Figure 3
From: Gas transport across the low-permeability containment zone of an underground nuclear explosion
Illustrated are fluctuations in barometric pressure monitored in the tunnel (i.e., tunnel barometer, dark blue line) and at SGZ on the mesa surface (light blue line). The pressure offset due to the elevation difference between the tunnel and SGZ (~268 m) is about 25 millibars (mb). When this offset is eliminated with the different vertical scales in the figure, the pressure signals at SGZ (light blue line) and in the tunnel (dark blue) essentially overlap each other. The red line is the cavity pressure history which fluctuates very little (~1 mb) compared to the other measurements for most of the pressure record. For part of the record, the cavity pressure signal appears to track the tunnel pressure history because the cavity pressure-measurement line was disconnected from the borehole prior to injection to prevent damage to the pressure sensor and then left to record tunnel pressure variations. The green line is the cavity pressure synthesized using the measured atmospheric pressure fluctuations (light blue line).
