Quake was waiting to happen
S.B. Bhatia

The Epicentre of the Muzaffrabad earthquake (Saturday, October 8, 2005) which measured 7.4 on the Richter Scale and which affected area in northern Pakistan and parts of Kashmir, lies in one of the most spectacular and tectonically complex regions of the Himalaya.

The worst affected areas of Balakot and Muzaffrabad , close to the epicentre, lie in the axial region of a tongue-like “projection” around which the rock formations exhibit abrupt hairpin like bend — as if the “projection” acted like a pivot resisting or obstructing the northward movement of the Indian Plate.

This spectacular geological structure was first discussed in a publication of the Geological Survey of India (1931) by the late Dr D.N. Wadia, the doyen of Indian geology and the founder Director of the Wadia Institute of Himalayan Geology, Dehradun, who referred this geological structure as “Hazara Kashmir Syntaxis” (HKS). Wadia’s concept of a syntaxial bend was soon accepted and recognised by geologists the world over.

In recognition of his work, Wadia was soon elected a Fellow of the Royal Society, London — the first Indian geologist to be so honoured.

Besides the hairpin like bend, Wadia also mapped several “Thrust” faults which, sort of envelop the axial region of the syntaxis. Four of these thrust faults (see figure) designated as MBT, PT, MCT and the MMT, extend and splay out on either side of the syntaxis and have been mapped throughout the Himalaya on a regional scale.

A thrust fault is defined as a low-angle reverse fault in which the “hanging wall” appears to move up. relative to the “foot wall”. In the case of a normal fault, the hanging wall appears to move down (due to gravity) relative to the foot wall.

The trust faults of the HKS also form a loop around the apex of the syntaxis and bring successively older and metamorphosed rock formations to lie over the younger rock formations (35 million years) which form the core of the syntaxis.

The epicentre which lies WNW of Muzaffrabad and west of Balakot occurs in a structurally complex zone where one of the thrusts — the PT — intersects the MBT north of Balakot but separates again and splays out westward south of the town . North of Balakot, the axis of HKS bends northeast wards and continues beyond as Nanga Parbat Syntaxis (see figure).

The MBT which dips 50° due east north of Balakot, dips steeply >.70° near Muzaffrabad with a stratigraphic displacement of 3300m.

Yet another major dislocation plane — the Jhelum Fault — which is a left-lateral strike — slip fault, dislocates the MBT between Balakot and Muzaffrabad (Kazmi and Jan, 1997). This fault (shown in solid black line in figure ) offsets the western limb of the HKS by about 31 km.

The Muzaffrabad earthquake apparently resulted as a sequel to movements along the PT and MBT intersection near Balakot, compounded by the left-lateral displacement along the Jhelum Fault. The Balakot-Muzaffrabad axis, thus, had the potential of a major earthquake and it is surprising that it did not occur all these years.

Two other worst affected areas — Mansehar (shown M in the figure) and Islamabad (shown IS in figure) lie close to and south of the MCT and the MBT respectively. These two thrust faults were also apparently activated as a sequel to the major tectonic movements in the vicinity of the epicentre.

The writer is a retd. Professor of Geology, Panjab University, Chandigarh

Safer construction

• Get the design of multistorey and public buildings approved from a structural engineer.
• Always keep foundation of the building on a hard soil with proper width and depth not less than two feet.
• Use only good quality cement, bricks and steel during construction.
• Keep the shape of the building rectangular (the length should not be more than three times the breadth).
• Try to avoid balconies, projections and cantilevers. These are more dangerous and collapse first during an earthquake.
• Properly secure the false ceiling with walls of the room.
• Bureau of Indian Standard strongly recommends (1:1½:3)/M-20 mix for all type of RCC work.
• All the walls of the buildings should be provided with reinforced cement concrete band (beam) at the plinth level and door-level on all the walls.
• Construct multi-storey buildings with RCC column and beam type construction (RCC framed structure).
• Keep the height of the parapet wall three times of its thickness.
• Spend more on structural safety than outer finishing of the building.

— Raj Kumar Aggarwal

Trends
Earthquake observatory

Geologists affiliated with the US National Science Foundation’s Earth Scope Project have drilled a hole more than three km deep into California’s San Andress fault to study earthquakes in an acting fault zone.

“We now have the first opportunities to measure directly the conditions under which earthquakes begin and grow,” says Herman Zimmerman, director of NSF’s earth sciences division. — PTI

Remains of flying reptiles

Remains of two new species of (120-million -year-old flying reptiles have been found in a fossil rich area of norheastern China, an international team of scientists said.

