Installation of Strain Meters and a Long Period Vertical Pendulum at the Nevada Test Site

摘要

A three-axis quartz strain gage with a sensitivity of 10 to the (-9) power was installed in Tunnel U12p at the Nevada Test Site and has been operated continuously since October 1968. During this time, permanent strain changes were observed as a result of several large explosions in this area. In addition, transient strains with time constants of many minutes were observed following explosions and tentatively to pressure decay in the cavity. The most recent collection of strain changes which were produced by the HANDLEY event show that on the average, the maximum strain offset is proportional to the inverse cube of the distance. This reinforces the early speculation that the region over which an explosion may significantly alter the local stress field is quite small, being tens of kilometers rather than hundreds of kilometers. (Author)