When will Next MegaFlood Hit California and West Coast?

It is close to 100% safe to say that it will hit sometime between now and 2112 because historically they average one every 200 years. By studying silt accumulations in coastal areas scientists are now able to predict historically when Megafloods have occurred in the past. When a Megaflood occurs we can expect about 1/4 of the towns and cities either washed away completely or flooded completely and so at least 25% of the population of California would be homeless during and after this event.

In the last event in 1862 Sacramento was completely under about 10 feet of water and the Sacramento River was 20 miles wide up to Redding, California from accounts of witnesses and Newspapers at the time, and several southern California  Towns and Villages were completely washed away and I believe Weaverville was washed away in the north. So, this event is not an IF event but only a When event. Also, since the Capitol of California, Sacramento was underwater,  Leland Stanford eventual founder of Stanford University was Governor of California and had to move the state government by boat and ship to San Francisco. Also, the state went bankrupt because 1/4 of the taxable land in California was lost or damaged.

Here is a quote from the most recent Scientific American Study

 The flood layers can be dated using the common radiocarbon-dating method, which in this application is accurate to within about 100 years. A study of the marsh cores by one of us (Ingram) and geographer Frances Malamud-Roam revealed deposits from massive flooding around A.D. 1100, 1400 and 1650. A distinct layer from the 1861–62 event is difficult to distinguish, however, because hydraulic gold mining in the Sierra Nevada foothills during the decade before and after the flood moved enormous volumes of silt and sand that essentially wiped out whatever traces the floodwaters might have left.

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So, if we know for sure that Megafloods in California actually took place around 1100 AD, 1400 and 1650 and 1862 AD then we should prepare Californians for the next one in whatever practical way we can that is likely to hit within the next 100 years.

To learn more about the last one in 1862 here is more from Wikipedia.

Great Flood of 1862 - Wikipedia, the free encyclopedia

It is now 150 years here in 2012 since the last Megaflood in California. It will be 200 years in 2062.