Prof D Chandrasekharam

The 8.9 magnitude Honshu earthquake of March 11, 2011,   occurred due to thrust faulting within the Japan trench. The tectonic configuration of Japan and its surroundings is very complex with 4 plates meeting just below Japanese islands. The islands lie over four plates: the Pacific, North American, Eurasian and Philippine sea plates. The Pacific plate  subducts into the Eurasian plate, the junction of these two plates lie just beneath Hokkaido and Honshu. This is the main Japanese trench and the rate of subduction of the Pacific plate is about 83 mm/year. The length of the Pacific plate is about 2000 km. Thus the geological and tectonic settings of the Japanese islands is very complex and at any given point of time one of these four plates move/thrust giving rise to major earthquakes. The depth of focus of the earthquakes varies from 700 km to 25 km or less.  The eastern margin of the Japanese islands, along the subduction zones is the loci of several active volcanoes.  The 1400 m high Shinmoedake volcano, located over this foci in Kagoshima Prefecture, Kyushu (southwest Japan) has become active after the Honshu earthquake throwing ash and rocks to a height of 4  km.

Earthquakes of this magnitude is not uncommon in and around Honshu. This is not a rare event that occurred at this site.  Over nine earthquake of magnitude >7 occurred in this area since 1973.  An earthquake of magnitude 7.8 struck in an area 260 km north of the 3/11 earthquake in the year 1994. This earthquake caused injuries to 700 people.  Similarly in 1978, an earthquake of magnitude 7.7 struck 35 km south west of the current 3/11 event. This caused injuries to 400 people. Besides this, 8.4 magnitude earthquake of Sanriku in 1933, 8.3 magnitude earthquake of Tokachi in 2003 are note worthy earthquakes in this region. All these earthquakes occurred due to thrust faulting below the Japanese Islands.  Between 9^th March and 11^th  March, 2011, Honshu experienced several foreshocks of magnitudes of  7.2 to 4.2. before the 3/11 earthquake. The main shock was followed by > 100 aftershocks and the after shocks are still rocking the region.

We have  witnessed two devastating earthquakes of magnitudes 9.1 ( Sumatra)  in 2004 and the recent 8.9 magnitude earthquake of Honshu accompanied by tsunamis. The Honshu tsunami occurred even before Sumatra tsunami faded out of our memory. The Sumatra earthquake occurred due to thrust faulting, similar to the one occurred in Honshu, where 1600 km long ocean plate fractured with a slip of 15 mts. The land near Banda Ache was lifted to a height of about 30 m. The tsunami generated due to this major event caused over 250000 deaths in Indonesia, Sri Lanka and India and causing dislocation of population in several coastal regions bordering the Indian Ocean. In the case of Honshu earthquake, the lateral shfit currently estimated is about 8 m. More data on the slip amount is being calculated. Both the earthquakes are shallow with the focus depth placed between 25-30 km. But the dimension of Sumatra earthquake and tsunami is larger by several factors compared to the Honshu earthquake. The Sumatra tsunami could travel 3500  km from the source caused devastating damage. A similar features was expected from Hnashu tsunami but the energy of the waves attenuated even before they could reach the nearby islands. The wave height measured at Hawaii islands, located at a distance of 6300 km from the epicenter was about 0.7 m.  

Majority of the earthquakes over Honshu occurred due to slip at shallow levels. The buildings in Japan are built strictly according to the codes. This is the reason one could see pictures in the television where tall structures in Tokyo were swinging at the time of the earthquake and returned to its normal poison. The death toll due to  earthquake in Sendai is far less compared to that due to the tsunami. We have to learn a lot from the Japanese civil engineers about making tall earthquake resistant structures. We do have codes on papers. Only an earthquake of magnitude half of that of Honshu will be able to prove how strong these structures are!!

The recent events all along the Pacific rim only demonstrates the dynamic changes that are taking place within the internal Earth system. We have a long way to go to  understand the dynamics of this system. Earth Sciences need to be given priority at school level itself, like other countries, to generate state-of-art younger generation of earth scientists to tackle such natural disasters in future. As far as Indian coast is concerned, the east coast is more vulnerable to tsunami related disasters as the coast is in line of sight of the grate Andaman-Nicobar-Sumatra – Sunda arc system. The west coast is not facing such arc system and hence chances of tsunami related disasters occurring are minimum. Only normal faulting, as evident from several earlier faults events, is a cause of concern, both on shore and off shore of the west coast, as reported in 1985 based on an integrated geophysical and geological analysis.

