Estimates of yet-to-find impact crater population on Earth

One hundred and seventy-six craters on Earth are currently accepted as resulting from bolide impact; this list is growing at a rate of approximately two craters per year because of new discoveries and revised interpretations. Here we take the subset of craters most relevant to sedimentary basin exploration and utilization (Phanerozoic kilometre-scale craters) and tackle the question of how many remain to be found in Phanerozoic strata on Earth. A surprising range in predictions of crater numbers is obtained from published crater population functions, reaching two orders of magnitude variation for craters in the range 1-5 km diameter. This range in predictions is largely due to variations in treatment of impactor breakup in the atmosphere. Also required is quantification of the total area and timespan of Phanerozoic sediment currently preserved on Earth; an estimate of 8.87 x 10(15) km(2) a is derived here. Together with a relatively conservative crater population function this yields a prediction of 845 craters; subtracting the 131 known Phanerozoic craters larger than 1 km leaves a predicted population yet to find of 714, of which 228 are larger than 2.5 km. Uncertainties, subsets of this population, and spatial distribution are also considered.