Question

What causes the most injury in hurricanes?

Answer 1

Most of the injury that results from a hurricane results from tidal (storm) surges and flash flooding.

Explanation:

Before we take a look at why flooding is so pervasive and deadly we first need to understand why a hurricane, or in the South Pacific, a typhoon can manipulate water.

Hurricanes have a, calm, central, low pressure region called an "eye" (as in the idiom "in the eye of the storm") which creates a vacuum. Along with the winds which cause water to pile up and the immense speed of the storm the vacuum created by the eye causes the sea level to rise in front of the storm's most violent section, the "eye wall" (the border of fused cloud between the eye and the rest of the storm, the winds are the strongest here). Here's a video that explains a storm surge better that I ever could:

Footage Courtesy of: The Weather Channel

A storm surge is essentially a massive swell with waves on top of it (some storm surges have reached 46 feet [14 meters] in height). The storm pushes the sea water along until the storm makes landfall. Once the storm makes landfall all of the water in front of the storm is forced up onto land which results in significant flooding, like this:

Footage Courtesy of: eriutyne37tynietyinr (YouTube user)

The storm surge and flooding can cause people to drown, severely damage buildings and land (saturated ground can cause landslides), sweep cars away (it only take 2 feet of water to move a car), down trees and power lines, destroy food supplies, and causing disease (especially from contaminated water), all while slowing emergency responses (by limiting access to the region).

I hope this helps!