Friday, October 31, 2008
The Himalayas are categorized as having local and shallow aquifers, the Indus-Gangetic plains belong to one homogeneous groundwater basin and the southern peninsular region is a complex hydrogeological province. These are somewhat misleading categories in that they are not mutually exclusive. For example local and shallow aquifers are found all over India. And the Himalayas have plenty of regions of complex hydrogeological structures. But combined with recharge potential the map gives on a broad scale the likely patterns of aquifer yield across the country.
Looking at Maharashtra I could not help noticing that areas of complex hydrogeological structure and medium to low recharge potential spatially coincided with the vast majority of cases of farmer suicides in the state. This is the region north of Hyderabad and east north east of Bombay. Over the last 6-8 years more than 2000 farmers have committed suicide. The immediate explanation for most of these cases is indebtedness. Farmers borrow money to meet high farming input costs or for other personal reasons and fall into a debt trap if crops fail or give a low yield. The Maharashtra government compiled the results of several studies of farmer suicides and identified conditions that made farmers in these regions particularly vulnerable. These were:
Disruption in regular rainfall cycle since 2001. Long dry spells, deficient monsoon.
Single crop a year, and Cotton the dominant crop. About 70% of farmers who committed suicide had planted cotton.
93 percent of land rain fed. 98 percent of the farmers who committed suicide had no irrigation.
Yield limited by rain, but regular rise in cost of input lowered margin of profit.
Volatility in market price further lowered return.
Commitment to money lender did not leave anything with the farmer.
Farmers are heavily dependent on monsoon rains to water crops. But how does complex hydrogeology figure in this. This agricultural region sits on top of the Deccan basalts. Aquifers are local, shallow, deep, all sorts and show lateral and vertical heterogeneity in their water storage capacity and transmissivity. I have seen this in the field. The situation can change from high yield to bone dry over a distance of tens of meters. So a farmer with a small landholding of a hectare or so - and there are plenty of them in this region- may just have the bad luck of farming on top of an unyielding basalt. He then has to rely entirely on the rains or get into a groundwater sharing agreement with a neighboring farmer who might have a yielding aquifer under his farm. But during times of water stress there is too little water to go around resulting in crop failure or low yields.
Another problem is that not enough attention has been paid to managing the available groundwater resource. Farmers use dug wells as a primary water extraction method but using the dug well to replenish the aquifer during times of good rain is not practiced widely. This has led to aquifer overdraft and a steady diminishing over the years of the groundwater resource. Not all cases of farmer suicide can be linked to water problems. Crops can get wiped out by pests, yields could have been low due to soil degradation, some instances where Bt Cotton seeds failed and then there are probably cases where despite decent yields farmers simply made irresponsible financial commitments. But the link of low yields to ready availability of water is real.
Tushaar Shah a groundwater expert with the International Water Management Institute has made a strong case that focusing on groundwater replenishment will go a long way in preventing crop failure and improving yields. He gives an example:
Over 86 million hectare of India’s rain-fed areas, mid-season or terminal droughts regularly take a toll on the kharif crop. At such times, using around 1000 cubic metres per hectare of water from wells just-in-time to water a wilting crop just once can raise crop yields by 30-230 percent over rain-fed yield levels.
Off course if the wells themselves are dry then there is no backup for failed rains. A Tata Institute of Social Sciences report on farmer suicides found that farmers had little or no groundwater available to them during times of rain failure. A combination of complex hydrogeology and poor management of groundwater resources has exerted a powerful influence on the lives and livelihoods of Maharashtra farmers.
Mr. Shah makes the following recommendation for complex hydrogeological terrains:
What hard-rock India needs is a new mindset of managing dug wells as dual-purpose structures, for taking out water when needed and putting water into the aquifers when the surplus is running off. Recharging aquifers needs to get the first charge on monsoon run off. Unfortunately, government planners give it the last priority.
Water available for recharge is estimated after allowing for the requirements of existing and planned surface reservoirs. This is absurd in a country where 70 percent of irrigated areas and 90 percent of drinking water needs are met from groundwater.
Is the government listening? The Prime Minister of India's special relief package for Maharashtra farmers wants to attack the problem on a broad front which includes tinkering with the economics of cotton farming, encouraging a diverse array of crops and reducing dependence on pesticides and fertilizers. But water underlies any successful agricultural strategy. In terms of water it lists irrigation development as the only long term solution to the water problems faced by farmers and doles almost 10 times more money to irrigation development than to watershed development. Irrigation development in the language of the government of India means canal irrigation (read mega infrastructure projects) and not local groundwater irrigation.
