In 2010, a powerful earthquake in Chile affected the rotation of the earth. This earthquake was so powerful that it moved a city in Chile about 10 feet. However, this earthquake is not the most powerful earthquake to have ever occurred. Fortunately, many powerful earthquakes take place under the sea, where people and animals do not get hurt. However, earthquakes that occur on the ocean floor can sometimes cause destructive tsunamis that result in more destruction than the earthquake itself may have caused. Earthquakes can also cause avalanches in mountainous regions. While most earthquakes are caused by natural causes, nuclear tests or mining activity can also trigger earthquakes to occur. Many folk stories and myths exist about why earthquakes occur. For example, according to Japanese mythology, a large fish named Namazu is responsible for earthquakes. According to researchers, animals like snakes and ants sometimes seem to be able to predict earthquakes quite accurately. For example, researchers have noticed that some ant colonies evacuate their mounds shortly before an earthquake occurs.