User:Shawnbrowngeo/Provo segment of the wasatch fault

The Provo Segment of the Wasatch Fault is located on the eastern boundary of the Basin and Range Province(BRP). It is approximately 59 to 70 kilometers in length and is conservatively estimated to be capable of a 7.2 to 7.4 moment magnitude earthquake based on assessments of paleoseismic trench analysis of Holocene alluvial sediments of several sites spanning across the segment. Fault displacement of major earthquakes recorded are between about 3 and 6 meters. The average recurrence interval estimated from a 14,ooo year record is approximately once every 1500 to 2600 years. The last event large enough to record surface rupture is believed to have been about 450 to 700 yrs ago. When determining recurrence intervals of active faults geologists are often able to establish a timeline, amount of net verticle tectonic displacement, and length of rupture based on the collection and analysis of trenches as well as by other means. The segment spans from the Traverse Mountains as the northern boundary to Dry Mountain at the southern boundary.

Tectonics & Geologic Setting
Extensional tectonic forces affect many parts of the earths crust. These can result from crustal-scale related to plate motion, as a component related to major reverse or strike-slip faults in a secondary sense, or as extension due to gravitational collapse of elevated terrain. The Basin and Range is currently undergoing a process of extension resulting in hundreds of thousands of potentially active fault systems. The BRP consists of mostly normal slip faults, or faults that tend to slip in a relatively verticle motion. Most of these fault systems have long recurrence intervals, ranging from hundreds to thousands of years, making it very difficult to predict future earthquakes that are potentially threatening to the lives of people, as well as property and economic losses.

The Wasatch Fault Zone
At about 350 kilometers in length, the Wasatch Fault Zone is one of the largest North American Fault sysetms. It is generally trending north and is divided into ten sections or segments. The eight most southern sections are located in Utah. One section straddles the Utah-Idaho border and the northernmost section is entirely in Idaho.

Segmentation of Normal Faults
Normal fault traces tend to vary from about 10 to 50 kilometers in length. They are often seperated from adjacent normal faults by stepovers. In a structural sense these stepovers or gaps often but do not necessarily mark a boundary of a segment. A seismogenic or earthquake generating segment is traditionally thought of as being a portion of fault that has slipped more or less independantly of other segments in the area. Historically moment magnitude greater than a 7.0 might rupture an entire segment and continue into a neighboring segment. When this occurs the neighboring segment's rupture does not span across the entire segment and the displacement of the neighboring segment is also much less when compared to the displacement of the initial segment or the segment containing the epicenter of the earthquake. .