Ganga Earthquake, Nile, Deep Sea Habitats

Some readings over the past few weeks:

1) An Earthquake Changed the Course of the Ganges. Could It Happen Again?  Sediment load carried by big rivers like the Ganga often choke up channels and force the river to cut another path. Sudden channel shifts can also occur due to tectonic movements. A recent survey of the Ganga about 100 km south of Dhaka, Bangladesh , identified an old channel of the Ganga. Exploring this area, researchers came across veins of sand cutting across the sediment layers. These veins or sand dikes were  injected into the surrounding sediment. They are a sign of major ground trembling triggered by a large earthquake. Ground motion may pressurize buried sand and inject it  upwards. Further studies showed that this event may have been a 7-8 magnitude earthquake that occurred 2500 years ago. Kevin Krajick writes about this discovery and the larger geologic context.

2)  Lessons from the Nile about rivers and society. The Nile river has sustained agriculture, human habitation, and royal dynasties for millennia. A Nature Geoscience editorial summarizes a collection of sedimentological and geomorphologic studies that track the evolution of the Nile through the Holocene. Phases of the river cutting a deep valley changed to phases of the river flooding laterally and building fertile floodplains. This geomorphological evolution driven by climate change and more recent dam building have influenced agriculture and social systems in the past as well as the present. 

3) Ocean Exploration: Meet The Deep. I highly recommend this site. National Ocean and Atmospheric Administration, U.S.A., has compiled some stunning photographs and videos of deep sea habitats and the diverse forms of life that inhabit this little understood world. Corals, sponges, brittle stars, molluscs, worm tubes- attached to the bottom, living around energy sources such as hydrothermal vents and cold seeps. It is an absolutely fascinating exploration of the biodiversity of the deep sea. 

Octocoral and Brittle Star: Source NOAA Ocean Exploration

As a bonus, these images make great wallpaper for your mobile phone!

Links: Earthquake Detectives, Origin Of Life, India Water Act

Reading from the past few weeks- 

1) How earthquake scientists solved the mystery of the last “Big One” in the Pacific Northwest. The American northwest is a tectonically active region. About 150 km west of the Pacific coast is the Cascadia subduction zone. Here, the Juan de Fuca, Explorer, and Gorda tectonic plates slide underneath the continental plate of North America. Large earthquakes have occurred in the past and will occur in the future. 

Reporter Gregor Craige has written a book, On Borrowed Time: North America’s Next Big Quake, in which he explores the region's earthquake potential and the cross disciplinary studies that enable scientists to understand past earthquake history as well as the impact a big future earthquake will have. Canadian Geographic has shared an abstract from his book. The earthquake puzzle was solved by combining information from tree rings, Native American peoples memories of past events, and Japanese record of tsunamis. It is fascinating reading. 

2) To unravel the origin of life, treat findings as pieces of a bigger puzzle. Was life's beginnings in a warm little pond or in a deep sea hydrothermal vent? Did lightning provide the energy, did asteroids provide the organic matter? There are many many scenarios that try to provide an explanation to this vexing question. 

One of the leading researchers of this field, Nick Lane, and his colleague Joana Xavier, have summarized some of the key arguments and problems of the field in this tour de force of science writing. Highly recommended! 

3) Analysis: The Great Indian Water Act Of 2024. In more good news for industries, factories and foreign investors, yet another Indian environmental law has been diluted to facilitate “ease of business”. Shailendra Yashwant begins his analysis of The Water Amendment (Pollution and Prevention) Act, 2024 Bill on this depressing note. Amendments seek to "rationalize criminal provisions". Polluters can now escape jail time and get away by just paying a fine. All this when climate change and water security is one of the big challenges facing India. 

Readings: Deep Time Mexico, Neanderthals, Early Mammals

Relish these articles.

1) Mexico City Deep Time Sickness.  Modern day Mexico City is built on the bed of lakes that formed around 2 million years ago. The Mexica people in the 14th century constructed a series of dams and dykes partitioning salt water and fresh water areas. They developed agriculture called as 'chinampas' on islands made up of mud and organic debris. This region became the city state of Tenochtitlan. Later in the 16th century this vast lake was drained by Spanish Conquistadors. Over time, extraction of groundwater is causing compaction of the soft sediment. The ground is subsiding unevenly across different parts of the city. Ground shaking by frequent earthquakes is making the problem worse. As cracks grow and widen, buildings tilt, and the ground shakes, the citizens have become acutely sensitive or "tocado" to geology altering their everyday lives.

"Deep time is often framed as something antithetical to immediacy, something totally separate not only from everyday experience, but also the idea of history itself. But if we are living in a moment in which experiential time, historical time and deep time are colliding, which of these times are being written onto the walls of Mexico City apartments?" 

