PERMFILE50024

• Permit No: M1988112
• IBM Index Class Name: Permit File
• Doc Date: 11/8/1988
• Section_Exhibit Name: APPENDIX B SEISMOLOGY STUDY
• Media Type: D
• Archive: No

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' segment will not support a single rupture event along the
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ale glacial deposits seems
to decrease in the vicinity of Medano Creek as shown in
' Figure 1. Sand cover in this area unfortunately apparently
' obliterates scarps so that further segmentation remains
' speculative. Rupture along a 48 km zone from Blanca Creek
to San Isabel Creek would seem to provide a maximum event
for this fault segment. Table I presents a summary of
recurrence rates for the Sangre de Cristo fault. Data is
from McCalpin (1981) and Kirkham and Rogers (1981).
' Recurrence was computed using the number of offsets of
each individual unit rather than using cumulative offsets.
' Hence, the recurrence times differ somewhat from those of
McCalpin.
Using an average fault displacement of 2 meters (McCalpin,
1981), the seismic moment for an earthquake along this zone
is calculated to be M0= 3.8X1026 dyne.cm. The moment
magnitude for such an event would be ML= 7.0.
Menges (1987) reports the results of mapping fault
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scarps a
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a San Luis Valley in northern New Mexico. More than 40 detailed
' scarp profiles were studied. Single event displacement along
scarps averaged 1.8 m with a return period of approximately
10,000 years and a slip rate of less [han 0.15 mm/yr. Common
fault rupture segmentation is 10 to ZO km.
Farther south within the Rio Grande Rift in the Albuquerque
Basin, Machette(1978) has documented four ruptures within
the last 500,000 years on the "County Dump" fault for a
' return period of from 90,000 to 190,000 years. Golombek (1984)
also studied normal faults in the Albuquerque Basin and
' based on deformation rates found return ranging from 14,000
to 20,000 years (0.1 to 0.15 mm/yr) for individual faults and
' 7,000 years (0.3 mm/yr) for long term extension of the entire
Albuquerque Basin.

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