RAC Meeting 2007
Meeting Materials/Presentations:
Minutes of ANSS Pacific Northwest Regional Advisory Committee
15 February 2007 (convened at the University of Washington Seismology Lab)
Minutes prepared by Tom Yelin, U.S. Geological Survey. Revised 3/5/07
Meeting began at 10:25. The list of attendees is at the end of these minutes. Red text is related to action items, purple marks committee reminders to the PNSN.
John Vidale, Director of PNSN welcomed the group and provided and introduction. He briefly reviewed the agenda, the component institutions of the PNSN, the PNSN's sources of funding and in-kind support.
Next, he reviewd the major initiatives on which the PNSN is currently working:
1. High-resolution Shakemaps:
2. Adding building fragility information to HAZUS;
3. Improving speed and accuracy of initial earthquake notification;
4. Working toward real time aftershock probability calculations;
5. Research on earthquake early warning technology;
6. Upgrading of network infrastructure (both in Seattle and out in the field).
Murdock Initiative
The Murdock proposal was successful. About 15 temporary Traveling Array (TA) stations will be converted to permanent network stations, equipped with three-component broadband sensors and three-component accelerometers. Budget considerations may prevent all 15 from being equipped with accelerometers.
It is possible, although by no means certain, that the state of Oregon and the Pacific Northwest National Laboratories Seismology Group at Hanford may be able to purchase additional seismic equipment to be installed at other TA sites. Oregon might fund the purchase of between 2 and 8 stations and Hanford 3 or 4.
John showed a map of the PNSN broadband instrument network after the TA sites have been converted.
Paul Bodin briefly described the process by which the TA sites were selected. Station selection for conversion to permanence is nearing completion.
Other instrumentation developments
The UW will soon purchase six portable broadband sensors and recorders. These may be helpful in a variety of projects, including aftershock studies, seismicity studies in areas of poor coverage, and possibly building response studies.
Current state of PNSN
368 stations stream data to Seattle. These include the Earthscope TA stations, which will be moving out of the region over the next year or so, with the exception of the 15 TA sites that will be converted to permanent status with the Murdock funds.
240 of these 368 stations are maintained by the PNSN: 95 strong motion, 23 broadband, and 122 short-period vertical-component weak-motion stations.
Some time was spent discussing the challenges of accurate location of offshore earthquakes, brought up partly in the context of the M5.3 well offshore Oregon the previous day. Currently, such earthquakes are considered outside of the PNSN's authoritative region. They are generally located and have magnitudes determined by the USGS's National Earthquake Information Center (NEIC).
Vidale mentioned the PNSN's intention to change the "Authoritative Region" for the PNSN to the entire states of Oregon and Washington, to general agreement.
The PNSN is currently inadequate in its routine magnitude calculation capability above about magnitude 4.5. The AC strongly encouraged efforts to improve its capability for magnitude estimation and apply it to both onshore and offshore events. Rapid determination of the magnitudes of Cascadia subduction events larger than about M8 from near-field data presents considerable technical challenges.
Strong Motion Issues
Tim Walsh noted that DNR building in Olympia has accelerographs inside the structure but there is no companion free-field site.
Instruments in WA and OR currently operated and maintained by the USGS National Strong Ground Motion Program will likely be turned over to the PNSN over the next few years.
C.B. Crouse asked if there are adequate resources at the PNSN to adequately maintain all these new sites. Steve Malone replied there probably was not. C.B. urged that sites that have produced useful recordings of all the large Puget Sound earthquakes in the past 60 years still have recorders at them be maintained.
Availability of strong motion data to engineering community
Considerable time was spent discussing the long-standing problem of how to provide the engineering community with acceleration time series data in a timely and convenient fashion.
C.B. noted that most (if not all) modern digital accelerographs have virtually flat responses in the frequency band of primary engineering interest, so conversion of the seismologist's times series that are in digital counts to acceleration is simply a matter of multiplying by the correct scale factor.
Malone proposed that some of our engineering colleagues look at what kind of time series data are available on the web (e.g., Southern California Earthquake Center, California Strong Motion Instrumentation Program, or the Japanese effort, which was praised by C.B.).
Marc Eberhard, Leon Kempner, C.B., T.J. McDonald, and Ray Cakir agreed to form an informal committee to define what a strong motion database might look like and to look for existing web sites that might serve as model for the PNSN, which it could pattern its own effort after. It was also suggested that John Hooper be invited to participate in this effort.
It was reported that IRIS has agreed to archive continuous strong motion data from the PNSN, a useful move, although this archive will not provide the necessary easy access for the engineering community, hence the need to create a special database.
