Seventh Annual IRIS Workshop

June, 1995, Jackson, Wyoming

Participants at the Seventh Annual Workshop*

The Seventh Annual IRIS Workshop was held June 22-24, 1995 at Jackson Lake Lodge, Wyoming, just south of Yellowstone National Park. More than 200 IRIS members and friends attended the Workshop, making it the largest to date. The majesty of the Grand Tetons, abundant wildlife and the relaxing ambiance of the Lodge provided a stimulating environment for review of recent IRIS accomplishments and planning for the future. One important purpose of the meeting was to present an overview of the IRIS-2000 proposal, which at the time of the Workshop was in the final stages of preparation for submission to the National Science Foundation.

A session on the "Great Deep Earthquakes of 1994" highlighted the significance of the March 9, Tonga (M7.4) and June 9 Bolivian (M8.3) earthquakes which by serendipity occurred beneath PASSCAL experiments. With the extensive data available from the GSN and the PASSCAL deployments, these events are the best studied deep earthquakes and have led to some serious revision of explanations for the origin of deep seismicity. Both events have rupture planes in excess of the dimensions expected for "metastable" wedges of material within the subducted slab. In addition to contributing to the debate about the nature of deep earthquakes and the dynamics of subducted slabs, GSN data from these simple and powerful sources enhance the study of whole Earth and core structure, by adding to the relatively rare collection of free oscillation data and providing clear observations of complex core phases.

The IRIS-2000 proposal identifies new trends in telemetry and communications, for both global and local data collection, as among the most important technical developments for IRIS over the next 5 years. This was the motivation for a Workshop session which covered topics such as frame relay and spread-spectrum radio techniques. A specific application of telemetry in seismology is in the development of arrays and talks and posters presented at the Workshop showed some of the powerful analysis techniques that can be applied to array data. An expanded role for the IRIS Data Management System in helping to coordinate earthquake information is also envisioned in the next five years. Talks on the experience of other groups like the Sequoia Project and UNIDATA, and some predictions on future uses of the Internet, provided stimulating guidance on directions for IRIS activities in this area.

The cataloging of global seismicity and the development of systems for monitoring nuclear test ban treaties benefit from the expanded global coverage of the GSN and the availability of data in near real time. Within regional and national networks, the use of broadband data is revolutionizing the assessment of regional seismicity and earthquake hazards. A session on "Earthquake Parameterization" looked at some of the technical issues involved in making more complete use of these new data and described the improved characterization of sources using broadband data. Poster displays and demonstrations were even more popular this year than at past Workshops - with presentations overwhelming the poster display area and flowing into the auditorium. Posters described a wide variety of projects based on the use of IRIS facilities and provided a stepping off point for discussion of future projects. Demonstrations of the facilities provided by PASSCAL, DMS and the JSP Center helped new members and students become familiar with the resources available from these IRIS programs.

Over the past few years, Workshops have included talks and field trips designed to expose participants to the geology, seismology and ecology of the Workshop environs. In keeping with this tradition, talks and field trips this year took advantage of the stimulating vistas and geological uniqueness of the Teton and Yellowstone areas. One of the scientific sessions highlighted the geophysical structure of the Yellowstone and its significance in the tectonic framework of the western US. Jennifer Ziegler from the Teton Science School presented a talk on the Natural History of the Teton Range. Bob Smith of the University of Utah lead an afternoon field trip to the Teton fault. Bob was one of the original founders of IRIS and grew up in the Teton area. He has devoted much of his professional career studying the geology and seismicity of the region. He also provided an introductory guide to Yellowstone Park, helping many Workshop participants to take advantage of the proximity to Yellowstone to take a day trip there following the Workshop.

A view of the Grand Tetons from Jackson Lake Lodge*

Bison feeding in Yellowstone National Park
(photo courtesy of Ralph J. Miller III)

Demonstration and poster area*

Bob Smith leading a field trip to the Teton Fault*

(*photographs courtesy of Michael Hasting, Naval Air Weapons Station, China Lake, CA)

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