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  • Michael Olaniran
Michael Olaniran
University of Missouri-Columbia

Corresponding Author:[email protected]

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The question of the reliability of GPS measurement as an index for intraplate seismicity is raised here. Geodetic measurement of slip rate along the Longmenshan Fault -a thrust structure that straddles the border of the Indo-Australian Plate and Eurasian Plate produced 􀂦gures as low as 3mm/year, despite this low return, the magnitude 7.9 Wenchuan earthquake occurred along this fault. Similar pattern was discovered in both the New Madrid, South Carolina and Wabash seismic zones, where geodetic derived strain rates of less than 2mm/yr fail to account for the recurrence of magnitude 7 earthquakes every 500 years. Other intraplate settings like Europe, Australia, South Africa showed similar results, hence leading us to question how reliable a tool geodetic measurement is in predicting the likelihood of earthquakes occurring in the future. I conclude that seismic hazard assessment of intraplate earthquakes based solely on geodetic strain rate measurement and the location of occurrence of past (historic) earthquakes is spatially limited and could be misleading, this is because where strain release occurred (as past earthquakes) does not necessarily have to be the exact location where strain accrual for future earthquakes take place, as evidenced by the inability of the GPS strain rate to resolve seismic moment release in all of the seismic zones in Central-Eastern United States . Strain release in the future might occur on a distant unidentified fault through transient stress perturbation -one that might have been erroneously classified as ‘safe’ based on near-zero strain rate picked up by today‘s GPS measurements.