week3+4 chapt 1 : earth and natural environmental hazards dr. mohammed ajjour university of...

Week3+4 Chapt 1 : Earth and Natural Environmental Hazards

Dr. Mohammed Ajjour University Of Palestine

2009,

Chapter 1The Earth and Life 4.6 Billion years ago , Sun and other planets were formed from Premordial

Nebula. During the first some million years, Volcanoes erupted and some

redistribution of elements of the Earth took place and different layers were formed

In Low areas condensation of water vapour from volcanoes formed water in oceans and seas ( sweet water first, later salty from rocks).This process is still ongoing.

Atmosphere gases accumulated from volcanoes ( water vapour, hydrogen sulphate, ammonia, nitrogen , argon and Helium ,no oxygen at this stage. Ultra violet radiation penetrated easily and oxygen formed through UV and H2O splitting was reduced immediately by Gases (chemosynthesis phase).

. University Of Palestine 2009, Dr. Mohammed Ajjour

University Of Palestine 2009, Dr. Mohammed Ajjour

3500 Million years ago some simple species of Bacteria were found, which are able to exist in absence of O2 and to photosynthesise CO2 to produce free oxygen. Some of these are still there.

Since the last 550 million years, the concentration of free O2 increased to present level allowing the existence of other species

At present ,these Species undergo different changes and adaptations..

During this long history ,the geological processes produced minerals (Gold, diamond, phosphate, Iron..etc)and Fossil Energy Sources ( Oil, Coal, gas ).

At the last end Human life began

Con. The Earth and Life 35

00 Million years ago some simple species of Bacteria were found, which are able to exist in absence of O2 and to photosynthesise CO2 to produce free oxygen. Some of these are still there.

Since the last 550 million years, the concentration of free O2 increased to present level allowing the existence of other species presence of Oxygen. At present ,these Species are undergoing different changes and adaptations..

During this long history ,the geological processes produced the minerals ( like Gold, diamond, phosphate, Iron...etc)and Fossile Energy Sources ( Oil, Coal, gas ).

Earth Sphers From environmental point of view, the Earth , and its surrounding is

divided into five spheres or systems, which interact with each other and affect our live:

Lithosphere or the rocky stony crust الصخري .الغالف Pedosphere or the soil Part. التربة Hydrosphere or the watery part. المائي الغالف Atmosphere or the gaseous part. الجوي الغالف Biosphere or the living parts. الحيوي الغالف

Energy and matter move between the spheres and organism can live in.


At its centre, the Earth has a solid inner core, 1370 km in radius, made from iron with some nickel. This is called the core اللب

This is surrounded by an outer core, about 2000 km thick, also of iron with nickel, but liquid, although of very high density.

Movement in the outer core acts like a self- exciting dynamo and generates the Earth’s magnetic field.

Outside the outer core, the mantle (الستار (, made from dense but somewhat plastic rock, is about 2900 km thick.

The structure of Earth

At the surface a thin crust of solid rock, about 6 km thick beneath the oceans and 35 km thick (but less dense) beneath the continents. It is called the crust القشرةاالرضية

The outer 100-120km is called اLithosphere ( الصخري (الغالف


Earth and lithosphere

Lithosphere: • Composed of fractured rocks;- • Thickness 100-120km; It includes the crust and

outer part of Mantel

- Composed of continental plates in continuous motion leading to the formation of Continents, ocean bottoms and mountains , Earthquakes , and volcanoes


it is the result of weathering and erosion of outer crust.

in addition to its rocky materials , It contains humidity , air and organic matter, Very important for plants

Located above the lithosphere, It is that thin outer part of loose rocky materials that can support life .

The quality of pedosphere is determined by many internal and external factors Type of soil depend on the rock origin, weather and climate, topography, etc.University Of Palestine 2009, Dr. Mohammed Ajjour

The Pedosphere التربة

Under this term all kinds of water are included , such as Rivers, Seas, Oceans ,ice , glaciers ,Lakes , Rain Water, Ground Water …..etc.

More than 70% of earth surface is covered by water Quality of water is different and depend on

dissolved amounts and kinds of minerals. Common Ions are chlorides, Sodium, Sulfates, Calcium , Potassium

Water is a major factor in changing the surface of the pedosphere.


The Hydrosphere

The Atmosphere It extends from few meters below soil surface to few

kilometres above. Air is composed of Nitrogen gases 78% Oxygen 21% argon 0,9% Carbon dioxide 0.03% in addition to sum

other gases. The Troposphere is the most important part of the

Atmosphere where most of the air is present, and weather and climate actions and interactions take place.

This part is very important for life as a resource .University Of Palestine 2009, Dr. Mohammed Ajjour

It includes all forms of terrestrial life in soil, water and air

Around 4.5 million species of organisms exist .

Most species depend on Photosynthesis .


The Biosphere

-Earthquakes - Volcanic hazards - Floods - Tornados and storms - Desertification


Natural Environmental Hazards

Earthquakes and their Hazards

Earthquake is movement of the earth due to sudden release of energy.

Rocks are continuously under pressure. Increased pressure above the elasticity limits of rocks leads to break down of rocks and release of energy in the form of waves causing earth movement .

Earthquakes occur in specific areas or lines, mostly in oceans, and are rare in the rest of the world. These areas with high frequency of earthquakes are called plates. The lines surrounding each plate are called Plate Boundary.There are seven large plates, a number of smaller ones, and a still larger number of ‘micro plates’.


Earthquakes and their Hazards

In some cases Two plates are moving apart . In such areas , Red Sea and Atlantic Ocean , quakes occur rarely and in low magnitude .In other cases Where plates move towards one another and collide . In such cases like in Japan , Iran . Indonesia and the Pacific Ocean , earthquakes occur very frequently and in high magnitude ( grade 8 in Richter scale ).


Cont. Earthquakes and their Hazards

In the third form of cases plates move past one another causing increased distance between continents . In such areas earthquakes occur less frequently ( about 10 or hundred years )and in lower magnitude ( less than 7 grade in Richter scale ) . .

Richter scale : open scale for Quake magnitude. One grade measure 30 times more ( or less ) than the next grade.University Of Palestine 2009, Dr. Mohammed Ajjour


Earthquake Damage ( Intensity of the Quake, measured by Merkali scalee from 1-12) depends on many factors:

The magnitude of the Earthquake The distance from the center of the

earthquake The types and properties of the

materials at the site The nature of the building



Earthquakes may cause following changes:• Ground motion and Faulting, when a Quake

with high magnitude occurs ground surface moves like a grass field in windy day causing collapse of Building and faulting of surface.

• After Shock :A Quake that follows the main shock and increases the damage of Buildings and losses .

• Fire s in Cities and homes• Landslides in mountain areas • Changes in ground surface and topography.• Flooding of rivers (dam failure ) and

Tsunamis in coastal areas


week3+4 chapt 1 : earth and natural environmental hazards dr. mohammed ajjour university of...

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