Thermal Expansion of the Tectonic Plates

Theory:

Thermal Expansion of the Tectonic Plates due to warming of the South China Sea is contributing to Earthquakes on the Convergent Boundaries of the Southeastern Portion of the Eurasian Plate.

Theory by Kevin G. Boechler

 

 

Note: Please read the information below and feel free to contact me with feedback; I am desperately seeking historical data on the South China Sea temperatures even by means of SST data if that is all that is in existence.

Italicized text was written By Kevin G. Boechler,  

 

Saskatoon, Saskatchewan, Canada.

kevinboechler@sasktel.net

 

 

Purpose

The purpose of this report is not to quantify thermal expansion of the tectonic plates due to warming global water temperatures: Nor the frequency of earthquakes on the convergent boundaries of the Eurasian plate in the South China Sea region. There are far too many unknown conditions (Variables) to enable a calculation.

 

 The intent of this report is to present the theory that the South China Sea warming will result in thermal expansion of the tectonic plate possibly initiating earthquakes that would not have happened for many years. Not only to say, warming of the planets Oceans and Seas is a variable in the calculations measure change in the thermal expansive state of the tectonic plates; but to put forth the theory that oceanic plates in thermal contact with warming ocean/sea water could expand enough to generate an earthquake that with normal tectonic plate movement would not have resulted in many years through plate movement alone.

 

This theory is to include the concept that when there is any change in the Ocean/sea temperatures in areas of the plates that are in thermal contact with the water temperature change; there will be a change in the thermal expansive state of the plate. And depending on the modulus of elasticity of the plate may even result in divergent plate activity on boundaries that act in convergence due to plate movement alone; this when in contact with significantly cooling water.

 

Study of the ocean/sea temperature when there is a large linear length of shallow water resting on tectonic plate will serve to produce the most startling results. The South China Sea is resting largely on the Eurasian continental crust, close to the sea surface and subject to a warming Sea Surface Temperature (SST).

 

 

 

Earth: Plate Tectonic Theory

Plate tectonic theory is a relatively new idea, having been formulated in the early 1960s. Plate tectonics states that the Earth's surface, both land and water, is divided up into several pieces like giant jigsaw puzzle pieces. There are 14 such pieces, 7 large and 7 small. Unlike a puzzle, though, these plates move around - sliding past each other, bumping into each other, or moving away from each other. Understandably, the largest plates include the Pacific, North American, Euasian, Antarctic, and African. For comparison's sake, the Pacific is the largest plate at 14,000 km in width, while the Cocos is the smallest at 2,000 km in width.
There are two types of motions, absolute and relative. Relative motion between the plates, however, is much more involved. The boundaries at which two plates move away, come together, or slide past one another can be classified as divergent, convergent, or transform, respectively. A less common boundary is between three, forming a triple junction. Examples include the Mendocino Triple Junction and the East African Rift Zone.
A divergent boundary occurs as two plates move away from each other. The phenomenon known as seafloor spreading occurs with oceanic crust. On the other hand, two continental plates moving away from each other create rift valleys, where broad areas of land are moved upward. The mid-ocean ridges today are 60,000 km long, making them the largest continuous mountain chain on the planet. An example of an oceanic divergent boundary is the Mid-Atlantic Ridge, which is an underwater mountain range in the Atlantic. Due to plate tectonics, the ridges are spreading out further at a rate of 2.5 cm per year.
A convergent boundary occurs as two plates come together. As this occurs, one plates goes beneath another at a subduction zone. Earthquakes are frequent here. Volcanic ridges and oceanic trenches are also formed. One example in the Pacific Ocean is the Mariana Trench, a chain of active volcanoes. Between an oceanic and continental plate, a continental margin arc and trench systems are made. Earthquake faults and volcanoes are common as well as thrust faults, which are breaks in the Earth's crust. Converging plates involving at least one continental plate also have the characteristic of thickening some of the land at the edges. This increase in thickness forms some mountains and plateaus. One example of a convergent boundary mountain range is the Andes Mountains in South America and the Tibetan Plateaus in Asia.
Plate tectonic theory has helped to explain many phenomena on Earth. The plates have shaped the planet's topology since its formation 4.65 billion years ago. Today, researchers are continuing studies in this area.

