| Date | Time (UT) | Latitude | Longitude | Depth (km) | Magnitude | State/Province | Felt | Mechanism | |
| 1999/06/30 | 15:27:32 | 40.64 | -111.58 | 12 | 3.5 | Utah | ? | 19990630152732 Mechanism | |
| 1999/07/03 | 01:43:54 | 47.076 | -123.463 | 40.0 | 5.40 | Washington | y | 19990703014354 Mechanism | |
| 1999/08/20 | 13:50:26 | 44.78 | -112.77 | 14.0 | 4.83 | Eastern Idaho | Y | 19990820135026 Mechanism | |
| 1999/09/09 | 11:38:43 | 38.89 | -111.99 | 5.0 | 3.7 | Utah | 19990909113843 Mechanism | ||
| 1999/10/22 | 17:51:15 | 38.08 | -112.73 | 6 | 4.0 | Utah | ? | 19991022175115 Mechanism | |
| 1999/12/22 | 08:03:31 | 38.76 | -111.59 | 4 | 4.3 | Utah | n | 19991222080331 Mechanism | |
Note: "SW Study only" means that the earthquake was processed for the purpose of obtaining group velocities for tomographic studies. In the case of earthquakes in California, the definitive source parameters are obtained from the California Integrated Seismic Network.