Thursday, December 27, 2007

When A Forest Is Not a Forest

A dense growth of trees and underbrush covering a large area - The American Heritage Science Dictionary

A large tract of land covered with trees and underbrush - Unabridged (v 1.1)

A large area covered with trees and undergrowth - Oxford dictionary

Judging by these definitions could one call the area shown in below image as a forest?

If the Union Ministry of Environment and Forests (MoEF) has its way, then this dense growth of trees and underbrush (Law College land, Pune city) cannot be called a forest and can be exploited by commercial interests without permission from MoEF. The reason is an attempt to define forests in a way that excludes the common sense definitions of forest, three of which I quoted above. According to the new proposed definition, only those areas notified by the government as forests in any Act or recorded in any government documents as forests can be considered a forest. Other dense growths of trees and underbrush not under government control need not apply although the Supreme court has allowed the common sense definition to be considered irrespective of ownership. Only the Indian bureaucracy can come up with such an absurdity. Consider the situation in the image below.

Here the entire area in the image (reserved hills of Pune city) is a notified forest regardless of whether it is actually covered with trees or is barren. I have no problems with this. Afforestation can rejuvenate barren lands. With global warming threatening India, such large scale afforestation programs on barren forest land can contribute in mitigating climate change in many ways. So then why not protect already dense growths of trees which happen not to be official forests? If these lands lose protection as they will if this perverse definition is adopted, they will no doubt be stripped of their green cover in no time. According to the Forest Survey of India, around 2.5% of the total land area of India is covered by Trees outside Forests, i.e. woodlands, sacred groves, and other clumps of trees not officially under government control. This comes to around 80,000 sq km, which is an awful lot of greenery with no potential protection from the government.

Governments like blanket rules. So much easier to implement than to let scientists examine case by case whether an area is ecologically sensitive and should be protected regardless of whether it is an official forest or not. Doing that would be giving Indian scientists too much power. Never! Inch by inch, Act by Act, definition by definition the Indian government is abdicating its responsibility to conserve and manage India's forests and biodiversity. Our basic philosophy of forest management has not changed since the days of the British raj. They looked upon Indian forests as a resource to be exploited. Forest management working plans were written with this in mind. The focus has been and still is on timber and mono-culture plantations and not on conservation and biodiversity. Successive Indian governments have been no more enlightened in their thoughts and actions. Do you think the timber and mining industry has any say in the matter of this new "definition". These are worrying times for the environmental health of our country.

Wednesday, December 19, 2007

The End of Darwinian Evolution?

It’s hard to make predictions, especially about the future- American baseball player Yogi Berra, or was it Mark Twain who made this comment? Either way, it’s hard to disagree. Maybe that’s why I chose to study geology. So much easier to figure out what happened in the past! Darwin’s Last Gasp was the provocative title of an editorial in the Times of India a few days ago. Mukul Sharma writes:

With globalization in progress the different races are no longer going to be evolving away from each other. Unlike what happened earlier when humans dispersed to separate regions and developed unique gene pools that made them less alike, the trend now is being reversed with a tendency of merging into a single mixed humanity.

The other reason why Darwinian evolution may finally have to give up on its mechanisms is because natural selection is about to be bypassed altogether by genetic manipulation technology. Ultimately - say in about another 50 years or so - artificial selection using genetic engineering techniques will make evolution forever irrelevant, at least as far as our species is concerned.

The research that prompted this article suggested that human adaptive evolution fueled by the advent of agriculture and a population explosion has accelerated over the last ten thousand years or so. That may well be so says Mukul Sharma, but not anymore. Take his first assertion. Humans are migrating in large numbers and mixing up the gene pool and that’s the end of Darwinian evolution for humans. Is it the end of evolution or the end of evolution through natural selection commonly known as Darwinian evolution and what’s the difference between the two? Most people take evolution to mean adaptive evolution through natural selection i.e. a change over generations to a better adapted state. It is this kind of evolution that the research on accelerated evolution concentrated on. Biologists have a more inclusive definition which is changes in the frequency of alleles in a population from one generation to the next. Evolution is a process that causes heritable changes in the properties of populations over generations. Individuals don’t evolve. Modern population migrations cause great demographic changes especially given the declining fertility rates in many western nations. So, say with Indians immigrating to England in large numbers, northern European genes will decline in frequency relative to south Asian ones. The genetic structure of the population will change over generations i.e. it will evolve. Even without migration, populations can evolve without natural selection taking place. This is by a process known as random genetic drift. Biologists acknowledge that the vast majority of mutations may not be advantageous but neutral or almost neutral, meaning they do not affect reproductive fitness. Natural selection is blind to such neutral changes and the frequency of such genes can fluctuation randomly over generations until just by chance one allele completely replaces the alternate version i.e. the mutation becomes fixed in the population. So mixing of populations won’t stop humans from evolving even in the absence of natural selection. And it certainly has not stopped acting in the poorer countries where enormous differences in mortality rates still exert strong directional selection pressures for change.