 

http://www.platetectonics.com/book/index.asp

 

 


http://en.wikipedia.org/wiki/Plate_tectonics#Major_plates

 

Measuring plate movement

Geologists discovered absolute plate motion when they found chains of extinct submarine volcanoes. A chain of dead volcanoes forms as a plate moves over a plume, a source of magma, or molten rock, deep within the mantle. These plumes stay in one spot, and each one creates a hot spot in the plate above the plume. These hot spots can form into a volcano on the surface of the earth. An active volcano indicates a hot spot as well as the youngest region of a volcanic chain. As the plate moves, a new volcano forms in the plate over the place where the hot spot occurs. The volcanoes in the chain get progressively older and become extinct as they move away from the hot spot (see Hawaii: Formation of the Islands and Volcanoes). Scientists use hot spots to measure the speed of tectonic plates relative to a fixed point. To do this, they determine the age of extinct volcanoes and their distance from a hot spot. They then use these numbers to calculate how far the plate has moved in the time since each volcano formed. Today, the plates move at velocities up to 18.5 cm per year (7.3 in per year). On average, they move nearly 4 to 7 cm per year (2 to 3 in per year).

 

Ocean/Sea Temperature Change

Oceans (from Okeanos, Greek for river, the ancient Greeks noticed that a strong current flowed off Gibraltar, and assumed it was a great river) cover almost three quarters (71%) of the surface of the Earth, and nearly half of the world's marine waters are over 3000 m deep.

This global, interconnected body of salt water, called the World Ocean, is generally divided by the continents and archipelagos into the following bodies, from the largest to the smallest: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean, and the Arctic Ocean. The last one is oceanographically better described as a mediterranean sea, however.

Smaller regions of the oceans are called seas, gulfs, straits and other names.

Geologically, an ocean is an area of oceanic crust covered by water. Oceanic crust is the thin layer of solidified volcanic basalt that covers the Earth's mantle where there are no continents. From this point of view, there are three "oceans" today: the World Ocean, and the Black and Caspian Seas that were formed by the collision of Cimmeria with Laurasia. The Mediterranean Sea is very nearly its own "ocean", being connected to the World Ocean through the Strait of Gibraltar, and indeed several times over the last few million years movement of the African Continent has closed the strait off entirely, making the Mediterranean a fourth "ocean". (The Black Sea is connected to the Mediterranean through the Bosporus, but this is in effect a natural canal cut through continental rock some 7000 years ago, rather than a piece of oceanic sea floor like the Strait of Gibraltar.

 

Warmer Seas

http://airsea-www.jpl.nasa.gov/publication/paper/Liu-etal-2003-jecss.pdf

 

Using satellite data, the scientists link the increase in major storms to rising sea surface temperatures, which they believe have been influenced by global warming. However, the researchers will not go as far as to say that global warming is spinning up these larger storms.

"We're not saying that global warming is causing there to be more intense hurricanes," study author Peter Webster of Georgia Tech told LiveScience. "What we're saying is that sea surface temperatures are rising, and the intensity of hurricanes is associated with that. The warmer the sea surface temperature, the more intense the hurricanes."

 

Over the last 100 years, the global sea level has risen by about 10 to 25 cm.

Sea level change is difficult to measure. Relative sea level changes have been derived mainly from tide-gauge data. In the conventional tide-gauge system, the sea level is measured relative to a land-based tide-gauge benchmark. The major problem is that the land experiences vertical movements (e.g. from isostatic effects, neotectonism, and sedimentation), and these get incorporated into the measurements. However, improved methods of filtering out the effects of long-term vertical land movements, as well as a greater reliance on the longest tide-gauge records for estimating trends, have provided greater confidence that the volume of ocean water has indeed been increasing, causing the sea level to rise within the given range.

It is likely that much of the rise in sea level has been related to the concurrent rise in global temperature over the last 100 years. On this time scale, the warming and the consequent thermal expansion of the oceans may account for about 2-7 cm of the observed sea level rise, while the observed retreat of glaciers and ice caps may account for about 2-5 cm. Other factors are more difficult to quantify. The rate of observed sea level rise suggests that there has been a net positive contribution from the huge ice sheets of Greenland and Antarctica, but observations of the ice sheets do not yet allow meaningful quantitative estimates of their separate contributions. The ice sheets remain a major source of uncertainty in accounting for past changes in sea level because of insufficient data about these ice sheets over the last 100 years.

 

 

Global Surface Temperature Trends

 

The year 2005 was the warmest year in over a century, according to NASA scientists studying temperature data from around the world. 

The result indicates that a strong underlying warming trend is continuing. Global warming since the middle 1970s is now about 0.6 degrees Celsius (C) or about 1 degree Fahrenheit (F). Total warming in the past century is about 0.8° C or about 1.4° F.

