Plate Tectonics

Global geological phenomena have been described by theory of plate tectonics. Plate tectonism assumes the movement of plates at earth’s crust influenced by convection of magma inside the mantle. Tectonic plates are the segments of lithosphere which move and change in shape and size continuously (Condie, 1997). Lithosphere, the rigid and brittle outermost mechanical layer of the earth, extends up to 100 km beneath the surface (California State University, n.d.) and deformation and faults are resulted from the movements of rigid lithospheric plates. Faulted rocks in El Salvador, folded rocks along the San Andreas and folded and faulted rocks in the Himalayan region are few examples of deformed rocks (California State University, n.d.).

Activities of tectonic plates, cooling mechanism of earth’s mantle and mantle convection illustrate plate tectonics theory. Niu (2014) assumes the consumption of tectonic plates into the earth’s interior through subduction zones. Continental drift, sea floor spreading and mantle plumes are other geologic phenomena related with plate tectonics. Niu (2014) described the mantle plume as cooling mechanism of the earth’s core.

Water, its highest heat capacity and role of ocean as a sink to cool the mantle has been identified as one of the driving forces of plate tectonics (Niu, 2014). In contrast, size, circumference and ridge length of a plate has fewer influences on plate motion (Forsyth and Uyeda, 1975 cited in Niu, 2014). Movement of tectonic plates has three principle mechanisms: divergent, convergent and transform. Plates move apart from each other at divergent plate boundaries, plates crash with each other along convergent plate boundaries and plates slide with each other along a transform plate boundary (Kean University, n.d.).

References
California State University (n.d.) Natural Disasters [Online] Available at http://www.csus.edu [Accessed on 20 may 2015]
Condie, K.C. (1997) Plate Tectonics and Crustal Evolution [Online] Available at http://www.bayanbox.ir/view [Accessed on 15 May 2015].

Forsyth, D. and Uyeda, D. (1975) On the Relative Importance of the Driving Forces of Plate Motion- Geophysics Journal International, Vol 43, pp. 163-200.

Kean University (n.d.) Plate Tectonics [Online] Available at http://www.kean.edu [Accessed on 21 may 2015].

Niu, Y. (2014) Geologic Understanding of Plate Tectonics: Basic Concepts, Illustrations, Examples and New Perspectives. Global Tectonics and Metallogeny, Vol 10 (1), pp. 23-46.

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Richter Scale

The devastating earthquake measuring 7.9 Richter scale has already killed more than 5000 people in Nepal.  Earthquake with higher Richter scale are more damaging and dangerous. Earthquake can be measured in different scales and Richter’s scale has been used most widely. Charles F. Richter developed the scale in 1936 at California, USA.  The intensity of the earthquake is measured by Richter scale.

Seismic waves indicate the energy transported through the earth during the earthquake. The amplitude of a wave refers to the amount of displacement of a particle on the medium from its rest position (the Physics Classroom, 2015). The amplitude has a relationship with the energy transported by the seismic wave. “The energy transported by a wave is directly proportional to the square of the amplitude of the wave “(the Physics Classroom, 2015).

Richter scale measures the size of an earthquake and logarithm of the amplitude of earthquake is determining factor (BGS, n.d.). Amplitude of the earthquake increases tenfold with a whole number increase in the scale. Earthquake with a magnitude up to 5.4 is noticeable but less damaging. Severe damages to buildings and infrastructure are likely to occur from an earthquake with Richter scale 7 or higher (matter project, 1999).

Recent bigger earthquakes include Sumatra, Indonesia earthquake of Richter scale 9.1 in December 2004, Sendai, Japan earthquake of Richter scale 9.0 in March 2011 and Bio-Bio, Chile earthquake of Richter scale 8.8 in February 2010 (Philips, 2011). Earthquake can’t be predicted however high risk areas and earthquake prone zones can be identified.

 References

British Geological Survey (BGS) (n.d.) What is Earthquake Magnitude [Online] Available at http://www.earthquakes.bgs.ac.uk [Accessed on 28 April 2015].