This despite the revealing statistic that even though thousands of crores of Rupees have been spent on canals, they irrigate just about 15% of arable areas over the landmass of India and marginal farmers and farmers with small landholding benefit most not from canal networks but through groundwater irrigation.
Monday, October 27, 2008
This earthquake was unusual for the Himalayan region as it occurred along a shallow fault and caused a surface rupture. i.e the cracks and deformation was visible at the surface. Deformation due to earthquakes is usually mapped by spotting offsets in artificial and natural linear features like walls and fences or gulley's and streams. That is incredibly hard to do in remote steep terrains like the Kashmir Himalayas. So the researchers used before and after earthquake images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard the NASA Terra satellite to try and spot this rupture. A team of geologists had mapped this fault using ground surveys but this is a time consuming process and so a complimentary image analysis was done to evaluate whether imagery can provide a reliable way to quickly identify zones of deformation to aid rescue efforts after an earthquake.
The images below are ASTER false color composites which clearly show the fault trace highlighted by a linear zone of white color. These are landslides that occurred along the hanging wall of the fault. Only a small section of the trace is seen in the images.
Source: NASA Earth Observatory
False Color Composites are prepared by assigning the three primary colors red, green and blue to the three wavelength bands which analysts feel contain the maximum information about surface features. This arbitrary assignment of colors to bands results in features appearing in colors unnatural to the human eye. Hence the term False Color Composite. Depending upon sensor design a range of wavelengths from the visible part of the wavelength spectrum (reflected energy) to the thermal part of the spectrum (emitted energy) can be collected for study. ASTER the sensor used in this study as the name implies senses energy in both the thermal and reflected part of the spectrum. Only the reflected portion of the spectrum was used to process the images in this study.
Satellite sensors break up the reflected or emitted energy coming from the earth's surface into discrete regions or bands to allow better discrimination of surface features. This works because different surface features reflect or emit efficiently in different wavelengths. A judicious selection of bands can then be used to create maximum contrast between different surface features.
When using reflected energy, usually this wavelength combination as is in this image is near infrared, red and green. The wavelength range is from about 0.5 microns (green) to about 1 microns for near infrared. In this case red color has been assigned to the near infrared band since healthy vegetation reflects a lot of near infrared. Water appears blue and built up areas and landslides which are zones where vegetation has been stripped off and fresh rock and soil exposed appear gray and white respectively, indicating a very high reflectance in the smaller wavelengths.
The surface rupture of the Kashmir earthquake extends over 75 km. Another paper which studied the tectonics of this earthquake has concluded that the rupture has occurred along some subsidiary faults and not along the major boundary fault where strain is apparently still accumulating.
This does not bode well for the Kashmir region.
Update: Robert Simmon a NASA researcher in an email to me points out an error in my post. I gave the impression that the fault trace was mapped using landslides as a guide. This is not so. The fault trace was delineated by mapping the ground deformation i.e the offsets caused by the slip along the fault were mapped by correlating the before and after images. Landslides in fact obscure the fault trace such that the before and after images can't be correlated along such patches.
Wednesday, October 22, 2008
To my pleasant surprise Michael Wood took the story way back to Africa and the late- Pleistocene migration of Homo sapiens from Africa around 80,000 years ago. These humans migrated into India soon thereafter taking most likely the coastal route from Arabia into India. There are still relict populations in India which have believed to be descendants of these early settlers. I wrote a post about this some time back. These include the mainland tribals like the Korku and the Kuruba and those in the Andaman chain of islands like the Sentinelese. Mitochondrial genetic analysis supports this contention as the Korku and the Kuruba have one of the oldest mitochondrial genetic markers outside of Africa. The figure below shows migration routes of Homo sapiens reconstructed from genetic analysis.
Source: Univ. of Texas
Wood meet some of these tribal communities and discussed rituals that may be holdovers from very early times. There were some silly moments like when he asked one of the tribals "how does it feel to be the first human in India", but he did highlight the genetic work that is being done to unravel the history of early human presence.
