The Extended Column Test: Test effectiveness, spatial variability, and comparison with the Propagation Saw Test

The Extended Column Test (ECT) is a new stability test that aims to assess the fracture propagation potential across a 0.90 m wide isolated column. This paper: 1) describes the test procedure and presents new recording standards for the test, 2) uses two independent datasets (each consisting of over 300 tests) to assess the effectiveness of the test, 3) looks at the spatial variability of ECT results from several test grids, and 4) compares adjacent results between the ECT and the Propagation Saw Test (PST) on stable and unstable slopes. Our results indicate that the ECT is an effective stability test, with a false-stability rate less than other standard snow stability tests. Results are sometimes quite spatially uniform, though occasionally slopes may exhibit variable ECT results. In comparison to the PST, our data suggest that the ECT has a lower false-stability rate, but a higher false instability rate. Overall, the ECT is better at discriminating between stable and unstable slopes in our dataset. No test is perfect and all tests must be used in conjunction with additional data, but our results show that the ECT is valuable additional tool for assessing snow stability.