The notion that natural selection has stopped working on human populations is mainly related to advances in medical technology and the overall improvements in standards of living. This undoubtedly has led to a relaxation of mortality selection, the most familiar form of natural selection. People who used to die before reproducing due to disease and poor health linked to bad genes now don’t die in the same numbers. Such faulty genes therefore don’t get eliminated from the gene pool. For example the frequency of genetically determined red-green color blindness is about 5-10% higher in western urban males than in traditional hunter gatherer or non-industrialized farming societies living today. This is an indication that selection has been relaxed in western populations. But natural selection works on humans (and other organisms) in several other ways at various stages of our life cycle, and these have not been affected by medical advances so far. These other forms of natural selection are 1) selection at the gamete stage, 2) selection at the embryo stage and 3) sexual selection at the reproductive stage. There is some evidence that selection can weed out defective sperm mostly based on the extreme gymnastic contortions sperm cell have to perform within the female reproductive system. It is possible this is selection for the quality of sperm. And there is also some evidence that there are more mutations in early-stage cells than in the final fertilized egg, suggesting that mutations are being weeded in the female gamete as well. Out of several hundreds of million sperm cells, only a few taste success, and out of 5-7 million oocycts only a few hundred or so become eggs, so selection most probably is playing a role eliminating faulty cells at this stage. How would selection work at an embryonic stage? About 60% of our genes are expressed at this stage, ones involved in basic cellular physiological functions and those involved in development. Again bad genes which are expressed at an early stage in the embryo will cause faulty development of the embryo and likely death. The estimate is that about 80% of conceptions that are lost before birth are likely the result of natural selection. Finally there is sexual selection. If individuals have the ability to screen potential mates for bad genes, then such choice may lead to elimination of these genes as bearers of these genes remain without a partner. Do humans have such abilities? As usual Darwin got there first by referring to a French and Scottish study which showed that single men had twice the natural death rate as married men at years 20 to 30. Similar patterns exist in Asia, Europe and America and being single is apparently one the biggest risk factors for human beings. This may off course mean that marriage improves health, but the other explanation that health improves your chances of marriage is also highly probable. It is likely we make conscious choices or get unconsciously influenced regarding the genetic quality of potential mates.These forms of natural selection will continue to affect us humans even during demographic changes, population mixing and the current medical technologies.

Mukul Sharma’s second assertion is that “artificial selection using genetic engineering techniques will make evolution forever irrelevant, at least as far as our species is concerned”. In making this assertion he misses the altogether important point that artificial selection is also a mechanism of Darwinian evolution and contrary to making evolution irrelevant it has the potential of transforming it into an even more potent force. Darwin himself began his one long argument using artificial selection carried out by pigeon breeders and domestication of cattle to ram home the point that populations can change very rapidly through such means. Darwin thought of natural selection as acting through the differential survival and reproduction of individuals. Artificial selection if society goes in for it will change human populations not by eliminating individuals or banning some from reproducing but by preferential representation of certain genes by making changes at the early gamete stage of the life cycle. Initially such selection will focus on disease genes but there could be other types of changes possible. Recently I read an article about the super rich in Newsweek magazine. The tendency is to form exclusive clubs and networks and isolate oneself socially and culturally from the rest of the plebeian population. If this trend of cultural isolation continues then how long until certain groups opt for genetic isolation through artificial selection? Will we see evolution of enhanced features or abilities in certain groups? All this is speculation. Most predictions about the future including the ones I am making will be wrong. Humans may decide to regulate the use of genetic engineering for certain medical applications only, or it may go the other way, where cultures may decide to isolate themselves from other groups and go in for strong directional evolution in many traits through artificial means. An as yet undiscovered pathogen may evolve to which our medical knowledge have no answer to, restoring strong mortality selection.