Black carbon, Carbon Dioxide and geothermal !!

These three are intimately related! One causes global warming while the other  controls global warming!!

 Over centuries, civilizations used firewood, biomass and dung cake to sustain  lives. For both cooking and heating purposes this was and is the cheap and easily available stock to humans. Excess use of any such energy sources is harmful and the consequences are being felt by the current generation. In the current industrial era, besides the above fuels, fossil fuels like coal, diesel and kerosene enhanced the black carbon (BC) content in the atmosphere further to our misery!!  Changing weather pattern, fast retreating glaciers, droughts,  flash and summer floods are the consequences of such uncontrolled BC emission. Carbon dioxide also plays a major role but CO₂ has a long term effect while BC has a short term effect. 

Coal, fuel wood, dung cake and agricultural waste are consumed maximum in that order in India. According to 1996-2001 data, 286 Mt (million) of coal, 302 Mt of fuel wood, 121 Mt of dung cake and 116 Mt of agricultural waste was consumed in India.  The consumption of these fuels has increased by several folds due to increase in population and hence demand. BC emission factor of these fuels in that order is ~ 0.8, 1.1, 4.4 and 1.3 g/kg. 

BC  absorbs sunlight turning it into heat. Thus, a layer of BC in the atmosphere, while emitting a third of this absorbed heat back in to space, keeps the earth’s surface warm. More BC in the atmosphere means more heat over the surface of earth. As the BC increases the earth’s surface gets hotter and hotter!! Simple logic.  Thus BC causes change in the heat input at the top of the atmosphere. This is known as “Radiative Forcing (RF)”.  According to the Intergovernmental Panel on Climate Change (IPCC) 2007 report,  RF of BC is of the order of + 0.34 W/m² while forcing of CO₂ is of the order of + 1.66 W/m². 

 What is Black Carbon?? The black soot, that all of us observe in our daily life, is known as black carbon (BC). BC forms due to combustion of carbon based fuels at high temperatures.  Thus the sources of BC are fossil fuels (coal, oil, gas), biomass, agricultural waste, dung etc. The life of BC in the atmosphere is about a week, while CO₂ lingers for several decades. Both BC and CO₂ have tremendous effect on global warming and glacier retreat. BC has strong light absorbing property. Thus short term control of global warming can be accomplished by controlling the BC emission. If BC emission is controlled then half our problems related to global warming is solved!! In developing countries like India and Africa, BC emission emerge mainly from rural sector while transport sector is the main source of BC emission in the developed countries.  High percent of biomass and dung is used in rural regions for cooking, space heating and consumption of such fuels is high during winters.

The emission values reported in the literature for BC and other related aerosols in the atmosphere varies like the climate!  There is no consistency in the emission values reported. The values keep changing between the authors and sometimes with the same author!. Each authors claims that their value is the best!!

 According a paper published in “Atmospheric Environment” in 2002 the BC (India) emission of dung cake  is 0.25 g/kg and that of crop waste is 0.47 g/kg. Another paper that appeared in the same journal in 2005 reported BC emission of dung cake from 2.2 to 6.6 g/kg and that of agricultural waste from 0.2 to 2.4 g/kg!! Value reported by the same author also varies with time!! Perhaps such discrepancies may be related to the betterment of analytical techniques and demographic data. Such uncertainties are ( E.g. see Jr. Geophy. Res., 2004) due to extrapolation of data such as population, per capita consumption ( varies by a factor of 3!), economic data etc. and also due to over prediction of fuel-use measurements!!.

 Irrespective of these numbers, the truth is, India, next to China, is the leader in BC emission!.

 The total BC emission by India ( 2000 base value) as reported earlier, was 600 Gg (Jr. Geophy. Res., 2003, v,108) while in 2008 this value has changed to 1343 Gg (Geophy. Res. Lett., 2008, v. 35)!!.  Thus one gets two values for per capita emission of BC in India. One at 600 g and the second, just double this value!! It is safe to take the minimum value for all discussions.

