International Seismic Safety Organization* 20 September 2012 POSITION STATEMENT ON EARTHQUAKE HAZARD ASSESSMENT & DESIGN LOAD FOR PUBLIC SAFETY International Seismic Safety Organization* 20 September 2012 Signed by Benedetto De Vivo, ITALY – Indrajit K. Ghosh, USA – Allen W. Hatheway, USA – Jens-Uwe Klügel, SWITZERLAND – Vladimir G. Kossobokov, RUSSIAN FEDERATION – Ellis L. Krinitzsky, USA – Efraim Laor, ISRAEL – Alessandro Martelli, ITALY – Lalliana Mualchin, USA – Giuliano Panza, ITALY – Antonella Peresan, ITALY – Mark R. Petersen, USA – Francesco Stoppa, ITALY – Augustin Udias, SPAIN

Catastrophic disasters associated with occurrence of natural forces such as 2004 Sumatra-Andaman earthquake & tsunami, 2005 Katrina hurricane, 2008 Wenchuan earthquake, 2009 L’Aquila earthquake, 2010 Haiti earthquake, 2011 Tohoku earthquake & tsunami, etc could have been reduced or even avoided by being adequately prepared beforehand for the largest potential events. Long recurrence or low probability earthquake information provided by any group as the basis to ignore such eventualities as “too rare” are not reliable and unrealistic: they can and will happen again as unpredictable surprises. We need to be prepared for such eventuality to avoid great disasters. Essential earthquake information as the basis for necessary actions for safety are outlined below:

First, fundamentals of earthquake source and hazard: The driving forces that generate these deadly events are a part of the nature of the earth throughout geologic time and will remain so indefinitely. The timings of future earthquakes are not predictable, it is not possible to provide when they will occur with certainty. The general locations of potential large earthquakes are well known globally by earthquake monitoring and geologic studies. The largest potential earthquake (maximum credible earthquake, MCE) size for such locations can be realistically estimated with confidence. This is the most powerful and destructive, superceeding all other possible events by definition. Preparing for such hazardous event ensures reduction or avoidance of potential disasters. This point is the most important key to remember! The hazard scenario for MCE is estimated by DSHA or NDSHA as the basis for all preparations, from land-use planning and building code regulation to emergency management.

Second, what cause disasters: The consequences of earthquakes and inadequate preparations. Tsunamis, liquefaction and land-slides are the consequences of earthquakes. Collapsed and failures of buildings, bridges, and other structures are the consequences of inadequate preparations. Inadequate preparations include using low earthquake design, much lower than produced by such events so that buildings cannot withstand earthquake forces and they failed . Inadequate preparations include not warning people for such possible eventualities.

Third, keys to safety: Have realistic estimate of MCE’s and its scenario as an ultimate target for civil protection. Plan new settlements outside earthquake-prone or in relatively “safe” areas. Building structures must be designed and constructed to withstand earthquake forces. Evacuate to a safe place when warned of an impending earthquake. Moving quickly to pre-determined safe locations in the event of a sudden earthquake. Have a comprehensive large scale plan in the event of MCE’s.

Fourth, implementation: Strategic and public buildings as well as critical structures be designed and constructed to withstand forces from MCEs. Do not use PSHA for such applications as they are not reliable and unrealistic, too dangerous for civil protection. Do not use design load determined by earthquake recurrence interval or ground motion return period because such will not work when the largest event occurs. Your building must be able to resist the largest event anyway as they are fixed to the ground. Avoid sites that were too close to earthquake source that would experience severe shaking and potential surface fault rupture displacement.

Conclusions: Disasters can be reduced or avoided by- Designing and constructing strategic and public buildings as well as critical structures to withstand forces from the MCEs. Not using forces calculated by PSHA as they are not reliable and generally mislead to unexpected losses. Evacuate to a safe place when warned of an impending earthquake. Move quickly to pre-determined safe locations in the event of a sudden earthquake. Be wary and suspicious of earthquake policy based on recurrence interval, return period, and probability as these are highly unreliable and unrealistic from experience and recent observations. They may have a different agenda than public safety, especially when the cost and rarity are emphasized.