Is there a possibility of even more fundamental changes to our genome? Evolutionary biologist Mark Ridley has speculated that our current level of biological complexity is limited by mutational load mainly through copying errors when our DNA gets replicated. Nearly 2 billion years ago repair enzymes evolved that reduced copying errors from about 1 in 10,000 to about 1 in 10,000 million. This enabled an increase in biological complexity. There is a hint that our mutation rates are very high. For humans it takes on average about five estrus cycles for a fertile male and a fertile female to produce a baby. This indicates, although is not proof, that the four unsuccessful attempts are related to genetic errors mostly copying errors. Could we fashion an even more efficient repair enzyme, one that reduces the error rate even further multi-fold fueling evolution of humans towards even greater complexity? The only certainty is change. I would wager (to be settled by my potential descendants :-) ) that 5,000 years from now our descendants will be as different from us as we are from our ancestors who lived 10-15,000 years ago.

Monday, December 17, 2007

More Chest Beating About Climate Change

Finally what has been and has not been achieved at the recently concluded climate change conference in Bali? Going by the infantile jingoistic Indian media, this was the place where India stepped up to the plate and saved the world from a global meltdown perhaps literally. The Times of India has a lot of space devoted to how India lead by knight in shining armor Kapil Sibal forced the U.S to change its position and cornered Europe into supporting the Indian position.

Some excerpts from the Times of India:

"India beams as climate deal clinched"

"India led by science and technology minister
Kapil Sibal, clinched an almost impossible deal at the UN conference on climate change in Bali"

"At this point,
Sibal intervened to put forth the Indian position yet again. It's unusual at such a forum and the aggressiveness of the minister shocked many.....America had been cornered"

" It was a hard-fought win, but we have secured India's position....."

Infantile stuff, more like what you see in England's gutter press after that rare football victory against Germany. So what is this deal that the Indian media is crowing about?

Apparently now further talks will take place on two tracks, one comprising those countries who have agreed to mandatory emission reductions, essentially building on the talks of the Kyoto protocol, and the second track comprising those countries who have not agreed to emission reductions. This two track formula is important as it leaves the door open for countries to join mandatory reductions. Agreeing to this formula, prevented a total collapse of talks. This means that negotiations would now continue beyond the Bush administration and hopefully will deal with a new, more cooperative U.S. administration.

Reading plainly it means that no binding agreement was reached on any issue! Its like that old joke about the four procrastinators who after a long meeting agree unanimously to meet again.

What does this mean for India?

No binding targets in reducing emissions

Vague promises to transfer subsidized new clean technology to India and other developing nations

But India has agreed to seek ways to make "measurable, reportable and verifiable emission cuts"

No money to upkeep forests using clean development mechanisms such as carbon credits.

Doesn't sound like too much of a victory to me. Sunita Narain the director of Centre for Science and Environment in Delhi in an interview with CNN-IBN was also pessimistic stating that technology transfer is an old issue being rehashed at this conference. So far 15 years of talks and not a dollar has been transferred. We still have to at some point start making those emission cuts. And that bit about no money to upkeep forests sounds very foreboding.

Some thoughts on human behavior. Can we really think that U.S negotiators are that stupid and ill prepared or even allowed to "change their minds" at the last minute? The clouds of discontent have been brewing for a long time internationally and lately within the U.S. The Bush administration is in its last year. Does one really think that U.S negotiators were oblivious to all this and came to the conference really believing that they could swing everything in their favor? I suspect they were ready to support the consensus all along but held on to see how much their luck lasts. Sure some pressure works, but this pressure has been building for a long time both internally and most notably the threat from EU to boycott a U.S sponsored meeting on climate change in Hawaii. A country which declares war against the wishes of the entire world is not going to be bothered by a few boos and shouts. Negotiators do have some latitude but it is naive to believe that they will be pressured at the last minute into taking a position that is not allowed by the brief given to them. But the Indian media will have us believe that Kapil Sibal changed all this. I don't mean to disparage the efforts of Mr. Sibal. By all accounts he did a stellar job. But a little more balanced reporting please.

