Thursday, February 24, 2011

No - Christchurch Earthquake Not Caused By Moon Alignment With Other Planets

I've noticed an increase in traffic on my blog. Search phrases are pointing to some old posts I wrote about astrology and earthquakes. Here are a couple of examples:

Regarding the Christchurch earthquake, Chris at Highly Allocthonous has a post explaining the cause of the earthquake in terms of the regional tectonic set up and the forces involved. And see this USGS summary of the earthquake.

As for the astrologers .. here is my experience with one of them..

Was September 08 Earthquake Month?

Astrologers claim high success rates in their "predictions" but you have to examine their methods - the ones I have encountered don't give location information nor do they give a geological hypothesis in terms of the setting and stresses involved just why an earthquake is likely at a given location. Simply saying an earthquake is going to take place on a particular date or within a time interval does not count as a prediction because the frequency of big earthquakes on earth is quite high - 10-11 earthquakes of 6-7 magnitude occur every month, 3 -4 earthquakes of 5+ magnitude occur every day and more than 20 earthquakes of 4+ magnitude occur every day somewhere on earth.

Without a location and a geological justification there is no way to validate the claim. Astrologers can point to any one of the many earthquakes that shake the earth everyday as the one they "predicted".

Tuesday, February 22, 2011

Remotely India # 6: Chambal River - Badlands ...And Bad Men n Women

Geology and Livelihoods - 8

In the alluvial Gangetic plains, the rivers that catch everyone's eye are the Yamuna and the Ganga with their source in the high Himalayas and their standing in Indian society as the holiest of India's many holy rivers.

But the alluvial Himalayan foreland is also fed by rivers originating in the Indian craton (continental crust formed in early earth history) on the high northern flanks of the Narmada rift zone. These cratonic rivers flow north northeastwards and join the Yamuna or Ganga.The map below shows Himalayan and Cratonic rivers flowing into the north Indian foreland basin.

Source: R.Sinha et al 2009

The Chambal is the largest of these cratonic rivers. From source to its confluence with the Yamuna it is about a 1000 km long. It flows over both the Deccan Basalts and Proterozoic Vindhyan strata and contributes significant amount of sediment to the foreland basin.

The Chambal river badlands is a late Pleistocene-Holocene degradational landscape. In the image below the badlands can be recognized by the closely spaced dendritic network of gullies. The location is just west of the town of Morena in Madhya Pradesh.

Rivers and their associated floodplains go through aggradational and degradational phases. In an aggradational phase the river is carrying a large sediment load and flooding results in deposition of this sediment in the flood affected areas. This periodic deposition builds up or aggrades the floodplain.

Conditions may change. For example during longer wet periods and increased rain intensity river discharge increases. Sediment is not deposited locally but is carried out of the system to the sea.  In these conditions rivers incise or cut into their own deposits. The river channel becomes situated in a deep valley detached from its floodplain. Starved of sediment, the floodplain degrades as erosion along the main channel and smaller streams cuts gully and ravines forming badlands.

Below is a pictorial representation of this process.

 Source: Gibling et al 2005

Sedimentological and stratigraphic analysis of facies and dating of sediment by Optical Stimulated Luminesence along the Ganga, Yamuna and some cratonic tributaries suggest (Ref) that in this region badland formation coincided with the intensification of the south west Indian monsoon at the end of the Last Glacial Maximum around 15 thousand years ago and likely continues today, amplified over the last couple of millenia by intense human reworking of the landscape.

Another mechanism that may initiate a phase of river incision is tectonic uplift and tilting of the region. Tectonic upwarp may steepen stream gradients increasing their erosive power. That mechanism has been invoked by some to explain phases of incision of the Yamuna and the Chambal. However many researchers have pointed out that late Pleistocene - Holocene river incision episodes in basins of varied tectonic settings from Nepal , Bangladesh and northern India all coinciding with monsoon resurgence points to a regional climatic control.

