Friday, September 02, 2005

The bright side of the New Orleans catastrophe

[A] lot of geoscientists were expecting something far, far worse to happen in the immediate future, destroying New Orleans and other cities in the area more completely, with less warning and with casualties in the millions throughout the Mississippi valley.

In the winter of 1811-1812 a fault line located in the Mississippi valley released a series of four powerful earthquakes - the strongest estimated at over 8.0 on the Richter Scale - which were reported in the small town of New Madrid in what is now Missouri. At that time very few people lived in the Mississippi valley, but there were multiple reports of giant tidal waves in the river, of the river reversing course in the upper Mississippi and its tributaries, of massive landslides along the banks, of entire islands disappearing, houses being swallowed whole in the town of New Madrid, entire lakes being drained and 150,000 acres of forrest being swallowed whole. The last and strongest of the earthquakes was felt as much as 1000 miles away where it rang church bells in Boston. Because so few people lived in the region the loss of life and property was minimal - and very hard to estimate, because those impacted likely disappeared in the flood waters or were swallowed whole, with no one really aware that they had ever been there. A much weaker magnitude 6.8 earthquake in 1895 caused substantial physical damage in New Madrid and surrounding towns, and again was felt up to 1000 miles away.

The New Madrid fault line is still there and still active. There are several small tremors registered there every week. Because it is an intraplatal fault burried under layers of sediment its behavior is unpredictable and the impact of earthquakes there is very different from what we are used to seeing in California. A quake of magnitude 6.0 in California is significant, but a quake of the same strength on the New Madrid fault line would be substantially more damaging. A full 8.0 earthquake like the 1812 event would produce almost unimaginable destruction all along the river.

Today there are large cities and millions of people along the Mississippi. A major New Madrid earthquake would cause damage in at least 20 states, with a massive tidal wave in the river, immediately destroy enormous amounts of river traffic and all the bridges. It would shut down power throughout the region, wipe out every small riverbank town, destroy every levee protecting New Orleans, virtually wiping the city off the map, it would likely cause a large portion of Memphis to be destroyed in massive landslides, and there would be major building damage and loss of life in St. Louis as well as short-term flooding. Because of the large cities now in the region, the likely result of such an earthquake would probably be millions of lives lost and hundreds of billions of dollars in damage.

Geoscientists predict that there is likely to be at least a 6.0 quake on the New Madrid fault line by 2010, and that there is a 90% probability of an even more powerful quake before 2040. Detailed planning manuals have been written on how to prepare for the inevitable next earthquake in the region, and there are even a number of disaster novels which use a New Madrid earthquake as their theme. The governments of the states in the region have also formed a special commission to plan for disaster relief when the earthquake hits.

What's happened in New Orleans as a result of Hurricane Katrina is horrifying, but the state and local governments should have been better prepared to deal with it, because they've known for 200 years that disaster was coming - they just thought it was going to be a massive earthquake, not a hurricane.

The larger problem is that the earthquake is still coming - likely within our lifetimes - and in the aftermath of Katrina they should take a lesson from their failures and prepare for it properly. No new buildings should be allowed in the area which are not both earthquake and flood resistent. The city of New Orleans should be redesigned and perhaps even relocated in preparation for future disaster. And something has to be done about Memphis. Those famous picturesque neighborhoods located on bluffs above the Mississippi are literal death traps just waiting for an opportunity to slide into the water in complete destruction. They also need a real disaster plan, with a regional coordinating authority and permanently stocked emergency shelters in a stable and accessible region.

If you - like all of us - have been horrified by Katrina and the situation in New Orleans, remember that it could have been worse and more importantly, remember that the next major New Madrid earthquake is still coming and we need to prepare.

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