From early Pleistocene settlers the show moved on to the Holocene and the enigmatic Indus valley civilization which lasted from around 3500 B.C to 1800 B.C. Wood talked a lot of town planning and trade between the Indus valley people and centers of civilization in what is now Iran and parts of the Middle East and then talked a little about the demise of this civilization caused most likely due to an increased aridification of the western Indian continent beginning around 2500 B.C. The show then moved on to the arrival of people starting 1500 B.C., speaking an Indo-European language, proto-Sanskrit. The locus of Indian civilization migrated eastward to the Gangetic plain but Wood emphasizes that there is a continuity in the cultural transition from the Indus valley to the Gangetic plains. The focus was on how these Sanskrit speaking people developed the Vedic culture and complex societies around the Gangetic plain. Using linguistic and archaeological evidence he traced the origin of these Sanskrit speaking people to central Asia.
What was left out from this rather predictable but decently presented sequence was any mention of where and when did Dravidian speaking people originate. This is the other big language family in India today, spoken mainly in the south of the country. Dravidian is considered by many linguists as part of the Dravidian-Elamite family of languages that once were spoken all over the northwestern part of Indian subcontinent extending into Iran. Exactly where the center of origin of this language family was is still uncertain but geneticist Luigi Luca Cavalli-Sforva suggests that it could have been the northwestern part of India or it could be farther west towards Iran and the Caspian region.
What is clear is that Dravidian or proto-Dravidian speakers were in India before the arrival of proto-Sanskrit speakers. Linguists like Colin Renfrew suggest that it is likely that the entry and spread of Dravidian languages in India coincided with the farming dispersal and agricultural expansion that began in the Middle East and which expanded into north western parts of the Indian subcontinent around 8,000 years ago. Dravidian languages entered India through demic diffusion of agriculturists and Dravidian speaking people were the first Neolithic farmers of India. This extended history of Dravidian language origin and dispersal was given no attention in the show. These people are the likely candidates who built the Indus valley civilization and Wood missed out on exploring this thesis further. I've noticed this in many documentaries about India. The attention is always on the arrival of the "Aryans" a term used to describe people speaking Indo-European languages. They in fact arrived much later than Dravidian speakers. Today Dravidian is spoken mostly in the south, an example of language displacement by latter arrivals. There is however a northern enclave in Pakistan where Brahui, a Dravidian language is still spoken.
This is not really a rant on Dravidian vs Indo-European languages. I mentioned that Indo-European speaking people displaced Dravidian languages to the south, but Dravidian speaking farmers too must have displaced or made extinct Austro-Asiatic languages or other unclassified languages spoken by the earlier hunter-gatherer settlers of the continent. The history of India is one of immigration and emigration and superimposition of layer upon layer of language, culture and ethnicity.
I particularly liked one sentence Michael Wood said about India:
India is a country where all the pasts of the human species are still living.
That is a very evocative description of the country and its people. It makes you imagine the great antiquity of human habitation in this part of the world.
Tuesday, October 21, 2008
NPR no doubt taking my cue has a similar "How To Be Conversant About Climate" conversation with Michael Oppenheimer, faculty in geosciences Princeton University, about how to convince Uncle Sal at the dinner table that global warming is not only real but is primarily caused by human activity. Oppenheimer is of the view that while the debate about whether warming is taking place is over and settled, there are differences which are quite genuine and not as easily dismissed on how to deal with this problem. That problem has economic, political and cultural roots and needs to be confronted without taking a "I am right and you are wrong" stance.
There is a second good talk on the show. This explores the broader question of why people find it hard to believe in science and scientists. Uncertainty in interpreting data and the results of an experiment, dissent and debate is built into the scientific process. It is the nature of the beast. But it is often bewildering to people that even after say 2-3 decades of work, there is no certain answer from scientists on a problem. People take that as a weakness of the system, a signal that science may not give them ready answers. Maybe we want that certainty, maybe we need closure on a problem, maybe we need to be reassured that yes this is the one correct answer, that we all too readily succumb into believing a confidently told but scientifically unsupported story.
And again how easily available information on the Internet can be at once a boon but also a hindrance and sometimes has dangerous consequences when people in responsible positions choose to believe wild assertions. Harry Collins of Cardiff University gives the example of parents refusing to vaccinate children with the MMR vaccine because they fear that it may cause autism in their child, something that has been refuted by solid scientific work.
Then there is the case of Thabo Mbeki, ex-President of South Africa, who after reading articles on the Internet announced publicly that retro-viral drugs to combat AIDS don't have any helpful effect. The media too bears some responsibility of spreading disinformation through their insistence on giving both sides on the story equal weight even though one side is just illogical and is not supported by any body of evidence and simply does not warrant such attention.
