Japan was struck by a massive tsunami on Friday caused by an earthquake of an 8.9 magnitude–one of the largest quakes the country has ever seen. The sudden natural disaster has claimed 300 lives and has left 700 missing, said BBC.

Several hours after Japan was hit, the waves penetrated the west coast of the U.S., overturning vessels in Santa Cruz, California and smashing the shore of Crescent City, near Oregon’s border, with waves reaching up to 8.1 feet.

Massive waves also battered the shores of the Hawaiian islands although its people were warned in advance to seek appropriate shelter.

The destructive wave in Japan took out farm fields, roads and towns. A warning has been issued on the entire pacific ocean basin, affecting 50 countries, according to CNN.

The wave was about 231 miles from Tokyo. More than 31 aftershocks have been felt by the city’s residents, the largest measuring at a 7.1. Aftershocks can happen days or even weeks after the primary earthquake occurs.

Government officials in Japan declared a state of emergency for fear of a nuclear meltdown at five nuclear reactors whose cooling systems have failed.

The tsunami has the potential to thwart the nation’s slowly progressing economic recovery and trigger an increase in Japan’s already hefty public debt, which is already 200 percent of its gross domestic product, according to the Wall Street Journal.

A Geology 1001 course’s geological explanation of the disaster:

The earthquake’s epicenter, or point above where the earthquake originated (the focus), is on a deep ocean trench. Beneath this trench lies a thrust fault with a hanging wall to the west and a footwall to the east.

Over the course of hundreds of years, the upper portion of the hanging wall has been bending. Japan’s natural disaster is a result of the elastic rebound of the hanging wall to suddenly, simply, straighten out.

The seismic waves produced by this virtually instantaneous “straightening out” of the edge of one of earth’s plates was most likely felt by those Japanese coastal civilians closest to the epicenter, roughly five minutes before the tsunami’s disastrous effects hit shore.

The waves of this tsunami were generated at the earthquake’s epicenter and travel at about the speed of a jetliner.

What’s interesting about this powerful natural disaster is that if you were sitting in a boat in the ocean somewhere near the epicenter, you most likely couldn’t tell that Japan was about to experience something horrific. In the open ocean, the tsunami’s wave’s amplitude, or height, is about one meter high, whereas the wave’s length, or distance across, is roughly the width of Minnesota. So when these vast bodies reach the shallow water near land, the real disaster begins.

This tsunami is able to penetrate the west coast of the U.S. because the type of wave generated by the earthquake loses very little energy with distance.

With an 8.9 magnitude, this earthquake is the fifth largest experienced in the last 100 years.