Science test

1: What is an Earthquake?

Q: What causes an earthquake?
A: Earthquakes are caused by forces inside the Earth that cause rocks to move along faults. When rocks move past each other, their rough surfaces temporarily catch, creating stress. When this stress becomes too great, the rocks break, releasing energy in the form of seismic waves.

2: Elastic Rebound Theory

Q: What does the Elastic Rebound Theory explain?
A: The Elastic Rebound Theory explains how energy is stored in rocks as they bend under stress. When the stress exceeds the rock's strength, it breaks and releases energy as seismic waves, causing an earthquake.

3: Types of Faults

Q: What are the three main types of faults?
A:

  1. Normal Faults - Caused by tension, the hanging wall moves downward.

  2. Reverse Faults - Caused by compression, the hanging wall moves upward.

  3. Strike-Slip Faults - Caused by shearing, plates slide past each other horizontally.

4: Normal Faults

Q: What is a Normal Fault?
A: A normal fault occurs when tension pulls the crust apart, and the hanging wall moves downward, commonly found at divergent plate boundaries.

5: Reverse Faults

Q: What is a Reverse Fault?
A: A reverse fault occurs when compression pushes the crust together, and the hanging wall moves upward, often found at convergent plate boundaries.

6: Strike-Slip Faults

Q: What is a Strike-Slip Fault?
A: A strike-slip fault occurs when shearing forces cause plates to slide past each other horizontally, commonly found at transform plate boundaries.

7: What are Seismic Waves?

Q: What are seismic waves?
A: Seismic waves are energy released during an earthquake that travels through Earth’s interior and across its surface, causing the ground to shake.

8: P-Waves (Primary Waves)

Q: What are P-waves?
A: P-waves are the fastest seismic waves, and they compress and expand the ground in the direction of travel. They can travel through solids, liquids, and gases, and are the first waves to arrive at seismic stations.

9: S-Waves (Secondary Waves)

Q: What are S-waves?
A: S-waves are slower than P-waves, and they only travel through solids. They shake the ground side to side or up and down, and they cause more damage due to their vertical motion.

10: Surface Waves

Q: What are surface waves?
A: Surface waves are seismic waves that travel along the Earth’s surface. There are two types: Love waves and Rayleigh waves.

11: Love Waves

Q: How do Love waves move?
A: Love waves cause the ground to move side to side in a horizontal motion, perpendicular to the direction of travel. They are the fastest surface waves and the most destructive.

12: Rayleigh Waves

Q: How do Rayleigh waves move?
A: Rayleigh waves cause the ground to move in an elliptical, rolling motion similar to ocean waves. They spread out the most, giving them a long duration on seismograph recordings.

13: Locating an Epicenter

Q: How is the epicenter of an earthquake located?
A: The epicenter is located using triangulation. Three seismograph stations measure the distance to the epicenter, and the intersection of the circles from these stations locates the epicenter.

14: Time-Distance Graph

Q: What is a time-distance graph?
A: A time-distance graph shows the travel times for P-waves and S-waves, and the difference in arrival times helps calculate the distance from the seismograph to the epicenter.

15: Shadow Zones

Q: What are shadow zones?
A: Shadow zones are regions where seismic waves are not detected because of the bending of P-waves and the inability of S-waves to travel through liquids. These zones help map Earth’s internal structure.

16: Relationship Between Depth, Density, and Pressure

Q: What is the relationship between depth, density, and pressure?
A: As depth increases, both density and pressure increase. This causes changes in how seismic waves behave as they travel through different layers of Earth.

17: Moho

Q: What is the Moho?
A: The Moho is the boundary between Earth’s crust and mantle, marked by a change in seismic wave speeds and densities.

18: Magnitude vs. Intensity

Q: What’s the difference between magnitude and intensity?
A:

  • Magnitude: Measures the energy released by an earthquake, typically measured using the Richter scale.

  • Intensity: Measures the observed effects and damage caused by the earthquake at specific locations.

19: Richter Scale

Q: What is the Richter scale?
A: The Richter scale measures the magnitude of an earthquake based on the height of seismic waves recorded on a seismograph. Each increase of 1.0 on the scale represents a 10-fold increase in wave size and 32 times more energy released.

20: Tsunamis

Q: What causes a tsunami?
A: Tsunamis are caused by underwater earthquakes that displace large amounts of water, creating massive waves that can travel across the ocean. When they reach shore, they can reach heights of over 30 meters.

21: Liquefaction

Q: What is liquefaction?
A: Liquefaction occurs when shaking from an earthquake turns wet soil into a liquid-like state, destabilizing foundations and causing buildings to collapse or tilt.

22: Seismologists

Q: What do seismologists study?
A: Seismologists are scientists who study earthquakes and seismic waves. They use seismographs to record the intensity, duration, and location of seismic activity.

23: Seismographs and Seismograms

Q: What are seismographs and seismograms?
A:

  • Seismographs are instruments that register seismic waves and record the time of arrival for each wave.

  • Seismograms are the printed records created by seismographs that show the intensity and time of seismic waves.

24: Earthquake Preparedness

Q: How can buildings be made more earthquake-resistant?
A: Buildings can be constructed with flexible foundations, such as rubber-steel cushions, which absorb the energy of seismic waves. Circular moorings are used to allow buildings to move with the shaking and reduce the risk of collapse.

