Seismic hazards investigations at Los Alamos National Laboratory, 1984 to 1985

Technical Report · Thu Oct 01 00:00:00 EDT 1987

OSTI ID:5163306

Gardner, J N; House, L

The Pajarito fault system, part of which skirts the western boundary of Los Alamos National Laboratory, is a major, active structural element of the Rio Grande rift. We have mapped over 100 km of interrelated fault zones and traces that constitute the fault systmem in the vicinity of Los Alamos. The style of deformation in the fault system gradually transforms from normal slip, to normal oblique slip, to dominantly right lateral strike-slip motions from south to north. Most significant movements (>100 m) on the fault system in the vicinity of Los Alamos have occurred within the last 1.1 million years. Portions of the fault system may have associated microseismic activity. Available evidence indicates tha major movements have occurred on the fault system in the last 500,000 years and as recently as 350,000 years ago, 240,000 years ago, 42,000 years ago, possibly <10,000 years ago, and 2000 years ago. Some limited, inferential field data imply the fault system generates characteristic earthquakes in the magnitude (Richter) range 6.5 to 7.8. Extrapolation of frequency-magnitude relations, derived from the 10 years of data from the Los Alamos seismograph net, to estimate large expectable earthquakes is unrealistic, and based on the findings of other workers the result is most likely a substantial underestimate. 77 refs., 11 figs., 4 tabs.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5163306
• Report Number(s): LA-11072-MS; ON: DE88007166
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
EARTHQUAKES
RISK ASSESSMENT
LASL
SEISMICITY
EVALUATION
GEOLOGIC FAULTS
HAZARDS
HISTORICAL ASPECTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
NATIONAL ORGANIZATIONS
SEISMIC EVENTS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
580201* - Geophysics- Seismology &amp; Tectonics- (1980-1989)
510500 - Environment
Terrestrial- Site Resource &amp; Use Studies- (-1989)