Ravined badlands border long stretches of the Chambal as seen in the image above but also occur along the Yamuna, Betwa and Sengur rivers. The incised main channel of the river and the ravines expose older sediment. In these older sediments, earlier degradational and aggradational episodes can be recognized and coincide with fluctuations in monsoon intensity interpreted from coeval Arabian sea cores containing variations in pollen abundance which records variation in terrestrial vegetation and planktonic foraminiferal abundance which records oceanic upwellings related to monsoonal circulation.

These badlands and incised channels of the Yamuna, Chambal and other smaller cratonic rivers have given geologists a priceless opportunity to study the interplay between fluvial processes and climatic changes mainly the influence of the Indian monsoon on sedimentary processes over the last hundred thousand years.

I am leading into a different topic for the rest of the post- a somewhat warped installment of my long running series Geology and livelihoods, the reason being that in the Chambal region for long centuries people have developed a parallel economy based on dacoity. Some of India's most infamous outlaws have operated from this region. Dongar-Baturi, Pana, Sultan, Man Singh, Amritlal, Lakhan, Gabbra and Putli Bai (the first documented women dacoit of the Chambal), Kallan and more recently the notorious Nirbhay Gujjar (in photo, source).. the list is long.

The reasons are many and the badlands and ravines play an important role through history. They are situated close to the power centers of ancient north India, Delhi and the kingdoms of Rajasthan. Rebels used to retreat and hide in its byzantine gullies and engage in guerrilla warfare. That metamorphosed over time to looting and making a living that way, a culture of highway banditry developed.

From ancient times to recent, people took to being outlaws for different reasons. Droughts which are common in this region drove many to desperation. A rigid caste system often ignited inter caste violence and initiated revenge cycles that lasted generations. The rugged terrain meant that farming land was scarce and land disputes escalated to murderous outbursts and often a point of no return. 

The background was always the gullied landscape in which the outlaws could escape and hide from their enemies and the law.

Annie Zaidi surveying this region has found out that dacoity has changed with the times. These days gangs earn a livelihood not by old fashioned looting and raids on villages and travelers but by kidnappings for ransom and protection rackets.

Geology influences this new economy too. At the fringes of the alluvial badlands outcrop Archean granites and gneisses, Proterozoic marbles, limestones and sandstones and the Deccan Basalts,all of which are extensively quarried, often illegally.

These quarries are in remote areas and gangs extort protection pay from owners in exchange of safety.

Chambal geology, both recent and ancient has sustained illegal livelihoods for centuries.


View Larger Map

See: Geology and livelihoods

Sunday, February 13, 2011

Rich Will Suffer More From Climate Change - Update

I was fortunate to catch a repeat of the program I wrote about in my last post. Climate Matters on DD Lok Sabha TV was featuring the topic Climate Change and Urban Settlements.

The moderator was Dr. Suman Sahai and the panelists were Dr. Ashok Jaitly of TERI and Mr. Roy of Hazard Center Delhi. It was Mr Roy who made the comments on the rich likely to suffer more from climate change.

I caught the larger context in which these comments were made. The question asked by Dr. Sahai was on vulnerability of populations to climate change and whether technology can help in adaptation and mitigation.

Mr. Roy answers were what I had highlighted in my last post, essentially he was arguing that since the poor have so little they are less vulnerable - as he put it .. a person living by the sea in a boat will not lose out to sea level rise!..and ... the moderator chipped in with the gem..there will be more fish...

He argued that the poor already have the technology to survive and adapt in harsh conditions giving the example of shepherds in Rajasthan and the people resettled out of Delhi. He didn't elaborate what this technology was and whether it had helped them not just survive but improve their lives substantially over their previous experiences.

As a couple of commentators on my previous post have pointed out it is not a question of the poor just surviving on little or adapting or being less vulnerable but crucially how do we lift people out of poverty and enable them to better their lives in the face of many challenges that they face such as their lands being appropriated for various developmental projects and their habitats degrading due to over exploitation of resources like groundwater, with erratic climate now likely adding to their woes.

