An aspect of Simi Valley 's location , situated beside the Simi Hills , is that it lies in a high-risk area for the wildfires that sweep through Southern California 's mountain ranges every few years . Simi Valley is also at risk for earthquakes . The valley is surrounded by faults ; the closest ones being the Santa Rosa Fault to the Northwest , the Northridge Hills Fault to the Northeast , and the Chatsworth Fault to the South . In 1994 , portions of Simi Valley received significant damage from the Northridge earthquake . See Nuclear Accident at SSFL for information on the accident and associated risk ( s ) to residents
Northridge earthquake
1994 Northridge earthquake
Simi Valley, California