The Effect of Secondary Arrivals on Regional Earthquake Locations

Relocations of Actual Data

Relocations of foreshock/mainshock/aftershock sequence along with historical events for the region. Arrival errors were set to the "regional" errors described in Chapter 5, as these produced the best results in the synthetic relocations. We also relocated the events using PPCs for the P phases. The addition of regional LANL picks to the data set helps to stabilize the mainshock to the surface rupture when S phases are not defined. The use of S phases in this case causes the mainshock to be located south of the main rupture, near the original EDR catalog location. However, the majority of the other events near the mainshock are cocentrated more around the main rupture when S phases are used. A more precise S model for this region should improve the locations. The use of PPCs tends to cause more scatter for the IASP91 model. This is not surprising since the PPCs were only defined for the P phases.

S Defined S Not Defined
No PPCs PPCs Used for P Phases No PPCs PPCs Used for P Phases

Introduction | Catalog Locations with Secondary Phases | Ground Truth Constraints on Relocations Near a Large-Magnitude Event
Synthetic Tests Pt. 1 | Synthetic Tests Pt. 2 | Relocations of Actual Data | Relocations Using S Phases for the Asia Study Area | Summary