Both a good listen.
Friday, October 17, 2008
Here are some stats:
In 1985, the number (number of papers indexed by Thomson Reuters) was approximately 12,500, and for the next 15 years the total never much exceeded 14,000. Around the year 2000, however, the number began to tick upwards, rising to nearly 17,000 in 2001, reaching 20,000-plus in 2003, and winding up at more than 27,000 in 2007.
and regarding citation stats...
Physics, as it happens, features prominently in the next set of graphs(2), which plot the nation's relative citation impact (that is, India's citations-per-paper average compared against the world average in each respective field) in 14 main fields in a series of overlapping periods from 1985 through 2007
. ...although the impact of India-based research lags the world average in the fields shown, the nation has been on a discernible upswing since roughly the year 2000, with notable gains in, for example, Geosciences(3), Neurosciences(4), and Biology & Biochemistry.
Geosciences citations have improved from being 30% of the world average to around 50% of the world average.
A slight improvement I guess over the last 20 years or so, but the condition of a lot of geoscience departments, especially those in state universities leaves a lot to be desired in terms of quality research output. I don't want to analyze this to death. Yes we are improving, but still far behind the U.S, Europe, Britain, Japan and China. A lot has been written on what ails Indian science. Here is a polemical view. And here is a more detailed and critical analysis.
I want to digress and write on a different matter.
I survey the research literature in sedimentary geology quite a bit and all along there has been only the rare publication by India based geologists in the leading geology journals on sedimentary topics. With one peculiar exception. Bengali geologists mostly based in eastern Indian Universities have been consistently publishing papers on sedimentary geology in internationally recognized journals.
I've often thought about this on and off and a number of reasons come to mind.
1) Proximity to sediments. Jadhavpur University Kolkata, Presidency College, Kolkata, Indian Statistical Institute, Kolkata, IIT Kharagpur and School of Mines, Dhanbad, where a lot of Bengali geologists are based are all within a days driving distance from a variety of sedimentary terrains. These include the Ganges-Brahmaputra fluvial- estuarine-delta complex, the Mio-Pliocene Himalayan foreland and the late Paleozoic-early Mesozoic Gondwana continental rift basins. But proximity cannot be the only reason. Plenty of other Indian universities to the west and south and north sit right on top of Proterozoic and Mesozoic basins.
2) Institutional support. The east is where the systematic study of geology began in India. Kolkata was the seat of British administration until the capital shifted to Delhi in the early 1900's. The Geological Survey of India was established in Kolkata in the late 1800's. There is a long tradition of geology in this part of the country reflected in well funded geology programs in various universities.
3) Economic incentives. There is coal in the eastern rift basins and oil was discovered early in the eastern state of Assam. There was a requirement for expertise in sedimentary geology and eastern universities developed strong sedimentary geology programs to provide it.
4) But Universities are only as good as the people who work in them. Geology frankly has never been a field which attracts the brightest students in India. Parental, social and economic pressures lead to Medicine, Engineering and Management being preferred. Among sciences, Math, Physics and Chemistry suck in the best. But there has been strong social and cultural support in Bengal for pursuing any kind of an intellectual career. So maybe many more bright Bengali students become geology researchers than elsewhere in India.
I remember my first ever meeting with my graduate adviser in the U.S. Meet me at 8.00 am sharp, he barked on the phone. And so I went to his office, braving a bitterly cold mid-west January morning. He was a Bengali sedimentary geologist and a fine one too. Winner of the SEPM paper of the year award for 1986 for his seminal work on alluvial sandstones from the late Paleozoic-early Mesozoic rift basins of eastern India.
Maybe there is a germ of truth to my thesis :-)
Monday, October 13, 2008
Strange Maps is one of these sites. A wonderful collection of weird, creative and humorous ways of depicting the world in "maps".
Having spent long late afternoons in Appalachia sipping sweet tea after a day's fieldwork this one I could relate to all too well; the north to south distribution of McDonald's selling unsweet and sweet tea in Virginia.
Source: Eightoverfive.com via Strange Maps
I am not sure how many geo-bloggers have this site on their blogroll. It's a refreshingly different spot. You can't really categorize it as a geoscience blog although there are posts on geology related topics. But it's just the spatial depiction of information that caught my interest. Maps always give you a different perspective, makes you ponder over previously unrecognized connections. You can create your own story of places visited, geology observed, people you have met. Definitely worth a regular visit.
