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1990-01-09_REVISION - M1988112 (6)
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1990-01-09_REVISION - M1988112 (6)
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Entry Properties
Last modified
6/19/2021 9:53:59 AM
Creation date
11/21/2007 5:31:22 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1988112
IBM Index Class Name
Revision
Doc Date
1/9/1990
Doc Name
FAX COVER
From
STEFFEN ROBERTSON & KIRSTEN
To
MLRD
Type & Sequence
AM1
Media Type
D
Archive
No
Tags
DRMS Re-OCR
Description:
Signifies Re-OCR Process Performed
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?0 61.09 12::7. S 76; ~-a5 ??s'r SF Y. DEt~ 0' <br />w. <br />BATTLE MOUNTAIN RESOURCES, SAN LUIS PROJECT <br />CM[Rp ADEQUACY LETTER RESPONSES <br />Page 14 of 28 <br />A review of seismic records of the past ]10 years show that seismic <br />activity in the San Luts Valley ~,as been virtually absent. A review <br />of technical literature pertai,~ing to seismicity 1n the project <br />vicinity, however, revealed that Kirkham and Rogers (1981) in their <br />study of Colorado Earthquake ^~*.ential, identified the Sangre de <br />Cristo Fault, which trends nori south at the base of the foothills <br />to the west of the project site. This fault is located relative to <br />the project on Figure D.1-1 in the April 1989 submi:sion to the <br />Colorado MLRD. The interpretation of the fault was that it should <br />be classified as an active fault bass o on its apparent rupture having <br />occurred within the last 10,000 years (Holocene). <br />To augment the regional study, SRK commissioned Dr. Charles Glass <br />to further evaluate the seismic potential of this fault. Copies of <br />Dr. Glass' reports are contained in Appendix B of the April 1989 <br />submission. Dr. Glass' findings indicated that the maximum credible <br />earthquake (MCE) for the portion of the Sangre de Cristo Fault in <br />the project vicinity is a Richter Magnitude of 6.8 to 7.0 and that <br />a very conservative and somewhat tentative estimate of the <br />probability of its occurrence in the next 100 yrs ranges from 0.6 <br />to 12 percent. This equates to a probability of .06 to 1.3 percent <br />that the MCE will occur in the next 10 yrs or the operational life <br />of the facility. However, statistical models used to predict the <br />recurrence interval of earthquakes require a relatively complete <br />catalogue of historical seismicity. There is virtually ro historical <br />seismicity for the San Luis Valley over the past 11(I years. Dr. <br />Glass estimates that there is a 25 percent chance that the MCE along <br />this fault has a recurrence interval less than 10,000 years and <br />agrees with Kirkham and Rogers estimate that the Sangre de Cristo <br />fault last exhibited movement 1,940 to 4,715 years ago. <br />Current seismic theory suggests that the build-up of stresses along <br />a large fault occurs prior to release of those stresses through a <br />major seismic event. Increase in stress is Indicated by t'^ <br />occurrence of minor seismic activity as the stress builds. The 1• <br />of seismic activity in the San Luis Valley indicates that str•e~ <br />across the Sangre de Cristo Fault have not been increasing and than <br />the occurrence of a major seismic event along this fouls; in the near <br />future is doubtful. Oue to the indicated low probability of the <br />occurrence of the I?CE event, SRK determined that the seismic design <br />criteria for the tailinys facility Should be based on ~'' potential <br />for regional seism, activity. <br />As indicated in Section D.1.2 of ttie aNproved permit applic <br />Algermissen et al (1982) suggest a peak yiound acceleration fc <br />project area of 0.139. This acceleration has an associatted 90 pe <br />probability of not being exceeded in 250 years. To util+ze *his c: <br />for a pseudostatic analysis the peak ground acceleration i<_ ~1rdu:.ad <br />to prod~ca a., egravalrnt acceleration. <br /> <br />
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