INTERMEDIATE RANGE EARTH MOTION MEASUREMENTS

Technical Report · Wed Oct 31 04:00:00 EST 1962

OSTI ID:4755020

Swift, L M

Data were obtained on the Gnome shot (3.1 plus or minus 0.5 kt: detonated at a depth of 366 meters in Salado halite, near Carlsbad, New Mexico) to improve the capability of extrapolation and prediction criteria for earth motion at long ranges from underground shots, primarily to permit evaluation of damage capability to surface and subsurface offsite structures. Acceleration measurements were made at the surface and at shot depth at four ranges from 800 to 9500 meters. Surface measurements of particle velocity were made at 402 and 805 meters uslng three-component velocity gages, and at five stations from 8380 to 9357 meters using seismometers. Pressure measurements were made in the fluid in four annuli of the Shell James Ranch No. 1 well, about 9.5 km from surface zero. Where feasible, acceleration and velocity data were integrated to show velocity and displacement. Subsurface accelerations and velocities were only slightly higher than the predictions based almost entirely on high explosive tests (Cowboy). The scatter in surface acceleration, velocity, and displacement allows no precise conclusions on the relationship between subsurface and surface motion, but they were mostly less than twice the subsurface motions. Spalling of the surface formation was observed out to about 1000 meters. Negligible structural response was observed at the Shell well. This test demonstrated that predictions of free field earth motion at intermediate ranges based on standard scaling laws are satisfactory for range settings in a medium such as halite even when the scaling ratio is large. Measurements at 8000 to 10,000 meters show that extrapolations made from pre-Gnome results were high by an order of magnitude and that the change of frequency (at a fixed range) with charge size was much more pronounced than on pre-Gnome tests. This points up the necessity for designing pre-shot tests to permit true scaling. (auth)

• Research Organization: Stanford Research Inst., Menlo Park, Calif.
• NSA Number: NSA-17-016265
• OSTI ID: 4755020
• Report Number(s): PNE-111F
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

GEOLOGY, MINERALOGY, AND METEOROLOGY
INSTRUMENTS
MEASURED VALUES
MOTION
NUCLEAR EXPLOSIONS
PARTICLES
PRESSURE
PROJECT GNOME
SEISMOLOGY
UNDERGROUND EXPLOSIONS
VELOCITY
WELDS