The cumulative volume of seismic data archived at the IRIS Data Management Center, 2008 The cumulative volume of seismic data archived at the IRIS Data Management Center (left) for major seismic networks totals 81.3 terabytes as of August 2008. The annual number of terabytes shipped from the IRIS DMC (right) for the same seismic network types is twice as much data as new data arriving at the DMC, and will total more than 35 terabytes to end users in 2008. (Image courtesy of T. Ahern.)