ae oe ee ‘ . a Se in: Me CO! OReo each‘situation above factors, it is necessary lo anilyze Pesp.:aes. 4predicting possibleground*motions and structural isin unite motion prround of theeffects express wayto One | oncarth,-Le., 32 feet per second change in ‘body experiences As a . . “#yvelocity for each second'that the acceleration occurg.s “pyle ‘of thumb”—the threshold of ground motion ‘thata Maye (Yse00) of “x. ““sbeperceptible to humans -is one-thousandth rT af es gyeh. Ground motions canbe accentuated at higher places e er =: ngs, buildi fall is frequrntly "As another “rule of thumb,” one-tenth of a "4" . ‘aeaccepted:ad the eriterionsfor threshold of property. damage pres: u + However, this is baged on-damage from earthquakes and vt “# tae serit data showthatscismigwaves generated by nuclear detona-” and chemical high ‘explosives result in legs damaging “tons oi o than would be predicted for thy same peak acceleration flects 4 * are repeated shocks: At period of time for each shock. Also, there — , j in moat cases. ‘Thus, strijetures are subjected to more damagab ing effects because of the number of shocks and greaterdura: oe pel, “tion of each shock than ‘Would be the case for the same peak acceleration experienced as a result of ground motion.from an underground nuclear explosion. OP “*Since nuclear detorations produce ground motions, it has . - been speculsted that theymay “trixxer” a natural earthquake. It is not possible to have a natural earthquake, ‘however, ‘:without prior storage of strain enerzy—a process that occurs wt." t erin the Strom an earthquake. ‘Partof this difference mayfor.alonger fact that ground motions from earthquakes persist Ses were ‘situated under conditions favorable to the wuplificatioggy ‘aeraer the*ground motions, “No.structural dumage fron: yrowng é.ee»« mation has been experienced beyond about six miics fromt}. 3 wre considered. The Deta The meximum range at which seismic waves from the larg: est nuclear detonations to date at the Nevadn Seat Bile are 28 ES Boa OF ae meget weg ae wa & ec a Fey “ E854¢ Since-ground motions from ynderground nuclear explosion i aNd there is a need to predict marginal daineye tu slructired $55+BFforsuch explosions a new’approach is required. The analyti PtJe are’ develoyed, conservative’estimates of the effects may.t Regie. made by comparison with*damage which might he expeptat uffrom .the same amplitudegf ground motion in an curthquake Set ne Te ‘ Be ae f : ng “ Sd, nay ate a ae re eee iva: oe if am . . : & d * and : a ¥ B he y n £ “ ate ground motions of more than small amplitude. The possibility that light damage may result, therefore, must be EE 4 ath 1. &are different in nome respects from those from an varlhquak explosion several miles deep in an earthquake susceptible explosions the site is selected with anfety in mind so that struc: .tures outside the test area wili not ordinarily be subjected to sen” ences. of geophysical principles arereaulting in a steady improvamen L-aeodigallie’ in methods of prediction of ground motionsfor planned event - area to be-near a zone where the stress might be great enough . The response of structures to earthquakes has been the subject of study for many years and satisfactory procedures have been developed for design of structures to withatand the . effects of earthquakes. However, i these cases the interest is in significient structural damage, rather than plaster crack. ing or other minor effects. In the ease of underground nuclear ®: . “gt Records of ground motion are now available for many unde geesot ground ‘nuclear explosions.“ Analyses of data and upplicatic ‘over a period of years. “It would be necessary to conduct an. ‘fer an incipient quake to be triggered. =" siterof“the nuclear detonatigns. roy fw brags le ee il na ON ~ & ao BPS OT eee + RRrere mRmeRE To EY I NETO SeTE Re . ‘ HE ten ie ae - en of “g." This refers ‘to the:acceleration that a freely’falling s §¢known to have been perceived by persons withuul benef. soacaz of ingtruments has been about 100 miles. Theae few person : : rs fe cr alee vo: + . é. 4