Confidential manuscript submitted to JGR-Solid Earth Seismic source spectral properties of crack-like and pulse-like 1 modes of dynamic rupture 2 Yongfei Wang 1 , 2 , Steven M. Day 1 3 1 Department of Geological Sciences, San Diego State University, San Diego, California, USA. 4 2 Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA 5 Key Points: 6 • Corner frequency changes in crack-like and pulse-like models 7 • Stress drop estimate varies with source characteristics 8 • Double spectral decay slopes 9 Corresponding author: Yongfei Wang, [email protected] –1–