Hi Beth,

With humor intended, if you are a member of the geology community you need to be careful about responding to one of my posts. If the other geology professionals find out about it they might decide to take away the “Pet Rock” that each geologist is given at graduation.

They are apparently willing to forgive Roger because he insists that “Earthquakes can’t be predicted” in every second note that he posts.

I posted that previous note after I looked at the USGS earthquake history map and did not see any records of any other powerful earthquakes in that area. So, that led me to suspect that there might be a lot of strain accumulated at other locations along that fault zone. And they might just be waiting for a little additional push before they fracture.

I am going to guess that tsunami alerts are issued almost automatically based on the earthquake magnitude and location. And I suspect that the ocean area sensors might be mainly used to track the location of the wave front rather than determine what the tsunami height will be when it reaches land. Not knowing for certain, I could be wrong on that.

The wave out in the ocean is I believe just a minor swell in the ocean that travels at a tremendous speed. The destructive tsunami wave does not form until the swell gets to a sloped area along the shore. Then the water can’t go forward any more and goes upwards instead. If I remember correctly, that one that hit parts of Indonesia a number of years ago was something like 60 feet or more in height when it came ashore.

It sounds like they thought that a tsunami from that Canada area earthquake might be 3 feet high when it got to shore. But it was less than that when it arrived.

Also, only certain types of earthquakes generate a tsunami. Ones where two plates are sliding sideways past one another do not if I remember correctly. It has to be an earthquake where one plate is sliding beneath another as I gather was the case with that Canada earthquake.