The Handy Geography Answer Book. Paul A Tucci

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      The ruins of Pompeii attract tourists today, but it is difficult to imagine the horror of an entire city wiped out by a volcano.

      How was Pompeii destroyed?

      In the year 79 C.E., the volcano Mt. Vesuvius erupted and buried the ancient Roman town of Pompeii under 20 feet (6 meters) of lava and ash. Pompeii is famous because excavations of the city, which began in 1748 and continue to this day, provide an excellent look at Roman life at the beginning of the millennium. The covering of the city by debris preserved not only the places where people last stood but also paintings, art, and many other artifacts. The nearby city of Herculaneum was also buried and perfectly preserved. Although a much smaller version of Pompeii, it contains some of the best art, architecture, and examples of daily life in Roman times and is only twenty minutes away from Pompeii. Even loaves of bread that were baking on the day of the eruption are preserved in a nearly 2,000-year-old bakery.

EARTHQUAKES

      What creates earthquakes?

      The tectonic plates of the Earth are always in motion. Plates that lie side by side may not move very easily with respect to one another; they “stick” together, and occasionally they slip. These slips (from a few inches to many feet) create earthquakes and can often be very destructive to human lives and structures.

      What is an epicenter?

      An epicenter is the point on the Earth’s surface that is directly above the hypocenter, or the point where earthquakes actually occur. Earthquakes do not usually occur at the surface of the Earth but at some depth below the surface.

      What is a fault?

      A fault is a fracture or a collection of fractures in the Earth’s surface where movement has occurred. Most faults are inactive, but some, like California’s San Andreas Fault, are quite active. Geologists have not discovered all of the Earth’s faults, and sometimes earthquakes occur that take the world by surprise, like the one that occurred in 1994 in Northridge, California. When earthquakes occur on faults that were previously unknown, they are called blind faults.

      What is the significance of the infamous San Andreas Fault?

      The infamous San Andreas Fault lies at the border between the North American and the Pacific tectonic plates. This fault is situated in California and is responsible for some of the major earthquakes that occur there. Los Angeles is on the Pacific Plate, but San Francisco is on the North American Plate. The Pacific Plate is sliding northward with respect to the North American Plate, and, as a result, Los Angeles gets about half an inch closer to San Francisco every year. In a few million years, the two cities will be neighbors.

      Was San Francisco destroyed by earthquake or by fire in 1906?

      In 1906, a very powerful earthquake struck San Francisco, California, which sparked a fire that destroyed much of the city. In an effort to preserve San Francisco’s image with residents and would-be visitors, official policy regarding the disaster stated that it was not the earthquake but mostly the fire that destroyed the city. Official books and publications produced after the earthquake referred to both the fire and the earthquake as having caused the damage. In fact, the earthquake did considerable damage to the city and killed hundreds.

       Will California eventually fall into the ocean?

      No, it will not. The famous San Andreas Fault, which runs along the western edge of California from the San Francisco Bay area to southern California, is known as a transverse fault. This means that the western side of the fault, which includes places like Monterey, Santa Barbara, and Los Angeles, is sliding northward with respect to the rest of the state. In a few million years, the state’s two largest urban areas, San Francisco and Los Angeles, will be right next to each other. The fault is moving at about two centimeters (just under an inch) a year.

      A view of San Francisco taken from the Union Ferry Building and looking toward Market street shortly after the 1906 earthquake and fire.

      Which states are earthquake-free?

      While a twenty-year period isn’t an excellent indicator, there are four states that had no earthquakes between 1975 and 1995: Florida, Iowa, North Dakota, and Wisconsin.

      Is there a high risk of earthquakes in the Midwestern United States?

      Great earthquakes struck the New Madrid, Missouri, area in 1811 and 1812. They caused considerable damage (some areas experienced shaking at the level of XI on the Mercalli scale) and were felt as far away as the East Coast. The potential exists for future earthquakes in the region, since earthquakes have occurred there before. Planning and preparedness continues throughout the region, centered at the junction of Missouri, Arkansas, Illinois, Kentucky, Tennessee, and Mississippi.

      What should I do in the event of an earthquake?

      Duck, cover, and hold! Duck under a table, counter, or any area that can provide protection from falling objects. Cover the back of your head with your hands to help protect against flying debris. Hold on to the leg of the table or anything solid to ride out the shaking.

      Is it safe to stand in a doorway during an earthquake?

      While a doorway is a nice, structurally sound place to be during an earthquake, officials have found that many people are injured when a door swings open and closed during an earthquake, so you may want to avoid standing in a place where your fingers can become crushed.

      What is the Richter scale?

      The Richter scale measures the energy released by an earthquake. It was developed in 1935 by California seismologist Charles F. Richter. With each increase in Richter magnitude, there is an increase of thirty times the energy released by an earthquake. For example, a 7.0 earthquake has thirty times the power of a 6.0 earthquake. Each earthquake only has one Richter magnitude. The strongest earthquakes are in the СКАЧАТЬ