Cascadia's Fault; Jerry Thompson; 2012; Harper Colins; 330 pgs

I was watching a documentary on earthquakes about 9 days ago, based in part on this book. I ordered the book and started reading two days later.

I thought myself fairly knowledgeable on earthquakes, but I was wrong. Mostly because most of what we know we have found out in the last decade or two. The book is written as a sort of detective novel, leading up to its big conclusion. 

Many people of my age probably think that we are in a largely earthquake free zone. Geologists thought so too, but wondered why the Cascadia had not had a large quake when every other part of the ring of fire did. They rationalized that our rocks are slippery so stresses can be relieved regularly. After Sumatra and the 250,000 dead there, interest picked up in Cascadia.  Could a Magnitude 9 quake be in our future too?

In the olden days, lo, several decades ago in the sixties, plate tectonics was only just gaining acceptance. In the eighties, lasers were used to measure distances between points to see if the earth was moving. This was expensive and difficult. Then GPS came along. Geologists were not interested in GPS coordinates per se, they were interested in how far apart two rock-fixed points were. This was cheap and easy. Soon tons of data was pouring in and computer simulation started taking off. The other thing they did was to look for evidence of past quakes in multiple different ways. They found it.

Spoiler alert… We are due. The Juan De Fuca Plate is now called the Cascadia Subduction Zone Fault and it has let rip every 400 years or so with a massive quake. The last was 400 years ago.

If you live in the interior, you are laughing. If you live on the coast of Vancouver Island, you are fucked. Depending on the nature of the shaking, many buildings in Vancouver (esp brick and mortar "medium-rises") will collapse. In the worst case scenario, the entire west coast of North America from LA to Alaska may be hit hard. The expected tsunami would hit Crescent City like a hammer, and would probably do significant damage in Japan.

It is a good story. The evidence of the turbidite cores, tree rings, oral histories, ghost forests etc all come together nicely. The upshot is that we should be spending more on earthquake preparedness and building reinforcement.

One nice sub-story came from a ten year old British girl in Phuket who had been taught what to look for. She spotted the signs of an incoming tsunami. She convinced her parents and saved her family.    

Cascadia is Sumatra. The death toll will be lower, but the damage worse. The good news is that while earthquake prediction is still a dark art, predicting what tsunamis will do is becoming relatively easy. For example, next time, we will be able to tell the Sri Lankans to bug up (not out) even if they are on the lee side of the island… which actually got hit worse than the weather side  did. You will have to read the book to find out why.  

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