A beautiful and unnerving article by Lachlan Summers.

2) Did Neanderthals Speak? Archaeologist Anna Goldfield summarizes our current state of understanding of the throat anatomy of Neanderthals and how they might have sounded. There is a nice audio clip too! 

3) Warm Blooded Mammals. When did warm bloodedness or endothermy evolve in mammals? Katherine Irvine writes about a new study of ear canal bone structures indicative of endothermy. An analysis of fossils suggest that warm bloodedness, along with a host of traits typically associated with mammals, arose by around 233 million years ago. 

Articles: Earthquake Temperatures, Marshes, Ocean Drilling

Sharing some good stuff I came across recently.

1) Taking the temperature of faults. From AGU News. Rocks get hot as they slide past each other during faulting. Chemical changes in organic molecules and helium content in zircon crystals are sensitive to temperature changes. Scientists have used these to estimate short lived temperature rise during faulting. Understanding patterns and magnitude of earthquake generated heat informs us about earthquake intensity, heat dissipation, and fault movement history. 

2) Why a Marsh: "Neither land nor water, maybe both, a marsh is a balancing act, a collaboration between changing elements, uncertain by its very nature, in flux"

A beautiful long essay by Daniel Wolff and Dorothy Peteet on marshes and wetlands and the vital role they play in ecosystem functioning. Especially fascinating is the description of Piermont Marsh, along the banks of the Hudson river, north of New York City. Sediment cores going back a thousand years preserve a record of climate change and human modification of the landscape. The marsh was first exploited by Native Americans and then more extensively by European settlers. It is a detailed look at the wealth of information a wetland can yield about climate, ecology, and human disturbance of the environment.

3) Drilling Into the Sea Bed: This is a really interesting summary of scientific ocean drilling by Neena Notman . They are attempts going on to reach the earth's mantle by drilling into the sea bed. Although drilling in the deep ocean seems daunting, this makes more sense than trying to reach the mantle from land. The crust making up the continents is much thicker. Ocean bed drilling offers a short cut to the earth's mantle. We know about the mantle mostly through geophysical data. Actual samples of the mantle are rare. Recovering pristine pieces of the mantle will allow us to validate what we've gleaned from geophysics. Drilling is also going on along a subduction zone to understand the nature of fault interface and rock properties.

 

Himalaya Overview, African Population History, Iceland Volcano

 From past couple of weeks:

1) This is a fine synthesis of geological, geophysical, seismic and geodetic data of the growing Himalaya mountains. The review examines the interplay and feedbacks between seismic cycles and tectonic deformation. Earthquakes result in rock deformation and faulting. Tectonic structures developed this way over million of years, in turn, influence stress accumulation and the extent and location of earthquakes.

Building the Himalaya from tectonic to earthquake scales.

2) Holocene-age ancient DNA and genetics of extant populations is increasing our understanding of African population history.

The deep population history in Africa. 

3) The remarkable drone footage of the ongoing eruption of Geldingadalir volcano in Iceland.

Email subscribers who can't see the embedded video can view it here- Iceland Volcanic Eruption.

Himalaya Earthquake Article

Bibek Bhattacharya has written a fine article in liveMint about Himalaya earthquake risk. He describes the geological story fairly accurately and also properly focuses on our woeful preparedness in terms of citizen awareness and in constructing earthquake resilient buildings.

Seismologist Roger Bilham too has been talking and writing about this topic from time to time. He has been quoted in Mr. Bhattacharya's article. There was also an interview with him published in the July 19th edition of Times of India. Apart from reiterating the geologic risk, he says that "Earthquake engineers in South Asia have diligently responded to the need to ensure building codes are implemented".

I have low confidence in this assessment and one that is echoed in Bibek Bhattacharya's article. In India, there is always a wide gap between expert suggestions and proposed guidelines and their ground level implementation over which earthquake engineers have no control. Demonstrations of strong but light weight constructions by various NGOs always remain at a pilot project stage and are not widely realized in the new growth that is taking place. Wherever I have traveled in the Himalaya, especially in Uttarakhand which faces the risk of a magnitude 8 earthquake, I have noticed that mountain towns have become concrete death traps. A congested sea of buildings have mushroomed up willy-nilly with scant regard for safety. The article in liveMint gives one pointed example of this recklessness. The Shimla High Court building is an 11 story structure built on the edge of a hill. Who will regulate the regulators?

The prognosis is grim.

Palghar Earthquake Swarm

My article on Palghar's mystery earthquakes has been published in The Wire Science. The article is an explanation of a recent paper that was published in the journal Tectonophysics. It favors the view that groundwater circulation is causing slippage along faults. According to the scientists involved the earthquakes are due to these very local processes.