25: Fault Behavior in Earthquakes

Q: How does fault behavior affect earthquakes?
A: Faults cause earthquakes by allowing rocks to move past each other. The type of fault (normal, reverse, strike-slip) influences the direction and nature of the earthquake's motion.

26: What is an Aftershock?

Q: What is an aftershock?
A: An aftershock is a smaller earthquake that occurs after the main earthquake, caused by the adjustment of rocks around the fault zone.

27: Earthquake Damage

Q: Why do buildings sustain damage in an earthquake?
A: Buildings vibrate as a consequence of ground shaking. Damage occurs if the building cannot withstand these vibrations, especially high-frequency vibrations caused by P and S-waves.

28: How Does an Earthquake’s Epicenter Relate to Seismograph Distance?

Q: What is the relationship between the distance of a seismograph and an earthquake’s focus?
A: The farther a seismograph is from the focus of an earthquake, the longer the interval between the arrival of the P- and S-waves.

29: How Do Surface Waves Develop?

Q: How do surface waves develop during an earthquake?
A: Surface waves develop when seismic waves from the focus reach the epicenter. These waves move more slowly than P and S waves but can cause more severe ground movement.

30: Frequency of Vibrations and Building Height

Q: How do seismic waves affect buildings of different heights?
A: Compressional (P) and shear (S) waves primarily cause high-frequency vibrations, affecting tall buildings, while surface waves cause low-frequency vibrations that affect low buildings.

31: Primary Wave Movement

Q: How do primary (P) waves move?
A: P-waves move by compressing and expanding the ground in the direction of travel, similar to an accordion's motion.

32: Secondary Wave Movement

Q: How do secondary (S) waves move?
A: S-waves move in a shearing, crosswise motion, perpendicular to the direction of travel, causing more damage with vertical ground motion.

33: Focus and Epicenter

Q: What is the focus and epicenter of an earthquake?
A: The focus (hypocenter) is the point inside Earth where the earthquake originates. The epicenter is the point directly above the focus on the Earth’s surface.

 34: Seismic Wave Behavior

Q: How do seismic waves behave during an earthquake?
A: Seismic waves travel outward from the focus in all directions, with P-waves arriving first, followed by S-waves, and then surface waves.

35: S-Waves and Liquids

Q: Can S-waves travel through liquids?
A: No, S-waves cannot travel through liquids, which is why there is a shadow zone for S-waves in the outer core.

36: P-Waves and Liquids

Q: Can P-waves travel through liquids?
A: Yes, P-waves can travel through liquids, but they are slowed and bent when passing through the Earth’s outer core.

37: Seismograph Function

Q: How does a seismograph work?
A: A seismograph records earthquake waves by having a stationary marker trace vibrations on a moving drum as seismic waves reach it.

38: Energy Release in an Earthquake

Q: What happens when energy is released during an earthquake?
A: When rocks break due to stress, energy is released in the form of seismic waves, which radiate outward from the fault and are detected by seismographs.

39: Earthquake Impact on People

Q: How do earthquakes affect people?
A: Earthquakes can cause death, injury, and significant damage to infrastructure. Seismologists study them to predict and mitigate their effects.

40: Earthquake Prediction

Q: Can earthquakes be reliably predicted?
A: Earthquakes cannot be reliably predicted; however, understanding seismic zones and preparation can help reduce risk and damage.

41: Transform Boundaries and Strike-Slip Faults

Q: What type of fault is found at transform plate boundaries?
A: Strike-slip faults are found at transform plate boundaries, where plates slide past each other horizontally.

42: Subduction Zones and Reverse Faults

Q: What type of fault occurs at subduction zones?
A: Reverse faults occur at subduction zones, where one tectonic plate is forced under another due to compression.

43: Divergent Boundaries and Normal Faults

Q: What type of fault occurs at divergent plate boundaries?
A: Normal faults occur at divergent plate boundaries, where tectonic plates pull apart due to tension.

44: Duration of Earthquake Shaking

Q: What affects the duration of earthquake shaking?
A: The size of the earthquake, the distance from the epicenter, and the type of seismic waves affect how long the shaking lasts.

45: Tectonic Plate Movements

Q: How do tectonic plate movements lead to earthquakes?
A: The movement of tectonic plates due to tension, compression, or shearing causes stress along faults. When this stress is released, it results in an earthquake.

46: Tectonic Boundaries and Fault Types

Q: What type of fault is associated with tension at divergent boundaries?
A: Normal faults are associated with tension at divergent boundaries where plates are pulling apart.

47: Faults and Earthquake Strength

Q: How does the type of fault influence earthquake strength?
A: The type of fault affects the direction of movement and the release of energy, influencing the size and impact of the earthquake.

48: Earthquake-Induced Landslides

Q: How can earthquakes cause landslides?
A: Earthquakes can shake the ground to the point where unstable slopes collapse, leading to landslides, particularly in mountainous areas.

49: Energy Released During an Earthquake

Q: What happens to the energy released during an earthquake?
A: The energy released during an earthquake is transferred in the form of seismic waves that travel outward from the fault zone, causing the ground to shake.

50: Earthquake Magnitude and Destruction

Q: What does the magnitude of an earthquake indicate?
A: The magnitude of an earthquake indicates the energy released at the fault and the potential for destruction. Larger magnitude earthquakes generally cause more damage.

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