Flippant comments like a person living by the sea in a boat will not lose out to sea level rise do not begin to address the reality of the situation on the ground. I don't mean to suggest that Mr. Roy didn't feel that we should  improve the lives of the poor.. but his limited presentation of the issue did come out as a tad insensitive.

And no.. there won't be more fish with a sea level rise.. only a loss of coastal aquifers and coastal agricultural land.. and that means more landless migrants...

Saturday, February 12, 2011

Indian Think Tank : Rich Will Suffer More From Climate Change

I happened to catch the last few minutes of a discussion on climate change and its effect on India on DD Lok Sabha , a government television channel which along with public affairs programming also covers the lower house of Parliament where you can watch Indian politicians trade insults and throw shoes at each other..

Unfortunately I do not know the panelist's name.. and I don't know where he works.. but this is the gist of what he said -

.. the poor have shown that they can adjust to any conditions... look at the resettlement of the poor from Delhi... they have been given a place to live about 40 kms from where they were before..a place without proper infrastructure and far away from facilities.. but they are still surviving...they are sending their children to school.. we should learn from that..

..sea level rise won't be a major concern for the poor.. they can migrate and adapt.. in fact they may have more opportunities to fish..its the rich living in big mansions by the sea who will suffer the most from sea level rise..

...the poor people of Rajasthan have shown that they can adapt and live under harsh desert conditions..

oh yeah....sure.. now i get it... the poor have less to begin with, so they will lose less when their aquifers turn saline and their crops dry out.. fortunately they can just pick up their meager belongings and live a nomadic life..they are used to making best of the conditions around them... the rich..poor loves...don't have that luxury... they are stuck in their million dollar coastal mansions...waiting for the sea to swallow them up...yeah.. sure..sure.. makes sense...  no??

staggering indifference.. but not surprising in a country where in the name of development the poor are routinely displaced with a shrug that they will.. adapt.

Tuesday, February 8, 2011

Remotely India # 5: Lonar Crater

Move over Chicxulub Mexico of dinosaur extinction fame, move over Meteor Crater Arizona.. I've got my own meteorite crater right here in my backyard.

Okay... okay.. this crater didn't transform the planet, didn't disrupt ecosystems or cause mass extinctions.. but there it stands, a beautiful round hole punched in the earth.. testimony to the fragility and exposure of our planet to bombardments from space.

Lonar Crater is a small crater formed by the impact of a meteorite. It forms a 1.88 km diameter depression in the Deccan Basalts in eastern Maharashtra near the town of Aurangabad about 8-9 hours drive from Pune. There is a relief of about 135 meters from the rim to the surface of the lake. The image below is a rendering of the relief of the region produced by draping a satellite image over a digital elevation model.

Source: Maloof et al 2009

For years there was some uncertainty on whether this depression represented a collapsed volcanic cone or whether it is of impact origin. Meteorite fragments have not been found at Lonar. But there always were doubts about the volcanic origin since geomorphic features of the crater such as its excellent preservation, a very thin sediment cover in the crater lake and immature river incision features surrounding the crater suggested a much younger origin than the ancient Deccan Basalts.

Now detailed studies of the deformation of basalt flows in the crater walls and evidence of impact shock from the presence of maskelynite a glassy phase formed by shock conversion of plagioclase feldspar has put that debate to rest. Several types of glassy spherules show that the crater formed due to a meteorite impact.  Below is a geological map of the lonar crater which shows the distribution of the ejecta blanket. Series Q are Quaternary features: Qb - beach, Qe - ejecta, Qf - forest, Qh - histosol, Qi - irrigated alluvial fan, and Qt - talus. Series T represent basalt flow in the crater walls. Coordinate are in Universal Transverse Mercator Projection.

