Historical seismograms: Preserving an endangered species

Okal, Emile A.

doi:10.1016/j.grj.2015.01.007

Cited by 14 publications

(14 citation statements)

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“…It would be anticipated that many more such records could thus be processed in the future for the quantification of crucially important earthquake sources during that time window (1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978). This constitutes one more argument (if need be) for the permanent preservation of the relevant archives, and their eventual transfer to digital support (Okal 2015).…”

Section: O N C L U S I O N Smentioning

confidence: 99%

Historical tsunami earthquakes in the Southwest Pacific: an extension to Δ > 80° of the energy-to-moment parameter Θ

Okal

Saloor²

2017

Geophysical Journal International

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We extend to distances beyond 80 • the computation of the energy-to-moment slowness parameter introduced by Newman and Okal, by defining a regional empirical correction based on recordings at distant stations for events otherwise routinely studied. In turn, this procedure allows the study of earthquakes in a similar source-station geometry, but for which the only available data are located beyond the original distance threshold, notably in the case of historical earthquakes predating the development of dense networks of short-period seismometers. This methodology is applied to the twin 1947 earthquakes off the Hikurangi coast of New Zealand for which we confirm slowness parameters characteristic of tsunami earthquakes. In addition, we identify as such the large aftershock of 1934 July 21 in the Santa Cruz Islands, which took place in the immediate vicinity of the more recent 2013 shock, which also qualifies as a tsunami earthquake. In that subduction zone, the systematic compilation of for both recent and pre-digital events shows a diversity in slowness correlating with local tectonic regimes controlled by the subduction of fossil structures. Our methodology is also well adapted to the case of analogue records of large earthquakes for which short-period seismograms at conventional distances are often off-scale.

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Section: O N C L U S I O N Smentioning

confidence: 99%

Historical tsunami earthquakes in the Southwest Pacific: an extension to Δ > 80° of the energy-to-moment parameter Θ

Okal

Saloor²

2017

Geophysical Journal International

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“…According to the International Seismological Centre (ISC) online bulletin (https://www.isc.ac.uk/iscbulletin/search/bulletin/), 78 stations reported phase readings for the 1920 Haiyuan Earthquake (ISC, I. S. C., 2018). However, many of these records are no longer to be found due to war damage, fire, misplacement, and untracked lending over the years (Okal, 2015). Over 1 year of data hunting, we recovered 60 analog seismograms recorded at 27 stations in 12 countries on 13 unique types of instruments ( Figure 3 and Appendix B; also see Data Set S1 in the supporting information for archive contacts).…”

Section: Data Acquisition and Preparationmentioning

confidence: 99%

Magnitude of the 1920 Haiyuan Earthquake Reestimated Using Seismological and Geomorphological Methods

Kulikova

et al. 2020

JGR Solid Earth

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Reported magnitudes ranging between 7.8 and 8.7 highlight a confusion about the true size of the 1920 Haiyuan earthquake, the largest earthquake recorded in the northeast Tibetan Plateau. We compiled a global data set of previously unlooked‐at historical seismograms and performed modern computational analyses on the digitized seismic records. We found the epicenter to be near Haiyuan town and obtained a moment magnitude of MW=7.9±0.2. Following traditional approaches, we obtained mB=7.9±0.3 with data from 21 stations and MS(20)=8.1±0.2 with data from three stations. Geomorphologically, we mapped the surface rupture and horizontal offsets on high‐resolution Pleiades satellite and drone imagery that covered the entire western and middle sections of the 1920 Haiyuan earthquake rupture and compiled offsets reported on the eastern section from field measurements in the 1980s. Careful discrimination between single‐event and cumulative offsets suggests average horizontal slips of 3.0±1.0 m on the western section, 4.5±1.5 m on the middle section, and 3.5±0.5 m on the eastern section, indicating a total moment magnitude of MW=7.8±0.1. Thus, the seismological and geomorphological results agree within the uncertainties, a weighted average giving a moment magnitude of MW=7.9±0.2 for the 1920 Haiyuan earthquake. It is likely that earthquake magnitudes based on the historical M were systematically overestimated.

