From simplestlife
It was a close call but they did not realize it until the chunks of ice and rushing waves rocked the boat. According to scientists, landslides can cause tsunamis. In fact, a huge, landslide-generated tsunami occurred on July 9, 1958 in Lituya Bay, Alaska. The rockslide generated a 525 m splash-up immediately across the bay, and razed trees along the bay and across LaChausse Spit before leaving the bay and dissipating in the open waters of the Gulf of Alaska (earthsci.org).
While viewing the glacier in Tracy Arm Fjord in Alaska, a 200 foot tall piece of ice collapsed and sent chucks of flying ice and a huge wave that rocked the boat. A woman was injured and broke her leg.