One important point is that a link between groundwater and these tremors, even if it does exist here, represents a tipping point in a longer buildup of stress due to tectonic forces. The western margin of India is riddled by large fracture zones and faults. These structures haven't formed by groundwater movement. They are a legacy of earlier and ongoing crustal deformation due to regional and continent wide geological forces.  Groundwater flow or a build up of pore pressure cannot by itself generate enough stress to develop a fault de novo.

Dhundhalwadi is experiencing what is known as an earthquake swarm, a sequence of seismic activity with no clear peak (mainshock), and which is localised to one area. A recent study by researchers around India, including the National Institute of Seismology, has found one potential explanation for the swarm that draws a link between the monsoons, groundwater circulation and rock deformation...

Read more here.

Tsunami History Preserved In Indonesian Cave Deposits

How would you know if a coastline had been inundated by a tsunami say 5000 years ago? Well, a tsunami carries sediment stripped from the ocean bed and deposits this material over the flooded coastline, beyond the range of what a regular storm would. The problem is that such deposits have poor preservation potential and over time get eroded away. There are however some environments where such tsunami deposits may get preserved inland. These are estuaries, coastal marshes and lakes. Here, interlayered with normal estuarine, marsh or lacustrine sediment, one may find layers of sand of a distinctly different composition and texture and containing remains of organisms which live in an open marine setting. This implies a sudden incursion of marine waters into these inland coastal settings. The other coastal setting with a good preservation potential are caves. These too get flooded by storm surges and tsunamis and may preserve a record of such events in the form of sand deposits. The picture to the left (Source: Rubin et.al. 2017)  shows sand layers deposited by the 2004 tsunami.

In one such cave on the coast of Aceh, Indonesia a record of the 2004 tsunami along with sand layers deposited by 11 older tsunamis going back to 7400 years ago have been preserved.

Highly variable recurrence of tsunamis in the 7,400 years before the 2004 Indian Ocean tsunami-
Charles M. Rubin, Benjamin P. Horton, Kerry Sieh, Jessica E. Pilarczyk, Patrick Daly, Nazli Ismail & Andrew C. Parnell

Extract:

 We identify coastal caves as a new depositional environment for reconstructing tsunami records and present a 5,000 year record of continuous tsunami deposits from a coastal cave in Sumatra, Indonesia (Fig. 1), which shows the irregular recurrence of 11 tsunamis between 7,400 and 2,900 years BP. The sedimentary record in the cave shows that ruptures of the Sunda megathrust vary between large (which generated the 2004 Indian Ocean tsunami) and smaller slip failures. The chronology of events suggests the recurrence of multiple smaller tsunamis within relatively short time periods, interrupted by long periods of strain accumulation followed by giant tsunamis. The data demonstrates that the 2004 tsunami was just the latest in a sequence of devastating tsunamis stretching back to at least the early Holocene and suggests a high likelihood for future tsunamis in the Indian Ocean. The sediments preserved in the costal cave provide a unique opportunity to refine our understanding of the behaviour of the Sunda megathrust, as well as study in detail the sedimentology and hydrological characteristics of tsunami deposits.

There is one point that cannot be over stressed. The average recurrence time for earthquakes and tsunamis has been estimated to be on the order of several hundred years. However, there is a great variation in the actual occurrence, with several smaller tsunamis occurring just decades apart. While our understanding of earthquake mechanisms and tsunami generation will go on improving, ultimately what will save lives is better preparedness. This includes adherence to structurally appropriate building codes, functioning tsunami warning systems and well drilled and practiced disaster management plans. South East Asia has long neglected these issues and there needs to be a renewed focus on them.

Himalayan Gravel Flux And Flood Risk

Why should an understanding of sediment transport distance and whether that sediment gets broken down into coarser gravel or finer sand be of any practical use?

Here is a good example from the Himalaya.

Abrasion-set limits on Himalayan gravel flux- Elizabeth H. Dingle, Mikaël Attal & Hugh D. Sinclair

