In addition there is an undersea volcano off the coast of Oregon called the Axial Seamount. It is to the left of the Juan de Fuca plate which on the right subducts under the Cascade range fault. Subduction zone quakes are the strongest (9.0) or greater. The earth had 9 or 10 massive plates that are moving. In 1960 there was a subduction zone quake in Chile that was lasted for 10 minutes. It was a 9.5 quake. It unleashed a tsunami that killed thousands of people in Chile, Hawaii, Japan and the Philippines. A 9.5 quake releases 31.6 times the energy of an 8.5 quake.
For reference, an 8.35 quake releases the same amount of energy as two 25 Megaton Hydrogen bombs. The Good Friday quake of 1964 was centered 78 miles east of Anchorage. It registered at 9.2 or 9.3 on the logarithmic based Richter scale which would make it 31.6 times as powerful as those two 25 Megaton Hydrogen bombs. (And 10 times the amplitude.)
In the distant past Africa and South America used to be connected. Today Africa has shown signs of having a rift fault where parts of Africa are separating. THE NEW MADRID FAULT IS A RIFT FAULT MEANING THAT THE MISSISSIPPI RIVER WILL IN GEOLOGIC TIME WILL SEAPRATE AMERICA INTO TWO PARTS.
In the past quakes along either the Cascades or the San Andreas have triggered each other. That would make America useless to Israel and Wall Street. It would anger an abandoned people which might tempt the Powers That Ought Not to Be to unleash a series of really nasty plagues. Though that might not be necessary as we will have so many volcanoes that we will likely have another "1816 year without a summer."