Risk Management Series Designing for Earthquakes
A Manual for Architects
FEMA 454 / December 2006

10.1 INTRODUCTION
Earthquakes are only one of several hazards to which buildings are vulnerable.  
The two other significant natural hazards are floods and high winds, including 
tornadoes.  These hazards are extreme variants of benign natural processes.  
Earthquakes represent a highly accelerated instance of the slow adjustment that 
the earth makes as it cools.  High winds and tornadoes are an exaggerated form 
of the pleasant winds and breezes that freshen our everyday existence.   
Devastating floods are the result of excessive localized rainfall that, when 
normal, is necessary for the provision of water supply and the nurturing of 
plant life.  These natural hazards are not aberrations, are not malicious, and 
are part of nature’s order.
The traditional hazard to which buildings are vulnerable is fire, and history 
abounds with urban fire disasters right up to the present day.  Fire disasters 
are usually due to human errors and carelessness, but are sometimes originated 
by earthquakes and made more lethal by winds  (Figure10-1). Fire, however, when 
properly controlled, is an important contributor to human comfort.  Sometimes, 
of course, a fire disaster is the result of malicious intent.   The newest 
hazard - that of a terrorist attack on a building - is malicious, but is also an 
extreme form of everyday circumstance that we have come to accept: criminality. 
Building design has long recognized the need for locks and, more recently, 
remote cameras and sensing devices are also designed to prevent criminal - and 
now terrorists - from gaining entry to our buildings1
DESIGN FOR EXTREME HAZARDS BY CHRISTOPHER ARNOLD
10.2 MULTIHAZARD DESIGN SYSTEM INTERACTIONS
This publication focuses on design against earthquakes, but the other hazards 
must also be assessed.   Each of them has differing levels of risk—i.e., the 
probabilities and consequences of an event.  Some, such as earthquakes, floods, 
and high winds, are specific to certain regions.  The risks of terrorism are 
still uncertain compared to those of natural hazards that have a long history of 
statistical and scientific observation and analysis. Fires are more pervasive 
than any of the natural hazards.   However, design against fire has long been 
built into our building codes, in the form of approved materials, fire-resistant 
assemblies, exiting requirements, the width and design of stairs, the dimensions 
of corridors, and many other issues. 
An important aspect of designing against a single hazard such as earthquakes is 
the extent to which the design methods may reinforce or conflict with those 
necessary for protection against other hazards.  Multi-hazard design involves a 
risk assessment of all hazards at a programmatic stage to ensure that protection 
measures are not in conflict. Ideally, the measures used would focus on 
reinforcement rather than conflict, so that the overall risk management plan 
enables the cost of construction to be reduced.  
To assist the reader in evaluating the interactions between protective design 
methods, Table 10-1 summarizes the effects that seismic design measures may have 
on performance of the building in relation to other hazards. 
The horizontal rows show the five primary hazards. The vertical rows show 
methods of protection for the building systems and components that have 
significant interaction, either reinforcement or conflict. These methods are 
based on commonly accepted methods of risk reduction for the three main natural 
hazards, together with fire protection methods, and the methods for 
security/blast protection presented in FEMA 426, Reference Manual to Mitigate 
Potential Terrorist Attacks against Buildings, and FEMA 430, Site Design 
Guidance to Mitigate Potential Terrorist Attacks. 
The comments in this matrix are not absolute restrictions or recommendations, 
but rather are intended to provoke thought and further design integration.  
Reinforcement between hazards may be gained, and undesirable conditions and 
conflicts can be resolved by coordinated design between the consultants, 
starting at the inception of design.
Table 10-1 provides information to help the reader develop a list of 
reinforcements and conflicts for the particular combination of hazards that may 
be faced. Development of lists such as these can be used to structure initial 
discussions on the impact of multi-hazard design on the building performance and 
cost that, in turn, guide an integrated design strategy for protection.  The 
system and component heading list is similar to that used for the building 
security assessment checklist in FEMA 426, Reference Manual to Mitigate 
Potential Terrorist Attacks against Buildings.


[End of Chapter 10]