**Table 3. **Criteria Used to Remove Poorly Constrained Events

Criterium number |
Criterium |
Value |
||

1 |
Condition number |
< 100 |
||

2 |
Weighted RMS residual |
< 2.0 s |
||

3 |
Closest station distance |
< 150 km |
||

4 |
Azimuth gap |
< 200 degrees |
||

5 |
Average residual |
< 1.0 s |
||

6 |
Theoretical location error |
< 10 km |
||

7 |
Final iteration step |
< 3 km |
||

8 |
Depth |
> 0.1 km |
||

9 |
Horizontal shift |
< 10 km |
||

10 |
Vertical shift |
< 10 km |

The criteria were applied after relocation. Criteria 1, 3, and 4 check that a good station geometry is used to determine the location. Criteria 2 and 5 check that the location provides a reasonable fit to the data. Criterion 7 checks that the solution converges. Criterion 8 was required to remove a significant number of events that attempted to converge to a location above ground. Criteria 9 and 10 were used during the 1-D and 3-D inversion iterations to remove any events that were shifted a significant amount when relocated in the new velocity models.