermal expansion, drift, and high frequency seismic noise. </p> |
