Ak. Benson et Nb. Mustoe, ANALYZING SHALLOW FAULTING AT A SITE IN THE WASATCH FAULT ZONE, UTAH,USA, BY INTEGRATING SEISMIC, GRAVITY, MAGNETIC, AND TRENCH DATA, Engineering geology, 40(3-4), 1995, pp. 139-156
Gravity, magnetic, and seismic surveys were conducted across the Wasat
ch fault zone east of Springville, Utah, near the mouth of Hobble Cree
k Canyon. The geophysical data were acquired, processed, and interpret
ed to determine possible locations of larger [total offset greater tha
n 6 ft (1.8 m)], shallow normal faults within the fault zone. Interpre
tations of the individual data sets were integrated to help eliminate
spurious readings and to strengthen the interpretations. Visual method
s of integration, along with computer modeling, were chosen for this s
tudy. Furthermore, the geophysical data were correlated and integrated
with available trench data and surface data. In addition to verifying
locations of known faults, the geophysical surveys detected numerous
possible additional faults not previously mapped. Of particular intere
st is a newly discovered graben structure near the southern end of the
site, where building of new homes has recently been proposed. New str
uctural information about fault densities and styles was also determin
ed from the surveys. The fault concentration for this site is 1.3 faul
ts/100 ft (30.5 m), or one fault per 77 ft (23.5 m). Interpreted antit
hetic faults at the Hobble Creek site account for 65% of the total, wh
ile synthetic faults account for 35% with respect to the main fault st
rand. Information derived from this study should be useful during plan
ning and development of areas within the Wasatch fault zone. The chara
cteristics of subsurface deformation can be used to gain a better unde
rstanding of the potential for surface rupture at a given site. This i
s also useful in planning appropriate site development and remedial me
asures to help mitigate hazards associated with large-magnitude earthq
uakes.