EIIP Virtual Forum Presentation October 22, 2003
in the USGS Earthquake Hazards Program (EHP)
Stephen R. Walter
Associate Chief Scientist
Western Earthquake Hazards Team
U.S. Geological Survey
Moderator, EIIP Technical Projects Coordinator
The following version of the transcript has been edited for easier reading and comprehension. A raw, unedited transcript is available from our archives. See our home page at http://www.emforum.org
[Welcome / Introduction]
Amy Sebring: On behalf of Avagene and myself, welcome to the EIIP Virtual Forum! Today's topic is "What's Shaking in the USGS Earthquake Hazard Program?" The EHP is part of the National Earthquake Hazards Reduction Program (NEHRP) led by the FEMA.
I have the pleasure of introducing today's speaker, Stephen R. Walter. Steve joined the USGS in 1982 to lead the seismic monitoring of the northern California Cascade volcanoes that later expanded to include the rest of northern and central California. He began using GIS in the early 1990's, publishing seismicity maps for the San Francisco, San Jose, and Santa Rosa quadrangles, and eventually managing the Earthquake Team's GIS lab. In 2001 he accepted the assignment of Chief Scientist for Operations for the team.
Welcome Steve, and thank you for joining us today. I now turn the floor over to you to start us off please.
Steve Walter: Thanks, Amy. To begin, I'd like to describe the mission of the US Geological Survey. The USGS serves the Nation by providing reliable scientific information to:
1. describe and understand the Earth;
2. minimize loss of life and property from natural disasters;
3. manage water, biological, energy, and mineral resources; and
4. enhance and protect our quality of life.
I work with the USGS Earthquake Hazards Team where our focus is primarily on the first two elements. We do the scientific research on earthquake hazards and communicate our results to people like you who can use this information to make better decisions to protect lives and property.
In this presentation I will highlight three significant accomplishments that USGS, working with our partners, has achieved in the past 25 years: 1) Earthquake Monitoring, 2) Hazards Assessment, and 3) Paleoseismology.
First Accomplishment -- Earthquake monitoring and reporting:
Congress, through the National Earthquake Hazards Reduction Program (NEHRP), has given USGS responsibility for monitoring and reporting earthquake activity in the United States and around the world.
We are the only agency responsible for tracking and warning of earthquakes. We do this through strong partnerships with universities and other institutions to maintain regional, national, and global networks of seismic monitoring stations. In the past 25 years, we have made major improvements in seismic instrumentation and computer processing. This has dramatically improved both the quality and timeliness of our earthquake response.
We have gone from analog film recorders that took literally days to process to full-spectrum digital technology that detects and locates earthquakes automatically in near-real time. By "near-real" time I mean having an earthquake location on our Web site within about a minute of when the earthquake occurred. As I tell visitors, "If you feel an earthquake, go to our Web site and I can almost guarantee that by the time you get there, there will be a dot on the map for the earthquake you just felt". This first slide shows some very recent activity.
These significant improvements in detecting and processing earthquake data have put us on the threshold of the next generation of seismic network, a network we call the Advanced National Seismic System (ANSS). ANSS, authorized by Congress in November 2000, is a plan for at least 6,000 digital seismic stations to be emplaced in urban areas where the risk is greatest. This next slide shows the planned urban areas.
Half of the instruments will be placed in buildings and structures to provide critical information about building and site response for engineers. The other half will be placed in the ground to improve our ability to locate earthquakes and to better understand the earthquake process itself.
Perhaps most important, the increased station coverage will immediately provide much better information about where the shaking is strongest, information that is especially valuable to emergency response personnel. In areas where the station density is sufficient, we can post "ShakeMaps" on the Internet within about 5 minutes after an earthquake, showing regional severity and location of ground shaking.
ShakeMap is an automatically generated computer map of the severity and distribution of ground shaking that is available on the Internet within 5-10 minutes after an earthquake. Data from networks of seismometers can be used to produce a map showing the actual levels and pattern of strong ground shaking caused by an earthquake in an urban area. Emergency management officials and managers of transportation, communication, and energy grids can use these ShakeMaps to direct the response to the earthquake, minimize its effects, and speed recovery.
The ShakeMap shown on the next slide was created following the Yountville earthquake of Labor Day, 2000. It is significant because it shows that shaking is not always strongest at the epicenter, shown here by the red star.
In this case, the seismic energy was readily transmitted by the hard rock of the hills near the epicenter but it became trapped in the thick, water-saturated soils of the Napa River Valley. This caused an amplification of the seismic waves and much stronger shaking within the valley than otherwise would have been expected at this distance. ShakeMap takes surface geology into account and so gives a more accurate picture of where shaking is strongest information that can be invaluable to emergency responders trying to figure out where to deploy their resources in the minutes and hours after a damaging quake.
