How much warning do coastal communities generally have before a tsunami

Which of there factors contributed most to us westward expansion in the second half of the nineteenth century?

What is the "great pacific garbage patch"? (a) a large area of marine debris concentrated by rotating ocean currents (b) a large area around the pacific rim where debris collects from natural disasters such as tsunamis (c) an area in the pacific ocean where trash is intentionally dumped due to lack of landfill availability (d) a large trash dump located in hawaii

Which was not a country that massively built up its navy in the early 1900s? germany china united statesbritain