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“…While this preserves the data, it makes access no better than for the original. In addition, some of these records on microfilm have begun to deteriorate or have been threatened by disposal (Okal, 2015; See supplemental material). Recently, universities and research organizations world-wide have begun or have completed ambitious scanning projects transforming paper records into digital images making them more widely accessible.…”

Section: Preservation and Accessmentioning

confidence: 99%

“…The following lists projects reported elsewhere including Lee and Benson (2008), Okal (2015), and Okal (2017) or as noted. The list should not be considered complete.…”

Section: Appendix a Participantsmentioning

confidence: 99%

WORKSHOP REPORT: Securing Legacy Seismic Data to Enable Future Discoveries September 18-19, 2019 Albuquerque, New Mexico

Hwang¹,

Ahern²,

Ebinger³

et al. 2020

Preprint

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On September 18-19, 2019 a workshop on Securing Legacy Data to Enable Future Discoveries was held in Albuquerque, New Mexico engaging 29 researchers representing universities, national laboratories, and governmental agencies that included 4 international and 10 early career participants. The need and funding for this workshop grew out of a June 2018 event focused on legacy seismic data organized by the National Academy of Science Committee on Seismology and Geodynamics (NAS COSG), which sparked interest at both at the National Science Foundation and U.S. Geological Survey. The NAS COSG event identified a number of technical as well as financial challenges in trying to collect and build the datasets necessary to address key problems spanning large time periods that require legacy data. Not only are such datasets essential to evaluate global change in microseisms and extend time series of precursory phenomena, they are a crucial first step toward machine learning and other data intensive processing. Regardless, critical paper and magnetic tape records are at risk of loss or severe degradation.Presentations and discussions at the meeting were organized in three main themes: science drivers, data preservation, and future directions. Through a series of presentations by the participants, the workshop reviewed examples of tectonic, volcanic, national security and climate science questions that can best be addressed using legacy data. Next the workshop reviewed past and ongoing legacy data preservation efforts in the US and internationally, enabling participants to consider best practices. This second theme included a number of different software products to better scan analog legacy data. Several large-scale international scanning and digitizing projects, such as by Instituto Nazionale di Geofisica e Vulcanologia in Italy, SISMOMEx by the Universidad Nacional Autónoma de México, and Harvard University were described in detail. These efforts show that with sufficient resources, significant volumes of analog data can be preserved and securely archived. However, these efforts are currently only addressing a small fraction of the available high-value, legacy data worldwide. The workshop participants identified opportunities to coordinate activities internationally to achieve consensus on metadata standards. Initially, 39 metadata elements were identified. These elements can be grouped into 6 broad categories that parameterize the data including: 1) Time of Data, 2) Station/Channel, 3) Sensor, 4) Recording System, 5) Image File, and 6) Other. Participants were surveyed as to whether these elements should be required, recommended, optional, or omitted. Post-workshop, 20 additional metadata elements were contributed to the list. To reach consensus and maximize the utility of these efforts, additional vetting by the international community is warranted.At the end of the workshop, a list of next steps for legacy data activities was developed and summarized below:Analog holdings catalog. Create an inventory of analog seismic data holdings to identify current resources, connect potential users to resources, and aid in metadata discovery. Publications database. Create a database of research publications that use analog data as a resource to other researchers, inspire new studies, and provide evidence to the importance of this data.Data Availability. Develop policies to encourage legacy data submission to data centers working with existing centers on sustainable financial models.Standards. Begin work on creating FAIR compliant metadata standards to enable federated discovery and access. Establish best practices and standards for imaging and digitizing, learning from established projects. Pilot Project. Identify existing repositories to pilot federated data search and access utilizing proposed metadata standards, and retrieval of multiple data and metadata types. A pilot study will help to demonstrate the data’s value, enable consensus on standardization, and advance data processing workflows. Future Research. Identify strategies to enable future research through open source and standardization of both data and software. Identify targeted campaigns with specific research objectives defining the high priority science questions such as the identification of key stations to conduct imaging of all records and the identification of specific earthquakes for historical analysis.New Technologies. Identify enabling technologies to reduce human intervention in the end-to-end process of creating research ready, time series data.Other Communities. Attract a broader scientific community to apply seismological data in nontraditional research domains and communities with similar needs in preserving analog time series data. Outreach. Create a larger community of users through outreach at all career levels.

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Historical seismograms: Preserving an endangered species

Cited by 14 publications

References 50 publications

Historical tsunami earthquakes in the Southwest Pacific: an extension to Δ > 80° of the energy-to-moment parameter Θ

Historical tsunami earthquakes in the Southwest Pacific: an extension to Δ > 80° of the energy-to-moment parameter Θ

Magnitude of the 1920 Haiyuan Earthquake Reestimated Using Seismological and Geomorphological Methods

WORKSHOP REPORT: Securing Legacy Seismic Data to Enable Future Discoveries September 18-19, 2019 Albuquerque, New Mexico

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