Ch 5Natural phenomena and disaster

Geological disaster

Geology

• The science comprising the study of solid earth, the rocks of which it is composed, and the processes by which they change.

Why should we study geology?

>>to protect from the geological disaster...

What happened in 5 May 2014 in Chiang Rai?

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11 march 2010 ... In Japan

26 December 2004

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>> for knowledge of mineral resources

Tin & Tungsten

• Found in the valleys along the granite mountains along the west of the country

Copper & Iron

• Found in Loei, Nong Khai, Uttaradit

Gold

• Chae Hom, Wang Nuea(Lampang)

• Mae Chan, Mae Sai and Chiang Saen (Chiang Rai)

>> for knowledge about how to manage the land

Why does rice grow better in water?

• Most types of rice require moist growing conditions so they cannot grow in areas of low rainfall unless the rice field is artificially irrigated. While rice needs water to grow, it does not require standing water to grow. The idea that rice needs to be grown in water is a misconception. However, rice is almost always grown in water filled fields, called paddies. While not required, there are benefits to the rice plant when grown in such conditions. Rice fields flood more easily than other row crop fields, because rice is grown in clay soils. Water does not readily drain through clay soil. Most other crops will not grow in this type of soil.

An advantage of this growing condition is weed control. Major plant cell functions like elongation and multiplication require oxygen. Flooded fields have less available oxygen for plant roots. This prevents the germination and growth of weeds that would compete with the rice plant for nutrients and sunlight in the field.

Standing water is also a deterrent to insects that threaten rice such as the army worm and chinch bug. Standing water also offers a kind of temperature control for the crop. Anyone who lives near a body of water knows that water temperature changes more slowly than land temperature. So, on hot days the water filled fields keep the rice cool, and then warm it on cool nights. Standing water also helps in preventing excessive salt accumulation and the soil depletion.

The interesting thing about rice is not that it grows in flooded fields, but that it can tolerate flooded conditions. Rice plant leaves and the stems contain a series of internal air tunnels that funnel air down to the roots. In this way it is similar to aquatic plants. One third of the rice plant needs to be above water for this mechanism to work. Rice that is totally under water will die. That is why the water level is carefully monitored and controlled in rice fields.

Geological study

>>Earth Materials

• Igneous rock,

• Sedimentary rock

• Metamorphic rock

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>> processes of earth change

Internal processes

By plate tectonics

– Divergent boundary, Convergent boundary, Transform fault boundary

External or Surficial processes

• Geologic processes acting on the surface of the solid earth in contact with the atmosphere and hydrosphere.

• Includes: Weathering, erosion, mass wasting, rivers and streams, glaciers, work of the wind, coastal processes, and groundwater.

Pothole?

a cavity or hole which appears to have been drilled in the surrounding rocks by eddying currents of water bearing stones, gravel and other detrital matter

>>> Geologic history

• follows the major events in Earth's past based on the geologic time scale, based on the study of the planet's rock layers

• Earth formed about 4.54

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How the earth was created?

Geological map

William Smith (Father of English Geoloy)

Geological map

• a special-purpose map to show geological features; i.e rock units, geological structures and ages, 3d-orientation, etc

>>> By Department of Geology, Department of Mineral Resources

• Determine the extent of the mineral

• coal and petroleum exploration (Aimed at exploring areas of the Tertiary rock era)

• Tin exploration (aimed at granite area)

• 66 million to 2.58 million years ago,

Structure geology

• the study of the three-dimensional distribution of rock units with respect to deformational histories (e.g., mountain building, rifting due to plate tectonics)

• To understand the dynamics of the stress field that can be linked to important events in the regional geologic past

Chiang Rai Geology

Active fault : a fault that is likely to have another earthquake sometime in the future. one that has ruptured in the last 11,000 years

Phu Chi Fa

• a mountain in located at the eastern edge of Thoeng district, Chiang Rai

Geohazards

• a geological state which has the potential to create widespread damage.• include tectonic issues, such as earthquakes and volcanoes• other naturally-occurring processes such as landslides and mud flows

earthquake

• a sudden release of energy in the Earth’s crust that creates waves

Landslide

• Gravity is the primary factor in a landslide. Soil on a flat surface does not move. On a slope, gravity alone also may not trigger a landslide. But when another disrupting factor -- like rain -- comes into play, gravity will pull sediment downhill.

What can be factors for lanslide?

Sinkhole

• A hole in the ground caused by some form of collapse of the surface layer.

• The most significant factor in the development of sinkholes is the dissolution of the limestone underlying by acidic waters.

Soil creep

• the slow downward progression of rock and soil down a low grade slope

Bank erosion

• the wearing away of the banks of a stream or river