EarthQuakes Lecture Flashcards
Earthquakes:
Sudden shaking of the ground caused by the movement of tectonic plates beneath the Earth’s surface.
Tectonic Plates:
Large sections of the Earth’s lithosphere that move and interact with each other, leading to geological events like earthquakes.
Earthquake Drills:
Practice exercises to prepare individuals for proper actions to take during an earthquake for safety.
Emergency Preparedness:
Being ready and equipped to respond effectively to emergencies, such as earthquakes, to minimize harm and damage.
Seismic Waves:
Vibrations that travel through the Earth’s layers during an earthquake, including body waves (P-waves and S-waves) and surface waves (love waves and Rayleigh waves).
Faults:
Fractures in the Earth’s crust where tectonic plates meet and can cause earthquakes when they move.
Epicenter:
The point on the Earth’s surface directly above the origin of an earthquake.
Hypocenter:
The actual location where an earthquake begins underground.
Seismograms:
Records produced by seismographs that show the intensity and duration of seismic waves during an earthquake.
Richter Scale:
A numerical scale used to measure the magnitude of an earthquake based on the amplitude of seismic waves.
Moment Magnitude Scale:
A scale that measures the total energy released by an earthquake, providing a more accurate assessment of its size.
Magnitude:
The quantitative measure of the energy released by an earthquake.
Intensity:
The qualitative measure of the effects and damage caused by an earthquake.
Building Codes:
Regulations that specify the standards for construction to ensure structures can withstand seismic activity.
Seismic Waves Study:
Using the behavior of seismic waves to understand the composition and structure of the Earth’s interior.
Soft Sediment:
Loose, unconsolidated material that can amplify seismic waves and increase the potential for damage during an earthquake.
Bedrock:
Solid rock underlying loose deposits that can reduce the impact of seismic waves during an earthquake.
What causes earthquakes?
Earthquakes are caused by the constant movement of tectonic plates along faults in the Earth’s crust.
What is the epicenter of an earthquake?
The epicenter is the point on the Earth’s surface directly above the earthquake’s focus.
What is a fault?
A fault is a break or fracture in the Earth’s crust where tectonic plate movement occurs.
What are seismic waves?
Seismic waves are waves generated during an earthquake that carry energy away from the earthquake’s source.
What are the two main types of body waves?
The two main types of body waves are P-waves (compressional) and S-waves (shear).
How do P-waves and S-waves differ?
P-waves are faster and can pass through solids, liquids, and gases. S-waves are slower and only travel through solids.
What are surface waves?
Surface waves are seismic waves that travel along the Earth’s surface and cause most of the damage during an earthquake.
How are earthquakes measured?
Earthquakes are measured using instruments called seismometers or seismographs. The magnitude measures the energy released, while the intensity describes the earthquake’s effects and damage.
What is the Mercalli Intensity Scale used for?
The Mercalli Intensity Scale is used to measure the intensity of an earthquake based on the observed effects and damage.
Can human activities induce earthquakes?
Yes, human activities like waste disposal and nuclear weapons testing can induce earthquakes by altering stress patterns in the Earth’s crust.
How often do earthquakes occur?
Earthquakes occur every day, with over 1,000,000 earthquakes per year.
What are the primary causes of earthquakes?
Most earthquakes result from tectonic plate motion on faults. They can also be caused by volcanoes, explosions, mineral changes, and impacts.
What is the focus (hypocenter) of an earthquake?
The focus is the place where the fault slip occurs, usually on a fault surface. Earthquake waves expand outward from the focus.
What are the main types of seismic waves?
There are two main groups of seismic waves: Body Waves (P-waves and S-waves) and Surface Waves (Love waves and Rayleigh waves).
What are P-waves?
P-waves are primary or compressional waves that travel fastest through the Earth, passing through solids, liquids, and gases.
What are S-waves?
S-waves are secondary or shear waves that travel slower than P-waves and only through solids, never through liquids or gases.
What is the Richter Magnitude Scale used for?
The Richter Magnitude Scale is a logarithmic scale used to measure the amplitude of surface waves and the distance from the earthquake event. It is an old system not widely used by scientists anymore.
Can earthquakes be predicted?
Earthquakes can be predicted in the long term (tens to hundreds of years), but not in the short term (hours or weeks). Hazards can be mapped to assess risk and develop building codes and disaster planning.
What are the main types of faults?
The main types of faults are normal, reverse, and strike-slip faults.
What are Body Waves?
Body waves are the fastest waves that travel through the body of the Earth. They include P-waves (primary or compressional waves) and S-waves (secondary or shear waves).
What is the Mercalli Intensity Scale?
The Mercalli Intensity Scale measures the amount of shaking damage caused by an earthquake and uses Roman numerals to assign different levels of damage.
Focus (hypocenter)
The place where fault slip occurs
Hanging wall
Block above the fault
footwall
Block below the fault
Normal fault
The hanging wall moves down relative to the foot wall
Reverse fault
The hanging wall moves up relative to the foot wall
Strike-slip fault
One block slides laterally past the other block
Bedrock transmits seismic waves quickly making it
Less damage able
Sediments reflect and refract waves making it
Amplified damage
Earthquake damage
1- landslides and avalanche
2- liquefaction
3- fires
Tsunami
Results rd from displacement of the seafloor
Which one is more destructive surface waves or body waves?
Surface waves
Which one is faster body waves or surface waves?
Body waves
True or false: p-waves travel through everything
True
True or false: S waves travel by moving materials left and right?
False, they move materials back and forth
What does the P in p-waves stand for?
Primary or compressional waves
What does the S stand for in s-waves
Secondary or shear waves
What does the L in L-wave stand for
Love
What does the R in R-waves stand for
Rayleigh waves
How many stations needed to pin point the epicenter
At least 3
