Since humans have come along they have; removed soil, black topped forests, cut highways into bedrock, built cities on deltas, thus totally changing the earth's surface. For example if there was an earthquake in Vancouver, British Columbia, many catastrophic disasters will occurs. Most of the dams built to create reservoirs will either crack or burst, unleashing a torrent of water that will descend on the residential areas that border the rivers. Richmond will sink, because most of the city if not all is built on the Fraser River delta. The soft sandy ground, which the city is built upon, will liquefy and the ground will become unstable under the pressure of most of the buildings placed upon it. And the reason for all these disasters is the human interference in the hydrologic cycle.