2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

New Search

Fault Name	State
La Canada del Amagre fault zone	New Mexico

GEOMETRY
Dip (degrees)	50/60/40
Dip direction	E
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	17

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	6.50
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	0.02	23.3	3.47e-05	n/a	0.2
50	0.02	19.6	2.44e-05	n/a	0.6
60	0.01	17.3	1.91e-05	n/a	0.2

Comments
The La Canada del Amagre fault zone offsets 10.6 Ma dikes right-laterally by approximately 530 m, which implies a dextral slip rate of 0.05 mm/yr. Kinematic data suggested that all the slip post-dated about 5 Ma, which would imply a faster strike-slip rate of 0.1 mm/yr. Wong and others (1995, 1996) postulated a distribution of slip rates from 0.02 to 0.9 mm/yr, with a preferred rate of 0.1 mm/yr. The preferred rate was mistakenly used as a vertical rate in the 1996 national seismic-hazard maps. Since then, a vertical offset of 15 m on the 1.2 Ma Bandelier Tuff indicates a much slower, Quaternary slip-rate of 0.012 mm/yr. The 2002 maps used a vertical slip rate of 0.06 mm/yr, calculated as the average of 0.012 and 0.1 mm/yr, with the latter rate still mistakenly thought to be vertical. For the 2007 and subsequent maps, the long-term rate from the dextrally-offset dikes was discarded, and the shorter-term, Quaternary, vertical slip-rate from the Bandelier Tuff was used alone (0.012 mm/yr). The characteristic magnitude for this fault is fixed at M6.5 based on Basin and Range Province Earthquake Working Group recommendations documented by Lund (2006) even though the length of the fault would suggest a smaller earthquake. Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Comments

The La Canada del Amagre fault zone offsets 10.6 Ma dikes right-laterally by approximately 530 m, which implies a dextral slip rate of 0.05 mm/yr. Kinematic data suggested that all the slip post-dated about 5 Ma, which would imply a faster strike-slip rate of 0.1 mm/yr. Wong and others (1995, 1996) postulated a distribution of slip rates from 0.02 to 0.9 mm/yr, with a preferred rate of 0.1 mm/yr. The preferred rate was mistakenly used as a vertical rate in the 1996 national seismic-hazard maps. Since then, a vertical offset of 15 m on the 1.2 Ma Bandelier Tuff indicates a much slower, Quaternary slip-rate of 0.012 mm/yr. The 2002 maps used a vertical slip rate of 0.06 mm/yr, calculated as the average of 0.012 and 0.1 mm/yr, with the latter rate still mistakenly thought to be vertical. For the 2007 and subsequent maps, the long-term rate from the dextrally-offset dikes was discarded, and the shorter-term, Quaternary, vertical slip-rate from the Bandelier Tuff was used alone (0.012 mm/yr). The characteristic magnitude for this fault is fixed at M6.5 based on Basin and Range Province Earthquake Working Group recommendations documented by Lund (2006) even though the length of the fault would suggest a smaller earthquake. Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Wong, I., Kelson, K., Olig, S., Kolbe, T., Hemphill-Haley, M., Bott, J., Green, R., Kanakari, H., Sawyer, J., Silva, W., Stark, C., Haraden, C., Fenton, C., Unruh, J., Gardner, J., Reneau, S., and House, L., 1995, Seismic hazards evaluation of the Los Alamos National Laboratory: Technical report to Los Alamos National Laboratory, Los Alamos, New Mexico, February 24, 1995, 3 volumes, 12 pls., 16 appen. Wong, I., Kelson, K., Olig, S., Bott, J., Green, R., Kolbe, T., Hemphill-Haley, M., Gardner, J., Reneau, S., and Silva, W., 1996, Earthquake potential and ground shaking hazard at the Los Alamos National Laboratory, New Mexico, in Goff, F., Kues, B.S., Rogers, M.A., McFadden, L.D., and Gardner, J.N., eds., The Jemez Mountains region: New Mexico Geological Society, 47th Field Conference, September 25-28, 1996, Guidebook, p. 135–142. Lund, W.R., ed., 2006, Basin and Range Province Earthquake Working Group seismic-hazard recommendations to the U.S. Geological Survey National Seismic Hazard Mapping Program: Utah Geological Survey Open-File Report 477, 23 p, ugspub.nr.utah.gov/publications/open_file_reports/OFR-477.pdf.

Selected References

Wong, I., Kelson, K., Olig, S., Kolbe, T., Hemphill-Haley, M., Bott, J., Green, R., Kanakari, H., Sawyer, J., Silva, W., Stark, C., Haraden, C., Fenton, C., Unruh, J., Gardner, J., Reneau, S., and House, L., 1995, Seismic hazards evaluation of the Los Alamos National Laboratory: Technical report to Los Alamos National Laboratory, Los Alamos, New Mexico, February 24, 1995, 3 volumes, 12 pls., 16 appen.
Wong, I., Kelson, K., Olig, S., Bott, J., Green, R., Kolbe, T., Hemphill-Haley, M., Gardner, J., Reneau, S., and Silva, W., 1996, Earthquake potential and ground shaking hazard at the Los Alamos National Laboratory, New Mexico, in Goff, F., Kues, B.S., Rogers, M.A., McFadden, L.D., and Gardner, J.N., eds., The Jemez Mountains region: New Mexico Geological Society, 47th Field Conference, September 25-28, 1996, Guidebook, p. 135–142.
Lund, W.R., ed., 2006, Basin and Range Province Earthquake Working Group seismic-hazard recommendations to the U.S. Geological Survey National Seismic Hazard Mapping Program: Utah Geological Survey Open-File Report 477, 23 p, ugspub.nr.utah.gov/publications/open_file_reports/OFR-477.pdf.