Finally and more importantly than the antics at Bali, is India going to base future emissions policy on technology transfer promises, something that still needs painful long negotiations to achieve? Would that mean a neglectful attitude from the government towards alternative renewable energy? Does that mean a surge in coal plants to generate electricity on the premise that clean technology is on its way but may not happen at all or for some time? Does that mean more tracts of our forests to be given to commercial exploitation on the pretext that we are not receiving funds to protect them? We should not deceive ourselves into thinking that Bali was a great victory. If anything it might lull us into a complacency that might prove disastrous.

Wednesday, December 12, 2007

Radioactivity and India's Water Resources

From EurekAlert Earth Sciences Feed:

"Ice cores drilled last year from the summit of a Himalayan ice field lack the distinctive radioactive signals that mark virtually every other ice core retrieved worldwide. That missing radioactivity, originating as fallout from atmospheric nuclear tests during the 1950s and 1960s, routinely provides researchers with a benchmark against which they can gauge how much new ice has accumulated on a glacier or ice field."

What that means is that Himalayan ice fields are melting away rapidly, so rapidly that the characteristic signal of the 1950's atomic tests has been literally washed away with the melting ice. Much of the Indo-Gangetic plains depends upon glacial meltwater as a source of freshwater that feeds the massive north Indian rivers. If that supply dwindles then water shortages loom ahead. How big is India's water problem. A recent report released by the planning commission has this assessment:

“Currently, total water use (including ground water) is 634 BCM (billion cubic metres), of which 83% is for irrigation. The demand for water is projected to grow to 813 BCM by 2025 and 1447 BCM by 2050, against utilisable quantum of 1123 BCM – 690 BCM from surface water and 433 BCM from ground water. Clearly, the overall demand will outstrip availability in another 35 to 40 years, while ground water in particular will come under even greater pressure in the intervening years.”

So we are headed for a shortfall. The planning commission report provides several recommendations for narrowing the deficit including, artificial recharge of groundwater, extra storage of surface water, and improved efficiency of groundwater use by changes in groundwater law. The troubling part of the report is that it makes no mention of climate change and what effects melting glaciers, erratic monsoons, increase in frequency of droughts, all the expected fall outs of global warming may have on water availability. Has the utilizable quantum of 1123 BCM – 690 BCM from surface water and 433 BCM from ground water been calculated taking into account the expected fall in supply due to shrinking glaciers and erratic monsoons? If the pattern of rainfall changes from a slow steady fall to infrequent high intensity rains, how will that affect groundwater recharge? With glacier shrinking, the surface water availability will increase in the short term but decrease over the medium to long term. Has that been factored in? If rainfall pattern changes over large areas to shorter high intensity pattern, how should we best utilize the increased surface water flows? I did not read the entire report, but did read the conclusions and also did a word search for the terms melting / shrinking glaciers, global warming, climate change and came up with zilch. Sounds like the report assumes unchanging conditions that control water availability.

There already have been accusations that the government has massively overestimated the available water today. Though these new estimates have also been criticized (water debate), any planning commission report which may influence water use policy that does not take into account the changing water availability scenario due to climate change is cause for major concern.

Friday, December 7, 2007

Pleistocene Stone Tools From Near Pune

Some exciting news about 60 km from where I live in Pune. Archaeologists from Deccan College, Pune have discovered stone tools at Morgaon. These tools of Early to Middle Pleistocene age have been dated to about 800,000 years based on magneto-stratigraphic dating of volcanic ash deposits associated with these tools. These tools belong to the lower Paleolithic Acheulean industry, a style of tool making where both surfaces of the tools are flaked to produce symmetrical hand axes of distinctive pear and disc shapes.

