Earth Science

3.) List four facts that characterize the oceanic ridge system.
Four facts that characterize the oceanic ridge system are: firstly, it represents 20 percent of Earth’s surface, the oceanic ridge system winds through all major ocean basin like the seams on a baseball. Ridges vary in width from 600 miles to 2500 miles. The mid-ocean ridge represents an area where, lithospheric plates move apart and new crust is created by magma pushing up from the mantle . Also, the mid-ocean ridge system is an example of a divergent plate boundary.

4.) Briefly describe the process of continental rifting. Where is it occurring today?
As crust is pulled apart, rifts are formed and eventually become large enough for ocean to form. This is occurring today in the East African rift.

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2.) Compare a continental volcanic arc and volcanic island arc.
In a continental volcanic arc mountains formed in part by igneous activity associated with subduction of oceanic lithosphere beneath a continent. In contrast, volcanic island arc is a chain of volcanic islands generally located a few hundred kilometers from a trench where active subduction of one oceanic slab beneath another is occurring.
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1.) What is the age of the oldest sediments recovered using deep-ocean drilling? How do the ages of these sediments compare to the ages of the oldest continental rocks?
The age of the oldest sediments recovered using deep-ocean drilling is 180 million years. The age of these sediments compare to the ages of the oldest continental rock by 4 billion years of age.
2.) Assuming that hot spots remain fixed, in what direction was the Pacific plate moving while the Hawaiian islands were forming? When Suiko Seamount was forming?
The Pacific Plate was moving north-west while the Hawaiian islands were formed.When the Suiko Seamount was formed the pacific plate was moving north-west also.

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1.) What is an earthquake? Under what circumstances do most large earthquakes occur?
An earthquake is ground shaking caused by the sudden and rapid movement of one block of rock slipping past another along fractures in Earth’s crust called faults. Under the circumstances of seismic waves large earthquakes occur, when huge amounts of stored-up energy is released.

2.) How are faults, hypocenters, and epicenters related?
Faults, hypocenters and epicenters are related by preexisting faults tend to cause earthquakes where internal stresses have cause the crustal rocks to rupture or break into two or more units. Thus, the location of the slippage begins in the hypocenter and the epicenter is the point on Earth’s surface directly above the hypocenter.

4.) Explain what is meant by elastic rebound.
What is meant by elastic rebound is rock that behaves elastically, much like a stretched rubber band does when it is released. The rock is therefore returns to its original stress-free shape.

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1.) Describe the principle of the seismograph.
A weight is freely suspended from a support that is attached to bedrock. When earthquake waves reach the seismograph, the inertia of the weight keeps it motionless while the bedrock and the support vibrate.

2.) List the major differences between P,S and surface waves.
P waves travel through all materials, whereas S waves are propagated only through solids. Further, in all types of rock, P waves travel faster than S waves.

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1.) What does the Modifies Mercalli Intensity scale tell us about an earthquake? The Modifies Mercalli Intensity Scale tells us about the intensity of an earthquake, using California buildings as its standard. For example, the first point on the 12-point scale says: not felt except by a very few under favorable circumstances.

2.) What information is used to establish the lower numbers on the Mercalli scale?
The information that is used to establish the lower numbers on the Mercalli scale is the Bishop and Reno areas of the Loma Prieta earthquake.

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