On January 17, 1994, the Northridge quake struck in California and caused estimated damage of at least $30 billion, according to the Engineering News-Record. What caused so much damage, and what kind of building codes are supposed to ensure structures that can withstand earthquakes? Is it realistic to expect a building or a major structure, such as a highway bridge, to survive an earthquake? When can we say that a structure has survived or failed? Most of us do not understand the discussions of earthquake construction because the engineers talk in terms of horizontal shear from lateral loading, or vertical shaking, or shear damage and flexural damage. What are they talking about? And more important, what can they do about it? It can
