IRIS Releases New Poster on Seismology


As part of our education and outreach efforts, the IRIS Consortium has developed a poster to illustrate how seismology is used to explore the deep interior of our planet.

The poster consists of a high resolution schematic Earth cut open to reveal its basic structure, a seismogram section, and explanations of how we use seismology to infer the structure of the Earth's interior. The seismogram section shows traces of actual ground motion recorded during the 1994 Northridge earthquake. All major phases, such as P, S, PP, SS, PKP, PKIKP, and surface waves, are identified and highlighted. The schematic Earth shows the paths for all the rays identified on the seismogram section. Seismographic stations are marked at their angular distances from the epicenter, labelled, and visually linked to enhance the relationship between the individual ray paths, the locations at which the seismograms are recorded, and the composite seismogram section. The border of the poster includes descriptions of the Northridge earthquake, seismicity patterns, types of seismic waves, functions of a seismometer, and the Global Seismographic Network. Much of the information in the border of the poster is available as individual one-page handouts from IRIS. A one-pager of the main section of the poster is also available.

The IRIS E&O program is currently developing a teachers' guide for grades K-12 to accompany the poster. The poster is used in teacher workshops run by the E&O program at meetings such as the National Science Teachers Association convention and at teacher workshops run at individual IRIS member institutions. Copies have also been distributed to schools participating in the Princeton Earth Physics Project (PEPP). The poster and other materials developed by the E&O program are available from IRIS Headquarters. Contact Catherine Johnson, E&O Program Manager (

We would like to acknowledge Tracy Keaton Drew, designer and illustrator.

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