You mean that the pressure from an explosion follows the inverse cube of the distance, so even increasing the explosive power a lot wouldn't matter that much be

You mean that the pressure from an explosion follows the inverse cube of the distance, so even increasing the explosive power a lot wouldn't matter that much because the distance to damaging-pressure (for whatever threshold you choose) would only increase with the cube root of the factor it was increased by? How do you get 10% more? Based on that logic I'd expect the damage radius to be 1.6x the size for a 5x larger explosion, which would mean 2.5x the area inside a damage-threshold pressure contour.