Monte-Carlo simulation for estimating topographic disturbance to heat flow data

The Earth's surface topography disturbs the thermal field making measured superficial thermal gradients (heat flow) higher or lower than the deep value. Topographic disturbance can be removed from data by applying the respective correction. We estimated the effect of the rugged bottom of Lake Baikal on thermal gradients from the vicinity of boreholes BDP-93 and BDP-96 drilled in the lake sediments and deep borehole L-2 on the western shore of the South Baikal basin near Listvyanka Village. The corrections were computed using a Monte-Carlo simulation algorithm specially designed to quantify the effect of surface topography on the thermal field. The performance of the algorithm was checked by a test example. The corrections turned out to be vanishing in the area of underwater drilling but significant at L-2 where the thermal gradient in the upper 1 km of rocks was about 20% underestimated. The corrected heat flow in L-2 data increased from 50 to 60 mW/m2 and approached the values measured in the central South Baikal basin.