Geologytectonicsvkrao

Sethusamdram : Geology & Tectonics

Dr. V.K. Rao Deputy Director

National Geophysical Research Institute Hyderabad

NEERI Report – Tectonics ?2.5. Tuticorin Port Trust as NodalAgency

In February, 1997, the Ministry of Surface Transport made Tuticorin Port Trust as Nodal Agency for the Project, and subsequently the National Environmental Engineering Research Institute (NEERI), Nagpur was appointed by Ministry of Surface Transport in July 1997 to prepare the Initial Environmental Examination (IEE) of the Project The IEE study report indicated that the Project is environmentally safe with negligible effect on the eco system and the Marine National Park of the Gulf of Mannar. The report also recommended a particular alignment of the canal cutting the Pamban Island, east of Kothandaramasamy temple, which will cause least damage to the biota and the environment . As per instructions of the Ministry in February, 2002, NEERI was entrusted to conduct the following studies:-    

(i) Techno-economic viability, and

(ii) Environmental Impact Assessment.    

Tuticorin Port Trust later engaged M/s. L & T-Ramboll Consulting Engineers, Chennai in 2004 for preparation of a Detailed Project Report, which has clearly established the financial viability of the Project and has also prescribed a stringent Environmental Management Plan for preserving and conserving the rich bio-diversity in the project region.

ISSUES - I•Researchers recently drilled into corals off eastern island Kenya – Soil erosion increased dramatically

•Prof. Tad S Murthy of Canada has raised serious concerns on the devastation of Kerala through the proposed canal which will suck in the next tsunami waves if the present alignment is retained. The Chairman of Tuticorin Port Trust has completely ignored the warnings given by Prof. Tad S Murthy of Canada.According to V. Sundaram,this circling around Sri Lanka occurred because the Ramar Bridge acted as a natural shoal barrier preventing the inflow of waters. If the Sethusamudram Canal is dug through the bridge, it will act as the channel for the waters to flow directly into the entire Southern India coastline beyond Dhanushkodi and into the coastline of Kerala right into the Konkan region.

ISSUES - II•According to Dr. Ramesh, NEERI Environmental Impact Assessment (EIA), the study that gives the SSCP, its scientific legitimacy, has ignored the studies available on the sedimentation pattern of Palk Bay completely and has not fixed the exact locations wherein the dredged material would be dumped – these studies are crucial for the economic and technical survival of project, as they will give us an idea of how much sediment should be dredged each season and also prepare us for a study that will tell us where the dumped sediments will move every season.

•Subsurface geology has been studied only for the 20 kilo meter stretch of the canal in the Adam’s Bridge area. Nothing is known about the subsurface geology of the Palk Strait region.

ISSUES – III•Considering the fact that the canal’s length will be 54.2 km; if the sub surface turns out to be rocky, the cost of the project will go up many folds, and the effect of blasting these rocks would cause serious damages to the Palk Bay environment. This was clearly stated in the Technical Feasibility Report prepared by NEERI only to be politically ignored at the time of political sanction of SSCP.•The historical cyclone data for this region from the years 1860 to 2000 clearly indicate that cyclones cross this region and its neighborhood once in every four years. Historically, we have enough data to show that all these cyclones have caused severe erosion of the coastal stretch in the nearby areas from time to time by dumping the eroded material in Palk Bay and Adam’s Bridge area. NEERI’s EIA has not taken note of this natural phenomenon at all.

Rate of sedimentation, uplift &local tectonics- an indicator of ‘Neo Tectonics’

•Uplift in south Indian craton is being projected as 12mm /yr.

•Rate of sedimentation has been varying from time to time, 2-5.7 cm/100years

•Local tectonics controlled the sediments laid down in the depressions of Cauvery basin, which is known a Hydrocarbon potential zone.

OTHER ISSUES

Denudation rate varied along many places of South Indian shieldChanges in sea levels effect Tides, weather, climate.In gulf of Mannar, Coral mining has caused increase in turbidity of waterand the reefs have undergone noticeable deterioration

Imagine the slope of Indian & Sri Lanka

side and the effect in the study region

Present Ferry Service between India & Sri Lanka

Adam’s Bridge

Ridge formation between India & Sri Lanka

PLATES DISTRIBUTION

Type of deformation across Plates

Ocean – Ocean Subduction

Melting process during subduction

Sunda Trench : Subduction Zone

Sumatra-Andaman Earthquake - I

The Sumatra–Andaman earthquake began at 00.59 UT on 26 December, 2004 under the Sunda trench in the eastern Indian Ocean, where two of the Earth’s tectonic plates meet (Figure 1). The floor of the Indian Ocean is being slowly pushed under the Burma plate by convection currents in the underlying mantle. Over the previous few centuries this movement, called subduction, had been resisted by frictional forces, allowing enormous amounts of strain energy to build up along the fault where the two plates meet. On 26 December 2004, the applied stresses overcame the frictional forces on an area on the southern end of the fault off Banda Arch, Northern Sumatra.

Sumatra-Andaman Earthquake - II

There, the ocean floor suddenly plunged northeastward by up to 20 meters under the Burma plate, releasing almost all the accumulated energy in a huge rupture which propagated northwards along the subduction zone as far as the Andaman and Nicobar Islands. Large seismic waves were generated, and the

Seismogram of Tsunami

Friction effect of Tsunami

Here are some of the figures of Tsunami effects:

A cartoon of earthquake wave and long period gravity wave are shown. P wave travel through basalt and the Oceanic sediments forming multiple reflections (generated as low-order Rayleigh- spheroidal modes especially 0S2 and 0S3) whereas the gravity waves transmitting through water with very long wavelength of 430km. Frictional resistance offered by the seafloor and open Ocean, the wave front is proceeding with great energy.

Tsunami wavelength

Geology & Tectonics during 500-600 Ma

Sethusamdram : Age angle

American Space Agency NASA has declared that there exists a bridge 30 km long connecting Sri Lanka and India, constructed with the help of stones, which is known as ‘Adam’s Bridge’. The age of the bridge according to them is 1.75 million year old. This historical bridge, according to NASA is man-made with good scientific background. Incidentally this age 1.75 my age of this bridge converges with the mythological age of Treta Yuga because the Satya Yuga has the age of 1.73 m.y. and the Treta Yuga has the duration of 1.3 m.y. Hence, 1.75 m.y. comes exactly in the Treta Yuga.

Magnetic crust

Digital Tectonic Activity -Earth

Historical Seismicity

Trans Asiatic lineament –together with lithospheric up warps ~80 0East( our study )

Shmax-Tectonic stress

Geoidal Low-Undulation &Trans Asitic Lineaments

24,25-Mannar & Cauvery basin

Seismicity – Block tectonics

13-Coromandal Coast Fault- lineament analysis

Inferred active faults-Seismicity

Free Air Gravity Anomaly Map from Global Satellite Gravity Model

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Bathymetry Map

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