Abstract
AbstractA three-dimensional inversion of P-wave travel-time residuals from local earthquakes reveals a remarkable pattern of low seismic velocities in crustal rocks immediately adjacent to the active portions of the New Madrid fault system. Seismic velocities are lowest in regions of greatest concentration of earthquake activity near two intersections of linear trends in seismicity. The maximum reduction in compressional wave velocity is at least 7 per cent in the upper 5 km of the crust and at least 4 per cent in the depth range of 5 to 14 km. The reductions are consistent with a velocity decrease which would be expected if crustal rocks in the source zone contain fluid-filled cracks in which pore pressure is a substantial fraction of external pressure. The presence or absence of such fluids may explain why some portions of the faults in and surrounding the upper Mississippi Embayment are active while others are not.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