Rivers sourced in the Himalayan mountain range carry some of the largest sediment loads on the planet, yet coarse gravel in these rivers vanishes within approximately 10–40 kilometres on entering the Ganga Plain (the part of the North Indian River Plain containing the Ganges River). Understanding the fate of gravel is important for forecasting the response of rivers to large influxes of sediment triggered by earthquakes or storms. Rapid increase in gravel flux and subsequent channel bed aggradation (that is, sediment deposition by a river) following the 1999 Chi-Chi and 2008 Wenchuan earthquakes reduced channel capacity and increased flood inundation. Here we present an analysis of fan geometry, sediment grain size and lithology in the Ganga Basin. We find that the gravel fluxes from rivers draining the central Himalayan mountains, with upstream catchment areas ranging from about 350 to 50,000 square kilometres, are comparable. Our results show that abrasion of gravel during fluvial transport can explain this observation; most of the gravel sourced more than 100 kilometres upstream is converted into sand by the time it reaches the Ganga Plain. These findings indicate that earthquake-induced sediment pulses sourced from the Greater Himalayas, such as that following the 2015 Gorkha earthquake, are unlikely to drive increased gravel aggradation at the mountain front. Instead, we suggest that the sediment influx should result in an elevated sand flux, leading to distinct patterns of aggradation and flood risk in the densely populated, low-relief Ganga Plain.

Behind paywall, but I thought this is a good illustration of how insights into very fundamental earth processes can potentially help save lives.

Nepal Earthquake Aftermath- What Is Happening Underneath Kathmandu?

We continue to learn more about the buildup and release of strain along the master detachment fault underneath the Himalaya. The master detachment fault known as the Main Himalayan Thrust is the surface along which the Indian plate is sliding underneath Asia.

This data using GPS records of surface motion in the area affected by the 2015 Gorkha (Nepal) earthquake:

Himalayan strain reservoir inferred from limited afterslip following the Gorkha earthquake -David Mencin et al 2016 (behind paywall)

The magnitude 7.8 Gorkha earthquake in April 2015 ruptured a 150-km-long section of the Himalayan décollement terminating close to Kathmandu. The earthquake failed to rupture the surface Himalayan frontal thrusts and raised concern that a future Mw ≤ 7.3 earthquake could break the unruptured region to the south and west of Kathmandu. Here we use GPS records of surface motions to show that no aseismic slip occurred on the ruptured fault plane in the six months immediately following the earthquake. We find that although 70 mm of afterslip occurred locally north of the rupture, fewer than 25 mm of afterslip occurred in a narrow zone to the south. Rapid initial afterslip north of the rupture was largely complete in six months, releasing aseismic-moment equivalent to a Mw 7.1 earthquake. Historical earthquakes in 1803, 1833, 1905 and 1947 also failed to rupture the Himalayan frontal faults, and were not followed by large earthquakes to their south. This implies that significant relict heterogeneous strain prevails throughout the Main Himalayan Thrust. The considerable slip during great Himalayan earthquakes may be due in part to great earthquakes tapping reservoirs of residual strain inherited from former partial ruptures of the Main Himalayan Thrust.

The Himalaya cross section below shows seismicity along the interface of the Indian plate boundary faults.  MFT is the Main Frontal Thrust, MBT is the Main Boundary Thrust and MCT is the Main Central Thrust. These south younging sequence of thrust faults are thought to absorb the crustal shortening in the Himalayas. The youngest, the Main Frontal Thrust is thought to be active today, i.e. great earthquakes that nucleate underneath the Himalaya, rupture the surface along this fault system. All these thrusts faults are inferred to be splays of the Main Himalayan Thrust. Red and Orange dots are instrumentally recorded earthquakes.

Source: Bollinger et al 2014: Estimating the return times of great Himalayan earthquakes in eastern Nepal: Evidence from the Patu and Bardibas strands of the Main Frontal Thrust

Return Times Of Great Himalayan Earthquakes

Bollinger, L., S. N. Sapkota, P. Tapponnier,Y. Klinger, M. Rizza, J. Van der Woerd,D. R. Tiwari, R. Pandey, A. Bitri, and S. Besde Berc (2014), Estimating the return times of great Himalayan earthquakes in eastern Nepal: Evidence from the Patu and Bardibas strands of the Main Frontal Thrust, J. Geophys. Res. Solid Earth, 119, doi:10.1002/2014JB010970.

This is a very detailed study taken up along  two strands of the Main Frontal Thrust in Nepal south east of Kathmandu. Along this fault, the Neogene foreland basin Siwaliks are thrust over the Indo-Gangetic alluvium.

Crustal shortening taking place in the Himalayas as a result of convergence between India and Asia is accommodated along a sequence of south younging thrust faults; The Main Central Thrust, The Main Boundary Thrust and the southernmost Main Frontal  Thrust, which is active today. All these thrusts are interpreted to merge into a single decollment called The Main Himalayan Thrust (a "master fault" along which India subducts underneath Asia). The cross section below shows these major thrust faults flattening at depth and merging into the Main Himalayan Thrust. Earthquake clusters in red dots shows a region of the Indian slab which as it slides under Asia, often (over decadal to millenial times scales) gets locked. Rupture follows, thus releasing that accumulated slip. These ruptures propagate southwards and occasionally break the surface along the Main Frontal Thrust.