"The five warmest years over the last century occurred in the last eight years," said James Hansen, director of NASA GISS. They stack up as follows: the warmest was 2005, then 1998, 2002, 2003 and 2004.

http://www.solcomhouse.com/globalwarming.htm

 

The figure shows the combined land-surface air and sea surface temperatures (degrees Centigrade) 1861 to 1998, relative to the average temperature between 1961 and 1990

.The mean global surface temperature has increased by about 0.3 to 0.6°C since the late 19th century and by about 0.2 to 0.3°C over the last 40 years, which is the period with most reliable data. Recent years have been among the warmest since 1860 - the period for which instrumental records are available.

Warming is evident in both sea surface and land-based surface air temperatures. Urbanization in general and desertification could have contributed only a small fraction of the overall global warming, although urbanization may have been an important influence in some regions. Indirect indicators such as borehole temperatures and glacier shrinkage provide independent support for the observed warming. It should also be noted that the warming has not been globally uniform. The recent warming has been greatest between 40°N and 70°N latitude, though some areas such as the North Atlantic Ocean have cooled in the recent decades.

 

 

Global Ocean Temperature Change

 

 

Historical data examined by Levitus et al (Science, 1999) shows changes in the ocean heat content (to depths of 3000 meters) to be slowly increasing with substantial decadal time scale variations related to climate variability. The sequestering of heat deep into the ocean, mitigates global warming of the atmosphere. Deep heat increases reflect changes in properties of deep water formed at high latitude in winter.  

http://www.whoi.edu/institutes/occi/viewImage.do?id=19452&aid=10046

 

Unusually Warm Pacific water

 

 

This large area of unusually warm water in the northern Pacific may exist for a decade and have a long-term influence on climate, including long periods of drought in the southwestern United States.

http://www-ocean.tamu.edu/Quarterdeck/QD6.2/giese.html

 

 

 

 

 

 

http://www.rand.org/pubs/monograph_reports/MR1395/MR1395.appf.pdf

 

The water temperature of small enclosed bodies of water is more effected by climate change.

Like a small bay at a lake; in the fall the ice forms first in the shallow bays and melts first in the spring in the same bays as well in the summer the water is warmer.

 

 

Pacific Temperature Section, entire water column, T data contoured

 

http://www.piercecollege.edu/faculty/leesc/Ocean_10/Exercise/Profiles/Pacific/T/Tsection/0_6000/Pac_T_6_con.htm

 

The above chart is for the purpose of demonstrating a typical cross section of the Pacific Ocean to show the depth that warmer surface water reaches. Currents, tides, floor contour, winds, floor volcanic activity and other variables would provide varying results for a China South Sea cross-section. As no data is available for the China South Sea, the above chart may only be viewed in theory.

The theory being presented is that the Oceanic Plates that are closer to the Ocean/Sea surface will receive more energy from warming surface water.

The South China Sea varies in depth from 100m – 5000m, however a large portion of the lower South China Sea has a depth of less than 500m: Linear lengths likely effected by warming water are 1400Km - 2000Km long.

This same theory would imply that East China Sea would also be in danger of tectonic plate expansion due to the shallow shelf with a linear length in two directions of approximately 1000Km. Ultimately reducing the number of years before an earthquake in the region. This concern is increased with the possibility of currents taking the unusually warm  Pacific Water into the East China Sea.

 

 

 

http://www.showcaves.com/english/explain/Geology/PlateTectonics.html

 

Linear thermal expansion

 

The length of an object is one of the more obvious things that depends on temperature. When something is heated or cooled, its length changes by an amount proportional to the original length and the change in temperature:

 

The equation to calculate the linear expansion of a material is:

 

Change in Length = (Coefficient of thermal expansion of the material) X (Length of the Material) X (Change in Temperature of the material)

 

 

The coefficient of linear expansion depends only on the material an object is made from.

If an object is heated or cooled and it is not free to expand the object, or to damage whatever the object is constrained by. This is why bridges have expansion joints in them (check this out where the BU bridge meets Comm. Ave.). Even sidewalks are built accounting for thermal expansion.

Holes expand and contract the same way as the material around them. or contract (it's tied down at both ends, in other words), the thermal stresses can be large enough to damage the material.

Note: The direction of the expansion of the Eurasian (tectonic) plate in reality would be out from the centroid of the plate and in all directions. However only a portion of the plate is covered by the shallower warmer water. Being that the temperature change is so small and the thickness of the plates ranges from 2km – 10km while the Diameters range from 2000km – 14000km

It is assumed that the water on the South China Sea floor is resting on the Eurasian plate and as a result heat energy is transferred.

