The beauty of the USA West Coast is it's mountain ranges. While tsunamis are a concern they are limited in scope and damage to certain elevations.
There are the occasional surprises.
On the night of July 9, 1958 (click here) an earthquake along the Fairweather Fault in the Alaska Panhandle loosened about 40 million cubic yards (30.6 million cubic meters) of rock high above the northeastern shore of Lituya Bay. This mass of rock plunged from an altitude of approximately 3000 feet (914 meters) down into the waters of Gilbert Inlet. The impact generated a local tsunami that crashed against the southwest shoreline of Gilbert Inlet. The wave hit with such power that it swept completely over the spur of land that separates Gilbert Inlet from the main body of Lituya Bay. The wave then contiuned down the entire length of Lituya Bay, over La Chaussee Spit and into the Gulf of Alaska. The force of the wave removed all trees and vegetation from elevations as high as 1720 feet (524 meters) above sea level. Millions of trees were uprooted and swept away by the wave. This is the highest wave that has ever been known.
"...Mature forest did not extend all the way down to the shoreline...bands of younger trees of mature forest..."
The evidence to types of activity of Earth isn't necessarily in the way or where one expects it. The more scientists know the safer society is.
Is there any evidence that would lend to a catastrophic event? Yes. There is a bay within relatively short distance from majestic mountains. Those mountains put pressure on the land surrounding the bay. The pressure became too much for the weight of the existing land and water.
The ratio of mountain to the land that surrounds it at lower elevations dictates the potential to land slides. In this case, the ratio of a drastic change in elevation caused a cataclysmic event. It makes sense. The pressure from rock at elevation was far, far higher than the pressure of land at sea level to compensate to create a stable region. But, once the pressure was relieved it was over. At least for now.
...four topographic parameters (click here) (elevation, slope angle, plan form curvature, and aspect)...
Science in response to the need for knowledge. The glaciers would add a moving pressure and changing weight of the land as well. This landscape is complicated, but, not so much that it is undetectable to what occurred.
To completely explore the events a team of scientists would be required, a geologist (land), hydrologist (littoral water), oceanographer (bay) and glaciologist (ice) and a climatologist to bring life to the temperatures and winds. Water is sensitive to wind and temperature at it's surface and this is Alaska.