 In India, maximum BC emission is from rural areas like Leh. Leh is  located at an altitude of 4500 m in the Himalayas (in Ladakh province of J & K), where the temperatures falls 15 °C below zero in winters. Combustion rate of all fuels are low at this elevation. Dung cake, biomass and coal are extensively used to heat the homes and of course for cooking also. Guest houses, army and affluent society use cooking gas or “bukharis”,  a device that uses kerosene ( or some times saw dust) to heat rooms and homes. CO, CO₂ and BC are ejected out in to the space through an exhaust pipe. 

 Population of Leh is ~ 68,000 and with the reported per capita BC emission of 600 g (2000)  Leh alone is contributing minimum of about 0.04 Gg of BC annually. Similarly, Kargil with a population of 119,307 is contributing about 0.07Gg of BC to the atmosphere around the glaciers.  A similar emission figures can be assumed from other towns located at that altitude all along the higher Himalayas, extending from NW to E of India.  The BC emission from the foot hill Himalayas also reach higher altitude. During winter ( where BC emission is maximum) snow brings down all the BC floating in the atmosphere. This is the reason why many Himalayan glaciers appear black. It is easy to estimate the BC content in ice. Since it is possible to date ice, BC content in the atmosphere in the past can be estimated.

 The Gangotri glacier is retreating at a rate of 18 m/yr. This is really alarming and this observation is not disputed. The real “component” that is responsible for this retreat is BC

 Simulation studies conducted by Lawrence Berkeley National Laboratory in Feb 2010 showed that major contributor (~90%) for fast melting of glaciers is BC.

 How does this happen? BC deposition on white surface like snow and ice absorbs more light and become warmer faster than pure ice/snow and thus enhances melting process. If ones visits the Gangotri glacier, a major part of the ice body appears dirty ( black) because of small BC particles in it.

 BC content in ice cores recovered from ERG glacier is about 20 mg/kg. while global average BC content in snow is about 5 mg/kg. This is alarmingly high!! 15 mg/kg of BC in snow reduces about 1% of its albedo. This is a clear indication that the 18m/year retrieval of Gangotri glacier is due to this huge BC emissions from rural Higher Himalayan villages/towns.

 In addition, BC from Asian region also travel to the Himalayan region contributing additional amount to BC.

 Since BC heats the atmosphere, it creates local thermal anomaly thereby disturbing the normal atmospheric convection pattern that exerts tremendous influence on the precipitation. Perhaps this could be the reason for the flash flood that devastated Leh in 2010!

 The residence time of BC in the atmosphere is about a week while CO₂’s is several decades. So BC does not accumulate while CO₂ accumulates in the atmosphere. What it means is that through controlling BC emissions, global warming can be controlled within in a short period of time.  It is very easy to control BC emissions without compromising life comforts!! The pristine Himalayan ecosystem can be protected and fast deteriorating glaciers life can be restored by tapping the huge geothermal resources available in Leh.

 Straight away 150 million grams BC emision from Leh and Kargil  can be stopped immediately by tapping 2 billion kWhr of electric power from Puga and Chumathang geothermal provinces ( Himalayan geothermal belt)!!. In fact, Leh and Kargil may need maximum 10 % to 20 % (assuming future demand of Leh) of this power. The remaining can be supplied to the Kashmir valley there by further reducing BC emissions from the valley during winters. Once clean power at affordable price is available, there is no need to burn bio-fuels to keep the homes warm during winters!

 In fact, Lhasa, in Tibet gets it power from the Yangbajing geothermal province situated within the Himalayan geothermal belt that generates 0.2 billion kWhr of electric power. In fact the geothermal energy in Leh can also be used for green house cultivation and the Leh population can be self-sufficient not only with respect to electric power but also with respect to food. China has a major plan to tap the huge geothermal reserves from the entire Himalayan geothermal province, extending from Puga belt to Arunachal Pradesh and provide CO2, BC free power to all its cities, towns and villages in the southern part of China including Lahsa. This will make China to reduce CO₂ and BC emissions drastically and earn millions of dollars under CER and become a major “carbon trader) in the entire south and south-east Asia.

 There are other geothermal provinces in the mid India continent that can very well be used to have source mix for generating electricity thereby reducing dependency on fossil fuel based power and reduce carbon dioxide and BC emissions and also earn carbon credits through CER. The world as on today generates > 10,700 MWe of geothermal power. The technology is very well established. Now tremendous development in binary fluid / heat exchanger technology is rendering utilization of thermal waters with low temperatures ( as low as 80 °C) for generating electric power.   India has the expertise and technical know how. Only the policy makers need to have the will to develop it.