 

Example

 

Consider a 2 m long brass rod and a 1 m long aluminum rod. When the temperature is 22 °C, there is a gap of 1.0 x 10-3 m separating their ends. No expansion is possible at the other end of either rod. At what temperature will the two bars touch?

The change in temperature is the same for both, the original length is known for both, and the coefficients of linear expansion.

Both rods will expand when heated. They will touch when the sum of the two length changes equals the initial width of the gap. Therefore:

So, the temperature change is:

If the original temperature was 22 °C, the final temperature is 38.4 °C.

Tectonic Plate Expansion Analysis

Given:

Change in Length = (Coefficient of thermal expansion of the material) X (Leangth of the Material) X (Change in Temperature of the material)

Note: The relationship between Temperature Change and Change in Length is linear/directly proportional, and the Length of the material and the Change in Temperature are inversely proportional; the longer the object the less temperature change is required to have an impact on the change in the object’s length – This is a linear relationship.

About 90% of all earthquakes have depths < 100 km. Earthquakes can be grouped into three categories based on the depth of their foci:

1.      Shallow focus - Foci are less than 70 km depth. Most destructive earthquakes.

2.      Intermediate focus - Foci are between 70 and 300 km depth.

Deep focus - Foci are greater than 300 km.

http://www.geo.ua.edu/intro03/quakes.html

 

  Fig. 1. Geography and isobaths showing the bathymetry (m) of the South China Sea.

 

 

Type of Crust

Average Thickness

Average Age

Major Component

Continental Crust

20-80 kilometers

3 billion years

Granite

Oceanic Crust

10 kilometers

Generally 70 to 100 million years old

Basalt

OCEANIC CRUST Composition

·  More Dense (heavier): average density = 3.0 gm per cubic centimeter

·  Thinner: 0 to 10 km, average 5 km, thinnest at Mid-Ocean Ridges

·  Mineral Composition: mafic rocks such as basalt and gabbro enriched in Magnesium (Mg) and Iron (Fe)

·  Underlies Ocean Basins.

 

 

Coefficient of Thermal Expansion

 

10-6/°C

10-6/°F

Granite

7-9

4-5

Basalt

6-8

3.3-4.4

 

 

 

Assumptions

 

There are far too many variables to consider and quantify; many of them experiencing thermal change would have a profound effect on the degree of thermal expansion of the South Eastern potion of the Eurasian plate, as well as the other plates acting in convergence on the Eurasian plate.

ü      Any warming temperature on the outer edge of the earth’s mantle would be in addition to the expansion of the oceanic plates due to warmer ocean waters; while a cooling of the surface of the mantle would serve to offset the effects of warmer ocean waters. Possible mantle temperature variances were not considered as it does not have a bearing on the ability of the energy to reaches oceanic plates via increased sea temperature, however it is considered that the earth is heating though over a much greater time frame than what is discussed here.

ü      No data was located specifically outlining the temperature change of the South China Sea(0.310C was used for the purposes of this report; however the estimate is considered by the author to be very conservative given the large area of sea floor that has a maximum depth of 500m.)

ü      The Eurasian Tectonic plate movement is approximately 3.0 cm/year; 2.5 cm/yr is the plate movement at the Pacific Trench. (Some plates move as fast as 15 cm/yr. On average, they move nearly 4 to 7 cm per year (2 to 3 in per year). A smaller value was chosen as the Eurasian plate is one of the largest plates.) Although the temperature change in the South China Sea is a conservative estimate it has been assumed that the temperature of the plate has increased 0.310C as wel.l

ü      Since the objective of this report is only intended to show that a change in water temperature will contribute to a either a thermal expansion or retraction of the plates depending on the weather the change is a cooling or warming of the water: Factors such as the temperature of the of the Mantle are considered to be static.

 

 

Important Calculation

 

Therefore without considering any change in heat energy from the earth’s mantle.

 

Assuming a coefficient of thermal expansion of (8 X 10-6/ 0C) for Basalt, a 0.310C temperature change and a 2000Km length experiencing the temperature change:

 

 

Change in length Basalt = (8 X 10-6/ 0C)(2000Km)(0.310C)

Change in length Basalt = 0.00496 Km or 4.96m.