We continue to refine and extend the ShakeMap. For example, ShakeCast, short for ShakeMap Broadcast, is a fully automated system for delivering specific ShakeMap products to critical users and triggering established post-earthquake response protocols. ShakeCast allows utilities and other large organizations to automatically determine the shaking value at their facilities, set thresholds for notification of damage states for each facility and then automatically notify (via pager, cell phone, or email) specified operators, inspectors etc., within their organization who are responsible for those particular facilities.
The California Department of Transportation (CalTrans) is testing the prototype system now. They have more than 25,000 bridges and overpasses under their responsibility in California. ShakeCast will provide an instantaneous snapshot of the likely damage to each of these structures and will allow CalTrans managers to prioritize rerouting traffic, closures, and inspections following a damaging earthquake.
Complementing ShakeMap is the "Did You Feel It?" map that allows citizens to report how much shaking they felt after an earthquake. The automatically-generated and updated map shows shaking intensity organized by Zip Codes. These interactive Web-based maps provide the public with a forum to communicate their experiences, assess impact, and learn more about earthquake activity.
For example, the "Did you feel it?" map on the next slide shows that 731 people logged on to describe how strongly they felt a M3.4 event near Orinda, CA this past Monday morning.
Second Accomplishment -- Hazard assessment:
Hazard assessment provides the vital connection between earthquake science and the actions needed to mitigate seismic risk. Over the past 25 years, our hazard assessments have changed from paper maps showing only half a dozen broad hazard zones nationwide, to digital database containing expected ground shaking levels at more than 150,000 sites.
We completed a major revision in 1996, and an updated version was released last fall. We worked closely with partners and colleagues across the US to develop and review the new version.
This hazard map for the nation provides essential information for creating and updating the seismic design provisions of US building codes. In fact, the State of Washington recently adopted IBC2000 as the state building code; IBC2000 allows direct use of the USGS National Hazard Maps, and this was seen as one of the strong reasons for adoption.
Third Accomplishment -- Paleoseismology:
Paleoseismology is a new field of earth science that provides direct evidence for prehistoric earthquakes through careful examination of exhumed fault traces, drowned coastlines, and exposed riverbanks.
The problem that paleoseismology helps solve is that the historical catalog of earthquakes in the Western US is only about 150 years long at best, which is inadequate in view of the length of recurrence time between major earthquakes. The situation is even worse in the Central and Eastern US. Paleoseismologic investigations along active faults will extend our knowledge of large earthquakes back thousands of years, providing a much more accurate estimate of recurrence intervals for large events.
To summarize, all these are major accomplishments in the science that improve our nation's ability to protect people and property. They demonstrate clearly the essential role that Federal science plays in reducing our vulnerability to earthquakes.
A final thought before opening to questions we have made a lot of progress, but as population and infrastructure continue to concentrate in areas of high hazard, is the earthquake risk progressing even faster? With that, I will turn it back over to our moderator.
[Audience Questions & Answers]
Valerie Quigley: Greetings from the Berkeley Hills - I'm at LBNL. Prediction capabilities, Steve? There was an interesting article in Science News (I think) a few weeks ago about using satellite infrared images to help predict heat from ground stress.
Steve Walter: Valerie, I didn't see that article so I can't comment on such a short-term prediction method. A question to pose: which is more useful, long-term probability or short-term prediction?
Bob Robinson: Does the private sector have access to ShakeMap, and if so, how? Also I would vote for long term
Steve Walter: You bet. ShakeMaps are available on our public Web site (http://quake.usgs.gov/recent/shaking.html) as soon as they're produced, usually within 10 or 15 minutes of the event. We do provide a service (Shakecast) for those who want or need to info pushed to them:
Steve Reinbrecht: Do you have a ground-shaking hazards map for Europe that includes Turkey and Iceland?
Steve Walter: USGS doesn't as far as I know. I believe the seismologists in Europe are using similar methods to communicate the hazard there.
Amy Sebring: (I would argue we need both short term for warning and long term for mitigation.) Did I understand you were integrating data in real time with the HAZUS software for rapid damage assessments?
Steve Walter: HAZUS is an example of where we push the ShakeMap data. In future quakes, results from HAZUS will be based on the measured shaking intensities from the network as expressed through the ShakeMap that is a very big raster file!
Jennifer Vuitel: How have local officials embraced the Shakecast (and other) ideas?
Steve Walter: I know the idea was well received in southern California, where the customers actually pushed us to provide the service. I believe PG&E and Caltrans are two of our customers here in the Bay Area. I can get back to you later if you need a more complete list.
Kim West: I am in Southwest Wyoming about 250 miles south of Yellowstone and wonder what information you have about this area and ShakeMaps for areas other than Yellowstone.
Steve Walter: ShakeMaps are dependent on having a dense network of seismometers so until ANSS is fully installed, ShakeMaps won't be available automatically in most parts of the country. On the other hand, ShakeMaps can be approximated from knowledge of the rupture parameters following the event. It just won't be as timely as the ShakeMap system I described above.
