Global stacks of up to a million event-windowed seismograms are made by stacking short-term to long-term average (STA/LTA) functions of the data in different frequency bands for vertical broadband data (1990-2012) available from the IRIS DMC. Long-period versions include vertical and horizontal component data. Plots are available for each component and frequency band analyzed. For users wishing to plot or analyze the stacks themselves, ascii files with the STA/LTA stack values as well as values from stacking envelope functions are also available.

Global stacks page:
http://ds.iris.edu/ds/products/globalstacks