Image to the left shows the Acheulean tools from Morgaon (source Times of India). The age of these tools indicate that these tools were made by representatives of the now extinct species Homo erectus. This is an inference based on our overall understanding of human evolution and not due to the preservation of Homo erectus remains alongside the stone tools at this site. In India remains of Homo erectus are extremely rare. In fact, only one unequivocal fossil from the Narmada basin has been discovered. There could be many reasons for this such as the low preservation potential of terrestrial species to begin with or these fossils are preserved in very specialized geological contexts, or an interesting suggestion by anthropologist Parth R. Chauhan that hominin fossils many not be recognized as such since most such work in India is carried out by geologists or archaeologists and not physical anthropologists who are better trained to recognize hominin fossils. There is however quite a rich archaeological record of stone tools in India. The oldest unequivocal evidence is from Isampur in Karnataka, where again Acheulean style tools of around 1.2 millions years ago have been discovered. The Paleolithic tool finds in India have been nicely summarized here. Whatever the reasons for the lack of fossils, this presents a good example of the sometimes infuriating situation a field of study can find itself in. An abundance of one type of evidence and a virtual lack of a complimentary type. In this case, a rich collection of tools, but no signs of its maker. The lack of hominin fossils has certainly hampered studies of human evolution in the south Asian context. Tools indicate an early presence of the genus Homo in India (at least 1.2 million years ago), but we know little of the subsequent evolution of this species in India in terms of morphological changes interpreted in the context of changing climates and environments. Did Homo erectus evolve into a more modern form, know as the archaic modern human morphology as has been observed in Europe and Africa? Can the changing tool technology through the Indian Paleolithic record be interpreted in the context of such evolutionary changes? There is a potential here to make important contributions to the Multi-Regional vs Out-of-Africa debate on modern human origins, but at present that potential is unexploited.

In any case this is an exciting and important discovery. It supports our overall understanding of the evolution and migration of populations of Homo erectus which is considered the first member of the human family to have migrated out of Africa. The earliest evidence of this genus is from Africa dated to nearly 2 million years ago. The earliest evidence outside Africa is from Dmanisi in Georgia (central Asia) dated to about 1.7 million years ago. The Isampur tools indicate that populations of Homo erectus migrated into India at least 1.2 million years ago maybe even earlier. This latest discovery adds to our slowly increasing knowledge of the distribution of Homo erectus populations in India and the variation in stone tool technology prevalent at that time. It is another piece in an accumulating database, but by no means an earth-shattering find.

The Indian media should view this discovery as such and not launch into breathless, nationalistic "we got here first" or " we have the oldest stone tool technology" interpretations. There are hints this is already happening. From the front page of Times of India:

"The evidence - mostly Acheulean artefacts and tools made of basalt stone - comes relatively close to that of the oldest evidence of such tools found in Africa and dating 14 lakh years". How is a gap of more than half a million years close? And don't forget Isampur in Karnataka, which has already pushed back the date of Acheulean stone tools in India to 1.2 million years.

Monday, December 3, 2007

Bottoms Up to Prevent Climate Change

The Times of India science reporter Narayani Ganesh has this prescription for combating climate change:

What if we shifted the entire responsibility on to the shoulders of one well-known person, say someone like R K Pachauri, who heads The Energy Research Institute and the Nobel prize-wining Intergovernmental Panel on Climate Change? He could institute a climate hotline, a blog, office, radio talk-in show, agony uncle column or any other kind of public interface system that would encourage people to respond to, complain of, discuss, give ideas, share experiences and counsel/get counselled on anything related to saving the planet and ourselves from the scourge of global warming. Collection boxes - on the lines of those displayed by organisations like the Red Cross, CRY or PETA - placed at strategic points and monitored carefully could help assuage the guilt of individuals while galvanising fund-raising on a fairly large scale.

Ganesh is frustrated with the government's response to climate change and wants a bottoms up approach whereby eminent scientists will raise awareness by writing columns and funds for research in alternative energy are raised by placing collection boxes. Will this strategy work? I can imagine people responding to columns with plenty of suggestions and advice but will something like this change habits and behavior and genuinely lead to reduction in emissions? Recently the British rock band Radiohead allowed online downloads of their latest album on a voluntary payment basis. Fans could pay as little or as much as they wanted. Nearly two thirds payed nothing and the rest on average less than $3 for an album that cost about $16. If offered a free lunch people grab it with both hands. Radiohead's collection box remained nearly empty. Free lunches abound in India. The government doles out free electricity, subsidizes fuel, water, gas and roads and most people make full use of this largesse and seem not to be racked with guilt. Urban India is consumed by consumerism and a rural population is aspiring for that. We Indians have grown so used to these government handouts that columns and blogs by an over-hyped UN administrator and a few collection boxes are likely to be ignored.

