The Earthquake of December 20, 1932, at Cedar Mountain, Nevada and Its Bearing on the Genesis of Basin Range Structure

This paper presents a summarized account of field studies of the rifts or faults formed at the time of the earthquake, interpretation of structural data, and relation to some structural features of the western part of the Great Basin and California. Sixty rifts occur in a belt 38 miles long and 4 to 9 miles wide in a valley between two groups of mountain ranges. Horizontal movement on individual rifts and the en echelon pattern of the entire group indicate that the major movement causing the earthquake was horizontal-the east side toward the south with reference to the west side. This direction of relative horizontal movement is the same as that on the east front of the Sierra Nevada at Owens Valley and on faults in California, including the San Andreas rift. It is suggested, therefore, that movements in the western part of the Great Basin and California are definitely related. The rift area lies on the boundary between those ranges trending dominantly to the north and northeast and those ranges trending dominant-ly to the northwest. This line does not appear to have been pointed out previously, and it may be a tectonic line corresponding in some respects to the east front of the Sierra Nevada and the San Andreas rift.