The pilot decided to land at the strip to check on the welfare of two mining company employees working in the area. During the latter stages of the landing roll the nosewheel entered a soft area and dug in, causing the aircraft to overturn. As the mining company's base radio was unserviceable and the ground personnel were not expecting the aircraft, the pilot was not able to establish the condition of the strip. Although it appeared serviceable from the air, the strip contained a section where water from recent rain had accumulated and resulted in the surface in that area being soft and wet.