Earthquakes are caused by a sudden release of built-up energy in the Earth's crust. Tectonic plate interactions can cause plates to bend and slip past each other, releasing this stored energy in the form of seismic waves. The Richter scale is used to measure earthquake magnitude based on the amplitude of seismic waves, with each increase of one unit representing a 32-fold increase in energy. Tsunamis are large sea waves generated by earthquakes that cause vertical displacement of the ocean floor. Jordan experiences low to moderate seismic activity due to its location near the boundary of the Arabian and African tectonic plates.

1. Earthquakes
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3. A break in the rock (fault)
Bending of rocks by tectonic forces. The energy is being stored ,Frictional
forces are overcome and slippage takes place. The rocks snaps back
(spring back to their original position ). This produces the vibrations. This
springing back is called “elastic rebound”

4. Earthquake distribution
Depends on the probability of exposure of an area to occur Destructive
earthquakes on several factors:
1 - relative velocity of plate motion contiguous
2 - The type of relationship between the movement of the two plates the
two adjacent ones

5. Types of earth plates
closely spaced Plates

6. spaced land plates

7. Sliding floor plates

8. Body waves
Primary waves

9. Secondary waves

10. Surface Waves

11. Richter Magnitude Scale
•This scale is based on the amplitude of the largest seismic wave (P,S, or surface wave)
recorded on a seismogram.
•This scale has no upper limit
•The largest recorded earthquake is 8.9 to 9.0
•There is tenfold increase in wave amplitude for every one unit on the scale
•There is a 32-fold energy increase for every one unit increase on the scale.
•Moment Magnitude: several parameters are used for its calculation and can be successfully
used to distinguish between the strength of very large earthquakes.

13. Measuring the Size of Earthquakes
Intensity = a measure of the degree of earthquake shaking at a
certain location based on the amount of damage

15. Tsunami
Tsunami = seismic sea wave; a Japanese word = harbor waves.
•Vertical displacement of ocean floor along a fault.
•The amplitude of these waves is generally very small in open sea (< 1m) with wavelengths up to
several 100s km

16. Seismic situation in Jordan
Seismicity of the twentieth century in Jordan