AbstractThree‐dimensional P and S wave velocity (VP and VS) models and high‐resolution earthquake relocations are determined for the New Madrid Seismic Zone using double‐difference local earthquake tomography. The data set consists of arrival times and differential times recorded by the Cooperative New Madrid Seismic Network (CNMSN) from 2000 to 2007 and the 1989–1992 Portable Array Network and Data Acquisition deployment. Waveform cross correlation–derived differential times for the CNMSN data are also incorporated. The velocity solutions are compatible with previous solutions centered on the active arms of seismicity and cover a broader area, including mafic intrusions along the margin of the Reelfoot rift. Major features include elevated VP and VS associated with the mafic plutons and reduced VP and VS along and southeast of the Axial fault (AF), a major arm of seismicity trending along the rift axis. Low VP extends to a depth of at least 20 km along the portion of the AF that extends south of the Missouri bootheel. A locally high VP/VS anomaly imaged along the central portion of the Reelfoot fault is spatially correlated with a significant change in fault trend and is interpreted as a region containing high pore pressure and/or water‐filled microcracks.