Method of mapping permafrost by electromagnetic radiation to indicate thickness thereof

Claim 1

Method of measuring the distance to the bottom of a permafrost zone of an earth formation by means of an electromagnetic generating and receiving means located at a known geographical location adjacent to the upper surface of said permafrost zone to indicate the thickness thereof in a region of the earth in which said permafrost zone has a gradual variation in its depth versus horizontal distance characteristic such that a seismic record of said earth formation contains insufficient data to indicate the change in thickness of said permafrost zone as a function of said horizontal distance, which comprises: 1. after obtaining said seismic record of said earth formation in which slight changes in permafrost zonal thicknesses are undetectable therefrom, irradiating said permafrost zone with electromagnetic energy within a frequency range of 106 to 1011 Hertz by actuation of said electromagnetic generating and receiving means, 2. detecting reflections of the electromagnetic energy from at least said permafrost zone bottom which represents a frozenunfrozen interface, said interface forming an electro-magnetic discontinuity between the bottom of said permafrost zone and an unfrozen earth zone lying therebelow, 3. recording the two-way travel time for said energy to travel from substantially the upper surface of said permafrost zone to said remote interface within said permafrost zone and return whereby said travel time may be displayed to delineate the location, depthwise, of said remote interface of said permafrosT zone relative to the upper surface, and 4. utilizing the delineated locations indicative, depthwise, of said remote interface of said permafrost zone of said earth formation to determine static corrections for said seismic record of said same earth formation, which comprise: correlating said delineated locations indicating, depthwise, the remote interface of said permafrost zone to seismic events on said seismic record so as to provide a static correction for each trace of said seismic record, and adjusting each trace of said seismic record in accordance with said determined static correction.