Source: Bollinger et al. 2014

So, along this fault in front of the Siwalik  hills, there is evidence in the form of fault scarps and fault traces, offset and deformed strata, uplifted river terraces and stacks of colluvial deposits (sediments eroded from a fault scarp) of past earthquakes. This study examines this record in detail going back several thousand years. Its a long paper and there were sections where the reading is a hard slog and when my eyes glazed over, but it is rewarding to understand the techniques (geomorphic measurements, geochronology and shallow seismic profiling)  that have been applied to reconstruct earthquake history.

Abstract:

The return times of large Himalayan earthquakes are poorly constrained. Despite historical devastation of cities along the mountain range, definitive links between events and specific segments of the Main Frontal Thrust (MFT) are not established, and paleoseismological records have not documented the occurrence of several similar events at the same location. In east central Nepal, however, recently discovered primary surface ruptures of that megathrust in the A.D. 1255 and 1934 earthquakes are associated with flights of tectonically uplifted terraces. We present here a refined, longer slip history of the MFT’stwo overlapping strands (Patu and Bardibas Thrusts) in that region, based on updated geomorphic/neotectonic mapping of active faulting, two 1.3 km long shallow seismic profiles, and logging of two river-cut cliffs, three paleoseismological trenches, and several pits, with constraints from 74 detrital charcoals and 14 cosmogenic nuclide ages. The amount of hanging wall uplift on the Patu thrust since 3650 ± 450 years requires three more events than the two aforementioned. The uplift rate (8.5 ± 1.5mm/yr), thrust dip (25° ± 5°N), and apparent characteristic behavior imply 12–17.5m of slip per event. On the Bardibas thrust, discrete pulses of colluvial deposition resulting from the coseismic growth of a flexural fold scarp suggest the occurrence of six or seven paleo-earthquakes in the last 4500 ± 50 years. The coeval rupture of both strands during great Himalayan earthquakes implies that in eastern Nepal, the late Holocene return times of such earthquakes probably ranged between 750 ± 140 and 870 ± 350 years.

And in conclusion:

Certainly, the best path toward fully understanding whether and where great or giant earthquakes are likely to occur along the foothills of the highest mountain range on Earth will be to combine many exhaustive geomorphological and paleoseismological field investigations such as that presented here with extensive, long-term geodetic measurements, capable of narrowing uncertainties in estimates of the full seismic moment deficit.

Eyewitness Account Of A Great Nepal Earthquake

From 1934 - as reported by military officer Bhrama Shumsher Rana in his book  Mahabhukamp (The Great Earthquake) -

“The trees were moving as if they were agitated by a storm and it seemed that the tree-tops would touch the ground … Pillars and walls of houses were cracking,doors and windows slamming. With movements up and down, houses collapsed. Statues and decorations placed on top of temples and houses fell to the ground. The noise made by the houses collapsing was reminiscent of canon fire, as…during festivities. Because of the dust, it was darker and no one was able to see at more than a distance of 8 to 10 hands apart. This cloud of dust came from the city itself, invading open areas such as the Thundikhel—a large open and unconstructed space in the centre of Kathmandu—which was such as lost in a fog. People rushed to all these open spaces. Those who could not move themselves were seizing pillars, while others were searching to hide in shelters or ran to the fields. People would run on all fours like animals…”

“Cracks opened in the fields and roads. Water spurted from these cracks. There was flooding in all streams.Rivers like the Bagmati and Bishnumati were invaded by black muddy water. At some places, the water rose 8to 10 hands above the cracks. Many fields were flooded with water. Warm water and sand spurted from some of the cracks. The roads toward Balaju and Shankhamul were affected by a subsidence as large as one or both hands in height. There were few roads that were not cracked.”

via Bollinger et al 2014 

Kathmandu has been leveled and rebuilt several times over the past 1000 years or so. There are a series of posts on Dot Earth about damage done by the recent 7.8 mag Nepal earthquake, on building codes and earthquake preparedness.

