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Active Tectonics: Studies in Geophysics
history. Forecasting tectonic activity requires a long record, and therefore the tectonic geomorphology of landforms with long survival times will be an important ingredient in estimating tectonic hazards. Rates of geomorphic processes such as pedimentation or stream downcutting can act as a clock that starts ticking following the formation of a tectonic landform. Present limited knowledge of these rates suggests that during periods of active faulting in the Basin and Range province, fault-slip rates of about 0.1–1 m per 10,000 yr or greater are needed to generate high topographic escarpments, and these periods of active faulting may last on the order of a million years.
The Hurricane escarpment, in southern Utah, for example, was formed by an average fault-slip rate of 3 m per 10,000 yr. Landforms, such as scarps, produced by slip rates less than 1 m per 100,000 yr may be sufficiently obliterated by erosion to preclude the accumulation of relief across a mountain front. Relations between the recurrence interval of ground-rupturing earthquakes and mountain front development need closer study. Many of the methods described above can be easily used and rapidly applied, and, therefore, regional studies are both possible and desirable. The need for more data on geomorphic rates is a limiting factor on the interpretation of such analyses, and therefore Quaternary dating is a corequisite for continued research in the field of tectonic geomorphology.
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