Does seismic mitigation work? It’s a good question and one that demands a clear answer. But during a recent stakeholder workshop I attended for a seismic hazard map update, for a high risk area of the U.S. (and conducted by the top earthquake scientist for this region), the repeated tabling of this important question posed by the assembled delegates was met only by silence on the part of the presenters. Instead of an informed response the question was followed by a kind of deer in the headlights look by each of the scientist.
This session was a clear mismatch. It seemed that none of the top scientist on the platform had ever ventured much beyond the math and physics of the highly specialized theoretical seismology required to create a maps update. So the question, does seismic mitigation work, was simply outside their sphere of experience – hence the surprised response. It wasn’t that the presenters didn’t understand the question, or that the rather obvious answer was yes! – it’s just they were just the wrong type of scientists to provide the answer.
Figure 1: Example of beyond code design and construction for critical facilities, the recently completed U.S. Embassy in Haiti experienced almost no damage during the 2010 M 7.0 Haiti earthquake. Photo by Philip Caldwell
Professionally speaking, a scientist’s ability to answer a question is grounded in the fundamentals of the scientific process. In this particular case those conducting the seminar did not specialize in factual field data collection of post-earthquake structural performance and mitigation effectiveness, nor had their analyses been vetted through rigorous peer review. Therefore they had no accepted research upon which to base a response.
Which is too bad, because this was a highly influential gathering. They represented a wide cross section of stakeholders from banking, insurance, business continuity managers, water-gas-electric-telecom utilities, public safety, fire and rescue, building inspectors, air-land-water transportation managers and emergency managers at the local, state and regional level.
This who’s-who of movers and shakers in attendance at this seismic map update workshop absolutely needed to be completely familiar with the value of implementing comprehensive design for protection of high value assets, public policy making and building code enforcement. Here they were, gathered together in one place at the same time, actively looking for information to help them prioritize mitigation projects – an essential input to be considered in emergency response and recovery plans. Especially important in an area with an earthquake sequence that has been recently assessed by the re-insurance industry to result in approximately $150B USD of losses. Unfortunately, missing from the speaker line-up were experts able to deliver real world evidence.
Figure 2: URM, unreinforced masonry, is an issue for schools worldwide, the Louisa County High School was immediately condemned after the 2011 M 5.8 Virginia earthquake and had to be demolished. Photo by Philip Caldwell
Figure 3: Clear evidence for the effectiveness of modern U.S. building codes, a few days after the main shock event in Louisa County, Virginia there was no reported damage for the Emergency Operations Center. Photo by Philip Caldwell
Had the background of the scientist matched the interest of the attendees, the presentations would have been rich in observations and findings, confirming the real and measurable value for a wide variety of practical mitigation strategies. With the exception of extreme hazards, these sorts of practical methods can reduce or mitigate damaging impacts from strong ground motion shaking – even that produced by rare and minutes-long monster events such as the 2011 M 9.0 Tōkoku earthquake in Japan.
Figure 4: Subjected to extreme strong ground shaking for almost four minutes during the 2011 M 9.0 Japan earthquake this Sendai emergency operations command center continued to operate after the earthquake thanks to its structure being base isolated. Photos by Philip Caldwell
Figure 5: Protected by base isolation of the building, Japan’s national monitoring and warning center for volcanic hazards continued to operate after the main shock despite the long duration extreme ground shaking experienced during the M 9.0 Tōkoku earthquake as well as many smaller after shocks. Photo by Philip Caldwell
The workshop was a missed opportunity to provide compellingly clear and easy to visualize, intuitive proof that the incremental cost of mitigation can and does dramatically improve the resilience of essential infrastructure, as well as protecting the wellbeing of the public – the very people this audience was responsible for. For them, a below-the-weeds discussion about the finer points of the theory of tomography held little value or relevance.
It’s vital that we make the most of all the research and data we have at our fingertips to improve the resilience of essential infrastructure and protect the wellbeing of the public. Wind the clock back to 1886. In the aftermath of the M 7.0 Charleston, South Carolina earthquake the mayor was quoted in the newspapers with a prescience and wisdom 100 years ahead of his time, saying that if Charleston kept having damaging earthquakes it may be necessary to construct buildings with base isolation like that of Japanese temples which had withstood hundreds of years of major earthquakes.
Figure 6: Only in the last few years have researchers had mammoth scale shake tables to conduct controlled studies of full scale buildings on. Schneider Electric was a key partner in working with researchers at UCSD and its NEES collaboration to obtain the NSF grant for the first full scale building test in the U.S. – see https://www.youtube.com/watch?v=E30MaghaG0Q
Today we know empirically that earthquake mitigation for modern construction is both feasible and proven because it has showed itself to be effective in many real world events. At Schneider Electric, we have been working alongside the world’s leading scientists, engineers and governments to learn from real world damaging earthquakes and translating those lessons into improved building codes and construction methods for essential building systems.
Many of those lessons for protecting the mechanical and electrical systems of important buildings can be found in an ASCE engineering textbook that I co-authored “Earthquake Protection of Building Equipment and Systems.” This book is targeted at the design professional or critical facility manager who needs to develop a basic technical understanding of equipment specific earthquake mitigation topics and was written to fill a void on this topic in technical books. For additional tools, resources and product information, please register for our dedicated Consulting Engineer portal site.
In my next blog I am going to discuss the “how does it work” in a way that I hope will enhance your intuitive understanding of what lies behind the building code seismic provisions and why implementation of these protective measures is a no brainer starting point for smart cities.
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