How does the analysis of seismic waves reveal information about the nature of Earth's interior?
The nature of the layers, their properties, and the forces that influence them have been learned largely by the study of shock waves associated with distant earthquakes. Seismic waves, low-frequency pulses of energy generated by earthquakes, can spread rapidly into Earth in all directions and then return to the surface. Sensitive seismographs have allowed researchers to study the ways seismic waves refract and bounce off abrupt transitions between Earth's inner layers.
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If Earth were uniform (homogenous) throughout, seismic waves would radiate from the site of an earthquake in straight lines. If the density, or rigidity, of Earth increased smoothly with depth, seismic wave velocity would increase evenly with depth, and the waves would gradually bend upward toward the surface. If Earth were layered inside, some seismic waves would be reflected at the boundaries between layers, whereas others would bend. Seismic evidence shows that Earth is layered.
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During the formation of snow, the atmospheric temperature profile is:
A) almost entirely below freezing. B) below freezing in the upper part of the atmosphere. C) below freezing in the lower part of the atmosphere. D) above freezing in the middle part of the atmosphere. E) none of the above
Which of the following fast-swimming fish has the lowest body temperature?
A) Bluefin tuna (Thynnus) B) Bonito (Sarda) C) Mackerel (Scomber) D) Moonfish Opah (Lampris guttatus) E) Yellowtail (Seriola)
If Earth's remaining glaciers melt, how would the global sea level change?
A) hardly at all; most of the water would be absorbed by porous land and by increasing size of freshwater lakes and rivers B) the sea level would rise about 8 m C) the sea level would rise about 80 m D) the sea level would rise about 120 m
In legislation, the precautionary principle applied to climate change states that ________
A) alterations to legislation must be done in a way that maximizes environmental protection at the urging of scientists without recourse from the voting public B) lack of full scientific certainty shall not be used to postpone measures to prevent major environmental degradation C) permit trading should be undertaken with caution D) caution should be used in handling hazardous wastes E) all alternative sources of energy should be evaluated by the scientific community before marketing