Book Review on "Plate Movements and Past Climatic Conditions"

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Shallow focus earthquakes are created nears the surface of the earth commonly in plate areas that are experiencing stress from stretching or bumping into other plates, but not necessarily at the very edge of two plates. Deep focus earthquakes are deeper in nature, and usually occur near the seam of two plates or near a subduction zone where plates can shift at greater depths as they are begin overtaken.

3. CITE EXAMPLES of EARTHQUAKES THAT HAVE AFFECTED AREAS OUTSIDE the PLATE TECTONIC SETTINGS DESCRIBED in QUESTION 2.

Examples of other earthquakes are those that occur in the Midwest of the U.S. These quakes are brought on by underground magma chambers and pressure being released in the form of gasses. There are records of many fissures and chambers in the crust in this area that have resulted in significant earthquakes over the centuries.

4. WHAT MEASUREMENT MUST BE MADE on SEISMOGRAMS to DETERMINE the DISTANCEFROM a SEISMOGRAM STATION to an EARTHQUAKE EPICENTER?

In order to determine the distance of an earthquake from a seismogram, a scientist needs to be able to triangulate the earthquake through three different seismograph readings. The quakes amplitude, duration, and the time between the first P. And S. waves are necessary to calculate the exact distance from the seismograph reading that the earthquake occurred. Once distances are plotted from three different locations, it is possible to triangulate the epicenter using a map and the results of the seismogram calculations.

5. If YOU LIVE in an AREA AFFECTED by EARTHQUAKE, WHAT SHOULD YOU DO as an INDIVIDUAL to PROTECT YOURSELF?

Living in an earthquake zone isn't something to be scared of. First of all, people should have a first aid kit as well as at least three days worth of food and water on hand in case of an emergency. Authorities and help can often take a week or more to arrive after a quake. Secondly, people can prepare their home or work environment for a quake by strapping TV's and other large appliances to walls and making sure their buildings are up to code and legal.

6. WHAT NATURAL PROCESSES CAUSE EARTHQUAKE?

Earthquakes can be caused by a few different natural processes. First of all, as the plates shift, they bump into each other creating uplifts. This can cause tremors. Also, magma that is under pressure and is forced upward through the crust can cause earthquakes. Plate slippage and shifting against each other can cause earthquakes as well.

7. WHAT TECHNIQUES of EARTHQUAKES PREDICTION SEEM MOST PROMISING?

One of the most promising techniques for predicting earthquakes is to look at the historical timeline of previous earthquakes to help understand the frequency and size of specific quake patterns. Even though this seems rather archaic, it is one of the best methods scientists have to predict them.

8. WHAT AREAS in the UNITED STATES HAVE the HIGHEST FREQUENCY of EARTHQUAKES?

The areas in the U.S. that have the highest frequency of quakes are the areas that are most geologically active. The west coast as well as the rocky mountain interior in places like Yellowstone National Park. Earthquakes occur just about everywhere in the U.S., even in the mid-west, though they are relatively small and infrequent. The west coast, which is part of the Rim of Fire, is the most active earthquake zone in the U.S.

9. WHAT SECONDARY EFFECTS of EARTHQUAKES ACCOUNT for MOST PROPERTY DAMAGE?

The secondary effects of earthquakes that often account for much of the property damage are fire, floods, and exposure to elements. Many cities have gas pipelines that could rupture in a large enough quake where help wouldn't be able to arrive for days or weeks. Also, many quakes cause tsunamis, and these floods can wipe out entire coastal towns and cities as they have in the past. Finally, it is often very difficult for home and business owners to secure their property after a quake, so there can be looting and destruction of property through weather and exposure as well.

10. WHAT METHODS AREUSEDTOPREDICT THETIME and PLACE of FUTURE EARTHQUAKES?

As mentioned previously, scientists rely on both historical timelines of past quakes as well as seismic instruments to help warn them of immediate impending tremors. It is very difficult to predict a quake, but the longer a quake-prone area goes without one, the higher the chances are that it will soon be hit by a quake.

REVIEW QUESTIONS PAGE 171

1. HOW DO ERUPTIONS of VOLCANOES at HAWAII and OTHER LOCATIONS on OCEANIC CRUST DIFFER FROM ERUPTIONS of VOLCANOES in ISLAND ARCS LIKE PINATUBO?

The Hawai'i volcanoes eject solid basalt and other types of igneous rock from under the Earth's crust. The island arc volcanoes usually erupt ash and dust as well as hot gasses. These types of volcanoes are associated with other types of pyroclastic volcanoes that emit more than just raw igneous rock from subduction zones.

2. WHY ARE HEAVY RAINS COMMONLY ASSOCIATED WITH VOLCANIC ERUPTIONS?

Heavy rains are associated with volcanic eruptions because of the heat and moisture released by the eruption itself. Also, the ash particulates draw water molecules and ice to their surfaces and when they become too heavy to continue floating in the air they rain down with the rains.

3. HOW DO the SHAPES of VOLCANOES THAT ERUPT MAINLY PYROCLASITIC MATERIALS DIFFER FROM THOSE THAT ERUPT RHYOLITE and BASALTIC LAVAS?

Volcanoes that erupt pyroclastic material are different in that they incorporate dust, ash, and other sediments that tend to build up a rather loose, unstable hill or mountain that can crumble or be washed away during an eruption. The more basalt-based volcanoes deposit large amounts of very hard, thick basalt rock that builds up much more solidly over time and does not get washed away as quickly due to erosion or other eruptions or earthquakes.

4. HOW CAN VOLCANIC ERUPTIONS AFFECT GLOBAL CLIMATE?

Volcanic eruptions can affect global climate in many different ways. First of all, if the ash cloud is large enough it can block the sun's rays from entering the atmosphere and cause global cooling. It can also have widespread effects on weather patterns in general as the ash and hot air circulate into the atmosphere. Ice ages have been known to have come and gone based on massive volcanic eruptions. Also, if the ash cloud is black or soot is deposited on large ice or snow masses, the sun's rays will heat and melt these water deposits and further disrupt ocean currents and the weather patterns that follow them.

5. WHAT DANGERS DOES a VOLCANIC ERUPTION of the TYPE FOUND in ISLAND ARCS POSE to PEOPLE WHO LIVE WITHIN 25 KILOMETERS (15 MILES) of the VOLCANO?

Volcanoes found in island arcs pose many threats to people living within 25 kilometers. First of all, the tsunami's can wash away coastal towns and villages. Secondly, the ash cloud, which is usually a trademark of the island arc volcanoes, can cause health and breathing problems. Third, hot gasses can escape from the eruption and mix with sea water, ash, and other elements to form hot mudflows and even temporarily turn the sea around the island acidic.

6. In WHAT PLATE TECTONIC SETTINGS ARE the MOST ACTIVE VOLCANOES LOCATED?

The most active volcanoes are located near subduction zones. Hawai'i is home to the world's most active volcano.

7. HOW DO CALDERAS FORM?

Calderas form when eruptions of ash and pumice create a cavity below the volcano where the entire core of the volcano… READ MORE