Albuquerque Seismological Laboratory

History of the Albuquerque Seismological Laboratory (1961 - 2000)

History of the Lab

Location

The Albuquerque Seismological Laboratory (ASL)  is located on the Isleta Indian Reservation adjacent to the south boundary of Kirtland Air Force Base about 15 miles southeast of Albuquerque, New Mexico.  Access to ASL is provided through Kirtland Air Force Base.  The location in the Manzanito Hills is relatively isolated where instruments can be operated and tested without major disturbance from manmade noise sources.

Organization

ASL opened in 1961 as a seismological observatory and instrumentation laboratory in the Seismology Division of the U.S. Coast and Geodetic Survey (C&GS) .  In 1972, the Laboratory was transferred together with the National Earthquake Information Center (NEIC)  to the U.S. Geological Survey (USGS)  and is now part of the Branch of Earthquake and Geomagnetic Information in the Office of Earthquakes, Volcanoes, and Engineering.

Facilities

A cluster of five ASL buildings contains an engineering laboratory, an instrument shop, a network operations office, an electronics shop, a data processing computer center, administrative offices, and a warehouse.  A sixth building houses an operational headquarters for the Global Telemetered Seismic Network (GTSN) .  There are two surface vaults and two subsurface vaults used for testing and operating seismographic equipment.  The subsurface vaults, which are mined in a granite hill, are exceptionally quiet locations for testing seismometers.  A separate facility with two small buildings and five adjacent boreholes is used for testing and operating borehole instrumentation.

Laboratory Staff

The current full-time personnel authorization at ASL consists of 9 USGS and 31 contractor slots.  AlliedSignal Technical Services Corporation has been the contractor since 1983.  There are five geophysicists, one engineer, six programmers, seventeen field engineers, one bench technician, one electronics technician, three computer operators, three machinists, two seismic data analysts, two system administrators, and seven administrative personnel on the ASL staff.

Tasks

When the Laboratory opened in 1961 the assigned functions were to develop and test seismic instrumentation, to support a small network of domestic C&GS and cooperating observatories, and to operate a seismological observatory.  During the 1960s ASL became heavily engaged in field experiments and aftershock studies as well, but these activities ceased after the transfer to the USGS.  The three original functions, very much expanded in the case of the network operations, continue to be important functions of the Laboratory.  One major additional activity that spun off from global network operations is the processing and distribution of digital data collected from network stations.

Network Development and Deployment

Shortly before ASL was opened in 1961, the Seismology Division of the C&GS took on a major effort to deploy and manage a new global seismograph network, called the World-Wide Standardized Seismograph Network (WWSSN) .  Funded by the Advanced Research Projects Agency (ARPA) , the WWSSN involved the installation of 120 seismograph systems in over 60 countries and islands throughout the world.  It also involved the collection, review, and copying of the recorded seismograms, and the distribution of copies to researchers throughout the world.  Considered one of the most important advances ever in observational seismology, the WWSSN produced the data needed to support unprecedented progress in earthquake, explosion, and tectonic research.  The WWSSN also served as the foundation for network improvements and expansion that have taken place over the past twenty five years.

The responsibility for the part of the program involving the deployment, operation, and support of the WWSSN was assigned to ASL in 1962.  The ASL staff quadrupled, new facilities were built, and much effort went into organizing network support activities.  In the years that followed the deployment of the WWSSN, many of the stations were modernized and the global network expanded into regions not initially covered, including China and, most recently, the former Soviet Union, now known as the Commonwealth of Independent States (CIS) .  Although the equipment deployed today is considerably different than the WWSSN equipment, the operational activities related to network deployment and support remain much the same.

Technical Plans.  Prior to any new system development, a technical plan is developed that seeks to translate scientific objectives into achievable design goals for new data systems.  Important goals consistently include the use of higher dynamic range and broader bandwidth systems so that the entire research community benefits from the deployment of new data acquisition equipment.  Technical plans, such as those written for the China Digital Seismograph Network (CDSN)  and the IRIS/USGS Global Seismograph Network, insure that all of the organizations involved have agreed on common goals and methods of achieving those goals.

Equipment Design Specifications.  Specifications for new data systems are developed from the technical plan.  Most of data systems used in the global networks are procured through competitively awarded contracts, although some are designed and assembled at ASL.  In either case, specifications are developed for use in defining the instrumentation requirements.

Site Survey and Testing.  The selection of new sites for seismograph stations is often preceded by field testing with portable equipment to determine background noise levels so that noisy sites may be avoided.  Existing stations are always inspected prior to an installation to develop a site plan, including layouts showing the location of sensor systems, recording equipment, power equipment and power and signal cables.  Some preparation work, such as new power cabling and air conditioning, is almost always needed.

Site Negotiations.  Often, agreements must be negotiated and completed between the USGS and the organization that is to host the new station equipment.  Typically, ASL assists in site preparation, provides and installs the instrumentation, provides training, and furnishes continuing support in the way of supplies and maintenance help.  In return, the host organization operates and maintains the equipment and sends the tape data promptly to the ASL Data Collection Center (DCC) .  Original data are returned to the stations.  Most of the cooperating stations also report earthquake readings to NEIC.

