Efforts to Recover and Digitize Analog Seismograms from Harvard-Adam Dziewo ski Observatory

Abstract

The Harvard‐Adam Dziewonski observatory is one of the oldest seismic stations academically established in the United States, and it is owned and maintained by Harvard University (Leet, 1934). It is currently one of the Global Seismic Network stations operated by the U.S. Geological Survey (USGS)’s Albuquerque Seismological Laboratory (network code IU) and is also used as a testing facility for new instruments by Quanterra, Inc. The digital data from the Harvard seismic station since 1988 are readily available to the scientific community through the Incorporated Research Institutions for Seismology Data Management Center and are widely used for various research purposes. The data from this station are known to be of high quality, partly because the instruments are housed in a vault that is about 4.5 m below ground, ensuring reduced surface noise and a stable environment (e.g., nearly constant temperature and humidity). In this manuscript, we focus on the analog data that have been collected at this station prior to 1988. The vision of operating a high‐quality seismic station is attributed to a Harvard professor, J. B. Woodworth, who began seismic instrumentation in 1908 (Leet, 1934). Initially, two Bosch–Omori 100 kg horizontal pendulum seismographs were installed in the basement of the Harvard Museum of Natural History building in Cambridge, Massachusetts, and the two instruments operated until 1928. Ground‐motion monitoring continued at this location with two Milne–Shaw horizontal pendulum seismographs until April 1933. Only a handful of seismograms appears to have survived from this time period. In 1933, under the direction of L. Don Leet, a new seismic observatory (Fig. 1), one that is used today, was constructed at the Oak Ridge Observatory, also known as Harvard Astronomical Observatory, at Harvard, Massachusetts (note that this is about 40 km northwest of Cambridge, Massachusetts, where Harvard University is located). Instruments began recording ground motion at …