The Future of Macroseismic Intensity Assignments at the U.S. Geological Survey

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

The U.S. Geological Survey (USGS) “Did You Feel It?” system has been operating continuously for the last two decades (1999-2019). Although the collection and assignment of DYFI-based Macroseismic Intensity (MI) data depart from more traditional assignments, they are made more quickly, provide more complete coverage at higher spatial resolution, offer citizen input and interaction, and allow data collection at rates and quantities never before witnessed. DYFI decimal MI assignments are based on regression against traditional MI, and geocoding allows for spatial averaging; both of these strategies facilitate quantitative data analyses. New DYFI developments include Amazon Alexa-based voice activation, re-engineered software, an open API for third-party applications, and users can now replicate, filter, and update MI datasets via USGS web services. Other than DYFI, however, USGS does not maintain dedicated staff to assign traditional MI assignments. As concerning, neither DYFI nor Modified Mercalli Intensity assignments are particularly well defined for damaging level MI where buildings’ vulnerability assessment and damage grading plays a crucial role in assigning macroseismic effects and thus, requires engineering expertise. USGS is thus interested in pursuing MI data collection that combines the advantages of DYFI for crowd-sourced, massive MI data collection for lower MI (<VII, which is > 95% of all MI data collected) with professional assignments at higher MI based on the more systematic European Macroseismic Scale (EMS-98) methodology. We aim to support the development of tools for domestic MI collection that utilize engineering expertise via on-site reconnaissance, remote imagery, and other rapid data collection strategies. Employing EMS-98 domestically will require its adaptation for U.S. structures, partnering with professionals to calibrate EMS-98 to U.S. earthquake damage data, and developing outreach materials to facilitate its adoption for future domestic earthquakes.

Presenting Author: David J. Wald

Authors