EARTHQUAKE HISTORY OF BEAR RIVER VALLEY, IDAHO

THE AREA OF SOUTHEAST IDAHO TRENDING FROM THE BEAR LAKE TO NORTH OF SODA SPRINGS IS PROBABLY THE MOST SEISMICALLY ACTIVE AREA OF THE STATE. OLDER GEOLOGIC MAPPING HAS SHOWN LARGE INACTIVE FAULTS SUCH AS THE BANNOCK THRUST FAULT. MORE RECENT MAPPING FOR LIMITED AREAS HAS SHOWN SOME FAULTING CUTTING QUATERNARY DEPOSITS, BUT NO RECORD OF ANY DETAILED SEARCH FOR PROBABLY-RECENT FAULT MOVEMENTS HAS BEEN PUBLISHED FOR THIS AREA. THERE HAVE BEEN NO REPORTS OF EARTHQUAKES ASSOCIATED WITH EARTH MOVEMENTS SUCH AS FAULTING. A RECORD OF AT LEAST 22 EARTHQUAKES IN THE PAST 98 YEARS, CENTERED ON THE BEAR RIVER VALLEY, INDICATES UNUSUAL ACTIVITY AND NEED FOR MORE GEOLOGICAL STUDY. THE MOST RECENT EARTHQUAKE OCCURRED ON JULY 16, 1971, AND WAS FELT OVER ABOUT 400 SQUARE MILES. IN ONE VIEW, A LARGE NUMBER OF SMALL EARTHQUAKES IS CONSIDERED BENEFICIAL. IT IS PRESUMED THESE TEND TO RELIEVE ACCUMULATING STRAINS IN THE EARTH'S CRUST AND HELP TO PREVENT BUILDUP OF STRAINS SUCH THAT A DISASTROUS EARTHQUAKE WILL NOT OCCUR. ACCUMULATION OF EARTHQUAKE DATA HELPS TO IDENTIFY POSSIBLE AREAS OF ACTIVE FAULTING THAT SHOULD BE CONSIDERED IN ENGINEERING PLANNING. /AUTHOR/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 235-41

Subject/Index Terms

Filing Info

  • Accession Number: 00236445
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 3 1973 12:00AM