Earthquakes Triggered By Fluid Injection Along Faults

A friend sent me this abstract published in the Seismological Society of America 2014 annual meeting-

Triggered Earthquakes Far From the Wellbore: Fluid Pressure Migration and the 2008-2014 Jones Swarm, Central Oklahoma

KERANEN, K. M., Cornell University, Ithaca, NY, USA, keranen@cornell.edu; WEINGARTEN, M., University of Colorado, Boulder, CO, USA, matthew.weingarten@gmail.com; BEKINS, B., USGS, Menlo Park, CA, USA, babekins@usgs.gov; GE, S., University of Colorado, Boulder, CO, USA, Ges@colorado.edu; ABERS, G. A., Lamont-Doherty Earth Observatory, Palisades, NY, USA, abers@ldeo.columbia.edu

Earthquake relocations and hydrogeologic modeling show that the Jones earthquake swarm, occurring near Oklahoma City since 2008, is linked to disposal wells injecting high volumes of water along the Nemaha Fault. Felt and recorded earthquakes in the Jones swarm began in 2008, approximately 15 km from four high-volume wastewater disposal wells. These wells dispose of ~2-3 million barrels per month (4-5 million barrels per month cumulatively) in two adjacent locations on the downthrown side of the Nemaha fault. Earthquakes are observed to migrate away from these high-volume disposal wells up the structural dip and down hydraulic gradient. Hydrogeologic modeling shows that the increase in subsurface pore pressure resulting from the fluid injection is of sufficient magnitude to trigger slip on pre-existing faults. The region of increased pore pressure grows outward through time with injection. The larger, mapped faults in the subsurface may act as conduits or guides to fluid flow, and may transmit fluid pressure into basement. Our results demonstrate that wastewater disposal can raise fluid pressure and trigger earthquakes at tens of kilometers from the wellbore on existing faults.

Fracking for shale gas by itself has not been shown to trigger biggish earthquakes but the wastewater disposal that follows fracking has.

How does increasing pore pressures increase the chances of slip along a fault? High pore pressures reduce the effective normal stresses acting perpendicular to faults. These normal stresses resist shear movements i.e. fault blocks from sliding past each other. With increased pore pressure the effective normal stresses decreases, allowing shear movements.  Geophyicist Mark Zoback explains in more detail about the risks and management of seismic risk posed by wastewater disposal.

Sunday Reading: Science Of The Himalayas- Open Access

Current Science has a special section on the science of the Himalayas with papers on a wide range of topics including papers on the seismic importance of major fault systems, interplay of faulting, climate change and sedimentary processes and a surprise!... a study of volcanic arc associated Cretaceous carbonate reefs.. built not by corals but by those enigmatic weird bivalves.. Rudists... enjoyed reading that!

• Seismotectonic implications of strike–slip earthquakes in the Darjiling–Sikkim Himalaya
  Malay Mukul, Sridevi Jade, Kutubuddin and Abdul Matin
• Climate footprints in the Late Quaternary–Holocene landforms of Dun Valley, NW Himalaya, India
  Anand K. Pandey, Prabha Pandey, Guru Dayal Singh and Navin Juyal
• Palaeogeographic significance of ‘Yasin-type’ rudist and orbitolinid fauna of the Shyok Suture Zone, Saltoro Hills, northern Ladakh, India
  Rajeev Upadhyay
• Active tectonics in the northwestern outer Himalaya: evidence of large-magnitude palaeoearthquakes in Pinjaur Dun and the Frontal Himalaya
  G. Philip, N. Suresh and S. S. Bhakuni
• Active fault study along foothill zone of Kumaun Sub-Himalya: influence on landscape shaping and drainage evolution
  Javed N. Malik, Afroz A. Shah, Sambit P. Naik, Santi S. Sahoo, Koji Okumura and Nihar R. Patra1
• Intricacies of the Himalayan seismotectonics and seismogenesis: need for integrated research
  O. P. Mishra
• When did India–Asia collide and make the Himalaya?
  A. K. Jain
• Observed changes in Himalayan glaciers
  Anil V. Kulkarni and Yogesh Karyakarte
• Seismotectonics of the great and large earthquakes in Himalaya
  J. R. Kayal

V.K Gaur On Earthquake Research, Jaitapur Seismic Risk And Role Of Scientists

The Hindu carried an interview with Vinod Kumar Gaur, seismologist with the Centre for Mathematical Modelling and Computer Simulation. His work on the seisimic risk at Jaitapur southern Maharashtra where a nuclear power plant has been proposed was criticized by the Indian government and his colleague Roger Bilham denied entry into India on the grounds that he violated the terms of his tourist visa. I share the suspicion of many that the Indian government is too sensitive and insecure about anyone raising questions about nuclear safety and reacted pettily by banning Dr. Bilham.

Some excerpts:

You have been vocal in your scepticism of Jaitapur as the location for a proposed 10,000 MW nuclear power plant...

Not for the construction of the plant, which can be designed with safety features. But India’s western coast, a well-recognised zone of potential seismic vulnerabilities, is likely laced with ancient faultlines buried under sediments and waiting to spring back like a piano accordion under continental compression. It is intriguing that Jaitapur [on the Maharashtra coast], the chosen site for the world’s biggest nuclear power plant, should have been declared seismically safe without refuting these possibilities.

