Surface heat flux histories from geothermal data: Inferences from inversion

Past changes in the Earth's surface energy balance propagate into the subsu rface and appear as perturbations of the subsurface thermal regime. A singu lar value decomposition inversion (SVD) scheme has been used to reconstruct surface heat Aux histories (SHFH) from the heat flux anomalies detected in the subsurface. Synthetic data tests yield results in agreement with analy tical expressions. Inversion of a temperature log from central Canada is us ed to illustrate this procedure. Results show that reconstruction of SHFH i s possible with existing data. Application of this method to the existing g eothermal data base should permit a quantification of the energy balance at the Earth's surface for the past few centuries.