Site Preparation.  ASL often prepares or assists in the preparation of station sites, including the construction of vaults and boreholes.  Specifications prepared by ASL for vaults, boreholes and other station facilities are used worldwide.

Equipment Assembly and Checkout.  Whether the station equipment being deployed is developed at ASL or provided by a manufacturer under contract to the USGS, it is thoroughly tested and documented at ASL before shipment and installation.  Special power facilities are available to duplicate host country power.

Training.  In programs involving the deployment of new data systems, one or two station operators are brought to ASL for two to four weeks of training in system operation and maintenance.  Personnel from over 25 countries have been trained at ASL.  The training serves two very important purposes besides familiarization with the new equipment; it generates enthusiasm for the program, and it develops close working relationships between operators and the ASL personnel who provide support to the station.

Installation.  New station equipment is normally installed by a two-man team from ASL with assistance of local personnel over a period of three to five weeks, depending on the complexity of the system and type of sensors used.  The final week is devoted to the training of local personnel and completion of a comprehensive installation report that will become part of the permanent station record at ASL.

Network Support

Station Resupply.  The network operations center (NOC)  at ASL keeps inventories of supplies and spare parts for each station in the networks as well as an inventory of depot supplies so that the purchase and distribution of supplies is nearly automatic.  In fact, it is a very complex operation because of shipping procedures that must be used to accommodate a wide diversity of customs regulations.

Equipment Repair and Replacement.  Most of the hardware used in the data systems can be repaired and reconditioned at ASL.  Efforts are made to obtain the necessary circuit diagrams and any special test equipment needed to avoid dependence on manufacturers for repair work.  The depot is kept well stocked with major boards and modules that can be immediately shipped to a station as replacements for defective units that are later repaired at ASL and returned to stock.  There are duplicates in the shop of every type of data system supported by ASL.  The test systems are used to check out repaired modules and test software and hardware modifications.

Documentation.  Station files carefully maintained at ASL include the installation reports, maintenance reports, correspondence, shipping documents, and all other material related to the station operation.  The NOC staff also maintains the manuals, source codes, drawings, schematics, and other documentation describing the data systems, maintains detailed records of system modifications on a station-by-station basis, and maintains statistics on component failures.

Engineering Support.  The first modification to a new data system inevitably occurs before the first installation, and modifications are a continuing practice thereafter.  Engineering support for the networks is needed to monitor system performance, to identify design problems, and to design, test, and evaluate hardware and software changes that will improve data quality and reliability.  The new data systems used in the IRIS/USGS Global Seismograph Network (GSN)  are designed with such a high degree of modularity using standard off-the-shelf equipment that obsolescence can be entirely avoided if periodic system upgrades are possible.

Field Maintenance.  On-site maintenance by skilled technicians from ASL is a vital component of network support.  Despite the best design, diagnostic support, spare boards, and training, stations will occasionally develop problems that cannot be corrected by station personnel.  Direct lightning strikes, power system failures, and problems with borehole seismometers usually require expert assistance.  At some stations the skill level of the operator is not adequate to handle more common problems.  Field support is expensive, but it is the only way to maintain an acceptable level of data availability.

ASL Data Collection and Processing

With the advent of digital recording in the early 1970s, it became necessary to establish a data collection center (DCC)  at ASL specifically for the digital data.  Originally designed to review and process tapes from a 10-station global network, the capacity, complexity, and functionality of the DCC have been greatly expanded over the years.  In the early years, the ASL DCC archived and distributed digital data in the form of copies of the station tapes.  This was awkward for the data user because several different formats came into use as the networks expanded and it was necessary to mount tapes containing two weeks of data from each station in order to process a specific event .  In 1980, ASL began distributing network day tapes.  Each day tape contained 26 hours of concurrent data from all of the stations in the digital network making it far easier for a researcher to access event data.  Later, in order to deal with a proliferation of recording formats, the USGS, with the concurrence of IRIS and international organizations, developed a Standard for Exchange of Earthquake Data (SEED) .  The SEED format is being used for recording data at the new GSN field stations and has been adopted worldwide for distribution of data.  The SEED format also specifies a method of data compression that substantially reduces the quantity of data that must be archived and distributed.  The methods of distributing digital data to the data users has also evolved.  The ASL DCC has become a data 'wholesaler', rather than a data 'retailer' .  The DCC distributes network data to a number of data centers that now provide custom data services to individual users.

The data collection system consists of a network of MicroVAX and Sun computers with a large number of peripheral devices and a Sony 'jukebox' style optical mass store.  Networked high-performance microprocessors provide much more reliability than a single mainframe computer because a failure of a single microprocessor does not significantly impact the amount of data that can be processed.  This is vitally important because the flow of data from the networks is relentless.  The current amount of data processed for each network day is 275 megabytes.  This will reach one gigabyte in about three years when all of the new GSN stations are deployed.  The clustered design of the DCC also facilitates low-cost expansion.