My concern is that the various geological proxies of faultlines around Jaitapur and their possible implications on the plant and public safety have been neither adequately studied nor communicated. A clear picture of Jaitapur’s vulnerabilities and their quantification, needed in order to calculate the level of safety measures to be incorporated, is missing from the earthquake hazard assessment of the site. 

What, in your opinion, prevents a more thorough safety analysis of Jaitapur?

We have every technological possibility to exhaustively investigate the subsurface geology of Jaitapur including high resolution seismic imaging that can be carried out at a fraction of the project cost.

Scientists tend to downplay earthquake risks. It is convenient to do so. You keep everybody happy when you maintain status quo. But science only grows by addressing challenges, by considering alternative views and designing incisive experiments to prove or refute conjectures.

 and he has some harsh words about the lack of outreach role played by Indian scientists.

....Sadly, our scientific culture lacks responsibility and rigour towards public safety, and so denies society the advantage of information, and consequently resilience, against the natural disaster.

Read the full interview here.

My previous posts on this topic:

1) Politics And Pettiness In Indian Seismology
2) Note To Indian Govt: It Is Pointless Banning Seismologist Roger Bilham

Review Article: Recurrence Of Great Subduction Zone Earthquakes

Open Access in Current Science: 

Kusala Rajendran

The last decade has witnessed two unusually large tsunamigenic earthquakes. The devastation from the 2004 Sumatra–Andaman and the 2011 Tohoku-Oki earthquakes (both of moment magnitude ≥ 9.0) and their ensuing tsunamis comes as a harsh reminder on the need to assess and mitigate coastal hazards due to earthquakes and tsunamis worldwide. Along any given subduction zone, megathrust tsunamigenic earthquakes occur over intervals considerably longer than their documented histories and thus, 2004-type events may appear totally ‘out of the blue’. In order to understand and assess the risk from tsunamis, we need to know their long-term frequency and magnitude, going beyond documented history, to recent geological records. The ability to do this depends on our knowledge of the processes that govern subduction zones, their responses to interseismic and coseismic deformation, and on our expertise to identify and relate tsunami deposits to earthquake sources. In this article, we review the current state of understanding on the recurrence of great thrust earthquakes along global subduction zones.

The figure above shows the  Cascadia subduction zone, Pacific coast of N. America (source Rajendran 2013) . I looked through the Reference section and saw a number of recent papers addressing both the evidence for past earthquakes as well as the impact of the 2004 Sumatra earthquake on the Indian coastline. The acknowledgements indicate funding for this paper from the Ministry of Earth Sciences, Govt. of India. Its good to see basic geological research into subduction zone earthquakes being supported this way.

The Real Reason Behind The Santa Cruz Islands Earthquake

From Jesus and Mo..

And here is the less likely explanation.

Note To Indian Govt: It Is Pointless Banning Seismologist Roger Bilham

I wrote in my last post on the travel ban issued by the Indian Government to American seismologist Dr. Roger Bilham. The reason given was that he was engaging in activities inconsistent with his visitor visa status. These activities include attending scientific meetings and contributing towards understanding seismic risk at a proposed nuclear power plant at Jaitapur in southern Maharashtra. I do suspect that this is the real reason for the ban, which is that Dr. Bilham has irritated people in the Indian Government in charge of nuclear power plant safety by suggesting that the government's assessment of Jaitapur underestimates the risk of a large (6-7 mag.) earthquake.

Now he has answered his travel ban in the best way possible; by producing more science about the geology of the area around Jaitapur with implications for regional and site seismicity. He and his colleague Vinod Gaur have published this work in Current Science. It is open access and there is nothing the Indian Government can do to prevent his work from being widely discussed and disseminated (as I am doing now) and critically evaluated.

That by the way is what these scientists want as they outline several tests for their hypothesis and the hypothesis proposed by other geologists critical of Gaur and Bilham's earlier paper on this subject.

Politics And Pettiness In Indian Seismology

American seismologist Roger Bilham who has previously visited India many times to attend workshops and to meet colleagues on a tourist visa is now blacklisted and is being refused entry in to India.

A year ago he and Vinod Gaur of the Indian Institute of Astrophysics in Bangalore wrote a paper in Current Science  (open access) suggesting that there is small probability of a 6-7 mag earthquake near or at the site of a proposed nuclear power plant at Jaitapur in southern Maharashtra and that this should be taken in to account in the design of the plant. The paper was criticized by several Indian seismologists.  The scientific debate has been summarized by K.S Jayaraman.