 

Or assuming a coefficient of thermal expansion of (9 X 10-6/ 0C) for Granite, a 0.310C temperature change and a 2000Km length experiencing the temperature change:

 

Change in length Granite = (9 X 10-6/ 0C)(2000Km)(0.310C)

Change in length Granite = 0.00558 Km or 5.58m.

 

The above calculation does not consider the energy introduced from the earth’s mantle. The Mantle below the crust is very hot (1200 degrees Celsius), energy is released from the mantle to the tectonic plates. A warmer water temperature would act as an insulator keeping more energy in the plates causing expansion.

 

Assuming; The Eurasian Plate moves at 2.5 cm/year as it is one of the largest plates. (The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimeters per year (cm/yr))

Using the coefficient of thermal expansion of (9 X 10-6/ 0C) for Granite, a 0.310C temperature change and a 2000Km length experiencing the temperature change:

Determine the equivalent number of years of plate movement due to thermal expansion:

5.58m/2.5 cm/year = The equivalent plate movement,

558cm/2.5cm/year = The equivalent of approximately 225 years of plate movement. 

 

 

Length of line is 2000Km Depth through appox. Half the length is under 500m and through the last third a depth of 2000m-4000m

 

http://www.showcaves.com/english/explain/Geology/PlateTectonics.html

 

 

 

 

 

Global Surface temperature Data: The darker red indicates that some of the warmest water temperatures are in the area around the South Eastern Potion of the Eurasian plate.

 

 

 

http://encarta.msn.com/map_701512206/East_China_Sea.html

 

 

Prior studies of regional seas indicate upwelling of deep waters in the South China Sea south of Taiwan. Chao et al. (1995) use a numerical model of the South China Sea region with an abyssal tracer to demonstrate this upwelling. However, the model experiments were from coarse resolution, were forced only by climatological Hellerman-Rosenstien winds (thus no short time scale variations were included), and did not examine the causes of this upwelling. Gong et al. (1992) have conducted in situ hydrographic and chemical surveys to also observe the upwelling in this area. The mechanisms of this upwelling and its subsequent influence in the Yellow and East China Seas through the Taiwan Strait have not been examined.

 

 

 

 

 

 


 

 

 

 

 

http://www3.pdc.org/APNHVA/Atlas_Scenario.pdf

 

 

 

World Ocean and Sea Temperature Information:

 

World Resource Review Vol. 17 No. 3

 

http://global24.fatcow.com/WRR%20Goreau%20Hayes%20&%20McAlllister%20.pdf

 

1. Northwest Pacific

Intense HotSpots regularly line up along the axis of the Kuroshio Current and

the areas immediately down-current from it as far as Alaska. This accelerates

the velocity of heat transport into the northwest Pacific from the western

tropical Pacific, affecting climate of western North America. Since the

Kuroshio is the world's strongest current in terms of heat flow, these changes

have significant implications for increasing global heat fluxes from the

tropics to the temperate zone and for driving climate change in North

America. Such changes also are consistent with an increased strength of

typhoons in the North Pacific (Emmanuel, 1987).

 

2. Northwest Atlantic

Intense HotSpots regularly line up along the axis of the Gulf Stream Current

and the areas immediately down-current from it as far as Europe. This implies

that the velocity and total heat transport into the northwest Atlantic from the

Caribbean has accelerated. The Gulf Stream, the world's second strongest

current in terms of heat flow, appears to be strongly increasing the flow of

heat into the north Atlantic and adjacent European shores.

 

3. Pacific and Atlantic Equatorial Zones

A zone of consistently warmer water lies along the equator across the entire

breadth of the Pacific Ocean from Ecuador to Borneo, with the strongest

warming in the east. This suggests that upwelling from the Equatorial

divergence and the Equatorial Counter Current might be declining, as is the

upwelling in the core of the Eastern Pacific El Nino region, or since El Nino

years are excluded, that the strength of La Ninas are increasing. A similar, but

weaker, warm zone marks the equatorial Atlantic and the Guiana Current.

Such a feature is not found in the Indian Ocean, probably because it is overridden

by seasonally reversing Monsoonal circulation patterns.

 

4. Enclosed Seas

Enclosed seas (Gulf of Mexico, Western Caribbean, Hudson Bay, Baltic,

Mediterranean, Black Sea, Caspian, Red Sea, Persian Gulf, Sea of Japan, East

China Sea, South China Sea, Aral Sea, North Sea, and Baffin Bay), whether

in hot or cold regions, show increases in maximum monthly temperatures. As

these are areas of restricted circulation, heat must be building up in the

surface layers, depressing the thermocline, and reducing rates of internal

vertical exchange. Such change is in accord with predictions of increasing

hurricane strength in the Western Caribbean (Emmanuel, 1987).

