Our planet, the earth is unique as it supports life and allows it to evolve and flourish. Life thrives on this planet despite geo hazards, which are a challenge for the life to survive and sustain. Geo hazards have been part and parcel of the planet through the millennia. Events of destruction and reconstruction have been a part of the earth's history and affect even the contemporary life with an increasingly greater impact.
Prior to the development of scientific thought civilizations all over the world ascribed geo hazards as acts of God. Mythologies world over are full of stories connecting various geological events to supernatural powers. Later in the narrative we will read about one such Hindu mythology which has also been confirmed by the scientific observations.
Since the geo hazards were considered as expression of anger of the supernatural power, Geos or the Earth was always revered by all the religions. The Hindu mythology considers the earth as the mother and each morning before stepping upon the earth, a devout Hindu chants the following 'mantra':
'Samudra vasaney! Devi! Paravat stan mandaley!
Vishnu patni! Namstubhyam; paad sparsh kshamsva mey!'
Wearing attire of the oceans, goddess with mountain like breasts;
Wife of Lord Vishnu, Oh the mother earth,
I bow and touch thy feet, please pardon me.'
The Hindu mythology believed that the mother earth and her husband Lord Vishnu rested on the head of the serpent, 'Sheshnag'. The earth shook as per the mythology, whenever 'Sheshnag' shook his head.
Greeks and Romans thought Poseidon and Neptune respectively as the gods of water. Poseidon was considered as the lord of the earthquakes too, because the Greeks believed that the earth shook on his command only. Thunderbolts and lightening wee controlled by Typhon and Zeus. Hephaestus, a son of Zeus was supposed to be the god of the subterranean fire or the volcanoes. When the Greeks moved to Sicily, hey equated Hephaestus with local volcano god Vulcun or Volcanus. The eruptions of the mounts Etna and Stromboli were attributed to the wrath of the ire-god.
It was Thales of Miletus (about 624-565 BC) who took courage to describe the natural events not as supernatural acts, but as natural orderly events which could be investigated through observation and reasoning.
Human reasoning and logic took thousands of years to realize that geo hazards were caused by the nature's processes. There were several set backs for this thought to evolve because of the pressures from the religious lobby.
Today, the geo hazards are thought to be the manifestations of energy acting through matter. Events like earthquakes and volcanic eruptions are no more considered as the revenge of the gods: on the contrary, we know they arise due to release of stresses and strains of the earth's unstable interior; and from the escaping gases and heat through the crust.
Modern technology has now made possible the forecast of many geo hazards like tsunamis, volcanic eruptions, floods, landslides etc. Generally the forecast gives sufficient time for the population to move to safer areas. Yet in front of the hazard like an earthquake man is miserably helpless. The shaking earth leaves a trail of death and destruction, barely giving time to people to escape. Many countries besieged by earthquakes have resorted to construction of earthquake resistant houses and retrofitting of old houses to prevent collapse.
Except volcanoes the mainland of our country is affected by all other geo hazards like earthquakes, avalanches, landslide, floods and tsunamis. Andaman-Nicobar Islands though safe from the snow avalanches are affected by volcanic eruptions on the Barren island.
The Indian landmass after it broke away from Madagascar some 120 million years ago (m y) moved northwards like the Noha's Arc and began to collide with the Asian Plate. The collision produced the loftiest and the youngest mountain chains on the earth, the Himalayas. The collision still continues and the impacts are felt as earthquakes.
Geo hazards are linked to each other. For example, as earthquake can trigger a snow avalanche or a landslide. A landslide can block he stream in he valley and cause flash floods later. Earthquakes in the ocean bed trigger off tsunamis.
The collision of he Indian Plate is not merely responsible for the earthquakes. It has rather produced some of the fantastic landforms the Himalayas and valleys which gave rise to the mighty river systems of the Indus, Ganga and Brahmaputra. The Himalayas are the climate controllers of our sub-continent.
Mountain building movement that produced the Himalayas in today' context can be taken as one of the severest geo hazard. The end product is in front of us like the three beautiful valleys, in this region, viz. Peshawar (Pakistan), Kashmir (India) and Kathmandu (Nepal). Kashmir or sensu stricto Srinagar valley was a huge lake filled up to the brim which is at an elevation of approximately 13000 feet. 'Nilmat Puran' a Hindu scripture mentions about the hug lake and it has been confirmed by the scientists too. As per the 'Puran' life on the lake was controlled by a demon which used to kill innocent people. Sage Agastya came to the rescue of the people and he gave a mighty blow on the Pir Panjal range at Baramulla to create an opening that drained the lake, destroying the demon. The presence of fossils of lake plants and fruits like Trapa near top of the Pir Panjal range made the doyen of Indian Paleobotany, Dr. Birbal Sahni conclude that the lake existed till that level in the geological past. The Baramulla gap mentioned in the geological literature came up as a consequence of one of mountain building movements and the past lake actually drained through that gap. What are left today are only the remnants of the past giant lake.
Geo hazards are part of the earth's environment and they can not be wished away. Only way to tackle them is to know the answers about why do we have such hazards and when and how they occur. This knowledge can help the society to remain prepared for the unexpected and escape their impact.
Sometimes tragedy from such hazard is avoided through keen observation and common sense. In 1976 while exploring the remote interiors of Spiti valley in Himachal Pradesh I found my camp had been pitched on a nala bed strewn with boulders with sharp edges. Such edges are produced when rocks shatter due to freezing and thawing of water in the cracks in high altitudes. Many times these boulders fly off like cannon shots and are capable of killing people in their path. Had I agreed to sleep there, perhaps that would have been an eternal sleep for me!
Despite knowledge and information about the vulnerability of houses on mountain slopes, river banks and beaches, in the name of development people go on investing huge sums.
Nainital a beautiful lake resort of Uttaranchal is a classic example of human greed and apathy. It is well known that the northern flank of the hill in Nainital is prone to landslides yet massive construction activity through the ages has converted the place in to a concrete jungle. Investigations by the Geological Survey of India (GSI) have revealed that in the past three decades the northern hill slope has subsided by more than one meter. In 1881 a massive landslide from the northern hill top had filled up half of the lake within eight seconds killing about 200 people. One dreads to think of a repeat of those eight seconds.
There is no end to such follies. In the plains housing colonies on the flood pathways of rivers, in he name of 'riverside apartments' have come up or on the beaches 'sea side apartments' have come up making lives of the residents vulnerable. Yet we go on making such mistakes.
Geo hazards are a serious threat to our society and need constant updating of information about them. It is equally important to enlighten the society about the possible threats and make people aware. As we proceed through the stories of different geo hazards in the coming weeks we shall know more about them and also learn the ways to tackle them and remain safe.