  For more details on the geothermal resources of India please read earlier postings.

What is Black Carbon (BC)??

What is its role on climate ?

How much BC is emmitted by OECD and non-OECD countries, what are the sources of BC, how geothermal can help in reducing the effect of BC on climate

and all these issue will  soon be coming.

Keep watching this post

“”The nation that leads the world in creating new sources of clean energy will be the nation that leads the 21st century global economy”” ….. Barack Obama, President of  USA. 

“We have an ambitious agenda to put millions of people to work by investing in clean energy technology like geothermal and solar energy……” Steven Chu Energy Secretary, USA.

There are two perennial energy sources that are available to all the living beings on Earth ever since Earth was born about 4.5 billion years ago. Till now these sources never failed and will continue till human race want. Sun and Earth are like furnace transmitting heat to the surface of Earth.  Unlike coal, oil and gas, these sources will never deplete. Its depletion means– the end of human race. Life will disappear like the dinosaurs once Earth and Sun ceases to supply energy. The energy from these two sources is clean. Countries have realized this fact and started harnessing geothermal since 1904 when the first electric bulb glowed in Larderello. Over the years geothermal energy stared contributing to the electricity demand in a small way and now its contribution is greater than 10,000 MWe. With constant development in surface and subsurface technologies, countries have realizing that energy independence is better than energy security and investing more in to this green power. Wet geothermal systems may be limited in geographical extent but enhanced geothermal systems ( also know as engineered geothermal systems or hot dry rock systems etc) have no such boundaries. Perhaps in future every housing colony, super malls etc. may have its own independent electric supply systems through EGS.  France has successfully experimented and showed to the world how to create natural heat exchanger within granites. Australia will be the second country to tap this source.   India has large EGS resources waiting to be tapped.  

 The future energy need of all the countries will be met with by EGS systems.  For example, 2% of the energy (EGS) if tapped will be sufficient to meet the energy demand of United States of America, according to “  The Future of Geothermal energy “ of MIT 2006.

 “……….Over the next decade Geodynamics plans to build ten 50 megawatt (MW) power stations in Cooper Basin, and that may just be the beginning. According to Doone Wyborn, the company’s chief scientist, the area’s resources could support  hundreds of power stations with a total generating capacity of up to 12.5GW—more than all the geothermal power stations now operating worldwide……………… These benefits, in combination with growing electricity use worldwide, concerns about limited supplies of fossil fuels, and efforts to reduce carbon-dioxide emissions and prevent climate change, have prompted governments and investors to pour money into this emerging technology.  Google, for example, has invested more than $10m in two EGS companies in California, Potter Drilling and Alta Rock Energy. Meanwhile America’s Department of Energy has announced up to $338m in stimulus funds for 123 geothermal projects, with nearly $133m earmarked for EGS research……………………” states  “The Economist” dated 2 Sept. 2010. 

This year, President Obama announced $350 million to expand and accelerate the development, deployment, and use of geothermal energy throughout the United States. This funding will support projects in four crucial areas: geothermal demonstration projects; Enhanced Geothermal Systems (EGS) research and development; innovative exploration techniques; and a National Geothermal Data System, Resource Assessment and classification System. $ 140 million is allotted to support demonstrations of cutting-edge technologies to advance geothermal energy in new geographic areas, as well as geothermal energy production from oil and natural gas fields and low to moderate geothermal resources. $ 80 million is allotted to support research of EGS technology to allow geothermal power generation across the country. Conventional geothermal energy systems need wet geothermal sources while EGS makes use of available heat resources through engineered reservoirs, which can then be tapped to produce electricity any where. $ 100 million is allotted to support projects that include exploration, site location, drilling, and characterization of a series of exploration wells. Exploration of geothermal energy resources can carry a high upfront risk. By investing in and validating innovative exploration technologies and methods, Department of Energy, USA, can help reduce the level of upfront risk for the private sector, allowing for increased investment and discovery of new geothermal resources.

 EGS technology is more or less well established. Following France and Australia other countries like Germany and England are lined up to harness this heat. 

