Trivia quiz questions with answers about earthquakes.
Earthquake Trivia Quiz Questions With Answers
What is an earthquake?
A: An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves.
Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to do what?
A: To toss people around and destroy whole cities.
The seismicity, or seismic activity, of an area is the frequency, type and size of earthquakes experienced over what?
A: Over a period of
The word tremor is also used for what?
A: Non-earthquake seismic rumbling.
At the Earth's surface, how do earthquakes manifest themselves?
A: By shaking and displacing or disrupting the ground.
When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a what?
A: A tsunami.
Earthquakes can also trigger landslides, and occasionally what?
A: Volcanic activity.
In its most general sense, the word earthquake is used to describe any seismic event, whether natural or caused by humans that does what?
A: That generates seismic waves.
Earthquakes are caused mostly by rupture of geological faults, but also by other events such as what?
A: Volcanic activity, landslides, mine blasts, and nuclear tests.
An earthquake's point of initial rupture is called its what?
A: Its focus or hypocenter.
Where is the epicenter?
A: The epicenter is the point at ground level directly above the hypocenter.
Tectonic earthquakes occur anywhere in the earth where there is sufficient stored “what" to drive fracture propagation along a fault plane?
A: Elastic strain energy.
The sides of a fault move past each other smoothly and aseismically only if there are what?
A: No irregularities or asperities along the fault surface that increase the frictional resistance.
Most fault surfaces do have such asperities and this leads to a form of what?
A: Stick-slip behavior.
Once the fault has locked, continued relative motion between the plates leads to what?
A: Increasing stress and therefore, stored strain energy in the volume around the fault surface.
This continues until the stress has risen sufficiently to do what?
A: To break through the asperity, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy.
This energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and what?
A: Cracking of the rock, thus causing an earthquake.
This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as what?
A: The elastic-rebound theory.
It is estimated that how much of an earthquake's total energy is radiated as seismic energy?
A: Only 10 percent or less.
Most of the earthquake's energy is used to power what?
A: The earthquake fracture growth or is converted into heat generated by friction.
What are the three main types of fault, all of which may cause an interplate earthquake?
A: Normal, reverse (thrust) and strike-slip.
Normal and reverse faulting are examples of dip-slip, where the displacement along the fault is in what direction?
A: The direction of dip and movement on them involves a vertical component.
Normal faults occur mainly in what areas?
A: Areas where the crust is being extended such as a divergent boundary.
Reverse faults occur in areas where the crust is being what?
A: Shortened such as at a convergent boundary.
Strike-slip faults are steep structures where the two sides of the fault do what?
A: Slip horizontally past each other; transform boundaries are a particular type of strike-slip fault.
Many earthquakes are caused by movement on faults that have components of what?
A: Both dip-slip and strike-slip; this is known as oblique slip.
Reverse faults, particularly those along convergent plate boundaries are associated with what?
A: The most powerful earthquakes, megathrust earthquakes, including almost all of those of magnitude 8 or more.
Strike-slip faults, particularly continental transforms, can produce major earthquakes up to about what magnitude?
A: Magnitude 8.
Earthquakes associated with normal faults are generally less than magnitude what?
For every unit increase in magnitude, how big is the increase in the energy released?
A: Roughly thirtyfold.
An 8.6 magnitude earthquake releases the same amount of energy as how many atomic bombs like those used in World War II?
The energy released in an earthquake, and thus its magnitude, is proportional to what?
A: The area of the fault that ruptures and the stress drop.
The topmost, brittle part of the Earth's crust, and the cool slabs of the tectonic plates that are descending down into the hot mantle, are the only parts of our planet which can do what?
A: Store elastic energy and release it in fault ruptures.
Rocks hotter than about 300 °C (572 °F) do what in response to stress?
A: They flow, they do not rupture in earthquakes.
The maximum observed lengths of ruptures and mapped faults (which may break in a single rupture) are approximately how long?
A: 1,000 km (620 mi).
Thrust faults are generated by the highest, strike slip by intermediate, and normal faults by the lowest what?
A: Stress levels.
This can easily be understood by considering the direction of the greatest principal stress, the direction of the force that does what?
A: “Pushes" the rock mass during the faulting.
In the case of normal faults, the rock mass is pushed down in what direction?
A: In a vertical direction, thus the pushing force (greatest principal stress) equals the weight of the rock mass itself.
In the case of thrusting, the rock mass 'escapes' in the direction of the least principal stress, namely what?
A: Upward, lifting the rock mass up, thus the overburden equals the least principal stress.
All tectonic plates have internal stress fields caused by what?
A: Their interactions with neighboring plates and sedimentary loading or unloading (e.g. deglaciation).
The majority of tectonic earthquakes originate where?
A: At the ring of fire in depths not exceeding tens of kilometers.
Earthquakes occurring at a depth of less than 70 km (43 mi) are classified as what?
A: 'shallow-focus' earthquakes, while those with a focal-depth between 70 and 300 km (43 and 186 mi) are commonly termed 'mid-focus' or 'intermediate-depth' earthquakes.
Earthquakes often occur in volcanic regions and are caused there, both by tectonic faults and by what?
A: The movement of magma in volcanoes.
Such earthquakes can serve as an early warning of volcanic eruptions, as during the
1980 eruption of what mountain?
A: Mount St. Helens.
Earthquake swarms can serve as markers for what?
A: For the location of the flowing magma throughout the volcanoes.
These swarms can be recorded by what?
A: Seismometers and tilt meters.
A tectonic earthquake begins by an initial rupture at a point on the fault surface, a process known as what?
An aftershock is an earthquake that occurs when?
A: After a previous earthquake, the main shock.
An aftershock is in the same region of the main shock but always of a what?
A: Smaller magnitude.
If an aftershock is larger than the main shock, the aftershock is re-designated as what?
A: The main shock and the original main shock is re-designated as a foreshock.
Aftershocks are formed as the crust around the displaced fault plane adjusts to what?
A: The effects of the main shock.