Coordinates: 33°05′40″N 116°27′08″W / 33.09444°N 116.45222°W Earthquake Valley is a desert valley east of Julian, California, which contains parts of the Anza-Borrego Desert State Park. It is the location of the Shelter Valley Ranchos subdivision, which is also known as the unincorporated community of Shelter Valley. The official USGS place name for the geologic feature in which Shelter Valley is situated is "Earthquake Valley", and the 1959 USGS Topographic map makes no reference to Shelter Valley. The name of the unincorporated community Shelter Valley is typically used both locally and by the media to refer generally to the geological feature of Earthquake Valley, and it is common for both names to be referenced in publications after the 1962 establishment of the subdivision. Author, poet, artist and primitivist Marshal South lived in and wrote about the general area (including Julian, Mason Valley, Vallicito Valley, and his home in Blair Valley), in a series of articles for Desert Magazine between 1941 and 1948. A number of notable trails pass through the valley, including the Pacific Crest Trail, the California Riding and Hiking Trail, and the Southern Emigrant Trail.
Earthquake Valley was the site of a Kumeyaay village near what is now Scissors Crossing and Sentenac Cienega, a little cienega formed at the bottom of the watershed in the valley before it descends Sentenac Canyon.