David S. Brumbaugh

A tectonic boundary should be defined by changes in tectonic elements. Tectonic elements would include such parameters as structural style, stress orientations, volcanism, heat flow, seisrnicity and changes in crustal thickness. Examination of these tectonic elements for the southern Colorado Plateau suggests that the southwestern part of the physiographic plateau appears to be tectonically part of the Basin and Range province.

The purpose of this study was to gather and analyze previously unused data that led to improved locations for the 1906 (Ms 6.2), 1910 (Ms 6.0) and 1912 (Ms 6.2) northern Arizona earthquakes. Both ground shaking intensity patterns and instrumental data were used. The objective is to provide epicenter locations accurate enough to allow planners to decide what ground acceleration levels are most appropriate for northern Arizona.

Comments from each of the six public hearings are available for viewing. Note that the public comment period is now closed.

Public Hearing Comments

Draft EIS

The draft EIS public comment period closed November 7, 2019. All 30,000+ comment submittals are now under review for consideration in the compilation of the final EIS.

Media & General Info

Point of Contact
John Scaggs
Tonto National Forest

Apache Leap Special Management Area
Apache Leap SMA website