Presentation on theme: "8.6.2 Waves Explain how seismic waves provide scientists with information about the structure of Earth's interior."— Presentation transcript:
1WavesExplain how seismic waves provide scientists with information about the structure of Earth's interior
2Hurricane EarlRALEIGH, N.C. – Federal officials urged U.S. residents to prepare for possible evacuations and islanders in the Turks and Caicos braced for high winds Tuesday as powerful Hurricane Earl howled over open seas toward the East Coast of the U.S.The Category 4 hurricane, with winds of 135 mph (215 kilometers), was expected to remain over the open ocean before turning north and running parallel to the U.S. coast, potentially reaching the North Carolina coastal region by late Thursday or early Friday. It was projected then to curve back out to sea, perhaps swiping New England or far-eastern Canada.
3Indonesia's Sinabung volcano JAKARTA, Aug. 29 (Xinhua) -- Indonesia's Sinabung volcano in North Sumartra province erupted unexpectedly in the wee hours of Sunday morning despite its rise of seismic activity since Friday, which has force evacuatio of thousands of local people.Spokesman of National Disaster Management Agency Priyadi Kardono said the eruption has not been predicted much earlier like other volcanoes and authorities must conduct a quick preparation for emergency work as mount Sinabung's seismic activity has been monitored intensively only since Friday after it showed an increase in activity.Over 10,000 people have been internally evacuated after the eruption, Secretary of the provincial administration Edy Sofyan told Xinhua by phone.Priyadi said that aid from Jakarta will be sent within days.Mount Sinabung, whose last eruption occurred 400 years ago, is classified at category "B" which means it is not necessary to be monitored intensively, but other volcanoes in category "A," must be monitored frequently, head of National Volcanology Agency named only Surono told Xinhua over phone from the province.
4Earth’s InteriorThe Inner Earth is composed of three main parts; the crust, the mantle, and the core as shown in the diagram of the earth's interior
5Earth’s InteriorStudying the earth's interior can help us to understand earthquakes, volcanoes, plate tectonics and more about the inner earths natural processes.In general the earth's interior has been sorted by Gravity. Heavier elements like iron tend to sink toward the center or core of the earth. Lighter materials, the silicates, oxygen compounds and water have risen to become part of the crust. This action has created distinct layers within the earth and is still in process today.
6Earth’s Interior2. The Crust The crust of the earth is very slowly growing thicker. Volcanic activity is continually adding mass to the crust. Though the crust is solid it is made up of about 12 plates. They are called Tectonic Plates.These plates are in constant motion. The movement is caused by convection currents in the mantle. The movement is very slow, averaging about 2 inches a year. This is about like the growth of your fingernails
7Earth’s Interior 3. Convection Motion of material that is driven by heat is called convectionThe very hot temperatures within the interior of the earth produce motions of the liquid iron (currents) in the outer core, much like the motions of water in boiling waters (although much slower).
9Earth’s Interior 5. Mantle Earth's Interior - The Mantle Much less is known about the mantle than the crust. The crust we can see, measure, dig and drill. The mantle is different. We have little direct contact with the inner earth. We can tell some things about the mantle by studying volcanoes and what comes out of them.Much of what we believe is true about the earth's interior comes from studying Seismology. Seismology began as the study of earthquakes and the seismic waves they produced. These waves travel through the earth and move at different speeds in different materials. By studying these waves and how they move through the inner earth we can learn about the its structure.
10Earth’s Interior The upper mantle Is made up of rocks rich in magnesium and iron, and poor in silica; mostly peridotites.It is about 400 km thick and is much denser than the crust.It comprise 10% of the earth’s massThe Lower mantleIt is more dense and contains a greater amount of iron than the upper mantleIt is about 1900 km thickIt makes up 41% of the earth’s mass
11Earth’s Interior 6. The core Earth's Interior - The core The core is composed primarily of a nickel-iron alloy. There is an outer core that is liquid and an inner core that is solid.Outer coreIs about 2100 km thick.It makes up about 30 % of the Earth's total mass.Inner coreIs about 1300 km thick.It makes up about 2 % of the Earth's total mass.
12Earth’s InteriorSome points to remember in studying the earth’s interior:There are distinct layers to the earth’s interior.Heavier elements tend to sink to the coreLighter elements rise toward the surfaceMuch more is known about the crust than the mantle and core.What we believe is true about the mantle and core comes from studying seismology.