Real estate investors say that only one thing is important in their business - "location, location and location." The same is true, it seems of earthquakes. Location, seismologists report, is the reason that the earthquake that hit New Zealand on Tuesday - five times smaller than one that hit the same region last September - caused far more death and destruction. No one died and property damage was relatively not widespread in the magnitude-7 fall quake. Tuesday's magnitude 6.3 earthquake left 75 dead, hundreds missing and caused significant damage. The toll likely will grow in the days to come.
Tuesday's earthquake was centered about 3 miles from the heavily populated city of Christchurch. The September quake was centered about 30 miles away. Tuesday's quake occurred at a depth of 3 miles, shallow as temblors go, and therefore more damaging. The fall quake, scientists say, occurred at twice the depth of Tuesday's, which struck at the height of a work day. The fall quake occurred in early morning. Tuesday's mix of proximity and timing proved particularly deadly and damaging.
The earlier quake, however, possibly contributed to the death toll and damage this week. It and a series of aftershocks - Tuesday's quake was the strongest of them - likely weakened many structures, making them more vulnerable to later shaking. Tuesday's quake simply knocked down buildings that were more likely to be damaged or fall as the result of the earlier quake. Even New Zealand's strict building codes could not protect all structures. Many of those damaged Tuesday pre-date those laws.
The quake in distant New Zealand should serve as another reminder - recent temblors on Haiti, Chile, China and Pakistan served that purpose previously - that the United States is crisscrossed by fault lines. That should spur local, state and federal governments to update contingency plans to deal with natural disasters like earthquakes.
It should be a reminder, too, that communities near or in earthquake-prone zones need to develop and implement building codes designed to protect against earthquake damage. Given the unpredictability of earthquakes and the regularity with which small ones occur in this region, there is no reason to delay. A more powerful and destructive earthquake could occur at any time.
It is better to be prepared than not. Tuesday's quake is a potent reminder to all that the ground upon which we live is neither as firm nor as unshakable as we think. Those who live within shaking distance of the massive New Madrid fault that runs along Tennessee's western border - and that includes much of the tri-state region - or on or near smaller faults closer to home would do well to keep that lesson in mind.