Tectonic activity over millennia fractured the bedrock in this area, creating narrow vertical fractures. Because the groundwater in this area is under pressure due to the higher-elevation source, water was forced up through these fractures in the ground toward the surface. When Hazor’s tunnelers began digging down beneath the city, they probably saw some of this water seeping out through the cracks and realized there was a source of water right beneath their feet. Instead of tunneling to the springs outside the city, they dug out a water chamber right under the tell.