(Following the meeting, changes in the PNSN and IRIS software were made such that as of Feb 17, 2007 all real-time strong-motion data from the PNSN is being continuously archived at the IRIS DMC.)
The efforts of Art Frankel's group in the Seattle and Portland areas were briefly discussed.
ShakeMap
Malone reported on the history of the effort to implement ShakeMap in the Pacific Northwest. He talked about the most recent efforts to input high-spatial-resolution information about surface geology and Vs30 data for the city of Seattle (on a .75 arc-minute grid, which is about 1400 meter linear spacing) and to make some test runs of ShakeMap with these new data.
Malone briefly summarized the completed effort supported by the WashDOT and instigated by UW CE to use acceleration values produced by ShakeMap to estimate the probability of DOT bridge damage following a large earthquake. This system is currently working but has not been of use because no earthquake has been large enough near bridges in the past three years. This work will be reported in the paper noted below:
Ranf, R.T., Eberhard, M. and Malone, S., "Post-Earthquake Prioritization of Bridge Inspections." to appear in Earthquake Spectra, Earthquake Engineering Research Institute, April 2007.
The final project report to WashDOT can be retrieved from this link:
A discussion ensued about earthquake loss estimates in general and FEMA's HAZUS loss estimation software in particular. A lot of accurate information is needed to make good loss estimates: accurate ground motion information, and as C.B. pointed out comprehensive and correct building inventory information. The PNSN does not have the resources nor the expertise to address the building inventory issue.
Leon Kempner mentioned that BPA is using HAZUS by inputting all of their inventory and fragility information for the whole BPA system.
UW Multi-Geologic Hazards initiative
Robert Winglee, chair of the UW Dept. of Earth and Space Sciences, gave a brief report on the initiative to create a structure that would bring together University, local, State and Federal resources to address earthquake, volcanic, flood, landslide and tsunami hazards in Washington State. a white paper has been drafted and a workshop with potential participants will take place in late April at the UW.
Dealing with all these types of hazards involves four functions: mapping, monitoring, modeling, and mitigation. The biggest task of all is finding effective ways to translate the results of such activity into public policy.
Aftershock probabilities
Joan Gomberg spoke about beginning efforts to create a method for estimating aftershock probabilities for significant PNW earthquakes. Aftershock probabilities are already calculated in California on an experimental basis. The historical data and higher and more uniform rates of seismicity there make such estimates easier to calculate than is the case for the PNW.
Coastal Hazards Workshops and Lake Washington tsunamis
Bill Steele reported on two recent workshops to educate coastal communities and Indian tribes to use CISN display to provide real time earthquake and tsunami warning information to those communities. A $25K grant from the USGS supported this effort, which also involved the purchase and distribution of the necessary software and computers.
The Washington Department of Natural Resources is having a workshop at the UW on March 9 to discuss the issue of tsunamis in Lake Washington as the result of a Seattle fault event, and particularly the risk faced by the 520 bridge.
DNR's tsunami run-up maps can be found at www.dnr.wa.gov/geology
Next Meeting
The UW will be preparing its annual proposal to the USGS for seismic monitoring in September and October. It was agreed that an advisory committee meeting sometime early in that process might be helpful, if beforehand a list of specific questions and issues could be prepared for the advisory committee's consideration.
These issues and questions would be regarding what activities (especially new activities) might be proposed to the USGS. Bill Steele will keep the group posted on when such a meeting will be held, preferably with more lead-time than this meeting.
Action Items & Recommendations
1. The AC encouraged already-planned efforts to improve its capability for magnitude estimation and apply it to both onshore and offshore events.
We plan to implement moment tensor inversion in the next year or so, as soon as we plow through the chores queued ahead of it.
2. Formation of the "strong motion database" committee and launching its work (see details earlier in minutes).
A call to Woody Savage, Director of the NSMP, revealed that NSMP has created a very good website, and is currently testing it with the CISN, and planning to make it live April 1st. This leaves us with only the problem of our sending the NSMP our data in an automated way. Another phone call to Ralph Archuleta reveals COSMOS may offer a similar delivery system of strong motion data. So rather than designing our own delivery system, we need only work out data transmission issues, obviating the need for committee formation.
3. Recommendation to USGS that Art Frankel be urged to continue his long-term array studies in the PNW. Also, ask that Art make his data readily available to the engineering community and help him do it.
Vidale or Bodin will contact Frankel to investigate the logistics and specified advantages of pursuing this.
4. Next meeting, call out items on which AC is requested to comment, and notify with more lead time.
A sensible idea.