Geology topics

Jon Peterson

Publications and source records attributed to Jon Peterson.

7 recordsLinked to original sources

USGS2011

Albuquerque Seismological Laboratory--50 years of global seismology

The U.S. Geological Survey Albuquerque Seismological Laboratory is about 15 miles southeast of Albuquerque on the Pueblo of Isleta, adjacent to Kirtland Air Force Base. The Albuquerque Seismological Laboratory supports the Global Seismographic Network Program and the Advanced National Seismic System through the installation, operation, and maintenance of seismic stations around the world and serves as the premier seismological instrumentation test facility for the U.S. Government.

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USGS1989

IRIS/USGS plans for upgrading the Global Seismograph Network

This report has been prepared to provide information to organizations that may be asked to participate in a program to upgrade the global seismographic network. In most cases, the organizations that will be offered new instrumentation by the U.S. Geological Survey currently operate stations in the World-Wide Standardized Seismograph Network (WWSSN) or the Global Digital Seismograph Network (GDSN). The deployment of the WWSSN in the 1960's and the subsequent equipping of some WWSSN stations with digital equipment and borehole seismometers during the 1970's has been a remarkably successful program that generated the high- quality data needed to fuel an unprecedented period of progress in earthquake and tectonic research. The success of the WWSSN can be attributed to the importance of the data, to the strong commitment by participating organizations to international scientific cooperation, to the dedication and skill of the station operators, and to the resourcefulness of the staff supporting the network. Benefits have been widespread. The community of scientists world-wide has benefited from unrestricted access to a standardized base of calibrated data, and the participating stations have benefited from the donation of modern observatory instruments that have been useful for local earthquake studies and for the training of scientists and engineers. Now, an exciting opportunity has arisen to deploy a new generation of seismograph systems to replace the outdated equipment at many of the WWSSN and GDSN stations. The U.S. Geological Survey (USGS) is cooperating with the Incorporated Research Institutions for Seismology (IRIS) in a program to upgrade the global seismograph network. The equipment development phase is nearly complete with a prototype of the new broadband seismograph system currently undergoing final testing at the USGS Albuquerque Seismological Laboratory. Deployment of the new equipment is expected to begin in early 1990. As this report will demonstrate, the IRIS broadband seismograph system combines the very latest data acquisition and computer technology to produce seismic data with unprecedented bandwidth and dynamic range. Moreover, the system has been designed so that the high-quality digital data are accessible for local display and analysis. The functional design of the new system, which uses off-the-shelf modules and a standard computer bus, will make it much easier than it has been in the past to modify and upgrade the data acquisition system as improvements in technology become available. With adequate support for the program, the new IRIS seismograph system need never become obsolete. We want you to be aware of our plans and the possibility that you may be asked to participate in this ,program. The schedule for upgrading WWSSN and GDSN stations depends on the level of funding earmarked for the program by our National Science Foundation. We hope to deploy at least ten new GSN data systems each year. If you have any questions concerning this program, please contact the Albuquerque Seismological Laboratory, U.S. Geological Survey, Albuquerque, New Mexico 87115-5000. This report was revised in February 1992 in order to update information concerning the current program and instrumentation. The amp in Figure 1 was revised in June 1993, April 1994, December 1994, and September 1996 to reflect updated siting information. In September 1996 a composite photo of standard and optional components of the IRIS-2 GSN system hardware was added as a separate page between Figures 9 and 10.

