The Pacific Northwest Seismic Network (PNSN), in cooperation with the Seattle Seahawks and CenturyLink Field management has been involved with seismically monitoring some NFC playoff games. Installing portable instrument in the stadium helps us to test our instruments, telemetry, analysis and can help us better understand the vibrations recorded during a football game.
These are experiments. Earthquakes are not predictable but Seahawk fan enthusiasm is. Scientifically we like to investigate how an excited crowd energizes the stadium structure to shake, and how that shaking propagates into the surrounding ground. Other more technical motivations are listed below. As a public service, we are providing public views of the motions we are recording in near real time.
Where are the seismographs?
HWK1 is at field level under the east stands, HWK2 is on the second level of the west stands, HWK3 is in upper deck on east side, KDK is in a building just to the west of the stadium.
~3 sec delay and about 90 second duration with history scroll back.
~10 sec delay and 10 minute duration
~30 sec delay and hours duration
Attention seismologists: As of Feb 6, 2015 we have placed waveforms for the two week period around the two games in January 2015 at the IRIS DMC. You may obtain the data from HWK1, HWK2, HWK3 and KDK using the standard IRIS data access methods.
- The "Beast Quake" of Jan. 8, 2011 indicated to us that Seattle Seahawk fans can really rock the world. We want to test just how much, how long and at what frequencies they do rock the world.
- PNSN staff needs practice and training in rapidly setting up telemetered seismic stations. Siting, installing, acquiring and analyzing data as quickly as possible following large earthquakes or seismic swarms at volcanoes are goals of PNSN operations. Practice improves performance.
- We want to improve our understanding of unusual ground vibrations in an urban setting. Along with the portable instruments in the stadium there are permanent seismographs in nearby areas for recording large earthquakes. We want to understand the variability in ground motions at different sites under background conditions (at night) and during other seismic inputs (vibrations caused by large machines such as trains and, of course, by crowds of people as well as earthquakes).
- We want to improve our understanding of the vibrational response of a large structure. A stadium will vibrate with characteristic modes based on its design. Engineers can learn about different design elements by studying the recorded vibrations under different input loads.
- We are interested in how the PNSN web site is used by the general public. This experiment should attract a different user group than those normally interested in seismic events. We hope to learn something about how to make the website more generally useful and interesting.
- We need to test the response of the PNSN website to a possible large number of requests. We anticipate that after a future large earthquake there will be lots of interest in our website, but until such an event we don't have a way to test how well it will technically perform. With enough publicity this "Seahawk fan" experiment may provide a good test.
- We have a new set of strong-motion seismographs that should be easier and faster to install than our older versions. We need to practice their installation, data acquisition and analysis in realistic conditions.
- We need to test a newly designed and constructed tool called "QuickShake" that can provide very near real-time (within 2-3 seconds) seismic waveforms to web browsers and to test how this will scale up to large number of users for use by the general public.
- We need to practice using social media for gathering questions and comments from the public to better produce useful information products.
- There are on-going nagging scientific questions not fully answered from last year's experiments, such as exactly what is causing the relatively low-frequency signals that are not related to on-field action and that we have tentatively identified and called, "Dance Quakes".