| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
DEPARTMENT OF GEOLOGY AND GEOPHYSICS UNIVERSITY OF UTAH, SALT LAKE CITY, UTAH 84112
U.S. GEOLOGICAL SURVEY, DENVER, COLORADO 80225
GEOPHYSICS PROGRAM UNIVERSITY OF WASHINGTON, SEATTLE, WASHINGTON 98195
EG&G IDAHO, INC., P.O. BOX 1625, IDAHO FALLS, IDAHO 83415
Abstract
The 28 October 1983 Borah Peak, Idaho, earthquake (MS = 7.3) occurred in an area of low historic seismicity within east-central Idaho along a segment of the Lost River fault active during the Holocene. A dense network of portable short-period seismographs (up to 45 stations, station spacings of 2 to 10 km) was installed beginning several hours after the main shock and operated for 22 days. In addition to records from the portable instrumentation, data from permanent seismograph stations operating in Idaho, Utah, Montana, Oregon, Washington, and Wyoming provide a good regional data base. No foreshock activity above MC (coda magnitude) 2.0 was detected for the 2-month period preceding the main shock. The epicenter of the main shock is 
14 km south-southwest of the end of the surface faulting. This relationship suggests unilateral rupture propagating to the northwest. The distribution of 421 aftershocks of MC > 2 defines an epicentral pattern, 75 km x 10 km, trending north-northwest parallel to the surface rupture but displaced laterally southwest by 5 to 10 km. Aftershocks extend to depths of approximately 16 km and in the central and southeastern portion of the aftershock pattern define a zone, dipping approximately 45° southwest, that intersects the surface near the fault scarp. The entire aftershock zone as observed during the first 3 weeks was active shortly after the main shock occurred.
Fault plane solutions for 47 aftershocks show predominantly normal faulting with varying amounts of strike-slip motion. Tension axis orientations indicate a dominant extension direction of NNE-SSW during the aftershock sequence. There is considerable diversity among the aftershock focal mechanisms, even along the central and southeast portions of the fault where the hypocenters appear to outline the main fault break. We therefore interpret most of the aftershocks to represent complex fracturing on subsidiary structures adjacent to the main fault.
This article has been cited by other articles:
|
|
 |
|
  S. J. Payne, R. McCaffrey, and R. W. King Strain rates and contemporary deformation in the Snake River Plain and surrounding Basin and Range from GPS and seismicity Geology, August 1, 2008; 36(8): 647 - 650. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Taymaz, T. J. Wright, S. Yolsal, O. Tan, E. Fielding, and G. Seyitoglu Source characteristics of the 6 June 2000 Orta Cankiri (central Turkey) earthquake: a synthesis of seismological, geological and geodetic (InSAR) observations, and internal deformation of the Anatolian plate Geological Society, London, Special Publications, January 1, 2007; 291(1): 259 - 290. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. P. Zeiler, M. C. Stickney, and M. A. Speece Revised Velocity Structure of Western Montana Bulletin of the Seismological Society of America, April 1, 2005; 95(2): 759 - 762. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Stress Triggering of Conjugate Normal Faulting: Late Aftershocks of the 1983 Ms 7.3 Borah Peak, Idaho, Earthquake Bulletin of the Seismological Society of America, June 1, 2004; 94(3): 828 - 844.
|
|
|
|
|
|
G. P. Mavroeidis and A. S. Papageorgiou A Mathematical Representation of Near-Fault Ground Motions Bulletin of the Seismological Society of America, June 1, 2003; 93(3): 1099 - 1131. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Observing Earthquakes Triggered in the Near Field by Dynamic Deformations Bulletin of the Seismological Society of America, February 1, 2003; 93(1): 118 - 138.
|
|
|
|
|
|
The December 1872 Washington State Earthquake Bulletin of the Seismological Society of America, December 1, 2002; 92(8): 3239 - 3258.