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USGS1985

Description and preliminary testing of the CDSN Seismic Sensor Systems

The China Digital Seismograph Network (CDSN) is being designed and installed to provide the People's Republic of China with the facilities needed to create a national digital database for earthquake research. The CDSN, which is being developed jointly by the PRC State Seismological Bureau and the U.S. Geological Survey, will consist initially of nine digitally-recording seismograph stations, a data management system to be used for compiling network-day tapes, and a depot maintenance center. Data produced by the network will be shared with research scientists throughout the world. A national seismograph network must be designed to support a variety of research objectives. From this standpoint, the choices and tradeoffs involved in specifying signal bandwidth, resolution, and dynamic range are the most important decisions in system design. As in the case of the CDSN, these decisions are made during the selection and design of the seismic sensor system and encoder components. The purpose of this report is to describe the CDSN sensor systems, their important signal characteristics, and the results of preliminary tests that have been performed on the instruments. Four overlapping data bands will be recorded at each station: short period (SP), broadband (BB), long period (LP), and very long period (VLP). Amplitude response curves are illustrated in Figure I. Vertical and horizontal components will be recorded for each data band. The SP and LP channels will be recorded with sufficient sensitivities to resolve earth background noise at seismically quiet sites. The BB channels will have a lower sensitivity and are intended for broadband recording of moderate-to-large body-wave signals and for increasing the effective amplitude range in the short- and long-period bands. The VLP channel does not provide additional spectral coverage at long periods; its purpose is to make use of on-site filtration and decimation to reduce post processing requirements for VLP studies. Early plans also included a triaxial set of low-sensitivity accelerometers for recording strong signals from large local and regional earthquakes. The accelerometers are not being installed; however, they may be added in the future. The short-period signals will be derived from a three-component set of PRC-supplied Model DJ-I SP seismometers and US-supplied SP amplifiers. The seismometers will be installed in surface or shallow subsurface vaults, except at two of the stations where they will be installed in boreholes. The BB, LP, and VLP signals will be derived from Streckeisen STS-1 broadband sensor systems installed in vaults, except at one site where the LP signals only will-be derived from a KS-36000 borehole seismometer installed at a depth of 100 meters. Analog signals will be sampled and quantized by an analog-to-digital converter (ADC) that is part of the recording system. Sampling rates chosen for the CDSN are as follows: * SP 40 samples/second * BB 20 samples/second * LP 1 sample/second * VLP 6 samples/minute The ADC 16-bit data word format makes use of 14 bits to quantize the signal and 2 bits to specify an automatically ranged gain of 1, 8, 32, or 128. This will provide 84 dB of resolution and up to 42 dB of gain ranging for a total opera- ting range of 126 dB peak to peak. Magnetic tape cartridges, each having a capacity of 67 megabytes, will be used for recording the digital data. LP and VLP data will be recorded continu- ously. SP and BB data will be processed through an automatic signal detector of the type described by Murdock and Hutt (1983), and only detected events will be stored on tape. Detection parameters, such as turn-on sensitivity and mini- mum recording duration for the SP and BB channels, will be fully programmable and easily changed. One or more of the data channels may also be recorded on analog recorders. A CDSN recording system was not available at the time that the preliminary tests were performed on the CDSN sensor systems. This did not interfere with the principal goals of the testing which were to determine the best sensor installation techniques and to demonstrate the operational performance of the sensor systems, especially with regard to instrument noise and detection capability. When the CDSN recording system is available, additional tests will be performed to measure distortion levels in the full system and components. Distortion tests have been performed on the Streckeisen STS-1 broadband seismometers, the most critical component from the standpoint of linearity, and the results of the tests are reported by Wielandt and Streckeisen (1982). Calibration accuracy and stability are also important sensor system characteristics that cannot be defined without additional testing. These tests will be performed as the instruments are installed at the stations and periodically during operation.

