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Speed vs. Precision: The Tsunami Warning Center Duty Scientists' Dilemma

Session: Advances in the Science and Observation of Tsunamis [Poster]

Type: Poster

Date: 4/22/2021

Presentation Time: 03:45 PM Pacific

Description: 

The Pacific Tsunami Warning Center located in Honolulu, Hawaii, routinely issues a tsunami message product whenever an earthquake crosses the 6.5 magnitude threshold. In 58% of the cases, an observatory message (OM) reporting the preliminary source parameters preceded the issuance of an official tsunami message (TM). Scientists commonly assume that including more seismic stations in the analysis would automatically improve the quality of the preliminary source parameters. We tested these assumptions by matching 742 OMs issued between 2003 and June 2020 with the TMs that follow them. We then computed the corresponding epicentral offsets, magnitude residuals, and message delay times against the source parameters listed in later, more authoritative earthquake catalogs. Statistics for these parameters reveal that 55% of the Mwp magnitude estimates did not vary despite additional processing times between messages of up to 20 minutes. Paradoxically, 18% of the Mwp magnitude residuals worsened instead of improving. The magnitude estimates saw a modest median improvement of 0.1 magnitude unit in 27% of the cases. These results indicate that for the overwhelming majority (73%) of events analyzed by PTWC scientists, the initial parameters included in the OMs had an accuracy matching or exceeding the accuracy of those included in the TMs that followed. We find that the inclusion of more data, in an effort to solidify the initial analyses, does not significantly improve the earthquake parameters and can potentially slow down the response to a tsunamigenic earthquake. The operational data, however, confirm that when analyzing larger earthquakes that tend to have greater complexity, duty scientists will often need additional time to better estimate the preliminary source parameters.

Presenting Author: Victor Sardina

Student Presenter: No

Authors