Environmental Sciences Course Earth Sciences Dr.-Eng. Hasan Hamouda

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 2 Natural environmental hazards 1- Earthquakes 2- Volcanic hazards 3- Floods 4- Tornados and storms 5- Desertification

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 3 Faults Ways in which faults can move Normal fault Thrust fault Lateral slip

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 4 Earthquakes The movement of Earthquake waves through the Earth’s interior has given us a better picture of the earth’s interior.

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 5 P-waves are faster than S-waves. The density and elasticity of rock affects the speed of the waves. When p-waves hit the core, they are refracted and slow down. This creates a P-wave shadow 103º -143 º from the focus Earthquakes

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 6 S-waves can’t travel through liquids. When S-waves hit the outer liquid core, they stop. This creates a S-wave shadow at locations greater than 103º from the focus of the earthquake. Earthquakes

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 7 Earthquakes have even shown the depth of the crust. A sharp boundary between the crust and the upper mantle at about a depth of 30km exists. P-waves travel at 6.75 km/sec in the crust and 8 km/sec below this boundary. The depth of this boundary varies depending if it is under continents ( km) or under ocean floors (5 to 10 km). The speed of seismic waves increases with depth in the mantle except for a low velocity zone at km, this corresponds to the asthenosphere. Earthquakes

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 8 Measuring Earthquakes The strength of an Earthquake can be measured in two different ways Intensity: is a qualitative assessment of the kinds of damage done by an earthquake it is subjective (Modified Mercalli Intensity scale ( I to XII) Magnitude: is a quantitative measurement of the amount of energy released by an earthquake Richter Magnitude scale (open-ended scale) each step in the richter scale is: a increase 10-fold in movement a 30-fold increase in energy

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 9 Earthquake Damage depends on many factors: - The size of the Earthquake - The distance from the focus of the earthquake - The types and properties of the materials at the site - The nature of the building Earthquakes

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 10 - About 80% of earth’s surface, the seafloor as ell as the land, began as molten rock that rose from deep inside the earth. When it emerged onto the surface, it cooled and hardened into volcanic rock. - Volcanisms occur principally near plate boundaries. - Can be beneficial as sources of fertile soil, chemicals, and minerals - Can be troublesome-the dust and gas thrown high into the atmosphere in a severe eruption can partial block out solar radiation etc. - Destroying cities and even bringing civilization to an end. Volcanisms

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda Causes Heavy rainfall Coastal flooding due to sea storms Dam failures 2. Effects Primary (death, destroy buildings etc.) Secondary and tertiary (diseases, electricity and water cuts, etc.) Floodings

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 12 Tornados and storms 1.Tornados - Due to collision between cold air mass and warm-humid air mass. - Very low central pressure - Local effect - Short duration - Very strong (wind speed >450km/hr) - Famous in middle and southeast USA.

University Of Palestine International ENVI005 Dr.-Eng. Hasan Hamouda 13 Tornados and storms 2.Typhoons and hurricanes Circular with diameter reach 600 km; Duration many weeks; Wind speed >300 km/hr; When it reaches the coast it forms very high and strong waves reaches 7 m height. 3. Tsunami Very strong waves becomes with earthquakes and volcanoes.