The only semi-enclosed seas that do not follow this trend are the Indonesian Seas,

which are dynamically very different and discussed separately below.

semi-enclosed seas that do not follow this trend are the Indonesian Seas,

which are dynamically very different and discussed separately below.

 

5. Western Indian Ocean

The entire Western Indian Ocean shows higher than average warming, with

the strongest effects in the northwest area that lies in the core of the Somali

Current, where upwelling appears to have been reduced. The warm Agulhas

Current area also appears to be increasing in heat transport.

 

6. Bay of Bengal

The entire Bay of Bengal north of a line connecting Sri Lanka to the

Andaman Islands is a focus of warming. This warming is likely to produce

increasingly strong cyclones as anticipated by Emmanuel (1987).

 

7. Western North America

The entire western coast of North America shows increased warming. This

would be expected from decreased flow of the cold Alaskan and California

Currents, coupled with decreased upwelling.

 

8. Northwestern Africa

A strong increase in temperature off Northwestern Africa lies in the core of

the area normally affected by the Mauritanian upwelling system. This

temperature increase may indicate decreased upwelling in this area.

 

9. Southwestern Africa

The region normally affected by the cold Namibian Current and southwest

Africa upwelling system is warming sharply, probably due to reduced influx

of cold water by reduced cold current velocity or to a decrease in upwelling.

 

10. Australia and New Zealand

A distinct composite HotSpot surrounds Australia and extends as far as New

Zealand. This is consistent with increased warm current flow from the

equatorial Pacific and Indian Oceans on the east and an increase in the warm

Leeuwin current along the west coast of Australia.

 

11. Southwestern Atlantic

A HotSpot lies off southeast South America from Cabo Frio to the Malvinas

(Falklands). Cold water flow northwards from Antarctica may be diminishing

westerly wind-driven upwelling off Patagonia. Also a change in velocity of

the warm Brazil Current may be reducing local upwelling around Cabo Frio.

 

12. Western South America

Distinct warming is found along most of the western coast of South America.

This implies that the strength of the world's largest shelf edge upwelling area

is decreasing, and that the strength of the cold Humboldt Current is

decreasing.

 

13. Arctic margins

Distinct warming is seen around all the margins of the Arctic Ocean, with

strong HotSpots frequently found north of Iceland and around Spitsbergen

and Novaya Zemlya.

 

Coral reefs that are most vulnerable to HotSpots, if current trends

continue, are those that lie in the areas affected by increasing heat transport in

warm currents (such as the South China Sea, the East China Sea, The Ryukyu

Islands, Australia, the Equatorial Pacific, the Western Indian Ocean, the western

Pacific, Bermuda, Florida, the Northern Bahamas), and Australia, along with

those in semi-enclosed seas (such as the Persian Gulf, the Red Sea, the Gulf of

Mexico, and the Caribbean). These regions are the most vulnerable to losing coral

reef ecosystems and their species from severe bleaching events if current regional

warming patterns and trends continue.

 

http://global24.fatcow.com/WRR%20Goreau%20Hayes%20&%20McAlllister%20.pdf

 


A Sink for Regional Enviornmental Pollution?


Ecology and Resources
The South China Sea owes its distinctive ecosystem to three characteristics: its boundaries of archipelagoes and peninsulas, dotted by small islands and coral reefs; the striking variation in the characteristics of its sea floor, which averages 100 meters deep on the continental Sunda shelf and more than 5,000 meters deep in the Philippine basin; and its unusual monsoon weather patterns of reversing summer and winter rains and winds. The northeast monsoon between December and February and the southwest monsoon between June and August change the surface water circulation pattern with predictable regularity.

 

Crustal Composition of the Northern Margin of South China Sea (SCS):

Implication for Rheological Heterogeneity and Basin Evolution

Yang Wang (Guangzhou Institute of Geochemistry, Chinese Academy

of Sciences, Guangzhou, 510640, P. R. China; and also Department of

Geology, China University of Geosciences, Beijing, 100083,

P.R.China; e-mail: maryhiva@95777.com, wangyang@gig.ac.cn);

Jiyang Wang (Institute of Geology and Geophysics, Chinese Academy

of Sciences, Beijing, 100029, P. R. China; e-mail:

jywlpx@public3.bta.net.cn); Jinfu Deng (Department of Geology,

China University of Geosciences, Beijing, 100083, P.R.China; e-mail:

dengjf@21cn.com)

Based on the velocity structure of northern margin of South China Sea

(SCS) from the seismic refraction profiles, we infer crustal composition

as a function of depth by comparing these velocities with the results

from high-pressure laboratory measurements of seismic velocity for

rocks in the crust. The velocities of profiles were corrected to the

standard P-T condition (25 degree C and 600 MPa) according to the

geotherms constructed along each profile by 1-D and 2-D modeling.

