Collaborative Research: Investigating Effects of Geologic Complexity on Induced Seismicity, using M0-M5.7 seismicity from Prague, Oklahoma

Lead PI: Heather Savage

Unit Affiliation: Seismology, Geology and Tectonophysics, Lamont-Doherty Earth Observatory (LDEO)

May 2017 - January 2020
North America ; Oklahoma ; United States
Project Type: Research

DESCRIPTION: The recent surge in induced seismicity in the Midwestern United States, during which Oklahoma has catapulted past California in seismicity rate, has created controversy, captured the attention of the general public, and influenced policy. As a result, induced seismicity has become a focal point of earthquake science in the United States over the last few years; however, much remains to be learned about the mechanisms of induced seismicity. In this research the well-recorded 2011 Prague, OK earthquake sequence will be used to investigate deformation on a scale not commonly obtainable in seismicity studies (earthquake location with precision ~10 meters). Such well-located earthquakes allow for better understanding of how complex faults fail. Furthermore, laboratory experiments on the rocks from the Prague area will provide information on how strong and stable the faults are, and how pumping fluids into the faults might promote earthquakes. The Prague sequence contains three earthquakes greater than Mw5 and their robust aftershock sequences, as well as the foreshock sequences for two large events. The precision with which the Prague earthquakes can be located allows the failure processes to be considered on a scale comparable to fault structures measured in studies of exhumed faults. In addition, complementary laboratory experiments on lithologies from the Prague area will allow study of the effects of fluid pressure on fault strength and stability. The ultimate goal is to use the Prague dataset to probe the influence of fluid pressure and fault zone complexity on earthquake nucleation, propagation, and arrest. Specifically this work will address the following questions: 1) Do the faults near Prague show precursory activity that could be used to forecast rupture? 2) How does complex fault geometry control rupture? and 3) How do fault strength, strength heterogeneity, and fault stability play a role in induced earthquakes?