A powerful earthquake in Alaska didn’t trigger a big tsunami — here’s why

Last night, a magnitude 7.9 earthquake struck southeast of Kodiak Island in the Gulf of Alaska, prompting a tsunami warning that forced people to flee to higher grounds in the middle of the night. Fortunately, the tsunami waves were less than a foot high, and the advisories were canceled a little after 4AM local time. So why was Alaska so lucky?
Powerful quakes that happen out at sea are known to cause destructive tsunamis. In 2011, a magnitude 9 earthquake in northeastern Japan triggered waves