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USGS1982

Test and calibration of the Digital World-Wide Standardized Seismograph

During the past decade there has been steady progress in the modernization of the global seismograph network operated by the U.S. Geological Survey (USGS). The World-Wide Standardized Seismograph Network (WWSSN) has been augmented by new stations with advanced instrumentation, including the Seismic Research Observatories (SRO) and the modified High-Gain Long-Period (ASRO) stations. One goal in the modernization effort has been to improve signal resolution in the long-period band. A second goal has been to generate a global digital data base to support contemporary computer-based analysis and research. In 1976, a Panel on Seismograph Networks was established by the Committee on Seismology of the National Academy of Sciences to review progress in network seismology and recommend actions that would lead to an improved global data base for seismology. One recommendation in the Panel report (Engdahl, 1977) called for upgrading selected WWSSN stations by the installation of digital recorders. This was viewed as an economical way of expanding the digital network, which had proven itself to be a very promising new tool for earthquake and explosion research. Funds for the development and assembly of 15 digital recorders were provided to the USGS by the Defense Advanced Research Projects Agency and an ad Inoc panel of scientists was convened by the Committee on Seismology to advise the USGS on the selection of stations to be upgraded and on data recording requirements, A total of 19 digital World-Wide Standardized Seismograph (DWWSS) systems will be operational when all are installed. The additional systems were made available through purchase by the USGS and other organizations; for example, the University of Bergen purchased and installed a DWWSS-type recorder and agreed to furnish the USGS with the data. A list of operational and planned DWWSS network stations is given in Table 1.1. As one might expect, the digital recorder turned out to be somewhat more sophisticated than the original concept. It was decided to record three components of long-period data continuously, three components of intermediateperiod data in an event mode, and the vertical-component short-period data in and event mode (with the capability of adding short-period horizontal channels in the future). Special amplifiers were developed for use with the WWSS seismometers, and a 16-bit fixed-point analog-to-digital converter was chosen to provide increased resolution (as opposed to a 16-bit gain-ranged encoder). The microprocessor-based digital recording systems were developed and assembled at the USGS Albuquerque Seismological Laboratory (ASL) and ASL-based technicians began installation at WWSSN stations in 1980. The current and proposed locations of the DWWSSN stations, together with other stations in the Global Digital Seismograph Network (GDSN), are shown on the map in Figure 1.1. A system was operated at Albuquerque for about 18 months, serving as a test bed for evaluation studies. Although the network hardware has been available for some time, the installation of the DWWSSN has proceeded slowly. The National Science Foundation supported installation of six stations and the USGS is funding installation of most of the others; however, the network completion date is conjectural because of funding uncertainties. The DWWSSN stations are supported with supplies and technical assistance from ASL (subject to availability of funds). Data recorded on magnetic tapes are mailed to ASL where they are reviewed for quality, then merged with other GDSN station data on the network-day tapes. Hoffman (1980) provides a description of the network-day tape format. Zirbes and Buland (1981) have developed and published user software for reading and interpreting the day tapes. This report will serve several purposes. One is to provide nominal system transfer functions and calibration information that are needed in the analysis of DWWSSN data. A second purpose is to report on an evaluation of operating characteristics (calibration stability, noise levels, and linearity) that may limit the usefulness of the data and to determine if modifications may be needed to improve the data. It is not an exhaustive study in this respect. We continue to depend mostly on data user feedback to point out deficiencies and we solicit comments whenever anomalies are observed in the data.

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USGS1982

A note on transients in the SRO and ASRO long-period data

Data users have occasionally observed pulse-like transients in the long-period waveforms recorded at the Seismic Research Observatories (SRO) and at the Modified High-Gain Long-Period (ASRO) stations. In a recent paper, Dziewonski et al (1981) reported transients associated with earthquake signals record at some SRO stations, and the authors ascribed these transients to an unpredictable nonlinear system response. While some transients in the SRO and ASRO data are indeed generated by a nonlinear response (clipping), others are the result of linear processes. All event-associated transients are predictable in the sense that they are produced by large impulsive body-wave signals.