Source: Maloof et al 2009

Dating the crater using various methods had previously suggested an age ranging from 12 thousand years to 65 thousand years. A recent study by Maloof et al 2009 carbon dated soils preserved underneath the ejecta blankets. The dates indicate a very young maximum age of about 12 thousand years for the impact. On the other hand another recent study using Argon-Argon dating method on impact melt rock has suggested an age of about six hundred and fifty thousand years. The consensus though seems to be leaning towards a much younger age for the crater.

The crater has  received a lot of attention from geologists. Its importance lies in its very recent origin. High erosion rates on earth wipe away bits and pieces of any feature, many times making a detailed reconstruction of events impossible. In Lonar crater though, impact features are well preserved and have proved useful in understanding cratering mechanisms. Its location within a basaltic terrain makes it a good analogue for small impact craters on the moon and other rocky planets. 

Ecologically too the crater is a unique place. The lake has high salinity levels and hosts a variety of extremophile bacteria.

The Geological Survey of India protects the crater and its rim but not all of the ejecta blanket. Urbanization and agriculture are slowly destroying it.

Digital Elevation Model of Lonar Crater derived from GPS measurments:

Source: Maloof et al 2009

Thursday, February 3, 2011

Quality Management In Astrology

If you thought Astrologers in India don't go through rigorous scrutiny... then take a look at this:

They come with a quality stamp on them these days.

Wednesday, February 2, 2011

Milankovitch Cycles and Carbonate Deposition

Over at Open Mind, Tamino has written a series of excellent posts on Milankovitch climate cycles and how they influence the growth and decay of ice sheets.

Milankovitch cycles are orbital cycles which result in periodic fluctuations in the amount of solar energy received by the earth. Three types of cyclical changes in the earth's movement around the sun, eccentricity, obliquity and precession are said to determine climatic cycles on earth.

Read the posts (Part 1, Part 2, Part 3, Part 4).

These climate cycles are of great interest in my field of carbonate sedimentology. Ancient shallow water carbonate basins are often made up of  exquisitely layered strata with the same sediment type recurring at intervals throughout the sequence. The origin of this rhythmic deposits have been a subject of great debate and discussion.

One explanation has been that Milankovitch cycles causes growth and decay of ice sheets. This periodic locking in and release of sea water by ice sheets causes fluctuations in sea level resulting in changing water depths and cyclical deposition of sediment. A great many carbonate sequences have been explained as being deposited under the influence of sea level changes caused by such orbital forcing. The image below is one of the most famous examples of Milankovitch forced cycles.. the Triassic dolomite platform which makes up the famous dolomite mountains in Italy.

Source: The Latemar Controversy

The other popular explanation and which may well be correct in many instances as well is that shallow marine carbonate systems generate cyclicity by self organization i.e in these systems there is an inbuilt interplay between water depth, currents and sediment production and deposition. The locales of sediment production and deposition keep shifting in response to local thresholds resulting in the same conditions appearing and disappearing from any one particular region. The result is cyclical carbonate strata which are hard to distinguish from orbitally forced cyclical sediment.

This debate over the generation of carbonate cyclicity continues.. but the interest in not just academic. There are differences in the three dimensional geometry and internal structure of sediment bodies built up by orbitally forced cyclicity versus those built up by local thresholds.

Cycle thickness, lateral continuity of facies, the extent of sea level fall and the duration of exposure to fresh water are some of the differences between the two systems that will influence the pattern and movement of fluids in the basin which may result in differences in the patterns of porosity and permeability, two properties of great economic importance.

A petroleum geologist looking at a hydrocarbon lined pore space in a rock chip or thin section and wondering whether this porosity extends all across the basin will have to think big.. of large scale facies patterns, of cycles upon cycles, of fluid flow, of sea levels rising and falling, of continental configurations and paleo-geography... and even the movement of the earth across the heavens..

That's what makes geology such a fascinating subject of study..