A bottom's up approach, people's participation in minimizing climate change have a feel good quality to it. People appear altruistic and can feel less guilty without actually bearing any significant costs, which is why politicians will likely support such schemes. On the other hand, schemes that will make a real difference in reducing emissions, such as fitting carbon scrubbers to coal plants, charging more for electricity, tolling roads, introducing congestion charges for vehicles in urban centers are highly unpopular and unlikely to be introduced at least for some time. So, India will go through a strange phase whereby politicians will actively encourage useless schemes like scientists writing columns and collection boxes to raise funds for "research", while distancing themselves from regulations that impose limits on emissions. Our emissions and accompanying pollution will keep growing. Unless there is a political will to take tough decisions, a top-down imposition, the 3 Indians out of a 1000 with Internet connections, will have to make do reading Mr. Pachauri's blog on preventing climate change. Bottom's Up for that! :-)

Saturday, December 1, 2007

Earthquakes in South Maharashtra

The Amateur Seismic Centre, Pune website keeps a track of earthquake activity in south Asia. From their list of recent earthquakes these four:

24th November Chandoli region Mag: 4.3 10.57 a.m
24th November Chandoli region Mag : 3.8 11.35 a.m
24th November Chandoli region Mag: 3.8 12.35 p.m
24th November Chandoli region Mag: 2.8 3.53 p.m

Chandoli region lies in southern Maharashtra, which shows elevated levels of seismic activity as seen in figure below.

Source: Amateur Seismic Centre, Pune;

Two distinct clusters are seen in south Maharashtra, one centered along the western ghats in Satara and Kolhapur districts and another to the east around Latur. Both these areas have experienced devastating earthquakes in recent times. In 1967, the Koyna earthquake caused few hundred deaths and structural damage and then in 1993 the Killari earthquake in Latur district caused thousands of deaths and enormous structural damage.

Earthquakes as we learn in school are caused mostly in and around plate boundaries. There rock masses along faults are under frictional stress, i.e. friction between the rock masses on either side of the fault inhibits slip or motion. Plate movements and pore pressures keep adding shear stresses to this rock mass to the extent that the shear stress exceeds a critical value that overcomes the frictional stress. When that happens the rock masses suddenly lurch past each other releasing energy and causing an earthquake. But southern Maharashtra is far away from plate boundaries. What are causing these intra-plate earthquakes? Figure below (source: Sheth 2006) shows zones of structural weakness in south Maharashtra.

The Dharwar trend refers to very ancient zone of crustal weakness, one that formed during orogenic activity and associated rupturing and faulting of the crust in Precambrian times maybe around 2 billion years ago. This zone of weakness is buried in south Maharashtra below the Deccan volcanic pile (brown region) which is around 65 million years old. When plate motions caused India to split from Africa first, then Madagascar and then Seychelles, a process that occurred episodically starting around 170 million years ago and continuing to about 60 million years ago, the tensional forces involved created a series of faults and zones of weakness along the western margin of the Indian continent. Preexisting zones of weakness were more likely to fail during crustal stresses, hence the coincidence of the Dharwar trend with later zones of weakness such as the Koyna fault or rift zone. The Kurduvadi rift also probably coincides with a deep zone of crustal weakness, currently buried under the Deccan traps. The Killari earthquake does not coincide with the Kurduvadi "rift" but may represent a similar zone of crustal weakness further to the east of the Kurduvadi zone. The enhanced seismic activity resulting in the clusters of earthquakes in south Maharashtra occur in the vicinity of these zones of structural weaknesses and need to be understood within the context of the tectonic forces acting presently within these zones.

Beginning around 55 million year ago, the northward moving Indian plate collided with the Asian plate. The northward movement was met by resistance from the Asian continent and so the Indian continent has been under compressional stresses since. At first, the thought that a continental collision in northern India can have an effect on earthquakes in south Maharashtra about 1500 kms away seems absurd, but two types of evidence are available. The first is the nature of the earthquakes themselves. The mechanism of earthquakes are investigated by deriving a fault plane solution, which is an analysis of particle motions in the earth during the passage of the P or longitudinal waves which radiate in all direction from the hypocentre. The hypocentre is the point of origin of the earthquake and coincides with the point in the fault where the first slip of the rock masses occur. So, a fault plane solution tells us the direction of motion of the rocks along the fault. Such as analysis on the Koyna earthquake (Rao et al 1974) and the Killari earthquake (Mandal et al 1997, Gahalaut et al 2002) shows that the slip in case of Koyna is a strike-slip motion (rocks move past each other with very little vertical motion) while in the case of Killari it is a reverse thrust motion (fault block on the hanging wall move up relative to the footwall). Both these types of motions indicate compressive stresses.

