This two-week short course will address the importance of developing and maintaining modern seismological observatories, and will explore recent advances in the analysis of seismological data in support of basic research, education, and hazard mitigation. The Institute is designed to engage graduate students, post-doc fellows, and new faculty from across the Americas in an interactive collaborative learning environment including completion of collaborative research projects.
The Institute has four primary objectives:
Interested persons are encouraged to apply by the indicated deadline. Selected participants will receive travel support including air travel to and from Quito, lodging and meals through the duration of the institute. Women, under represented minorities and persons with disabilities are strongly encouraged to apply.
The Pan-American Advanced Studies Institutes (PASI) Program is a jointly supported initiative between the Department of Energy (DOE) and the National Science Foundation (NSF).
|Anne Meltzer||Lehigh University|
|Eric Sandvol||University of Missouri|
|Hugo Yepes||Escuela Politécnica Nacional de Ecuador|
|Sergio Barrientos||Universidad de Chile|
|Raymond Willemann||IRIS Consortium|
|Olga Cabello||IRIS Consortium|
The topics and the syllabus are designed to support the primary goals and to maximize impact and effectiveness for a range of audiences. The Institute will explore research frontiers for new and emerging scientists, and addresses the needs of advanced seismic networks as well as networks in the early stages of development.
The Institute is divided into two main sections, each a week in duration. The first section (first week) focuses on sustainable network operations and the second section (second week) focuses on data analysis to determine earthquake source parameters and Earth structure. The sessions on sustainable network operations will cover issues associated with quality control, data archiving, basic data processing, and recent developments in seismic event location. The sessions on data analysis will start with a broad overview of data products and new developments in broadband seismology followed by two separate tracks providing Institute participants the opportunity to work on a research project determining regional moment tensor solutions or using ambient noise tomography to determine velocity structure. The two-track approach is designed to target both scientists from regions with a large number of earthquakes and seismic hazards such as the Caribbean and countries like Ecuador, Peru, and Chile, as well as scientists in countries with fewer seismic events and less seismic hazard, such as Brazil. All Institute participants will hear introductory lectures on both regional moment tensor solutions and ambient noise tomography. Institute participants will then break into two groups to work on research projects then will come back as a group to share results. This broad base approach maximizes the impact of the Institute and is expected to lead to future collaborations across a wide range of research topics.
In order to accomplish this broad based approach we have drawn together a group of instructors with a diverse range of expertise and abilities. We have included instructors with specialties in the technical aspects of modern seismic network maintenance and sustainability and instructors who are expert in the analysis of the data both in terms of seismic event determination and imaging of Earth structure. An overview of the PASI syllabus is provided below in Table 1. This is followed by a brief description of each session.
|Time||Monday, July 11||Lecturer(s)/Instructors|
|9:00-9:30||Introduction/overview to PASI||Anne Meltzer|
|9:30-10:30||Relationship between network quality and research quality||Goran Ekstrom|
|11:00-6:00||Station installation||Bob Busby|
|Tuesday, July 12||Lecturer(s)/Instructors|
|9:00-6:00||Calibration and Instrument response||Erhard Wielandt|
|Wednesday, July 13||Lecturer(s)/Instructors|
|Thursday, July 14||Lecturer(s)/Instructors|
|9:00-6:00||Sustainable Network Operations: North American, Central America, and South America.||Steve Malone, Lloyd Lynch, Sergio Barrientos|
|Friday, July 15||Lecturer(s)/Instructors|
|9:00-11:00||Earthquake location: Overview, Recent developments, challenges and opportunities.||Felix Waldhauser and Cliff Thurber|
|11:30-6:00||Earthquake locations - Practicum||Felix Waldhauser and Cliff Thurber|
|Saturday, July 16||Lecturer(s)/Instructors|
|9:00-6:00||Earthquake location: Overcview, Recent developments, challenges and opportunities.||Felix Waldhauser and Cliff Thurber|
|Sunday, July 17||Lecturer(s)/Instructors|
|9:00-6:00||Station Site Visit||Otavalo, Ecuador|
|Monday, July 18||Lecturer(s)/Instructors|
|9:00-11:00||Data Products: introduction/overview||Goran Ekstrom, Marcelo Asumpcao|
|11:00-12:00||New Developments in Broadband Data||Goran Ekstrom|
|1:00-6:00||Introduction to Research Projects: Goals and Objectives, Introduction to earthquake source studies and Surface wave tomography||Doug Dreger, Sean Ford, Mike Pasyanos, Morgan Moschetti|
|Tue-Fri, July 18-22||Lecturer(s)/Instructors|
|9:00-6:00||Research Projects - two tracks||Dreger and Ford; Pasyanos and Moschetti|
|Saturday, July 23||Lecturer(s)/Instructors|
|9:00-6:00||Participant Research Symposium||Institute participants|
|Sunday, July 24||Lecturer(s)/Instructors|
|9:00-6:00||Future Research Roundtable||Institute participants and lecturers|
|Monday, July 25||Lecturer(s)/Instructors|
Link between data quality and research quality. Modern seismological methods of analyzing earthquakes and determining the structure of the Earth's interior require high-quality, well-calibrated seismic data. For example, good timing of seismograms is essential for the determination of precise earthquake locations, accurate gain and response characteristics are needed for the determination of earthquake magnitudes and focal mechanisms, and the accurate horizontal orientation of the seismometer is needed for determination of elastic anisotropy in the Earth. Continuity of operation and low levels of noise are additional factors that enhance the value of network data for research. Routine processing and analysis of all seismic data produced by a network, and the generation and review of routine data products has proved to be a useful approach to establishing network quality, identifying data problems, and maintaining the network quality over long periods of time. The specific types of useful data products will depend on the type and scientific and operational objectives of the network, but continuous monitoring of noise levels and quantitative comparison of observed and modeled seismograms for well-characterized seismic sources are two methods of general value.
