Historic Earthquake Records
In the basement of an old house in the Rafael Hills area of Pasadena, CA is a darkroom. The house was once the home of the Caltech Kresge Seismological Laboratory, and the photos that were developed in that room day after day for many years were photos of wiggly lines recorded on photographic film at seismic stations around southern California. The tedious work of developing seismic recording films was performed in many darkrooms throughout the U.S. until the late 1970s when a transition to digital recordings began. The science of earthquakes is relatively young, and yet these recordings of earthquakes from 1962 to 1978 from the World-Wide Standardized Seismic Network (WWSSN) are already in danger of degrading beyond the point of being usable.
From 1961 to 1996, 135 identical 6-sensor seismic stations were installed around the globe with funding from the Defense Advanced Research Projects Agency (DARPA), providing consistent and accurate data for earthquakes and nuclear explosions. The M8.5 1963 Kurile Island earthquake and the M9.2 1964 Alaska earthquake were recorded on the WWSSN stations. These recordings were responsible for some profound earth science discoveries, among them the undisputed evidence of the solid inner core of the earth.
Each station had 6 sensors with photo paper on 6 rotating drums that were changed out daily and developed onto paper that was then sent to the WWSSN Data Center (first in Boulder and later in Golden, Colorado). At the WWSSN Center, the paper records were all photographed on 70mm film chips, 35mm film rolls, and microfiche. By the time digital stations took over, there were 3.7 million 1-day-record film chips in the collection. When the Albuquerque Seismological Laboratory was established in 1961 in New Mexico, the collection was archived there, and another set was archived at the Lamont-Doherty Earth Observatory in New York.
A project to scan a small selection of the film chips to digital files was started in 1996. Since then, progress has been made in fits and starts, depending on the resources at hand. By the second half of 2018 the original selection of events was complete, but it represents only 5% of the total collection. Much more work is required to preserve the entire collection before it is lost to degradation. The completed selection that includes 153 earthquakes and 156 nuclear events (totaling 189,180 film chips and 26,824 scans) was determined by a team of researchers from academia and government agencies. The digital files take up 7.61 TB (Terabytes) of storage space and are archived at the Incorporated Research Institutes for Seismology (IRIS) Data Management Center, where digital records are archived directly from the current Global Seismographic Network (GSN) and Advanced National Seismic System (ANSS) networks operated and maintained by the USGS.
The days of photographic records of earthquakes, developing daily photos, archiving them on film chips, and then hand-digitizing the records are behind us, and there probably isn’t one station operator or seismologist who misses this laborious process. However, at this time 95% of the old records have still not been preserved. One hopes that the products of the arduous efforts from those 16 years will not be lost, and that the data may yet someday lead to the next great earth science discovery.
Historic Seismic Instrument Photos
In addition to archiving historic data from the early years, the USGS has also worked to archive photos and descriptions of early seismometers. Before the advent of the WWSSN, seismic instruments were in a somewhat experimental stage. There were several different widely used instruments in the seismic community, but even those were modified in different ways to meet different needs. Some of the only records of these instruments are a collection of several hundred photographs from the 1930s and 40s that were recently digitally scanned. The photos include instruments such as the Bosch-Omori horizontal seismograph that was at the Weston Observatory at Boston College, the Milne-Shaw seismograph that was in Honolulu, Hawaii, and the Benioff seismometer that was at the Tucson Magnetic Observatory. There are also some photos of influential seismologists from that time period.
The motivation behind the project to create a digital photo archive was to preserve some of the knowledge of seismological advances during this time period. Most of the photos have descriptions, but there are a few that remain a mystery. Perhaps now that they are available online, as well as stored at the National Archives, someone will recognize one of the enigmas and provide an identification!
- written by Lisa Wald, USGS, December 2018
For More Information
- Albuquerque Seismological Laboratory
- USGS Earthquake Monitoring
- Earthquake Science Timeline
- The Early History of Seismometry (to 1900)
- A. C. B. Alejandro, C. R. Hutt, A. T. Ringler, S. V. Moore, R. E. Anthony, D. C. Wilson; The Albuquerque Seismological Lab WWSSN Film Chip Preservation Project. Seismological Research Letters ; 90 (1): 401–408. doi: https://doi.org/10.1785/0220180275
- S. V. Moore, C. R. Hutt, R. E. Anthony, A. T. Ringler, A. C. B. Alejandro, D. C. Wilson; A Collection of Historic Seismic Instrumentation Photographs at the Albuquerque Seismological Laboratory. Seismological Research Letters doi: https://doi.org/10.1785/0220180267
The Scientists Behind the Science
Alexis Alejandro is a Pathways Intern at the Albuquerque Seismological Lab where she works with the instruments testing team. She studies both Earth & Planetary Sciences and Applied Math as an undergraduate at the University of New Mexico. In her free time, she enjoys spending time with friends and family, baking, and working on at home DIY projects.
Sabrina Moore is a Pathways Intern at the USGS Albuquerque Seismological Laboratory. She is an undergraduate senior at the University of New Mexico in the Department of Civil, Construction, and Environmental Engineering. Her career goal is to study structural resiliency after geological hazards. When she is not in the office or studying, she enjoys live music, hiking, and exploring the southwest.