Scientists say the Pacific plate is moving toward the northwest, while the North American plate is moving toward the southeast. These two huge plates come together at what is called a fault line. This line between the plates in California is called the San Andreas Fault. It is along or near this fault line that most of California’s earthquakes take place, as the two tectonic plates move in different directions.

The city of Los Angeles is about fifty kilometers from the San Andreas Fault. Many smaller fault lines can be found throughout the area around Los Angeles. A major earthquake in nineteen ninety-four happened along one of these smaller fault lines.

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BOB DOUGHTY: As we noted earlier, scientists began making major discoveries about plate tectonics in the twentieth century. One of those scientists was Alfred Wegener from Germany. One hundred years ago, he proposed that the continents had moved and were still moving.

Wegener said the idea came to him when he saw that the coasts of South America and Africa fit together like two pieces of a puzzle. He suspected that the two continents might have once been one, and then split apart.

Wegener believed the continents had once been part of a huge area of land that he called Pangaea. He said the huge continent had split more than two hundred million years ago. And, he said the pieces were still floating apart.

FAITH LAPIDUS: Alfred Wegener investigated the idea that continents move. He noted that a line of mountains that appears from east to west in South Africa looks almost exactly the same as a line of mountains in Argentina … on the other side of the Atlantic Ocean. He found fossil remains of the same kind of an early plant in parts of Africa, South America, India, Australia and even Antarctica.