The Indian Ocean. Copyright 2010 LessonSnips

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1 The Indian Ocean One of the five major geographic divisions of the world s ocean, the Indian Ocean is located in the Eastern Hemisphere. The Indian Ocean is bounded by three continents: Africa to the west, Asia to the north, and Australia to the southeast. The islands of Indonesia, located to the south of Asia and north of Australia, also form part of the eastern boundary of the Indian Ocean. The Indian Ocean joins the Southern Ocean at 60 degrees south latitude, which is south of the southern tip of Africa. The third largest ocean, the Indian Ocean is smaller than the Pacific Ocean and the Atlantic Ocean. It accounts for roughly 20 percent of the world s surface water while the ocean as a whole contains 97 percent of all the surface water on earth. The average depth of the Indian Ocean is about 13,000 feet or about 2.5 miles. The deepest point in the Indian Ocean is 25,340 feet or 4.8 miles. Sunda Trench This deepest point occurs at the Sunda Trench, often called the Java Trench. An ocean trench is a long, narrow depression in the ocean floor which corresponds to the junction of two tectonic plates. Tectonic plates are irregularly shaped pieces of the earth s crust that move in response to the interaction of forces from the earth s core and those found on the surface. The intersection of tectonic plates is typically an active earthquake and volcano location as well as the location of deep ocean trenches. The Sunda Trench is home to recent earthquakes and volcanic eruptions which are due to the presence of four tectonic plates, namely the Sunda, Burma, India and Australia Plates. The Sunda Arc of volcanoes lies in the vicinity of the Sunda Trench. Ancient volcanic activity created major islands of Indonesia, Java and Sumatra. The geological activity of the area caused the Sumatra-Andaman earthquake, also called the 2004 Indian Ocean earthquake. This massive earthquake originated on the floor of the Indian Ocean off the west coast of northern Sumatra. It measured a magnitude of 9.0 on the Richter scale of earthquake measurement, the second strongest on record. The huge earthquake shook the entire planet and triggered earthquakes elsewhere. Since the earthquake occurred in the ocean, it caused giant ocean waves which became

2 tsunamis that affected the coastal populations of fourteen countries including India, Indonesia, Malaysia, Somalia, Sri Lanka, and Thailand. The death toll is estimated at 230,000 people. Studies of the ocean floor after the earthquake indicate that major changes had occurred. Rocks weighing millions of tons were moved some seven miles from their previous location. Ancient undersea ridges were toppled while a new trench formed. Scientists are concerned that the recent earthquake activity in the Sunda Trench is just the beginning of further shifts in tectonic plates of the region which are likely to occur in the near future. Major Seas The Red Sea has played important roles in ancient history as can been seen from the writings in the earliest books of the Christian Bible. The Red Sea divides westernmost Asia from the northeast corner of Africa. The Sinai Peninsula of Egypt forms the barrier between the northern reaches of the Red Sea and the Mediterranean Sea of the North Atlantic Ocean. The Gulf of Suez at the northern tip of the Red Sea is the access point to the Suez Canal which links the Red Sea to the Mediterranean Sea. The Asian countries with borders on the Red Sea include Israel, Saudi Arabia and Yemen. African countries of the Red Sea include Egypt, Eritrea, the Sudan and Somalia. Since the Red Sea is surrounded by arid desert climate, it experiences a high rate of evaporation, causing it to be one of the saltiest (most saline) bodies of water on earth. The trench running north and south in the middle of the Red Sea reaches a depth of over 7,000 feet, but the average depth is about 1,600 feet. The Red Sea is a long narrow finger of ocean water that connects to the Arabian Sea, a portion of the Indian Ocean. The Arabian Sea is significantly larger than the Red Sea. The southern tip of India is one of the markers for the location of the Arabia Sea. The Arabian Sea follows the western coast of India and extends along the southern border of Pakistan and Iran. The area of the Arabian Sea bounded by Iran, Iraq, Saudi Arabia, and the United Arab Emirates is known as the Persian Gulf. The Arabian Sea is also bordered by the western Asia countries of Oman and Yemen. The Arabian Sea extends to the northeast coast of Africa, the location of Somalia.

3 This sea is also the location of the Republic of Maldives. This country is composed of over 1,100 volcanic islands and has the distinction of being the lowest above sea level of any country, with an average ground level of just under 5 feet.

4 Circle True or False after analyzing each of the following statements. 1. True False The Indian Ocean is bounded by three countries: Africa to the west, Asia to the north, and Australia to the southeast. 2. True False The islands of the Republic of Maldives, located to the south of Asia and north of Australia, also form part of the eastern boundary of the Indian Ocean. 3. True False The deepest point in the Indian Ocean occurs at the Sunda Trench, often called the Java Trench. 4. True False The geological activity in the vicinity of the Sunda Trench caused the 2004 Indian Ocean earthquake that killed hundreds of thousands of people. 5. True False The second largest ocean, the Indian Ocean is only smaller than the Pacific Ocean. 6. True False Scientists are concerned that the recent earthquake activity in the Sunda Trench is just the beginning of further shifts in tectonic plates of the region which are likely to occur in the near future. 7. True False The Gulf of Suez at the northern tip of the Red Sea is the access point to the Suez Canal which links the Red Sea to the Indian Ocean. 8. True False African countries with borders on the Red Sea include Israel, Saudi Arabia and Yemen. 9. True False The Red Sea is one of the saltiest (most saline) bodies of water on earth. 10. True False The Arabian Sea is significantly larger than the Red Sea.

5 Answers 1. False 2. False 3. True 4. True 5. False 6. True 7. False 8. False 9. True 10. True