New exascale-scale supercomputers advance scientists' ability to perform large-scale simulations. The regional earthquake simulations in the DOE-funded EQSIM project can now create high-resolution, spatially dense ground motions that provide new insights into understanding and quantifying seismic risk. However, accessing and working with these massive datasets, which can be over hundreds of terabytes, can be a significant challenge. In this talk, I will discuss our recent developments for practical data access and visualization of large HDF5 datasets.