Hat Tip: Geology News
Saturday, October 11, 2008
In Economic theory the winner’s curse refers to the idea that someone who places the winning bid in an auction may have paid too much. Consider, for example, bids to develop an oil field. Most of the offers are likely to cluster around the true value of the resource, so the highest bidder probably paid too much.
The same thing may be happening in scientific publishing, according to a new analysis. With so many scientific papers chasing so few pages in the most prestigious journals, the winners could be the ones most likely to oversell themselves—to trumpet dramatic or important results that later turn out to be false. This would produce a distorted picture of scientific knowledge, with less dramatic (but more accurate) results either relegated to obscure journals or left unpublished.Marginal Revolution has a more detailed debate in the comments section.
I don't read much geosciences in Nature or Science. But should I now pay more attention to papers in Carbonates and Evaporites instead of Journal of Sedimentary Research?!
Apologies to the Editors.
More importantly, is some of my unpublished PhD work really the real deal!?
Tuesday, October 7, 2008
Just a quick recap for those who have not been following this thread. Some astrologers claim that they can predict big earthquakes based on the alignment of the moon with the sun and other planets in the solar system. Mr. Amit Dave who lives in Mumbai is one such astrologer. He claims that certain alignments of the moon and sun (and other planets) exert tidal stresses on earth. No one doubts this. Nothing new here. The relevant question is whether these tidal stresses acting alone i.e. without input from internally generated tectonic stresses are enough to cause big earthquakes. The answer is clearly no.
In two earlier posts I exposed Mr. Dave's lack of understanding about geology and earthquakes and explained just why tidal stresses acting on their own are incapable of causing big earthquakes on earth. He never gave me a single substantive reply to my questions but kept making foolish claims about his "predictions" in the comments sections of my posts. So in this post I will try to explain what is a scientific earthquake prediction and whether Mr. Dave's "predictions" measure up to this standard.
The main confusion among people is between making the rather mundane claim that earthquakes will occur on any particular day against the more meaningful exercise of predicting a earthquake. Astrologers are unable to grasp this distinction or more cynically ignore it since the laypersons they are trying to reach certainly don't make this distinction.
When geologists make a prediction about a earthquake it is in this format:
An earthquake of magnitude ...6.5-7 Richter (range).. will strike ...time range..(usually in the range of the next few years) at location... Longitude X and Latitude Y due to ... hypothesis of how and why an earthquake is due /imminent in the declared region.
Astrologers ignore the third requirement of the location and are puzzled by the fourth. Why give a hypothesis of how and why an earthquake is imminent.
Here's why. Geologists studying earthquakes and working in a particular area have a hypothesis on how geological stresses may cause an earthquake. This hypothesis describes for example the rates at which strain is accumulating along a particular fault based on say the motion of the earth's plates. Or take tidal forces. Ultimately they can only act or trigger earthquakes by imposing stresses on the crust. So even a theory of earthquakes like Mr. Dave's which relies solely on tidal forces needs to explain in terms of the imposed stress and accumulating strain how , why and where these tidal forces are likely to cause a rupture. If an earthquake does occur in that region, this hypothesis can then be validated against what actually happened. It gives geologists a chance to test how good their understanding of earthquake mechanisms is.
Here is a great example of this process from the September issue of Geology in a paper that studies the big Kashmir earthquake of 2005:
.... We thus conclude that the 2005 event did not occur on the plate boundary megathrusts, but on intraplate active faults within the Sub-Himalaya. Consequently, the accumulated elastic strain around the complex northwestern margin of the Indo-Asian collision zone has not been significantly released by the 2005 earthquake.
What this means is that the earlier hypothesis that a big earthquake in Kashmir will likely take place along a major boundary fault zone was wrong. The earthquake instead took place on a subsidiary fault system. This however warned geologists that strain is still accumulating along the major fault and another big earthquake in that region is likely.
Science is a self correcting process. If we are to improve our understanding of earthquakes, a prediction must include a declaration of a hypothesis which can then be validated against what actually took place.
