The anomaly is located in Corridor 4-7 of Sub-Level 4 in the GLMZ Underworld tunnel system, a 30-meter stretch of passage between Junction 4-North and Maintenance Bay 12. The corridor is unremarkable in every observable respect — standard tunnel construction, standard dimensions, standard materials. Objects dropped in Corridor 4-7 fall slower than they should.

The effect is not visible to the naked eye. A ball dropped from hand height reaches the floor in the same apparent time as anywhere else. But it doesn't. Precision timing equipment reveals that objects in Corridor 4-7 fall approximately 0.7% slower than predicted by local gravitational acceleration. This is a tiny deviation — a ball dropped from 1.5 meters takes 0.553 seconds instead of 0.549 seconds. Four milliseconds. Invisible. Measurable. Real.

We have been measuring the effect continuously since its identification in 2210. It is strengthening. In 2210, the deviation was 0.4%. In 2212, 0.55%. In 2214, 0.7%. The increase is linear — approximately 0.075% per year. At this rate, the deviation will reach 1% by 2218 and 5% by approximately 2270. Extrapolation beyond that produces figures that I am not comfortable including in an official report, because a 100% deviation — objects that do not fall — would occur at approximately the year 3500. This is, of course, absurd. Linear extrapolation of anomalous phenomena is not science. But the data is linear. Four years of continuous measurement, zero deviation from a straight line.

The effect is spatially bounded. It begins at a sharp boundary 2 meters past Junction 4-North and ends at a sharp boundary 1 meter before Maintenance Bay 12. Outside the boundaries, gravity is normal. Inside, it is 0.7% less than it should be. The corridor floor, walls, and ceiling show no material difference from adjacent sections. There is no mass anomaly below, above, or beside the corridor. There is no energy source, no field, no detectable cause. Gravity in Corridor 4-7 is simply — slightly, measurably, increasingly — less.