The second type of evidence is from the Neogene deformation (23 million years to recent) of the Indian peninsular region around the Deccan traps. In the vicinity of Mahabaleshwar , the Deccan traps are folded into a south plunging regional anticline (Widdowson & Cox 1996). To the north in the Satpura, the high topography of the Pachmari hills has also been interpreted as being due to recent crustal warping and uplift (Venkatakrishnan 1984, 1987). And in the south, crustal arching along the Mangalore -Chennai axis (Subrahmanya, 1994) has resulting in the NE and SE flow of rivers on either side of the arch (see figure below; source Sheth 2006).

All this deformation has been interpreted to be of Neogene age on geomorphological evidence such as youthful steep topography and antecedent drainage (evidence summarized in Sheth 2006) and indicates a compressional stress regime in the Indian peninsula.

The fundamental zones of crustal weakness along which south Maharashtra earthquakes occur originally developed in the Precambrian and are 2-3 billion years old. These zones have been periodically re-activated first as tensional fractures and faults when India broke up from Madagascar and Seychelles and later as strike-slip and reverse faults as manifestations of the compressional stresses periodically building up in the Indian peninsula. There is a very ancient geological control on the Koyna and Killari earthquakes.

Finally a few thoughts on that nagging question: Did the Koyna dam cause the Koyna earthquake in 1967? The popular notion at that time was that the impounding of water in the reservoir imposed stresses on the crust caused the earthquake. But calculations of rock mechanics show that the increase in pore pressures at depth due to loading of even a few hundred metres of water is very small, orders of magnitudes less than required to cause rock failure by itself. However, if the tectonically created stress along faults are already at a critical level, then a small increase in pore pressure due to impounding of water may act as a tipping point causing slip along the fault. This seems to be the case at Koyna. The deep crustal faults appear to be at a critical level of stress and the pattern of seismicity correlates with the loading and unloading cycles of the reservoir (Pandey and Chadha 2003). Under the right circumstances of crustal stresses, dams may induce earthquakes but are not a primary cause. This is of significance in understanding the risk imposed by the various proposed dams in the Himalayas. There faults and tectonic instability is unavoidable. Understanding the stress regime along individual faults in the vicinity of the proposed dams is of critical importance.


Gahalaut V.K, Kalpna and P. S. Raju 2003; Rupture mechanism of the 1993 Killari earthquake, India: constraints from aftershocks and static stress change; Tectonophysics, Volume 369, Issues 1-2, 3 July 2003, Pages 71-78

Mandal P, Manglik A and Singh R.N., 1997; Intraplate stress distribution induced by topography and crustal density heterogeneities beneath the Killari, India, region; JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 102, NO. B6, PAGES 11,719–11,730

Pandey Ajeet P and Chadha R. K. Surface loading and triggered earthquakes in the Koyna–Warna region, western India; Physics of the Earth and Planetary Interiors, Volume 139, Number 3, 31 October 2003 , pp. 207-223(17)

B. S. R. Rao, T. K. S. Prakasa Rao and V. S. Rao 1974; Focal mechanism study of an aftershock in the Koyna region of Maharastra State; Journal Pure and Applied Geophysics

Subrahmanya, K. R., 1994, Post-Gondwana tectonics of peninsular India: Current Science, v. 67, p. 527-530

Venkatakrishnan, R., 1984, Parallel scarp retreat and drainage evolution, Pachmarhi area, Madhya Pradesh, central India: Journal of Geological Society of India, v. 25, p. 401-413

Venkatakrishnan, R., 1987, Correlation of cave levels and planation surfaces in the Pachmarhi area, Madhya Pradesh: A case for base level control: Journal of Geological Society of India, v. 29, p. 240-249

Widdowson, M., and Cox, K. G., 1996, Uplift and erosional history of the Deccan Traps, India: Evidence from laterites and drainage patterns of the Western Ghats and Konkan coast: Earth and Planetary Science Letters, v. 137, p. 57-69