Alright, on to Mr. Dave's "predictions". Here it is
1) 7th September 2008 -- 2020GMT ---- 7.2 On Richter scale at 12 Degrees East or/168 Degrees west ( Precise location both longitude and latitude is not possible as of to day)
2) 10th September 2008 --1950 GMT ---7.3 on Richter scale-at 66 Degrees east or 114 degrees West
3) 15 th September 2008 --0910 GMT----More than 7.5 on Richter scale -at 147 Degrees East or 33 Degrees west
4) 16 th September 2008 ---2015 GMT---- 7.5 on Richter scale -at 87 Degrees East or 93 Degrees West
The original prediction he gave me did not have even the incomplete location information. It is only when the USGS insisted that a location is necessary (he forwarded me a mail from the USGS) that he put in just the longitude.
But that's not it. These dates are way too specific and Mr. Dave then provides a hedge.
As per my theory the dates of September 2008 are already published in my blog. However one more thing required to be noted is that , the dates shown are the peak force dates ,and have maximum potential of triggering the quakes. However , the quakes follow a sinusoidal pattern. As the dates mentioned approaches nearer the quake intensity and frequency keep on increasing. After the dates have passed the tidal force slowly fades away.
And then not satisfied that his sinusoidal wave will cover enough ground, a few more dates:
Thus , there are fair chances of quakes of 6.5 to 6.8 Richter scale on following dates also. places not known.
27 th August 2008----0415 Hrs IST
31 th August 2008-----0115 Hrs IST
Also 22 nd and 23 rd September 2008----up to 7.0 on Richter scale
So, he has covered so much time with his spread of dates that he has ensured himself a high degree of "prediction" success.
Why is that? Because of the high frequency of moderate to big earthquakes, something most people are unaware of. 7-8 magnitude earthquakes occur at a frequency of 1-2 per month, 6-7 magnitude earthquakes occur 10-12 per month, 5-6 magnitude earthquakes occur 2-4 per day, and 4-5 magnitude earthquakes occur 20-25 per day.
As expected Mr. Dave claimed earthquakes of varying magnitudes on dates before, between, on and after his peak potent period. Not a single 7+ earthquake occurred on any of these days, but Mr. Dave blatantly misstated the magnitudes of these earthquakes. It is a comical list of claims, but one that speaks to his disingenuity. He seems incapable of reporting accurately even the most basic of facts.
You can check for yourself all this earthquake information by going on the USGS earthquake search.
But my main quibble is not with these reporting inaccuracies. I put that down to over-excitement. My objections are over procedures.
What is the justification for claiming that tidal forces caused the earthquake that was claimed and not one of the dozen others that took place on that day? All Mr. Dave is doing is choosing post facto from a list of earthquakes that occurred on the day, the earthquakes that is closest to the magnitude he gave or one he deems significant in some way.
I like to call this retrospective coronation.
Again, how does he know that tidal forces caused the bigger earthquake he has claimed and not a smaller earthquake that took place some where else? He doesn't know, but you see without a prior declaration of a location and a hypothesis it is impossible for anyone to verify his claim. And that suits the astrology community just fine.
That is why astrologers never give a location.
Mr. Dave will deny that he chooses earthquakes after they occur, but here is an example which gives his game away. He had "predicted" that an earthquake of magnitude 7.5 or so will occur on September 16th. Unfortunately for him there was no earthquake larger than 6 on that day. So what did he do? He claimed a 5.0 magnitude earthquake (he gives the mag. as 4.9) that occurred in the Satara district of Maharashtra as proof of his "predictions"!
It is stupid claims like this one that lays bare the intellectual bankruptcy of these bogus earthquake prediction schemes astrologers concoct from time to time.
Remember earthquake frequencies? There were 26 earthquakes on September 16 of magnitudes 4-6. There were 4 earthquakes of magnitude greater than the one he choose. How does he know that tidal stresses caused the Satara earthquake and not any one of the other 25? He doesn't. The only reason he choose to claim this particular earthquake is because thousands of people in the Mumbai-Pune area felt it. Humans react to and remember events that occur close to the place they live and Mr. Dave knew he could fool people into believing that he actually predicted that earthquake.
So astrologers are not really predicting a earthquake. They are simply just highlighting after the fact one out of the many that occur on any given day.
Location and a hypothesis, Location and a hypothesis, Location and a hypothesis. Without these any claim to a prediction is meaningless.
Did I mention even the incomplete location information given by him was wrong for all the earthquakes he has claimed?
I find this non-disclosure of location information most revealing! Mr Dave and other astrologers argue that they too are trying to save lives by coming up with a prediction system. That is as strange an argument as I have even come across. How on earth can you save lives if you don't specify where an earthquake is going to strike?
