Figure 7.46: A landslide in a neighborhood in Anchorage Alaska after the 1964 Great Alaska
earthquake. ( 29 )
Because the earthquake occurred at a subduction zone offshore, large tsunami (up to 70
meters (20 feet)) were created. Despite the intensity of the earthquake, only 131 people
died, mostly due to the tsunami and property damage was relatively modest, at just over
$300 million ($1.8 billion in 2007 U.S. dollars). The reason there was such a small amount
of damage for such a large earthquake is that very few people lived in the area at that time
(Alaska had only been a state for five years!). A similar earthquake today would cause
immeasurably more casualties. The number of people that an earthquake kills or injures
is often related to the time of day that it strikes and where it strikes. The most lethal
earthquakes strike densely populated cities when people are at work and school. Being at
home in bed is usually safer.
Earthquake-Safe Structures
The way a building is built—its construction—is a large factor in what happens during an
earthquake. Building construction is the reason many more people died in the 1988 Arme-
nia earthquake than the 1989 Loma Prieta, California earthquake. Although the Armenian
earthquake was only slightly lower in magnitude, the mud houses that are found through-
out the area collapsed. Most buildings in California’s earthquake country are designed to
be earthquake safe. However even earthquake safe buildings can be damaged by a large
earthquake.
Engineers who design earthquake safe buildings must understand seismic waves and how
they affect different types of ground. Skyscrapers and other large structures built on soft
ground must be anchored to bedrock, even if it is lies hundreds of meters below the ground
surface.