Station installation. Important aspects of seismic station siting, instrument selection, vault design, and power systems will be discussed. The features of vaults that provide good coupling to the Earth, thermal stability, and protection from flooding and animal intrusion will be reviewed. Station siting priorities will be summarized, including isolation from anthropogenic and natural noise sources, security, drainage, and reliability of power and telemetry. The properties of specific, commercially available sensors and data acquisition systems will be compared. Schematics of vaults used in the U.S. Transportable Array and in PASSCAL deployments in diverse settings of the Americas will be shared.
Calibration and Instrument Response. This portion of the Institute will be devoted to lectures and demonstrations on how to calibrate and verify the instrument response for broadband seismic stations. Accurate calibration of seismometers and tracking of complete system response is one of the most difficult and challenging tasks in maintaining a sustainable seismic network. The lectures will begin with a review of fundamental topics, including discretization of continuous time series, the discrete Fourier transform, the Z-transform and digital transfer functions, and digital filter theory including zero-phase and causal finite-impulse-response filters, and deconvolution of instrument response. The advanced exercises will include measuring and adjusting the transfer properties of seismometers and expressing them as complex frequency responses. Both electrical calibration methods (to measure the relative gain at different frequencies) and mechanical calibration (to measure the absolute gain) will be covered. Methods specific to force-balance accelerometers with force-balance feedback circuits, longperiod velocity sensors, and short period geophones will be developed. Calibration on a shake table and by comparison to a reference sensor will be described and exercises will use software developed by Wielandt, which he distributes freely and without restricting its use.
Sustainable Network Operations. The development of the Pacific Northwest Seismic Network and regional networks in the Caribbean and Chile will be used to illustrate the diverse aspects of network development and operations concentrating on those that make the network effective, efficient and sustainable over the long run. This daylong session will utilize both lectures and discussions to address both policy and technical issues associated with sustainable network operations. The themes and topics listed below will be covered.
Networks produce data and information products for research, education, and public service. Network operators need to balance demands of all of these goals. Routine information products are increasingly in demand by policy makers, the press and the public. Most networks also provide education and training opportunities for seismologists of the future. Long-term financial support for operations and human resource development is often the most difficult aspect of network management. A variety of support sources can help provide stability but can also generate expectations from various constituencies. Support for the acquisition cost of new equipment must be balanced with establishing resources for how this equipment will be supported in the long run. Open access and data sharing between networks in real time or near-real time benefits routine network operations, builds in redundancy, and produces more robust earthquake solutions and data for higher levels of analysis. Examples of seismic network operating systems currently being used in the western hemisphere will be described. The capabilities, comparative advantages, disadvantages and appropriate places for use of several open and freely available systems will be summarized.
Telemetry technologies for network operations include: analog radio and/or telephone, direct Internet connection (IP), digital over analog (modems), digital telephone, digital radio, satellite, and cell modem. Larger networks generally use a variety of telemetry technologies. The advantage of having a mix is that during telemetry failures (e.g. those caused by large earthquakes) not all stations are dependent on the same technology. Disadvantages include the need for multiple technical expertise and associated costs of this complexity.
Integrating strong-motion data into regional networks is becoming a standard practice. Modern digital strong-motion systems have sensitivities to small ground motions such that these data recorded in real-time can be considered part of a monitoring network for even small to moderate earthquakes. This is particularly important for engineering seismologists who utilize strong ground motions for helping to mitigate earthquake hazard.
Integrating automatic processing and manual analysis is a central and on-going part of all network operation and is necessary to produce a comprehensive and uniform catalog/bulletin. All modern networks have at least a triggering system to select seismic events of interest for further analysis. Many can do very comprehensive automatic analysis for event location, size and even fault characterization; however, manual review and subsequent modifications are always needed.
Providing information products via the web is an increasingly important responsibility of network operators. It is important to develop web materials that are region-specific, audience-appropriate and content-rich, with a minimum of fancy graphics, options or interactions. Web servers that can satisfy huge changes in load are critical in order to sustain operation following earthquakes that are widely felt.