Both of the downward continuation calculation of heat flux data under

steady state conductive assumption and the cooling plate non-steady

heat transfer model are used and compared in our modeling. The

average velocities are calculated for each position at 5-km depth

intervals to Moho depth. Then, the model for crustal composition of

northern margin of South China Sea (SCS) was developed. Beneath the sediment layer,

the relative uniform velocity of around 6.0 km/s in upper crust are

observed in northern margin of SCS, and i! t is matched by granitegranodiorite

or felsic gneiss in lithology. However, the lateral variation

of velocity in lower crust is significant in the northern margin of SCS.

The thick high velocity (>=7.0 km/s) lower crust exists in the eastern

and middle portions of the margin. Meanwhile, the velocity of lower

crust in western portion is in range of 6.5-6.8 km/s. After the P-T

correction, we infer the lithology of lower crust in eastern and middle

portions as mafic garnet granulite, or the mixture of mafic granulite and

upper mantle rocks. The composition of lower crust in western portion

is the mixture of felsic lithologies and mafic granulite, with a tendency

of increasingly mafic component with depth. The thermo-mechanical

profiles in northern margin of SCS were calculated from the thermal

modeling and crustal composition estimation. The results show the

lateral strength variation of lower crust exists between eastern and

western portions of the margin mainly due to the comp! osition

heterogeneity. Since the variation of crustal properties are believed to

result primarily from contrasting, pre-rift crustal structure across the

margin (Nissen et al, 1995, JGR, v100, 22407), we proposed that the

composition-related rheological heterogeneity of lower crust

had influenced the basin evolution in northern margin of SCS. The

ability of crustal rock to flow affects the style and kinematics of rifted

regions (Bertotti et al, Tectonophysics, 2000, v320,195). Therefore, no

flow occurred in the relative rigid east portion of the margin, and

subsidence affected the extending areas to form the Pearl River Mouth

basin. However, Xisha Trough, in where the felsic lower crust exists,

could not prevent the flow to take place. The lower crustal rocks move

towards the rifted zone causing isostatically driven upward movements.

These may explain why Xisha Trough has thin post-rifting sediment,

and failed to develop into the stage of sea-floor spreading.

 

http://www.agu.org/meetings/cc02cabstracts/wang-yang-stu-p.pdf#search='South%20china%20sea%20floor%20geology'  

 

 

 

Earthquake history for the South China Sea Area (Over magnitude 4.0). Yearly data from 1973 to present.

 

Area of Analysis

 

 

 

The yearly earthquake data is for earthquakes of a magnitude of 4.0 – 9.9 covering the following area:
  
  
 Latitude:   15.000N  -   15.000S
  
  
 Longitude:   130.000E  -    90.000E
  
  
 
This area encompasses convergent boundaries of the lower southeastern corner of the Eurasian plate.
 
  
 
  

  

 

 

Once enough South China Sea Temperature data is gathered a graph/chart will be inserted in this page mapping the historical change in Sea temperature data against occurrence of earthquakes for the convergence boundaries of the southeastern portion of the Eurasian Plate

 

 

                    U.  S.  G E O L O G I C A L  S U R V E Y
 
  
                     E A R T H Q U A K E  D A T A  B A S E
 
  
 FILE CREATED:  Wed Jun 14 00:02:58 2006
 Geographic Grid Search   Earthquakes=       331
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1973  -   1974   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data

 

FILE CREATED:  Wed Jun 14 00:05:24 2006
 Geographic Grid Search   Earthquakes=       331
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1974  -   1975   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data

 

FILE CREATED:  Wed Jun 14 00:06:26 2006
 Geographic Grid Search   Earthquakes=       446
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1975  -   1976   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data

 

FILE CREATED:  Wed Jun 14 00:09:11 2006
 Geographic Grid Search   Earthquakes=       520
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1976  -   1977   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data

 

FILE CREATED:  Wed Jun 14 00:07:38 2006
 Geographic Grid Search   Earthquakes=       602
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1977  -   1978   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data

 

