earthquake zones

earthquake zones

Nearly 95% of all earthquakes take place along one of the three types of plate boundaries. About 80% of all earthquakes strike around the Pacific Ocean basin because it is lined with convergent and transform boundaries (Figure 1.2). About 15% take place in the Mediterranean-Asiatic Belt, where convergence is causing the Indian Plate to run into the Eurasian Plate. The remaining 5% are scattered around other plate boundaries or are intraplate earthquakes. Earthquake epicenters for magnitude 8.0 and greater events since 1900. The earthquake depth shows that most large quakes are shallow focus, but some sub- ducted plates cause deep focus quakes.

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annual earthquakes

In a single year, on average, more than 900,000 earthquakes are recorded and 150,000 of them are strong enough to be felt. Each year about 18 earthquakes are major, with a Richter magnitude of 7.0 to 7.9, and on average one earthquake has a magnitude of 8 to 8.9. Magnitude 9 earthquakes are rare. The United States Geological Survey lists five since 1900 (see Figure 1.1 and Table 1.1). All but the Great Indian Ocean Earthquake of 2004 occurred somewhere around the Pacific Ocean basin. Location Valdivia, Chile Prince William Sound, Alaska Great Indian Ocean Earthquake Kamchatka, Alaska Tohoku, Japan Year 1960 1964 2004 1952 2011 Magnitude 9.5 9.2 9.1 9.0 9.0 The 1964 Good Friday Earthquake cen- tered in Prince William Sound, Alaska re- leased the second most amount of energy of any earthquake in recorded history.

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instructional diagrams

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questions

earthquakes happen along

a) known faults.

b) unknown faults.

c) minor faults.

-->  d) all of these

in an average year,

a) most earthquakes are strong enough to be felt.

b) one earthquake has a magnitude of 9 or greater.

-->  c) nineteen earthquakes have a magnitude of 7 or greater.

d) all of these

the location where most earthquakes strike is

-->  a) pacific ocean basin

b) indian ocean basin

c) atlantic ocean basin

d) mediterranean-asiatic belt

the convergence of the indian and eurasian plates causes

a) earthquakes

b) the rise of the himalaya mountains

c) a plate boundary.

-->  d) all of these.

all earthquakes happen at plate boundaries.

a) true

-->  b) false

which of these locations did not have an earthquake of a magnitude of 9 or greater since 1960?

a) kamchatka, alaska

-->  b) san francisco, california

c) tohoku, japan

d) valdivia, chile

some earthquakes are due to hotspots and other intraplate activity.

-->  a) true

b) false

the pacific ocean basin has a lot of earthquakes because it is surrounded by

a) convergent plate boundaries.

-->  b) transform plate boundaries.

c) divergent plate boundaries

d) convergent and transform plate boundaries.

seismometers only record earthquakes of magnitude 5 or greater.

a) true

-->  b) false

small earthquakes are less common then large earthquakes.

a) true

-->  b) false

diagram questions

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