Project Grant G24AP00227

PROJECT TITLE: WORKING GROUP ON UTAH EARTHQUAKE PROBABILITIES 2: COLLABORATIVE RESEARCH BETWEEN LETTIS CONSULTANTS INTERNATIONAL AND THE UTAH GEOLOGICAL SURVEYPROJECT PERIOD: 5 6 024 THROUGH 5 5 2026AWARD PURPOSE: THE RECIPIENT AND THEIR COLLABORATOR WILL CONVENE A SECOND WORKING GROUP ON UTAH EARTHQUAKE PROBABILITIES (WGUEP2) TO UPDATE THE 2016 EARTHQUAKE PROBABILITIES FORECAST FOR THE WASATCH FRONT REGION. THIS UPDATE IS NEEDED TO BETTER QUANTIFY THE HIGH SEISMIC HAZARD AND RISK IN RAPIDLY GROWING UTAH, WHERE THE POPULATION IS PROJECTED TO INCREASE FROM THE PRESENT 3.4 MILLION TO 5.5 MILLION BY 2050. THE 2016 WGUEP REPORT IS CONSISTENTLY CITED BY SCIENTISTS, POLITICIANS, PLANNERS, AND EMERGENCY MANAGEMENT PERSONNEL IN THE STATE. IN THE EIGHT YEARS SINCE THE ORIGINAL FORECAST WAS PUBLISHED, NEW INFORMATION HAS BECOME AVAILABLE ON QUATERNARY FAULTS IN UTAH, INCLUDING MORE RECENT PALEOSEISMIC DATA AND SEGMENTATION STUDIES FOR THE WASATCH FAULT ZONE AND OTHER REGIONAL FAULTS, AS WELL AS FOUR GEODETICALLY-BASED SLIP RATE MODELS DEVELOPED FOR USE IN THE 2023 USGS NATIONAL SEISMIC HAZARD MAP EARTHQUAKERUPTURE FORECAST. THE 2020 MOMENT MAGNITUDE (M) 5.7 MAGNA EARTHQUAKE HAS SHED NEW LIGHT ON THE POSSIBLE LISTRIC GEOMETRY OF THE NORTHERN SALT LAKE CITY SEGMENT, AND POTENTIALLY OTHER SEGMENTS OF THE WFZ, THAT SHOULD BE CONSIDERED IN AN UPDATED WGUEP2 FORECAST. THERE IS ALSO A NEED TO UPDATE THE WGUEP MOMENT MAGNITUDE EARTHQUAKE CATALOG, WHICH ENDED IN SEPTEMBER 2012, AS WELL AS THE RATES OF BACKGROUND EARTHQUAKES DERIVED FROM IT. THE EFFECTS OF STATIC AND QUASI-STATIC STRESS CHANGES ON THE WFZ HAVE ALSO BEEN ANALYZED AND THIS ISSUE NEEDS TO BE EXAMINED BY THEWGUEP2. WE ALSO PLAN TO EVALUATE AND CONSIDER A NEW TIME-DEPENDENT RENEWAL MODEL.ACTIVITIES TO BE PERFORMED: WGUEP2 WILL CONSIST OF TEN MEMBERS WHO ARE WIDELY RECOGNIZED AS EXPERTS IN GEOLOGY,PALEOSEISMOLOGY, SEISMOLOGY, GEODESY, AND GEOPHYSICS OF THE WASATCH FRONT REGION. A SERIES OF SIX IN-PERSON WORKSHOPS WILL BE HELD IN THE SALT LAKE CITY OFFICES OF THE UGS OVER THE COURSE OF TWO YEARS. DURING THAT TIME, RECENT INFORMATION AND DATA ADDRESSING THE TOPICS MENTIONED ABOVE WILL BE REVIEWED PRIOR TO EACH MEETING. WORKING SUBGROUPS WILL BE ORGANIZED TO SPEARHEAD EACH ISSUE E.G., NEW PALEOSEISMIC DATA, SEISMICITY ANALYSIS, ETC., IN THE SAME MANNER AS WAS DONE IN THE WGUEP. INPUTS WILL BE DEVELOPED THAT WILL BE INCORPORATED INTO THE PROBABILISTIC EARTHQUAKE FORECAST. DELIVERABLES AND EXPECTED OUTCOMES: A UTAH GEOLOGICAL SURVEY (UGS) MISCELLANEOUS PUBLICATION WILL BE PREPARED SIMILAR TO 2016 WGUEP. A JOURNAL PAPER THAT SUMMARIZES THE UGS REPORT WILL ALSO BE PRODUCED. A PRESENTATION TO THE UTAH SEISMIC SAFETY COMMISSION WILL BE MADE AS PART OF THE PUBLIC RELEASE TO THE NEWS MEDIA. PRESENTATIONS TOPROFESSIONAL ORGANIZATIONS WILL ALSO BE MADE. A USGS FACT SHEET WILL BE PREPARED BY THE USGS WITH ASSISTANCE FROM THE WGUEP2.INTENDED BENEFICIARIES: THE RESULTS OF THE 2016 WGUEP FORECAST ARE THE MOST WIDELY CITED INFORMATION ON EARTHQUAKES IN UTAH. THE WASATCH FRONT EARTHQUAKE PROBABILITIES HAVE BEEN INCORPORATED INTO PUBLIC POLICIES THAT HAVE DRIVEN GREATER AND MORE SUSTAINED EARTHQUAKE MITIGATION EFFORTS IN UTAH. THESE CONSENSUS BASED PROBABILITIES FOR EARTHQUAKES IN THE WASATCH FRONT REGION ARE WIDELY APPLICABLE TO BOTH SITE SPECIFIC AND REGIONAL HAZARD ANALYSES. DESIGNS OF BOTH IMPORTANT AND CRITICAL FACILITIES AND INFRASTRUCTURE ALONG THE WASATCH HAVE INCORPORATED THE RESULTS OF THE WGUEP FORECAST. INFORMATION FROM WGUEPS EFFORTS HAS BEEN INCORPORATED INTO USGS NATIONAL SEISMIC HAZARD MAPS RESEARCH PRODUCTS. WE EXPECT THAT THE RESULTS FROM THE WGUEP2 FORECAST WILL HAVE A SIMILAR FAR-RANGING IMPACT.SUBRECIPIENT ACTIVITIES: N A