FILE CREATED:  Wed Jun 14 00:08:21 2006
 Geographic Grid Search   Earthquakes=       437
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1978  -   1979   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:21:26 2006
 Geographic Grid Search   Earthquakes=       549
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1979  -   1980   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:22:37 2006
 Geographic Grid Search   Earthquakes=       660
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1980  -   1981   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:23:48 2006
 Geographic Grid Search   Earthquakes=       537
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1981  -   1982   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:27:11 2006
 Geographic Grid Search   Earthquakes=       594
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1982  -   1983   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:27:47 2006
 Geographic Grid Search   Earthquakes=       862
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1983  -   1984   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:29:03 2006
 Geographic Grid Search   Earthquakes=       863
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1984  -   1985   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:29:42 2006
 Geographic Grid Search   Earthquakes=       724
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1985  -   1986   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:30:41 2006
 Geographic Grid Search   Earthquakes=       762
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1986  -   1987   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:32:08 2006
 Geographic Grid Search   Earthquakes=       750
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1987  -   1988   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:32:50 2006
 Geographic Grid Search   Earthquakes=       770
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1988  -   1989   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:33:49 2006
 Geographic Grid Search   Earthquakes=       961
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1989  -   1990   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:34:44 2006
 Geographic Grid Search   Earthquakes=       921
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1990  -   1991   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:36:03 2006
 Geographic Grid Search   Earthquakes=       919
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1991  -   1992   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:38:17 2006
 Geographic Grid Search   Earthquakes=       904
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1992  -   1993   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:40:39 2006
 Geographic Grid Search   Earthquakes=       867
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1993  -   1994   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:41:25 2006
 Geographic Grid Search   Earthquakes=      1015
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1994  -   1995   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:42:32 2006
 Geographic Grid Search   Earthquakes=      1561
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1995  -   1996   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:43:24 2006
 Geographic Grid Search   Earthquakes=      1899
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1996  -   1997   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:44:37 2006
 Geographic Grid Search   Earthquakes=      1220
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1997  -   1998   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:45:15 2006
 Geographic Grid Search   Earthquakes=      1298
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1998  -   1999   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:46:14 2006
 Geographic Grid Search   Earthquakes=      1061
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    1999  -   2000   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:10:12 2006
 Geographic Grid Search   Earthquakes=      1398
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    2000  -   2001   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:11:24 2006
 Geographic Grid Search   Earthquakes=      1123
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    2001  -   2002   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:47:54 2006
 Geographic Grid Search   Earthquakes=      1297
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    2002  -   2003   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:48:35 2006
 Geographic Grid Search   Earthquakes=      1330
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    2003  -   2004   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:49:06 2006
 Geographic Grid Search   Earthquakes=      2358
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    2004  -   2005   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
  
FILE CREATED:  Wed Jun 14 00:50:01 2006
 Geographic Grid Search   Earthquakes=      5669
 Latitude:   15.000N  -   15.000S
 Longitude:   130.000E  -    90.000E
 Catalog Used: PDE
 Date Range: Year:    2005  -   2006   Month: 01/Day: 01   Month: 01/Day: 01
 Magnitude Range:   4.0  -   9.9
 Data Selection: Historical & Preliminary Data
 
 

 

Sources Sited/Relevant Sites

 

http://en.wikipedia.org/wiki/Image:Plates_tect2_en.svg

 

http://en.wikipedia.org/wiki/Plate_tectonics

 

http://www.platetectonics.com/book/page_2.asp

 

http://geology.about.com/library/bl/maps/blplatetypesehem.htm

 

 

World Ocean currents:

http://www.physicalgeography.net/fundamentals/8q_1.html

 

http://pubs.usgs.gov/gip/dynamic/understanding.html

 

http://www.rand.org/pubs/monograph_reports/MR1395/MR1395.appf.pdf

 

 

Ocean Temperature and Information

http://en.wikipedia.org/wiki/Ocean 

 

http://www.piercecollege.edu/faculty/leesc/Ocean_10/Exercise/Profiles/Pacific/T/pacific%20T%20list.htm

 

http://www.piercecollege.edu/faculty/leesc/Ocean_10/Exercise/Profiles/Pacific/T/Tsection/0_6000/Pac_T_6_con.htm

 

 

http://www.terrapub.co.jp/journals/JO/pdf/5404/54040347.pdf

 

 

http://www.supercivilcd.com/THERMAL.htm

 

http://www.china.org.cn/english/2002/May/33513.htm

 

http://geology.geoscienceworld.org/cgi/content/abstract/33/10/785