Avagene Moore: I am located in Middle Tennessee. I am as close as I want to be to the New Madrid threat. It has been nearly 200 years since that fault created Reelfoot Lake, etc. What is the appropriate stance to take re: the New Madrid? How aggressive should TN and the other Central US Earthquake Consortium (CUSEC) States be in their mitigation, preparedness and public information?
Steve Walter: Ava, as I recall, New Madrid has a repeat time (based on paleoseismology) of about 400 to 600 years. Trouble is, quakes don't always adhere to the average. Certainly construction standards should reflect the possibility of a quake next year, not next century. As to whether a homeowner should have earthquake insurance, that's always a question of personal comfort. Certainly, the information about the risk should be widely available.
Steve Reinbrecht: Steve, your USGS web site is very helpful. The site has opened up the eyes of my senior management.
Steve Walter: Thanks Steve. I think the Web site, being updated almost immediately after an earthquake, is about the best information we can provide and I want to point out that, since earlier this year, the updated maps have been available for the whole country, not just the west coast. "Did You Feel it?" maps, too, I believe.
Valerie Quigley: Sorry to go back to the prediction stuff. I was trying to find a link. Don't know where I read it, but I did find this. So, if you all get a chance, take a look at this Web site: http://ikfia.ysn.ru/IUGG%202003/abst/jsa10/010996-1.html It is a IUGG abstract of some research from China called: A Discussion of Thermal Process Around Strong Earthquakes by Using Satellite Infrared. I just thought it was an interesting approach. I think we should be concentrating on both methods. Certainly, sitting here in Berkeley on the Hayward Fault, we want to consider all options!
Steve Walter: No question if a method shows promise, it will rise to the top in the proposal / funding cycle.
Bob Robinson: Re: Predictions, to be honest the 30-year window of the current prediction for the San Francisco Bay Area (65% chance of a 6.9 or better in the next 30 years) is a hard sell in much of the private sector, it's just too wide a time frame. Where are we in terms of 10-15 year prediction windows, or even shorter?
Steve Walter: Bob, the 30-year window was chosen because it's a time span most folks with home mortgages can relate to. On the other hand, the statistics can be cast in any time frame you chose. 65% in 30 years translates into about 32% in 15 years. What's probably most needed is additional info on previous big events that will allow us to better know the recurrence interval and have more confidence in the probability. Short term prediction I'm afraid remains elusive until some new insight, perhaps infrared signals such as this abstract suggests, perhaps a tectonic signature seen in a closely spaced GPS grid, or perhaps emission of ultra-low frequency radio emissions as may have been emitted prior to Loma Prieta in 1989. Keep an open mind and measure everything you can think of might be the best approach.
Amy Sebring: Steve, I would think that the site is also useful in providing accurate information to the media, and hence to the general public. What has your experience been in this regard?
Steve Walter: I agree. I get calls from the media about events on the Web site that didn't even set off our response alarms. The downside is that there's sometimes an over-reaction to an event that really isn't significant but it's all part of an education process, both for the public and for us.
What we're hoping to see in the next few years is for the press and the public to develop an understanding of ShakeMap, since this really describes the effects of the earthquake much better than the epicenter map can. Turning on the news and seeing the earthquake represented as a ShakeMap (perhaps in the 3D terrain view the weatherman uses) will be a more useful way of conveying how important a given quake was. We need the public to understand that blue and green are ho-hum dont get excited until you start seeing yellows & oranges. We're considering producing video clips that show the level of shaking (say in a kitchen) for Yellow (intensity 7).
Isabel McCurdy: Since I live in the land of earthquake country on the west coast of Canada I was wondering if on the hazard map the earthquake color code bar is a standard?
Steve Walter: We standardized on the color code for the US just a couple years ago but it makes such intrinsic sense to use red for strong, blue for weak, yellow for intermediate that I would hope other people would adopt this standard, if they haven't already. I think the folks at the science center in BC are adopting some of these techniques.
Avagene Moore: Does the USGS have educational materials available in hardcopy as well as online for a community's EQ awareness campaign? How would one get them if hardcopies are available?
Steve Walter: Earthquake pamphlets have been produced specific to San Francisco, Los Angeles, and Eureka. They were included as supplements in the Sunday papers. More generic information on earthquakes can be obtained through the Earth Science Information Centers (ESICs) at any USGS center, i.e., Denver, Menlo Park, Reston. I think you can find reference on the USGS web site to all our publications.
Burt Wallrich: I am one of the estimated 1/3 of men with some degree of color-blindness. It is always helpful to have text to supplement color-coding.
Steve Walter: Burt, one of our seismologists has red-green color blindness and I believe he was consulted in choosing the colors used here. I admit I haven't asked him how easily he can read the ShakeMaps.
Amy Sebring: That's all we have time for today. Thank you very much, Steve, for your time and effort. You did a great job. I would also like to thank Kathleen Gohn at the USGS for helping to arrange today's session.
Thanks to everyone for participating today. Our session is adjourned but before you go, please help me show our appreciation to Steve for a fine job.