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<br /> <br />states in the va I ue of expected annua II zed bu II ding losses <br />from eacthquakes between 1980 and the year 2000. <br /> <br />Characteristics <br /> <br />Earthquakes are caused by fault movements within the earth <br />that produce vibrational waves which are transmitted through <br />the ground. Interaction of these earthquake vibrations with <br />the nearby surface and with the works of man results In the <br />damage and destruction that often accompanies moderate and <br />larger-sized earthquakes. The adverse effects may Include <br />severe ground shaking In the epicentral region, possible <br />ground rupture and di sp I acement I n the fau I t zone, and In <br />cases of adverse cond' t lons--ground fa I I ure--such as <br />landslides, sol I settlement, sol I I iquefactlon and ground <br />cracking. Indirect effects which can occur Include dam <br />failure and accompanying flooding, fires from ruptured gas <br />lines, uncontrolled fires due to failure of water <br />distribution systems. and health problems from dysfunction or <br />1055 of sanitary facilities. <br /> <br />Mitigation <br /> <br />When .the location of active faults of an area is well known <br />and surface rupture and displacement are known to accompany <br />earthquakes, building near faults should be avoided <br />completely except in cases where there Is no alternative, <br />such as for certain transportation and uti Ilty corridors. <br />However, the potentially active faults in Colorado have not <br />been studied in detail and ground breakage has not been <br />documented for historic earthquakes. <br /> <br />Mitigation of earthquake damage for Colorado must deal <br />primari Iy with the broader effects of ground shaking on <br />actual structures and on preventing associated effects such <br />as landslides through careful and conservative engineering <br />designs and building codes that are consistent with the <br />actual seismic hazard. Since the study of seismicity of <br />Colorado is at an early stage, there Is stt I I much to do In <br />the way of additional earthquake studies, public awareness, <br />improved governmental coordination and Implementation of <br />seismically appropriate building codes, land use controls, <br />and pol icies. Special attention should be given to seismic <br />safety of Institutional bui Idlngs such as schools, hospitals, <br />prisons, and other facilities where large numbers of citizens <br />are assembled. <br /> <br />Another special category consists of development activities <br />and structures that have the potenti al for severe offslte <br />Impacts. Such faci I itles must receive careful seismic <br />ana I yses and conservat I ve eng 1 neer I ng des I gns cons i stent with <br />the earthquake risk of their locations. included In this <br /> <br />." <br /> <br />category are nuclear faci I itles, large tailings Impoundments, <br />large reservoirs, hazardous waste storage and handling <br />facilities, deep fluid disposal wells, and any other activity <br />where a malfunction due to an earthquake could cause serious <br />adverse effects to adjacent lands. <br /> <br />( <br /> <br />Land Use <br /> <br />Land use policies for 'eas of Colorado that are subject to <br />earthquakes and their ~ ~ects are Just beginning to emerge <br />since the recent comp Ie' on of the cooperat I ve study of <br />potentia'lly active fault. of Colorado by the Colorado <br />Geological Survey and the ~ S. Geological Survey. Already <br />major projects whose fal lure ~uld cause hazard to adjacent <br />residents are receiving special ~ttention Including the use <br />of earthquake-res I stent dam desl8 s where I tis found proper. <br />It is ant i c i pated that as more a ta I I ed know I edge of the <br />seismic environment of the state rnerges and as current <br />knowl edge becomes better known. bu I ding regu I at Ions and <br />general land use policies should and, '11 be revised. <br /> <br />Case History <br /> <br />At 6:30 p.m. on November 7. 1882, a moderate-51. 'd earthquake' <br />shook Colorado and parts of the adjacent state.. Study of <br />reports Incl uded in newspaper articles which dl:. .crlbe the <br />earthquake suggest the earthquake centered I n the <br />Denver-Broomf i e I d area. The wa I I s of the Bou I der County <br />ra i I road depot cracked. P I aster fe II from wa 115 d the <br />University of Colorado. Inmates at the Jail In Gelden <br />supposedly demanded Immediate release. Several clocks ~~re <br />stopped by the violent ground shaking. Reports of falll,'g <br />plaster and other similar damage came from as far away a~ <br />Rawlins, Wyoming. <br /> <br />A cur lous aspect of th I s earthquake was that 1 t occurred just <br />after the close of the polls for the state elections. <br />Several newspapers suggested the eatthquake was nature's way <br />of protesting the outcome of the elections. <br /> <br />;, <br /> <br />51 <br />