Deadly Earthquakes

						April 1, 2002

		A People Under Siege The people of Afghanistan are under siege. They've endured a four-year drought that has caused families to starve and die. They've seen their country take a battering because the Taliban's self-appointed government did not cooperate with the United States' wishes to expose terrorists. And last week, the ground was shaken beneath the Afghan people by a series of earthquakes. Any of these hardships would be bad enough in isolation, but together they amount to a trial of unthinkable severity. The latest report from the U.N. states that last week's earthquakes left 800-1,200 people dead; it's estimated that 4,000 people are injured and approximately 20,000 are homeless. These numbers will likely change as rescue operations continue and the aftershocks continue. The series of shallow earthquakes ruptured the ground in the foothills of the Hindu Kush, a region about 100 miles north of the nation's capital, Kabul. Felt strongly across much of northern Afghanistan, the quakes did major structural damage. The market town of Nahrin — which has a population of 30,000 — was razed. Scores of nearby villages in the remote province of Baghlan were also reduced to rubble. View a map from the U.S. Geological Survey to see where the earthquake occurred. The first quake, which measured 6.1 on the Richter scale, was compounded by a series of aftershocks which amplified the damage. Aftershocks are among the range of difficulties facing rescue workers: damaged infrastructure, the presence of landmines, mountainous terrain, freezing rain, and poor communication lines. Just reaching the disaster site presents a challenge. While the epicenter is located only 160 kilometers north of Kabul, the journey over land is a grueling seven-hour drive. Many relief aid agencies were already in the Baghlan region, helping the displaced people to cope with the impact of war and an earthquake that occurred in February. By now, many more rescue convoys loaded with supplies — such as food, tents, and blankets — have made their way to Nahrin and the surrounding villages. Medical help has been given to the most badly injured people. Peacekeeping forces — American, British, Dutch, and German soldiers among them — are also helping out at the earthquake site.
						Quakes Caused by Bombs? Your students may ask if the earthquakes were triggered by the bombs that have been dropped on Afghanistan in recent months. The U.S. National Earthquake Information Center says this is not the case. The following information was taken from the Center's Web site: "The earthquake is the result of geologic processes that have been active for millions of years; its occurrence is independent of the recent bombing in Afghanistan. The depth and magnitude of this event preclude any connection with human activity."
		Learn About the Problem Math: Earthquakes are often remembered in the public consciousness not for the actual magnitude of the quake, but for the resulting death toll and the amount of destruction caused. Have students work the Tangible Math activity, Earthquakes, to learn if there is a direct correlation between the magnitude of an earthquake and the death toll. (This activity requires Logal Express. Get a free trial subscription.) Earth science: The Hindu Kush region is a very active earthquake area because it lies at the boundary between two of Earth's tectonic plates. Like the San Andreas fault in California, where the North American and Pacific plates meet, the Afghanistan/Pakistan-border region is a place where the Eurasian and Indo-Australian plates meet. If you look at a plate tectonics map of the area, you will see that the Indo-Australian plate is moving north, pushing under northern Pakistan. But much of the Afghanistan-Pakistan border area lies along a transform plate boundary, where the two plates slide past each other. However, just as they do in California, the plates do not slip past each other smoothly. Instead, they stick together, building up pressure and storing energy until they are suddenly — and violently — able to move. The energy released in that sudden movement is what causes what we experience as an earthquake. Think About the Problem Math: In the above Tangible Math activity, Earthquakes, students should have seen that the magnitude of an earthquake is not the only factor in the resulting death toll. Magnitude is a way scientists have of quantifying the energy released by an earthquake. Magnitude is commonly measured on the Richter scale. Each unit on the Richter scale equals a 10 times bigger or smaller jump in the pen on a seismograph. This is actually equal to a 31 times larger or smaller amount of energy released by the earthquake. How many times more energy is released by a 5.0-magnitude earthquake than a 4.0-magnitude earthquake? How many times more energy is released by a 6.0-magnitude earthquake than a 4.0-magnitude earthquake? Earth science: What other factors could make a 6.1-magnitude earthquake more deadly than a 5.0-magnitude quake? Consider the role of each of the following factors in the level of physical destruction and subsequent loss of life: magnitude of earthquake location and depth of quake focus type of soil and rock through which the earthquake energy waves travel local building standards time of day the earthquake occurs frequency and magnitude of aftershocks political situation in the country of the quake weather conditions during and following the quake Ask students to locate the following cities on a map. Then, based on the tectonic plates map in the Earthquake Lab, have them determine if there may be a relation between earthquakes happening within days, weeks, or months of each other in the following pairs of cities: San Francisco, California, and Los Angeles, California Istanbul, Turkey, and Mexico City, Mexico Seattle, Washington, and Jerusalem, Israel Cairo, Egypt, and Johannesburg, South Africa Tokyo, Japan, and Jakarta, Indonesia St. Petersburg, Russia, and Beijing, China				Earthquakes Daily Around 50 earthquakes occur every day in the world, most so minor that they don't make the news. Annually, roughly 18 major earthquakes occur, some in uninhabited areas. Deep and Shallow Quakes The focus of the March 25 earthquake was eight kilometers below the surface of Earth, making this a very shallow quake — intermediate-depth quakes typically occur at depths between 70 and 300 km. Because shallow-depth quakes are so close to the surface, they can do considerable damage even if they do not release much energy. When a quake occurs deep in the Earth, the planet itself acts as a buffer, absorbing energy; but when the quake occurs closer to the surface, the planet surface and human-made structures absorb the energy. According to the U.S. Geological Survey, the March 25 earthquake generated 95 times less energy than a March 3 event which registered higher on the Richter scale, but occurred deep underground. Students should note the difference between an earthquake's focus and its epicenter. The focus is the point below ground from which the energy is released. The epicenter is the area on Earth's surface above the focus.
		Extending the Problem For additional research, students can access this free collection of articles on earthquakes from Living Library. There are many educational Web sites dealing with earthquakes. Here are a few: Earthquake!: A collection of lessons, activities, research ideas, and resource suggestions Life Along the Faultline: A multimedia exhibit exploring California earthquakes from many angles: science, history, community, and more Virtual Earthquake: An interactive site designed to introduce the student to the concepts of how to locate an earthquake epicenter and how to determine the magnitude of the quake Faults, A Model of Three Faults: Instructions for students to build models of the three types of faults and learn some of the basic concepts related to each type Earthquakes for Kids: The United States Geological Survey site offers many educational and fun activities dealing with earthquakes If your school is located in an earthquake-prone area, you can review with your students the guidelines for earthquake preparedness and how to behave during and following an actual quake. The Red Cross Disaster Services: Plan for an Earthquake The Federal Emergency Management Agency (FEMA): Fact Sheet: Earthquakes The Association of Bay Area Governments (ABAG): Techniques for Mitigating Earthquake Hazards				News Resources Here is a selection of news stories on the recent events in Afghanistan. MSNBC's "Afghans live life parched by drought" Students may find the transcript of this BBC forum useful, in which a reporter describes her experience of last week's earthquake and the plight of the Afghan people. Afghanistan's modern history is a protracted saga of war and natural disasters. Read the BBC's timeline, and profile of Afghanistan.