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Show 6. GEOLOGY AND SEISMIC (EARTHQUAKE) ISSUES There are fault lines throughout the Wasatch Front and on part of the Uinta Range. Those on the South Slopes have shown surface activity for the last fifty years ( to citizens in the Duchesne area.) This activity has been noted from the 1920fs until October, 1977,in the specific area of Rock Creek and in the general area where the Upper and Lower Stillwater Dams are proposed. Citizen report, Duchesne - 1920's - an area of vibrations, $u.ila*ne. *-»d 'Ruck CtceK - 1931-1932 - when a child of 12, he and brother observed an area north and east of Slide Canyon where the earth had been opened up, trees recently uprooted, and area generally disturbed - 1948 - tremors f^.lt in Duchesne - 1976 - tremors felt at Rock Creek Resort, After July 4 - September 30, 19 7 7 - tremors felt in night at Rock Creek, Tabiona, Duchesne, and at Rangely and Grand Junction, in Colorado - additional tremors occured the following morning - there is a known crevice of undetermined depth near Duck Lake which is southeast of Rock Creek proposed Damsite. Efforts, to date, to determine the degree of monitoring of Seismic Activity IN THE REGION OF ROCK CREEK , have not produced satisfactory information. Consultation with the State of Utah Geologist, Mr. Ritzma, elicited the following information.* - that earthquake activity has been noted throughout the Wasatch Front for years. Tremors take place, and have, periodically. Fault lines have been determined for the entire area. When construction of any kind takes place, seismic activity is considered (in Salt Lake City). Anyway, the entire crust of the earth has fault lines, which produce notable activity at various times. One has to take risks. Progress cannot stop on the basis of what might happen one day. N NEVERTHELESS I cannot determine that where planned dam and reservoir constructions are to take place, one after another along a mountain slope, that seismic conditions have been given adequate concern. Monitoring points are not set up in this area. I cannot determine whether recent seismic tremors around Hell'Hole, within a twelve mile radius of the Rock Creek Damsite proposals, are causing a second look at Dam construction by the Bureau of Reclamation. Where the weight of water increase on the Great Sale Lake in the spring is notable on Seismic Instruments in the Geneoiogical Vault up Little Cottonwood Canyon, what consideration needs to be given to the |