 India is not lagging behind EGS resources. Perhaps, India has the richest EGS resources considering the volume occurrence of high heat producing granites.  About an year ago, in a publication entitled “ Granites and granites: India’s warehouse of EGS” in Geothermal Resources Council’s Bulletin followed by a recent proceedings published by the World Geothermal Congress 2010, it is stated “ Assessment has been carried out on the power producing capacity of thee granites using the U, Th and K content. For example, estimates on a small volume of granite from northern India indicate that they have the potential to generate minimum of 61160 x 10¹² kWh. Perhaps EGS, in future, may make India energy independent and wipe out the 78,577 MWe deficit.  Considering the total surface exposure of such high heat generating  granite over the Indian subcontinent (150000 sq. km), their depth of occurrence and the stress regime of the Indian plate Indian granites will be future warehouse of EGS…………… Indian government has realized this potential and making efforts, through slow, in bringing geothermal under the primary source mix. India in future can  disprove the IEA (2007) report that it will a major coal importer in 2030 if its geothermal resources are judiciously utilized not only for power generation but also in building and food processing sectors”…………states these publications.

“Deriving energy from subterranean heat is no longer limited to volcanic regions. By drilling deep wells into the ground, it can be made to work almost anywhere. Engineered geothermal systems (EGS) are based on a related principle, but they work even in parts of the world that are not volcanically active, by drilling thousands of meters underground to  mimic the design of natural steam or hot-water reservoirs. Wells are bored and pathways are created inside hot rocks, into which cold water is injected. The water heats up as it circulates and is then brought back to the surface, where the heat is extracted to generate electricity. Because the Earth gets hotter the deeper you drill, EGS could expand the reach of geothermal power enormously and provide access to a virtually inexhaustible energy resource” states a news item on “HOT ROCKS AND HIGH HOPES” (Inside story) in “The Economist” dated 2 Sept. 2010.

 Geothermal systems are based on circulating hot water, heated either by volcanic or tectonic ( deep continental rifts) systems. Such system where natural rain water circulates is known as wet geothermal systems.  As on today, according to the recently concluded “World Geothermal Congress 2010,  10,700 MWe of power is being generated from geothermal energy supplying 85 million Gwhr of electric power.                                                           

The future energy need of all the countries will be met with by EGS systems.  For example, 2% of the energy (EGS) if tapped will be sufficient to meet the energy demand of United States of America, according to “  The Future of Geothermal energy “ of MIT 2006. Currently  Soultz EGS systems has started functioning successfully. This will soon be followed by the EGS system in the Cooper Basin of Australia.

 “……….Over the next decade Geodynamics plans to build ten 50 megawatt (MW) power stations in Cooper Basin, and that may just be the beginning. According to Doone Wyborn, the company’s chief scientist, the area’s resources could support  hundreds of power stations with a total generating capacity of up to 12.5GW—more than all the geothermal power stations now operating worldwide……………… These benefits, in combination with growing electricity use worldwide, concerns about limited supplies of fossil fuels, and efforts to reduce carbon-dioxide emissions and prevent climate change, have prompted governments and investors to pour money into this emerging technology. Google, for example, has invested more than $10m in two EGS companies in California, Potter Drilling and Alta Rock Energy. Meanwhile America’s Department of Energy has announced up to $338m in stimulus funds for 123 geothermal projects, with nearly $133m earmarked for EGS research……………………” states  the above magazine.

 EGS technology is more or less well established. Following France and Australia other countries like Germany and England are lined up to harness this heat. 

 India is not lagging behind EGS resources. Perhaps, India has the richest EGS resources considering the volume occurrence of high heat producing granites.  About an year ago, in a publication entitled “ Granites and granites: India’s warehouse of EGS” in Geothermal Resources Council’s Bulletin followed by a recent proceedings published by the World Geothermal Congress 2010, it is stated “ Assessment has been carried out on the power producing capacity of thee granites using the U, Th and K content. For example, estimates on a small volume of granite from northern India indicate that they have the potential to generate minimum of 61160 x 10¹² kWh. Perhaps EGS, in future, may make India energy independent and wipe out the 78,577 MWe deficit.  Considering the total surface exposure of such high heat generating  granite over the Indian subcontinent (150000 sq. km), their depth of occurrence and the stress regime of the Indian plate Indian granites will be future warehouse of EGS…………… Indian government has realized this potential and making efforts, through slow, in bringing geothermal under the primary source mix. India in future can  disprove the IEA (2007) report that it will a major coal importer in 2030 if its geothermal resources are judiciously utilized not only for power generation but also in building and food processing sectors”…………states these publications.