The ISC (International Seismological Centre) is one of the oldest and most detailed seismicity catalog for global earthquake activity. The ISC catalog is actually an integration of many catalogs, they include many events outside the U.S. with lower magnitudes than the USGS, but are usually several months behind in the compilation. The site features both hypocenter catalogs and the associated arrival time picks (you can download the arrival-time picks used to construct each location).
The ISC Web Site
Searching the ISC Event Catalog
We'll focus on acquiring event information from the ISC. One of the things that you will notice pretty quickly is that the ISC includes more than one location for many events, since locations are estimated using different data sets by different groups. Hover over the ISC Bulletin link in the gray region near the top of the page and select "Search the ISC Bulletin" and then "Event Catalogue". You should see the page below.
Most of the search parameters are straightforward, specify a time range, a geographic location using latitude, longitude, and depth, and the a magnitude range if desired. I created a search for all the great earthquakes (M≥ 8.0) since 1899 using a global search. The search takes a bit longer than the other sites, but there is a "mirror" site at IRIS to help alleviate the load on the ISC site. I switched to that site.
I elected to include "links" in the output because I am browsing the results. This let's me drill deeper into the catalog by clicking on an event ID link. Here's the information for the Great 2011 Tohoku megathrust earthquake. The amount of information is voluminous, including many different moment-tensor estimates, a text summary of the earthquake parameters, a bibliography, individual arrival times, amplitudes and periods, etc.
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