The IRIS/USGS Global Seismographic Network was initiated in the mid-1980s to replace the aging analog stations of the Worldwide Standardized Seismographic Network (WWSSN). The GSN, with affiliate stations, has now grown to more than 150 installations, each equipped with very broadband seismometers and providing data to both the monitoring and research communities in real time. GSN’s growth has coincided with a substantial increase in the number of large earthquakes over the past two decades, including the Mw 9.2 Sumatra megathrust of 2004 and Mw 8.8 Chile subduction zone event of 2010. The upper graph shows the running average number of events ≥ M 8.0 per 10-year interval (from the PAGER catalog). The lower graph shows individual earthquake magnitudes and the history of stations in the WWSSN and GSN. GSN data have been used to characterize the temporal and spatial details of recent great earthquake ruptures in unprecedented detail and the plethora of large events has provided a rich source of data for investigations of deep earth structure. (Figure based on C. Ammon et al., Great earthquakes and global seismic networks. Seismological Research Letters, accepted, 2010)</p>


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