A powerful earthquake of magnitude 7.3 struck off the northeast coast of Japan on Friday evening. Thankfully, it caused little damage. The buildings in Tokyo wobbled for a few minutes and only some minor injuries have been reported.

This earthquake is nothing compared to the huge 2011 earthquake of magnitude 9 that killed more than 19,000 people in Japan. It caused the formation of 30-foot tsunami that swept away rice fields and entire towns.

Japan, an island nation stretching across some of the world’s most seismically active fault lines. To understand what it means, imagine Earth like a big puzzle where puzzle pieces are made up earth plates and the gaps between all the puzzle pieces correspond to plate boundaries called ‘fault’ lines. Earthquakes always happen along plate boundaries. Unfortunately, areas that are situated more directly on or near a ‘fault’ line are more prone to earthquakes.