Earthquakes 1 Flashcards
What is a Earthquake?
Shaking (vibration) produced by the rapid release of energy
What does a Earthquake Generate?
Seismic waves (travel through Earth)
What is the “Focus”?
Point of energy release; radiates out in all directions
What is the “Epicentre”?
Point of Earth’s surface directly above the focus
Where do Earthquakes occur?
Ring of Fire, Along faults associated with plate boundaries, accur on tectonic plates
is divergent shallow or deep?
Shallow
is convergent shallow or deep?
Can be shallow to deep
is shallow more or less damage from an Earthquake
More Damage
explain how strength of shaking from earthquake decreases?
diminishes with increasing distance from focus
what are Intraplate Earthquakes?
single plate, far from boundary, typically shallow
what are interplate earthquakes?
occur at boundaires between tectonic plates
What is the Earthquake Early Warning System
Rapid detection, real-time estimation of shaking hazard
- seconds to tens-of seconfs notice before strong shaking starts (detects energy)
Explain Earthquake magnitude and Frequency
The higher the magnitude the lower the frequency
Explain Nepal Earthquake
Mw =7.8 (modified mercalli intensity scale)
- Shallow (around 8km)
What is Earthquake Magnitude?
measurement of the energy released by an Earthquake
- measures amplitude of seismic waves on seismograph or amount of energy released
What is the Richter Magnitude?
based on distance and amplitude or size of largest seismic wave produced during an earthquake (logarithmic and moment magnitude)
What is Moment Magnitude?
measure of amount of energy released by earthquake
- Logarithmic; more effective for larger earthquakes
What do Richter magnitude and Moment magnitude have in common?
both are quantitative
What’s the difference between Richter Magnitude and Moment Magnitude
Richter is based on distance and amplitude, Moment is based on amount of energy released
Explain Earthquake Magnitude
quantitative measure of amount of energy released at its source
- Earthquake is one magnitude (not variable)
Explain Earthquake Intensity
Qualitative, amount of shaking, variable (depends on location)
What is faulting?
A response to stress
What is a “Fault”?
break between 2 blocks of rocks; blocks can move relative to each other (slowly or rapidly)
Within Faulting and Deformation explain the difference between “Elastic” and “Brittle” Deformation
Elastic is reversible, Brittle is permenant ruptures
explain how rupture occurs?
starts at the focus and propagates outwards (produces waves of energy called Seismic Waves)
What are the Three types of Faults?
Normal Fault, Reverse Fault, Strike-slip Fault
Explain Divergent, Convergent, and Transform Boundaries
- Divergent: plates goes opposite directions (left and right)
- Convergent: Plates going towards each other
- Transform: One plate up other plate down
which type of boundary are normal, reverse, and strike-slip faults?
- Normal: Divergent
- Reverse: Convergent
- Strike-Slip: Transform
What is Seismic Waves
Release of energy along fault
what are the three types of seismic waves?
P-Wave (primary)(body)
S-Wave (secondary)(body)
R-Wave (Rayleigh)(surface)
Explain P-wave
- Compressional waves
- Arrives first
- travels through solids, liquids, and gas
Explain S-Wave
- Shear waves
- Arrives second
- Travel only through a solid
Explain Rayleigh Waves
- Surface Waves
- Arrive after body waves
- Most damaging of all waves
How long is Wave period?
10 seconds
What is Attenuation?
weakening or removal of high-frequency waves
- occurs with increased distance; low frequency waves travel further
Why did mexico city recieve so much damage from earthquake?
a) low frequency waves affecting tall buildings
b) Material amplification
- subsurface materials respond differently to seismic waves
