Below is the text of an editorial written by Prof. John G. Anderson at the request of the local newspaper, the Reno Gazette Journal. It ran on the front page of the Business section, on Sunday, Jan 25, 1998, and altogether they gave it about a quarter of a page. Next to it, their reporter Mike Henderson wrote an article about the seismic code, with a large photo of the steel reinforcements from when the Silver Legacy Casino was being constructed.
Exceeding Seismic Code Pays in the Long Run
John G. Anderson
Professor of Geophysics
University of Nevada, Reno
Past Chairman (1992-1997), Nevada Earthquake Safety Council; Continuing Member
The Reno - Carson City region has an earthquake hazard. We have had 13 earthquakes since 1852 with magnitude over 6.0. Among urban areas in the US, only California cities along the San Andreas fault system have more earthquakes. Whether you are in Reno, Sparks, Carson City, Gardnerville or Fallon, there is a fault nearby. More research is needed before we will know if any of these communities have significantly higher earthquake hazards than the others. Although most of the large historical earthquakes were near misses for our communities - like the one south of Gardnerville in 1994 - sooner or later a fault directly beneath us will rupture. Then, we can expect shaking as strong as in the Northridge, California or Kobe, Japan quakes.
It is important for all of us, individuals and organizations, to have good emergency plans and to follow the checklists of what to do before an earthquake. But this takes place in the context of what the community decides to require for earthquake resistance of its structures. Fortunately, we have adopted a building code which places the entire region in either zone 4, which has the highest standards, or zone 3, which still provides significant earthquake resistance. My opinion is that this region should require zone 4 standards now, and under future codes should choose standards that exceed the recommendation of the national code-writing agencies.
Unfortunately, there is no simple answer to the question of how much more it costs to build to zone 4 than to zone 3 standards, or to the question of how much less it will cost to repair a zone 4 building after a severe earthquake. Both levels seek to assure life safety, but damage can occur. All we can say is that a structure built to zone 4 standards will often cost a few percent more, and will perform better.
Although a rigorous economic assessment of the alternatives is not available, I have two reasons to favor exceeding the recommendation of the national code-writing agencies. First, in my judgment, as the largest scientific uncertainties are solved, our estimates of the hazard here are more likely to go up than down. The second involves the trade-off in the code. The agencies that write the codes decide on the value of more earthquake resistance vs. the value of lower construction costs. Perhaps this trade-off is about right for an average city, but our region has some special circumstances: an economy that depends on our good reputation with potential tourists worldwide, more severe winters, and greater physical isolation. Damage hurts us more than an average community. Thus we should face the earthquake hazard more aggressively.
Here are a few more considerations:
The building code is not the only place to prepare for earthquakes. For instance, everyone dealing with tourism, from the executive to the desk clerk, should anticipate what tourists want to know immediately after the earthquake, where to get the information, and what they should do for the next few hours. Bracing furniture against earthquake forces is also very important - if a slot machine falls on a tourist, he will not agree that the buildings survival is adequate.
A change in our code makes an increasing difference as time goes on. Our population is growing fast. At the current pace, in 2050 about nine out of ten buildings will be post 1998.
Building codes aim to assure life safety, but may not prevent damage. The cost of repair can easily exceed the initial cost of more earthquake resistance. But the earthquake might not happen soon, in which case the gamble to decrease the earthquake resistance seems to pay off.
Putting more money into earthquake resistance might mean you have less to spend on other things. The person who builds a stronger house ends up with a higher mortgage, so he has a few dollars less every month for movies or car repairs, except that he might realize that earthquake insurance is not necessary. For a company, higher expenses for earthquake resistance could contribute to pressures to locate elsewhere or raise prices. And the government, when building bridges, has to either raise taxes a bit or spend less on other programs.
Setting higher earthquake standards than the national code-writers recommend thus will take a courageous political act. The seismologists, geologists and earthquake engineers at UNR and the Nevada Earthquake Safety Council believe that a community dialogue on appropriate seismic standards is warranted, and are eager to take part.