This May, Bilham was denied entry into New Delhi and deported.  The reason given was that he was coming for activities not consistent with his tourist visa status. Bilham suspects that this decision by the Indian government is due to pressure from a senior Indian seismologist.

From G.S Mudur's article in The Telegraph:

The government decision was presumably based on recommendations made by one or more influential seismologists in India,” Bilham wrote to the IISc on October 17 this year, in a letter where he has declined to evaluate the PhD thesis of a young scholar. 

The IISc had requested Bilham to assist in the evaluation of the thesis. 

“It has been brought to my attention that some younger colleagues have been intimidated by a retired (Indian) seismologist who once held a position in Hyderabad, from working with me, or being associated with scientific studies, or discussions,” Bilham told the IISc. 

“The intimidation takes the form of suggestions that future funding, or chances of promotion, or job security, may be placed in jeopardy if these young scientists are in any way associated with my name,” he wrote, adding that his presence on the panel of thesis examiners might turn detrimental to the future of the young scholar. 

If true, this is a sorry sorry situation. What was it that Prof Krishna Kumar wrote about Indian academia and research institutions recently?... 

Inadequacy of funds is, of course, worrisome, but it cannot explain the extent to which malice, jealousy and cussedness define the fabric of academic life in our country.

All that seems to be on full display here. Several Indian seismologists have spoken out against Bilham's entry ban. More scientists must speak out. Scientific differences and even personality clashes should not translate into bans for scientists. If the tourist visa is indeed a problem then Dr. Bilham should be asked to apply for the correct visa category. But just keeping silent shows our government as a whimsical petty system which takes offense at any dissent, in this case, someone pointing out that it may have been wrong in its assessment of seismic risk. So far there has been no detailed explanation from the government for Bilham's ban.

HT: Nanopolitan

Conversations About Seismic Risk Of The Proposed Jaitapur Nuclear Plant

I get mails from reporters asking me geology questions. I got one today morning from a reporter of a big newspaper about the controversy regarding the siting of a proposed nuclear power plant near the village of Jaitapur in southern Maharashtra.

With his permission I have pasted his question and my reply below-

Dear Suvrat,

After the press conference by Dr Bilham regarding the earthquake hazard  to Jaitapur. NPCIL has issued a press release, which mentions about the various studies carried out on behalf of NPCIL. They are mentioned in the file attached with this mail. I was wondering whether they have taken adequate test for the Jaitapur site.

I would be obliged if you could see the mail and give your feedback.

Warm Regards

XX

Dr. Bilham is Dr. Roger Bilham who along with Dr. Vinod Gaur recently published a paper (open access) on the tectonic situation and seismic risk along the southern Maharashtra region. My post summarizing the paper is here.  NPCIL is the Nuclear Power Corporation of India Limited and their press release can be found here.

Here is my reply. I've added a couple of words (in black for clarity) -

Hi XX-

The list itself covers all the geological studies that can be done. I cannot off course speak to whether individual studies were comprehensive or not. I am curious whether the NPCIL already has or is planning on making all these studies available to the public so that independent experts may evaluate the findings of the government scientists.

Geologically there are two limitations here. One is that, there is no reliable historical documentation of large seismic events from this area (Jaitapur). Second, there is no surface expression of faults and displacements along these faults that may give us some idea whether and with what frequency was this area affected by large earthquakes in pre-historic times. Therefore it is difficult to develop a robust statistical extrapolation of the risk of large earthquakes.

This uncertainty means that people can read what they want to into all the tests and theories about this area. People who don't want a nuclear plant can say.. look, an earthquake can hit any time.. just like Latur. No scientist can disagree with that.

On the other hand the nuclear establishment can say with some justification that over the life cycle of a nuclear plant (next 100 or so years) there is a small probability of a moderate size earthquake (6 -7 Richter) and an even minuter chance of a tsunami and we can deal with the engineering requirements.

I don't see any side giving way because the opposition to nuclear energy goes deeper than just geological considerations and its hard to change the government's mind on anything.   From what I have read about the general geology of the area I suspect that everyone can beat the geological risk angle to death and get nothing new out of it.

One impression I did make when I followed some of the panel discussions on the Tamil Nadu nuclear plant on TV shows is that some of the nuclear scientists were dismissive and even contemptuous of civic society concerns. Maybe a similar attitude has aggravated the situation at Jaitapur.

Cheers

Suvrat

Latur is the area in southern Maharashtra which suffered a 6.4 mag earthquake in 1993. It was long thought to be at low seismic risk. The Indian government is promising to engage with civic society on all aspects of the construction of the many planned nuclear power plants and in that spirit of openness I hope they make the relevant geological studies available for anyone to critique.

I will post more on this topic as the story develops.