Although Kansas is not seismically active, a strong earthquake could pose significant threats to the state. If an earthquake had occurred along the Nemaha Ridge prior to 2010, it could have destroyed the dam on Tuttle Creek Reservoir, releasing of water per second and flooding the nearby area, threatening roughly 13,000 people and 5,900 homes. A study in the 1980s found a moderate earthquake "between 5.7 to 6.6 would cause sand underneath the dam to liquefy into quicksand, causing the dam to spread out and the top to drop up to three feet." To address this threat, the Army Corps of Engineers completed a project in July 2010 that replaced the sand with more than 350 concrete walls and equipped the dam with sensors. Alarms are connected to these sensors, which would alert nearby citizens to the earthquake.