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USGS1982

Design concepts for a Global Telemetered Seismograph Network

This study represents a first step in developing an integrated, real-time global seismic data acquisition system a Global Telemetered Seismograph Network (GTSN). The principal objective of the GTSN will be to acquire reliable, high-quality, real-time seismic data for rapid location and analysis of seismic events. A secondary, but important, objective of the GTSN is to augment the existing off-line seismic data base available for research. The deployment of the GTSN will involve a variety of interrelated activities development of the data acquisition and receiving equipment, establishment of satellite and terrestrial communication links, site selection and preparation, training of station personnel, equipment installation, and establishment of support facilities. It is a complex program and the development of a sound management plan will be essential. The purpose of this study is not to fix design goals or dictate avenues of approach but to develop working concepts that may be used as a framework for program planning. The international exchange of seismic data has been an important factor in the progress that has been made during the past two decades in our understanding of earthquakes and global tectonics. The seismic data base available for analysis and research is derived principally from the Global Seismograph Network (GSN), which is funded and managed by the U.S. Geological Survey (USGS). The GSN comprises some 120 seismograph stations located in more than 60 countries of the world. Established during the 1960 s with the installation of the World-Wide Standardized Seismograph Network (WWSSN) , the GSN has been augmented in recent years by the installation of more advanced data systems, such as the Seismic Research Observatories (SRO), the modified High-Gain LongPeriod (ASRO) seismographs, and the digital WWSSN (DWWSSN). The SRO, ASRO, and DWWSSN stations have the common, distinctive feature of digital data recording, so they are known collectively as the Global Digital Seismograph Network (GDSN). The fundamental objective in operating the GSN is to create and update a seismic data base that is accessible without restrictions to organizations and research scientists throughout the world. The USGS provides cooperating stations with instrumentation, training, and continuing support, including supplies and on-site maintenance. In return, the host organization operates the equipment and sends the recorded data to the USGS. Analog data (seismograms) are microfilmed and about four million copies are requested annually by researchers. Digital data, which are recorded on magnetic tape, are organized by the USGS Albuquerque Seismological Laboratory (ASL) into networkday tapes and copies of the day tapes are furnished to data users through national and regional data centers. After copying, original data are returned to the stations and used for local research. Most of the stations in the GSN also provide the USGS with seismic readings « phase arrival times and amplitudes scaled from the seismograms. These readings are transmitted on a daily or biweekly basis via commercial or diplomatic communication channels. They are used by the USGS National Earthquake Information Service (NEIS) to determine the location and magnitude of earthquakes occurring throughout the world. The results are published monthly in bulletins that are distributed to the participating stations and virtually all scientific organizations that are involved in seismological studies. It is a much-valued service that provides a current, updated catalog of seismic activity on a global scale. The NEIS also has the responsibility for rapid reporting of large and potentially destructive earthquakes. The NEIS issues news bulletins as soon as possible after the occurrence of magnitude 6.5 or greater earthquakes (magnitude 5 or greater in the conterminous United States). The news bulletins are sent to disaster relief, public safety, and other interested organizations. Tsunami warnings issued to countries bordering the Pacific Ocean are based initially on earthquake location and magnitude data. Rapid reporting of earthquakes requires real-time waveform data or readings. Currently, signals are being telemetered from more than thirty stations in the United States to the NEIS, which is located in Golden, Colorado. An extension of the telemetry network to other countries will provide the seismological community with a significantly improved means of monitoring earthquake activity in real time; it will lower the response time for determining the location and magnitude of potentially destructive or tsunamigenic earthquakes and it will provide more timely information that may be needed by governments to respond promptly.

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USGS1981

Preliminary design study for a National Digital Seismograph Network

Recently, the National Research Council published a report by the Panel on National, Regional, and Local Seismograph Networks of the Committee on Seismology in which the principal recommendation was for the establishment of a national digital seismograph network (NDSN). The Panel Report (Bolt, 1980) addresses both the need and the scientific requirements for the new national network. The purpose of this study has been to translate the scientific requirements into an instrumentation concept for the NSDS. There are literally hundreds, perhaps thousands, of seismographs in operation within the United States. Each serves an important purpose, but most have limited objectives in time, in region, or in the types of data that are being recorded. The concept of a national network, funded and operated by the Federal Government, is based on broader objectives that include continuity of time, uniform coverage, standardization of data format and instruments, and widespread use of the data for a variety of research purposes. A national digital seismograph network will be an important data resource for many years to come; hence, its design is likely to be of interest to most seismologists. Seismologists have traditionally been involved in the development and field operation of seismic systems and thus have been familiar with both the potential value and the limitations of the data. However, in recent years of increasing technological sophistication, the development of data sstems has fallen more to system engineers, and this trend is likely to continue. One danger in this is that the engineers may misinterpret scientific objectives or subordinate them to purely technological considerations. Another risk is that the data users may misuse or misinterpret the data because they are not aware of the limitations of the data system. Perhaps the most important purpose of a design study such as this is to stimulate a dialogue between system engineers and potential data users. The NDSN system concept presented in this report is intended to serve as a point of discussion -- a strawman, if you will. It is a feasible solution to what we perceive to be the objectives of the NDSN, but it is not a unique solution. Current technology offers a variety of choices in meeting design objectives. We have examined some but not all of these choices. Although our fundamental concept of the NDSN is based on current technology, we have anticipated developments in several fields where state-of-the-art is evolving rapidly, notably satellite communications and database management. If the installation of the NDSN is delayed 5 - 10 years, we anticipate that the methods proposed to record, communicate, and manage the data may change, but it is likely that the fundamental data requirements will be the same. Therefore, in this study we have concentrated more on the types of data that will be generated at the NDSN stations and less on specific hardware that might be used in the data system. When the NDSN is budgeted, a second, more hardware-oriented design study may be needed.

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