Abstract

Between 1965 and 2003, the Carnegie Institution of Washington’s Department of Terrestrial Magnetism operated a continuous network of nine broadband seismographs with locations in South America, Japan, Iceland, Papua New Guinea, and Washington, D.C. The Carnegie seismographs designed in the 1960s by Selwyn Sacks were among the earliest broadband instruments, sensing between at least 30 s and 30  Hz. Given the scarcity of historic seismic data of comparable bandwidth and dynamic range prior to the widespread shift to force‐feedback instruments and digital recording around the mid‐1980s, this dataset is still of high scientific value today.

The Carnegie seismographs recorded data to magnetic tapes meant to be read and analyzed using a custom playback system. Since 1989 these tapes have been stored in a climate‐controlled, electromagnetically shielded room, which preserved them in reasonably good condition. However, some tapes now show signs of moisture damage, and reading them is difficult and time consuming by today’s standards, creating a barrier to the use of this dataset. To overcome these issues, we have undertaken an ongoing effort to digitize this dataset with the goal of making it publicly available in Standard for the Exchange of Earthquake Data (SEED) format at the Incorporated Research Institutions for Seismology Data Management Center (IRIS DMC).

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