NARROWS OF LAKE MEAD
Now look at the difference in the the high water marks here at the Narrows. Two years ago the marks were level and were level for many years.

Note: The high mountains of decaying lava on either side of the Narrows. The height of the slide falling into the water determines the height of the tsunami. There is constant seismic active going on now in this area and the lake bottom.
Here is the physical evidence of what is abut to happen.
Next is a look at the cracks and faults in mountains of lava on either side of the Narrows.