Data Collection.  Tapes arrive at ASL from the network stations by mail.  Most arrive within 60 days of the first day recorded on the tape.  Tapes normally contain one or two weeks of data.  Both nine-track tapes and tape cartridges are being recorded, although the new stations are all equipped with high-density cartridges.  Data from the station tapes are read into a disk staging area.  Media problems, such as bad spots on the tape, data loss in transit, field equipment misalignment, etc., are detected at this point and data recovery is performed where possible.  A subsidiary index is created and used to store all changes that are made to the record headers.  Original data are never modified, although some data records are deleted if considered unusable.

Time and Format Validation.  Header records are carefully checked.  They contain timing information and station parameters.  Errors occur in timing at the station if the operator incorrectly sets the clock or fails to correct for leap seconds, and sometimes when transients cause the clock output to jump.  These and other header errors are corrected while the data are in the staging disk.

Data Validation.  After the operator has verified or corrected the timing, a series of plots are made at random times to display data samples.  Calibrations are plotted to validate the instrument sensitivities.  Problems in data quality (spiking, telemetry gaps, digitizer malfunctions)  or in calibration are reported to the NOC for action.  In addition to the data plots, certain statistics, such as RMS background noise or spectra, are collected and stored in a database for summary reports and plots.

Station Data Permanent Archive.  After all processing of a station tape is completed, each station file, its indices, statistics, and status reports are backed up on a high-density tape cartridge.  Since the original station data and the index are both backed up, a 'before' and 'after' version of the file is saved.

Assembly of Network Volumes.  All station data are demultiplexed and repacked into a network volume format, in which the data from all stations are combined into time span units, normally days.  The network volume is written entirely in SEED format.  At this stage the corrected information in the subsidiary indices are combined with the original seismic data.

Final Archiving.  After assembly into the network volume format, the data are written onto the optical disk system which is segmented into a number of consecutive days for storage.  The 'jukebox' holds over 300 gigabytes of data on line, 49 platters with 6.4 gigabytes per platter.  The optical disks are the final archive media.  All of the digital data collected by ASL since 1971 have been loaded onto the mass store.

Data Distribution.  Network volumes, provided in units of network days, are loaded from the optical disk onto tape for distribution to data centers.  Currently, these volumes are distributed on high-density tape cartridges.

Status Reports and Database Maintenance.  Long-term statistical reports are produced in numeric and graphic form to present a history of the network or stations.  Several databases are kept which contain key information for the assembly of network volumes.  A station database includes all of the pertinent information about the field station (name, location, formats, etc) , and a channel database includes information about the channels (configuration, transfer functions, sensitivities, etc.) .  Other databases track the progress or location of data in the system.

Systems Development and Engineering

When the Laboratory was opened in 1961 much of the equipment used at the seismograph stations supported by the C&GS was designed and assembled in house.  Today, almost all equipment is purchased from commercial suppliers, but ASL provides strong leadership in systems development and engineering and has become an international center for the test and evaluation of seismic instrumentation.

System Development.  ASL has been responsible for the development of specialized seismograph instruments, such as strong-motion recorders, portable field equipment for recording explosions and aftershocks, test facilities, such as shaking tables, tsunami-warning systems for Alaska, Hawaii, and the Pacific, local telemetered seismograph networks, and digital data systems for global and regional networks, including the Seismic Research Observatories (SRO) , the Digital WWSSN, the CDSN, and the GSN IRIS-2 systems currently being deployed.  The Digital WWSSN and China Digital Seismograph Network systems were designed and assembled at ASL, but normally major systems development and assembly work is contracted or subcontracted to commercial firms.

Instrument Test and Evaluation.  Instrument testing is a natural extension of instrument and systems development work.  Extensive test facilities have been developed over the years, including shaking tables, special vaults and boreholes, and a large pool of test equipment.  Most of the testing and evaluation today is concentrated on new seismometers, both borehole and vault type, because there have been major improvements in seismometer technology in recent years.  Organizations that develop seismometers usually ask to have their instruments tested at ASL.  In recent years, seismometers from England, China, the CIS, Switzerland, and the United States have undergone testing at the Laboratory.

ASL Observatory

The principal reason that ASL was located in the southwest United States was to establish a new seismological observatory in a region lacking coverage.  ASL has continued to be one of the most important observatories in the USGS national network.  During the 1970s, the observatory functions were expanded to include regional and local seismicity studies using data from a telemetered network that encompassed the middle Rio Grande Rift.  A cooperative program was established with Los Alamos Laboratories and New Mexico Tech at Socorro to extend coverage through the rift area.  This program was halted in the mid 1980s and the ASL network was turned over to New Mexico Tech.  Today, signals from several observatory systems at ASL, including a prototype station of the new National Seismic Network, are telemetered to NEIC in Golden, Colorado for analysis.  The ASL observatory now includes a Soviet Universal Seismic System (USS)  that was installed in 1991.  The Soviet (now CIS)  station consists of a borehole seismometer and digital control and recording equipment.  There are plans to telemeter the signals from ASL back to the CIS in exchange for telemetered signals from a CIS station in Kazakhstan.

SUMMARY OF MAJOR ASL ACTIVITIES

 

Jon Peterson, former Lab Chief (Retired)