请帮我翻译一下：

Juan Louis, a junior geology major, decided to give an informative speech about how earthquakes occur. From his audience and analysis he learned that only 2 or 3 of his classmates knew much of anything about geology. Juan realized then that he must present his speech at an elementary level and with a minimum of scientific language. As he prepared the speech, Juan kept asking himself, “How can I make this clear and meaningful to someone who knows nothing about earthquakes or geological principles?” Since he was speaking in the Midwest, he decided to begin by noting that the most severe earthquake in American history took place not in California or Alaska but at New Madrid, Missouri in 1811. If such an earthquake happened today, it would be felt from the Rocky Mountains to the Atlantic Ocean and would flatten most of the cities in the Mississippi valley. That, he figured, should get his classmates’ attention. Throughout the body of the speech, Juan dealt only with the basic mechanics of the earthquakes, carefully avoid technical terms. He also prepared visual aids, diagramming photo line, so his classmates wouldn’t get confused. To be absolutely safe, Juan asked his roommate, who was not a geology major, to listen to the speech. “Stop me,” he said, “any time I say something you don’t understand.” Juan’s roommate stopped him four times. And at each spot, Juan worked out a way to make his point more clearly. Finally, he had a speech that was interesting and perfectly understandable to his audience.
注：机器翻译不要，谢谢了。