Earthquakes occur due to the sudden release of stored energy in the Earth's crust caused by the movement of tectonic plates and volcanic activity. An earthquake's hypocenter is the point where slippage first begins underground, while the epicenter is the point directly above on the surface. Earthquake size is measured by both intensity, based on observed property damage, and magnitude, using seismograph readings of ground motion. Larger earthquakes are better measured by moment magnitude, which estimates total energy released. Short-term predictions aim to provide warnings within hours or days, while long-term forecasts estimate likelihood of quakes over 30-100 years to help preparation. Homeowners can improve resilience by reinforcing structures and preparing emergency supplies

1. Earthquakes
Dr. Magdy Basta
Suez University
Faculty Of Petroleum & Mining Engineering
Petroleum Engineering Depatment

2. What are Earthquakes?
• A natural phenomenon in which a ground shaking is caused by the
sudden and rapid movement of one block of rock slipping past
another along fractures in Earth’s crust called faults or by volcanic
activity.
• Most large earthquakes occur along preexisting faults where past
earthquakes have caused the crustal rocks to rupture or break into
two or more units.

3. • The location where slippage begins is called the hypocenter, or focus
Earthquake waves radiate from this spot outward into the
surrounding rock. The point on Earth’s surface directly above the
hypocenter is called the epicenter .

4. Volcanic
activity
Plate
Tectonics
Movement
Mechanism

5. • Tectonic plates movement and
pressure differentials cause bending
in the crust.
• The crust adsorbs this energy up to a
limit above which the crust fails.
• The intensive stored energy is
released in the form of elastic waves
that cause earthquakes.
• Rocks tend to move relative to each
other in order to retain their stress-
free condition.

6. Determination of size

7. Determination of size
• Size of the earthquake refers to intensity and magnitude.
• Intensity is a measure of the amount of ground shaking at a particular
location, based on observed property damage.
• Later, with the development of seismographs, it became possible to
measure ground motion using instruments. This quantitative
measurement is called magnitude.

8. Magnitude of Earthquakes
1- The Richter scale: (9 grades)
• The Richter scale is calculated by measuring the amplitude of the
largest seismic wave recorded on a seismogram.
• Because seismic waves weaken as the distance between the
hypocenter and the seismograph increases, Richter developed a
method that accounts for the decrease in wave amplitude with
increasing distance.

9. Magnitude of Earthquakes
2- Moment magnitude:
• Moment magnitude is calculated by determining the average amount of
slip on the fault, the area of the fault surface that slipped, and the strength
of the faulted rock. Moment magnitude can also be calculated by modeling
data obtained from seismograms.
• Because moment magnitude estimates the total energy released, it is
better for measuring very large earthquakes. In light of this, seismologists
have recalculated the magnitudes of older, strong earthquakes using the
moment magnitude scale

10. Prediction of earthquakes
1- Short-range prediction:
• The goal of short-range earthquake prediction is to provide a warning
of the location and magnitude of a large earthquake within a narrow
time frame.

11. Prediction of earthquakes
1- Long-range prediction:
• In contrast to short-range predictions, which aim to predict
earthquakes within a time frame of hours or days long-range
forecasts are estimates of how likely it is for an earthquake of a
certain magnitude to occur on a time scale of 30 to 100 years or more.
These forecasts give statistical estimates of the expected intensity of
ground motion for a given area over a specified time frame.

12. Precautions of Earthquakes
1- Improve your home's earthquake resilience
Evaluate your home's earthquake resilience ,and improve it through steps such as
fastening down furniture and putting anti-shatter coating on glass windows.
2- Stockpile water and foodstuffs
you should have at least three day's worth of drinking water and foodstuffs
stockpiled. you should also have radios and flashlights prepared.
3- participation in disaster training
Get to know the people in your community better by getting actively involved in
community disaster training
4-Discuss disaster preparedness with your family
Verify how you will get touch with each other and where the relief shelters are.
The precautions will never end.....
.....and the dangers of earthquakes are also never end

13. What is the difference between ?
Strength of the EarthquakeIntensity Of the Earthquake
The strength of an earthquake is
constant, and this is the quantity
which are required to be
measured.
The intensity differs from one
point to another according to
the distance between the point
and center of the earthquake.

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