The creatures belong to a group of reptiles called pterosaurs, or winged lizards, that evolved the ability to fly and had previously only been discovered in Europe. — Reuters.

Rare yew trees cultivated

Chinese botanists have successfully cultivated rare yew trees with anti-cancer medicinal values, which have grown on the earth for about 2.5 million years.

The success makes it possible to increase the survival rate of artificially-cultivated yew trees and to extract anti-cancer substances from the rare plant, an engineer with the Suiyang Town Forest Bureau of northeast China’s Heilongjiang Province, Xie Ailin said. — PTI

Hydrogen cars

The idea of hydrogen powered, non-polluting cars is making progress but challenges still lie ahead, according to the latest progress report issued by the US National Research Council.

Fifteen countries are working to make fuel cell vehicles commercially available by 2020. — PTI

Cheap genome sequencing

Want your own personal genome sequenced ? Researchers said they had found a faster and cheaper way to do it that would cost only about $ 2.2. million.

George Church and colleagues at Harvard Medical School hope eventually to reduce the cost further to $ 1000 per genome — the entire DNA code of a person, plant or other organism. — Reuters

Human-like skin

A flexible, electronic skin could provide robots, car seats and even carpets the ability to sense pressure and heat, Japanese researchers have reported.

They described a new “skin” that not only senses both heat and pressure but that is flexible , chap and easy to make. — Reuters

Robotic surgery

Keyhole or laparoscopic surgery for obesity can be safely performed with a completely robotic approach, new research indicates. Whether this represents a real surgical advance or just a more expensive way of doing things however, is hotly debated.

With the robotic approach, mechanical arms are attached to the instruments that the surgeon would normally hold. To operate, the surgeon sits at a console with video monitor and moves attached instruments that activate the mechanical arms. In the present study, the console was in the same room as the patient, but it can be located hundreds of miles away, allowing the “telesurgery”. — Reuters

THIS UNIVERSE
PROF YASH PAL

Sometimes during a clear night we see a ring around the moon. What is the reason behind this phenomenon?

Prof Yash Pal

Very high thin clouds consist of ice crystals. One of the shapes of such crystals accurately sculptured hexagonal (six sided) rods. The light coming from the moon enters a face and is refracted out of another face, such that its angle with respect to the earth- moon direction is 22º. This is very much like when light passes through a prism. The angle of 22º is the angle of minimum deviation for a 60º ice crystal prism.

Therefore most of the refracted light is concentrated in a ring of that angular diameter. No ray coming from the moon and refracted by an ice crystal can emerge at an angle less than 22º. In other words, random orientation of the ice crystals floating in the atmosphere does not disturb this argument. In essence much of the moonlight within that ring is stolen and put in the region outside the ring; it can be shown by calculation or experiment that there is a strong concentration at the angle of minimum deviation, where the ring is seen.

You must have noticed that on the nights this phenomenon is observed the sky outside the ring looks a little translucent while within the ring it is transparent and darker; it is darker inside because of the reason given above, namely that 22º the moonlight passing through ice crystals gets concentrated on and beyond a cone of 22º. Incidentally this angle is determined by the refractive index of ice and the fact that our ice prisms are formed by alternate sides of hexagonal crystals - essentially 60º prisms.

The answer I have given might appear concentrated, but it will be transparent if you go through it again. Meteorological optics is a fascinating field - both aesthetically and scientifically.

What causes us to use different Fleming rules (left hand and right hand) to understand the relation between directions of current, magnetic field and force in generators and electric motors?

The basic science can be understood the following way. Electric currents produce magnetic fields. If we have a current loop it acts like a magnet with two poles. There would be a force between this loop and a magnet such that like poles will repel and unlike poles would attract. This force would be in a direction perpendicular to the plane of the loop. Reversing the direction of the current in the loop would reverse the direction of the force.

One can see that Fleming’s left hand and right hand rules give us an easy way of remembering the directions of the three mutually perpendicular vectors, namely the current, the magnetic field and the force.

Why most of the time various scientists try to challenge Einstein’s law of equivalence of mass and energy, E=mc2 ?

No serious scientist does that. Some people delight in trying to connect their name with that of Einstein. Challenging this well-established fact is not the way. There might be other things that Einstein said or pursued on which questions might be raised, or clarifications attempted.