|
|
|
|
|
|
Integrated Seismic-Hazard Analysis of the Wasatch Front, Utah Bulletin of the Seismological Society of America, June 1, 2002; 92(5): 1904 - 1922.
|
|
|
|
|
|
D. B. Mason Earthquake magnitude potential of the Intermountain Seismic Belt, USA, from surface-parameter scaling of late Quaternary faults Bulletin of the Seismological Society of America, October 1, 1996; 86(5): 1487 - 1506. [Abstract] [PDF]
|
|
|
|
|
|
S. M. JACKSON, I. G. WONG, G. S. CARPENTER, D. M. ANDERSON, and S. M. MARTIN Contemporary seismicity in the eastern Snake River Plain, Idaho based on microearthquake monitoring Bulletin of the Seismological Society of America, June 1, 1993; 83(3): 680 - 695. [Abstract] [PDF]
|
|
|
|
|
|
Y. DU, A. AYDIN, and P. SEGALL Comparison of various inversion techniques as applied to the determination of a geophysical deformation model for the 1983 Borah Peak earthquake Bulletin of the Seismological Society of America, August 1, 1992; 82(4): 1840 - 1866. [Abstract] [PDF]
|
|
|
|
|
|
T. S. YELIN and H. J. PATTON Seismotectonics of the Portland, Oregon, region Bulletin of the Seismological Society of America, February 1, 1991; 81(1): 109 - 130. [Abstract] [PDF]
|
|
|
|
|
|
S. Roberts and J. Jackson Active normal faulting in central Greece: an overview Geological Society, London, Special Publications, January 1, 1991; 56(1): 125 - 142. [Abstract] [PDF]
|
|
|
|
|
|
J. C. PECHMANN and B. S. THORBJARNARDOTTIR Waveform analysis of two preshock-main shock-aftershock sequences in Utah Bulletin of the Seismological Society of America, June 1, 1990; 80(3): 519 - 550. [Abstract] [PDF]
|
|
|
|
|
|
D. D. SUSONG, S. U. JANECKE, and R. L. BRUHN Structure of a fault segment boundary in the Lost River fault zone, Idaho, and possible effect on the 1983 Borah Peak earthquake rupture Bulletin of the Seismological Society of America, February 1, 1990; 80(1): 57 - 68. [Abstract] [PDF]
|
|
|
|
|
|
D. I. DOSER Foreshocks and aftershocks of large (M greater double equals 5.5) earthquakes within the western Cordillera of the United States Bulletin of the Seismological Society of America, February 1, 1990; 80(1): 110 - 128. [Abstract] [PDF]
|
|
|
|
|
|
D. I. DOSER and R. B. SMITH An assessment of source parameters of earthquakes in the cordillera of the western United States Bulletin of the Seismological Society of America, October 1, 1989; 79(5): 1383 - 1409. [Abstract] [PDF]
|
|
|
|
|
|
C. MENDOZA and S. H. HARTZELL Aftershock patterns and main shock faulting Bulletin of the Seismological Society of America, August 1, 1988; 78(4): 1438 - 1449. [Abstract] [PDF]
|
|
|
|
|
|
C. MENDOZA and S. H. HARTZELL Inversion for slip distribution using teleseismic P waveforms: North Palm Springs, Borah Peak, and Michoacan earthquakes Bulletin of the Seismological Society of America, June 1, 1988; 78(3): 1092 - 1111. [Abstract] [PDF]
|
|
|
|
|
|
S. M. JACKSON and J. BOATWRIGHT Strong ground motion in the 1983 Borah Peak, Idaho, earthquake and its aftershocks Bulletin of the Seismological Society of America, June 1, 1987; 77(3): 724 - 738. [Abstract] [PDF]
|
|
|
|
|
|
J. J. KING, T. E. DOYLE, and S. M. JACKSON Seismicity of the eastern Snake River Plain region, Idaho, prior to the Borah Peak, Idaho, earthquake: October 1972-October 1983 Bulletin of the Seismological Society of America, June 1, 1987; 77(3): 809 - 818. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