Matter Project (1999) Scales of Measuring Earthquakes [Online] Available at www.matter.org.uk [Accessed on 28 April 2015]

Philips, C. (2011) Earthquakes: The 10 Biggest in History [Online] Available at www.australiangeographic.com.au [Accessed on 28 April 2015].

The Physics Classroom (2015) Energy Transport and the Amplitude of a Wave [Online] Available at www.physicsclassroom.com [Accessed on 28 April 2015].

Toxic Chemicals in the Environment

Different forms of harmful chemicals have been released into the soil, water and air from our activities. Chemicals which can cause serious health effects, poisoning or death when ingested, inhaled or absorbed have been classified as toxic chemicals (Worldometers, n.d.). Industrial activities are major sources of chemicals into the environment. Worldometers (n.d.) estimated 310 kg of toxic chemicals being released every second in the world.

Fluoride, mercury, PCBs, perchlorate, chlorine, lead, arsenic, dioxin, DDT, MtBE, and DCPA are toxic chemicals which can be found in water (Global Healing Center, 2015). Sources, distribution and environmental effects of toxic chemicals are different. Chlorine used in disinfection, arsenic and lead occurring naturally in water, PAHs and PCBs has various toxic effects. Bio accumulative properties of mercury and lead have adverse effects on aquatic organisms and human beings (Department of Ecology, n.d.). Fluoride is carcinogenic and it has adverse effects on bone structure and acute reactions (Holistic healing, n.d.). Manganese has been identified as a neurotoxin associated with learning disabilities and deficits in intellectual functions in children (Zoni and Licchini, 2013 cited in Villanueva et al., 2014). Nitrates in drinking water have been found to have carcinogenic effects on oesophagus, stomach, bladder and colon (Villanueva et al., 2014).

Inhalation, Ingestion and direct contact with toxic substances are possible pathways of exposure to toxic chemicals (Department of Health, 2013). Toxicity could be produced by inhaling or breathing gases, vapours, dusts or mists or ingesting or swallowing of food, drink and other substances and touching the toxic substance with eyes or skin (Department of Health, 2013).

References

Department of Ecology (n.d.) Controlling Toxic Chemicals in Puget Sound. [Online] Available at http://www.ecy.wa.gov [Accessed on 30 March 2015].

Department of Health (2013) What You Know Can Help You- An Introduction to Toxic Substances [Online] Available at www.health.ny.gov [Accessed on 31 March 2015].

Global Healing Center (2015) What Other Toxic Chemicals in Water Affect My Health? [Online] Available at www.globalhealingcenter.com [Accessed on 30 March 2015].

Holistic Healing (n.d.) Fluoridation/Fluoride : Toxic Chemicals in Your Water [Online] Available at http://www.holisticmed.com [Accesse on 31 March 2015].

Villanueva, C.M. , Kogevinas, M. , Lordier, S. , Templeton, M.R., Vermeulen, R., Nuckols, J. R. , Nieuwenhuijsen, M. J. and Levallois, P. (2014) Assessing Exposure and Health Consequences of Chemicals in Drinking Water: Current State of Knowledge and Research Needs. Environmental Health Prospect. Vol 122 (3), pp. 213-221

Worldometers (n.d.) Toxic Chemicals [Online] Available at www.worldometers.info [Accessed on 30 March 2015].

Zoni, S. and Lucchini, R.C. (2013) Manganese Exposure Cognitive Motor and Behavioural Effects on Children : A Review of Recent Findings. Curr Opin Pediatr 25: 255-260 Cited In Villanueva, C.M. , Kogevinas, M. , Lordier, S. , Templeton, M.R., Vermeulen, R., Nuckols, J. R. , Nieuwenhuijsen, M. J. and Levallois, P. (2014) Assessing Exposure and Health Consequences of Chemicals in Drinking Water: Current State of Knowledge and Research Needs. Environmental Health Prospect. Vol 122 (3), pp. 213-221