Archiving continuous waveform data, for use in research projects and comparison of current with past earthquakes, is becoming standard practice. In determining the most appropriate choice for archiving technology, it is important to consider standardization and allow for transfer to upgraded media, because no matter what choice is made now, within a few years the data will need to be moved to a new technology. Use of existing archives provided by IRIS and ORFEUS is efficient and cost effective, and facilitates data exchange and seamless data discovery and access using widely accepted protocols.
Generating Metadata and SEED volumes. The Standard for the Exchange of Earthquake Data (SEED) is an international standard format for the exchange of digital seismological data. SEED was developed by the members of the International Federation of Digital Seismograph Networks (FDSN) for use by the earthquake research community, primarily for the exchange between institutions of unprocessed earth motion data. As a standard accepted by many seismologists worldwide and incorporating a rigorously defined set of metadata, SEED makes transmitting, receiving, and processing earthquake data easier and more accurate. During this portion of the Institute participants will learn how to generate SEED volumes from their own network data for data archiving and how to use this format in data exchange. Use of this data exchange standard helps network operators manage station metadata, instrument response information, and produce dataless SEED volumes to accompany waveform data. This work is essential before more advanced processing is begun. Use of the SEED data standard makes data exchange easy and promotes data sharing and open access. IRIS has several workshops on creating SEED volumes and this section of the Institute will build on that acquired expertise.
Multiple event relocation. This session will give an overview of multiple event location methods. It will introduce and apply the concept of double-difference and crosscorrelation methods for high-resolution seismic event location. The hypoDD algorithm will be used together with pre-prepared data sets that include network generated parametric data and high-precision delay-time measurements from similar seismograms to demonstrate relocation procedures and performance. Lecture material will include strategies for building differential-time networks, waveform cross-correlation, 1D and 3D velocity models for data prediction, regularization and data weighting, relative location error estimation, evaluation of solution robustness, and analysis of results. The lecture material will be illustrated with earthquake data from various tectonic settings. This section of the Institute will have a lab component where participants will work on selected data sets for software training and to acquire hands-on experience on the topics presented during the lecture. Participants with access to data are encouraged to bring their own data sets to the Institute in order to benefit from one-on-one instructor assistance. During the hands-on session, the pre-prepared or participant provided data set is used for software training.
Real-time double-difference seismic monitoring. This session will introduce a new real-time procedure that employs double-difference and cross-correlation algorithms in a seismic monitoring context. Institute materials will include strategies for building a relational seismic data archive, procedures for large-scale earthquake catalog relocation, evaluation of real-time performance and location precision. This will be illustrated using an operational prototype system for high-precision relocation of earthquakes in Northern California using near-real-time seismic data feeds. Discussions and lecturer assistance will be aimed at evaluating the potential to implement these new techniques into the operational procedures of seismic networks in South America.
Event locations and tomography. A final session will cover the fundamentals of 3D tomography and use of code for conventional 3D tomography (simul2000) and code for double-difference 3D tomography (tomoDD). During the hands-on session, a sample data set is used for software training. In addition, participants can bring their own data sets and obtain one-on-one assistance in analyzing it from the lecturer.
Station Site Visit Otavalo. Institute participants will travel to Otavalo to visit one of the stations in the Ecuadorian seismic network (OTAV), which is also a GSN station. The station is installed at the end of a 25 m horizontal tunnel excavated in an ophiolitic complex. This day will allow for a station site visit and a review of optimal deployment techniques, seismic data telemetry, and instrument calibration.
Data Products. Processing and analysis of data collected by a seismic network add value to the observations and make them useful to a broader range of scientists and researchers. There are many different data products that can come from a seismic network that are of different levels of complexity. For example, travel-time picks, earthquake locations, moment tensors, seismicity maps, site spectra, dispersion curves and tomographic models. Other operational data products are, for example, timing quality, up-time statistics, noise spectra, and calibration analyses. The systematic generation of data products from a network enhances the value of the network and aids in the monitoring and assessment of network quality.
New Developments in Broadband Data. Seismological research methods and practices continue to evolve in response to the revolution in broadband sensor technology, digital storage, and computation power. New techniques and algorithms for utilizing the full spectrum of ground motion in studies of seismic sources and investigations of Earth structure are being continuously developed and applied, leading to new discoveries and insights into earthquake processes and Earth structure. Recent advances have, for example, been associated with the cross-correlation of very large numbers of earthquakes seismograms recorded on multiple stations for the detection and precise location of traditional earthquakes and newly discovered ‘tremor’ sources, and the cross-correlation of continuous stochastic seismic signals (i.e., noise) for the determination of Earth structure. The simultaneous array processing of data recorded on local and regional networks is attracting renewed interest as a consequence of the computing and data-storage capabilities that are now available even on modest desk-top computers.
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