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Evaluation of Multiple-Event Location Methods Using Ground-Truth and Synthetic Data

Description: 

We investigate the accuracy and effectiveness of several commonly used multiple event relocation techniques to recover accurate hypocenter and uncertainty information using sparse datasets involving mostly regional-distance phase readings from ground truth (GT0 or GT1) real event clusters and synthetic sources. The compared techniques include Progressive Multiple Event Location (PMEL, Pavlis and Booker, 1983), MLOC (Hypocentroidal Decomposition algorithms provided by Global Seismological Services, based on Jordan and Swerdrup,1981), HypoDD (Waldhauser et al., 2000), and GrowClust (Trugman and Shearer, 2017). These techniques employ different methods to account for structural heterogeneity along the ray paths from sources to receivers or locally within the cluster source region. We compare the results to traditional single event location using the best available 3-D structural information in the study regions. We evaluate the methods in terms of mislocation with respect to GT locations and the size and accuracy of the derived uncertainty regions. It is expected that multiple-event, cluster relocation techniques will resolve relative epicenter position better than single-event location; however, questions remain about their effectiveness in recovering absolute hypocenter positions, or accurate estimates of location parameter uncertainties (e.g., Lin and Shearer, 2005). In a nuclear explosion monitoring context, the validity of the uncertainty assessments is often more important than the accuracy of the estimated hypocenters. Initial results indicate that location uncertainty estimates obtained from relative location techniques can be unrealistically small in many cases. We comment on possible causes embedded within the relocation codes that explain the obtained results.

Session: Advancements in Forensic Seismology and Explosion Monitoring [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Ileana

Student Presenter: No

Invited Presentation: 

Authors