The purpose of these archives by projects is to preserve scanned seismograms created by some special projects. The scanned image files will be searchable by some simple queries, and related materials will be available to aid the users. Seismograms will be downloadable (in originally scanned resolution) from the IRIS Data Management Center.
Volunteers and financial donors are welcome. Please contact William H.K. Lee at: email@example.com.
The World Wide Standardized Seismograph Network (WWSSN) began operations in 1961. One hundred twenty stations were installed, covering every continent. A station consisted of 3 short-period and 3 long-period seismometers, recording apparatus, radio-synchronized crystal clock, and calibration controls.
Data were originally recorded on photographic paper, then later on heat sensitive paper. The original records were photographed at the WWSSN Data Center using 70 mm film and stored by station and year on a 70 × 120 mm film chip. Lamont-Doherty Earth Observatory and the USGS Albuquerque Seismological Laboratory (ASL) each hold near-complete film chip sets of the WWSSN data. The slow degradation of these film chips has prompted this pilot project in 1999.
The film chips are black and white and have been digitally scanned with a resolution of 3200 dpi. The image has been cropped to exclude areas on the film chip which do not contain the image of the original record, however in all cases, the final product contains all of the original photographed record. The resulting grey-scale images have been saved at approximately 1/10th of the original film chip size as TIF files and then compressed using gzip. Enlarging the images by a factor of 10 results in images similar in size to the original analog record.
Use the Searchable Product Depository to find scanned seismograms
IASPEI sponsored projects were undertaken to scan original seismograms, station bulletins and copy marigram images.
This directory contains images of seismograms formally stored by the Caltech in the Kresge Seismological Laboratory, Pasadena CA. The images are a subset of the approximately 1 million paper records accumulated from 1928 through the mid-1980’s. The images were scanned in 2009-2010 by Google in collaboration with UC Santa Cruz as part of the Google Books project. Scans include fronts and backs of the paper records and are organized into directories that each corresponds to an individual box in which the records were originally stored at Kresge. The goal of this electronic library of seismograms is to allow users to simulate the experience of going to the paper archives and flipping through a box to find a record. The organization is imperfect and the search engine non-existent, but the original records are now as accessible to the world-wide user group as they once were to a small group of California seismologists.
A Wiki site is now available for the Caltech Archive community to post information on known issues with the scanned Caltech historic seismograms. As users discover interesting events, problems with the scans or other issues, posts should be made to this page. This information is meant to supplement the pdf documentation provided in the scan home directory.
Go directly to the Caltech Archive
Supported by volunteers
and financial donors
Last updated: August 29, 2011