One last requirement of a scientific prediction is the complete disclosure of negative results. Mr. Dave has never admitted that his location information is missing or wrong in all the cases. Another type of negative result is earthquakes that occur on days other than those given. Ambuj pointed this out sometime back. Mr Dave claims that big earthquakes occur solely due to tidal stresses and there are potent days when they will occur. Since his September prediction which appeared on my blog on July 13 to the date of this post, leaving aside the entire month of September, there were 25 earthquakes of magnitudes 6 and above. How does he explain these earthquakes which all fell on days when the heavenly bodies were not engaged in a destructive tango?
In fact how does he explain not just these biggish earthquakes but the hundreds of smaller earthquakes that occur every day?
Here is my suggestion for what Mr. Dave's next prediction should look like:
Magnitude X (range) , Time range , location in Longitude and Latitude and a hypothesis of how and why tidal stresses will cause strain to build up and rupture rocks in the region he has indicated. This is to be followed by a full disclosure of negative results.
If he does this I am sure the seismology community will follow his claims with interest. But just rolling the dice and jumping up in excitement whenever an earthquake happens to coincide with a full moon, new moon or quarter moon day is not acceptable.
I predict Mr. Dave will not accept this qualifying criteria.
I am sure because:
Gustav ,Hanna and Ike three major storms in first week of September08
Vanuattu quake of 6.5 on 8th September 2008 ,at 0305 Gmt
keep counting please
Astrologer / Engineer
Yes hurricanes too. With this mindset Mr. Dave will continue to fool himself and other ignoramuses who are already convinced that their destiny has been decided by the alignment of distant planets.
Saturday, October 4, 2008
From Earth magazine summary:
Then, on Sept. 17, in the shadow of the Blue Ridge Mountains, the Battle of Antietam began. The armies blasted each other with gunfire from dawn until nearly dusk. That day proved to be the single bloodiest day of the American Civil War, with more than 23,000 men lying dead or wounded in the valley’s fields by nightfall.
But in addition to the bullets and cannonballs, soldiers in both armies had another common enemy that day: carbonate rock.This was from an era where soldiers just used to line up on opposite sides and let go with their muskets and then charge at each other. The battle of Antietam in 1862 took place in the area surrounding the town of Sharpsburg, Maryland.
The fields are underlain by limestones and associated sedimentary rocks of Cambrian to lower Ordovician in age. Way back around 500 million years ago that area was part of a complex of Cambro-Ordovician marine sedimentary basins that stretched along the length of the now eastern U.S. Thousands of feet of carbonate sediments accumulated in these basins over time.
As with any depositional system the composition of the sediments varied over space and time. So there were depositional sub-centers where relatively pure carbonate sediments were being produced, other sub-centers which could be just a few 100 meters away accumulated a mix of carbonate and terrigenous clastic mud and sands. At places the original calcite sediments were replaced by the mineral dolomite.
Now these compositionally different sedimentary rocks respond differently to chemical weathering. Sediments composed of calcite (limestones) are most susceptible and over millions of years such areas will get worn down to relatively flat terrains. Areas with a mix of shale, limestone and dolomite respond differently. Limestone gets weathered faster than shale and dolomite and the results is a more uneven, undulating topography.
When the geologists mapped the casualty rates at Antietam to the underlying geology they found a correlation. The highest casualty rates were in those portions of the battlefield which were underlain by pure limestone and which had weathered down to a relatively flat terrain. On a plain, the opponent is in plain sight and there is nowhere to hide. The image below is a tilted view of an area known as Cornfield just north of Sharpsburg, where the casualty rate was especially high.
Here are a couple more images. The one below is a shaded relief map of the battlefield.
Source: Military geology of Antietam battlefield
The red circle in the upper part of the image is the Cornfield area. You can see the terrain is less dissected by streams and appears flat. The outlined area to the bottom of the image is more dissected by streams and shows a marked relief. This is the Burnside Bridge area which is a couple of miles from Cornfield and where soldiers could find cover in the deeply dissected gulley's and streams. Here casualty rates were three times lower than Cornfield.
The image below is a terrain profile of Cornfield and Burnside Bridge.
Source: Military geology of Antietam battlefield
Given time even granite terrains can wear down to a flat featureless plain. So the important factor here was not the composition of the rock by itself, but the difference in facies heterogeneity. Both sides during the Civil war used the terrain to their advantage. But studies which specifically try to draw out a connection of geology to a particular battle are rare and I enjoyed reading this one.