History of mankind is replete with stories of some terrible temblors. Some were fiction, some factual. Despite scientific and technological developments in leaps and bounds, man is helpless when the earth shakes. Earthquakes always take you unawares, generally in the dead of the night. People die not of earthquakes but of the falling roofs and collapsing houses. Earthquakes not only mean loss of lives, they cause economic losses too. Many people lose their bread and butter. The seismologists and people involved with managing such disasters are always trying to find way out. As per the science of seismology though it is not possible to forecast an earthquake but with the help of old records it is possible to work out the probabilities and also identify the susceptible areas.

The previous article 'When the earth trembles!' was devoted to the earthquakes that shook our land in the geological past. It is time to know about some fiery earthquakes of our history. In the matter of earthquakes the history does repeat itself. One need not be a seismologist to understand this. Just scratch the memory and many disasters of the past will flash by.

But human memory is volatile. Despite knowledge about earthquakes of the historical past, areas which have witnessed violent earthquakes are most inhabited in our sub-continent. The following narrative makes it amply clear:

The oldest record of earthquake is found in 3,000 years old Chinese scriptures. Descriptions of damaging earthquakes are found in the Iranian prose and poetry of almost the same period as the Chinese scriptures. Likewise many archeological marvels of the past are in ruins today (see 'Earthquakes threaten obelisks of culture').

Some devastating temblors of the sub-continent

As the story goes, Brahmanabad a flourishing town of Sindh, now in Pakistan, was razed to ground by a devastating earthquake in the historical past. However, there is no way to confirm the story. As such it can not be used for scientific studies.

The first semi-scientific record in India is that of Delhi-Agra earthquake of July 15, 1505. Thereafter in 1668, Seemaji a large town in western part of sub-continent with 30,000 houses vanished after an earthquake.

Kaifikhan a historian of Moghul period recorded in 'Muntakhabul-Ul-Lulab' that on 15 July 1720, people had assembled to offer prayers on 22nd 'Ramzan' a loud roar from the underground shook the people. So powerful was the earthquake that people were nonplused. Hundreds of lives were lost and innumerable buildings in Shahjenabad (Delhi) were razed to the ground. Minarets of Fatehpur mosque fell killing those underneath. Kaifikhan further recorded that similar shocks continued to terrorize Delhi for the next 40 days.

As the saying goes Calcutta (now Kolkata) was rocked on 11 October, 1737 by a devastating earthquake which cost 3,00,000 lives. Since there is no corroborative evidence, hence the possibility of the tragic incident been caused by a cyclone can not be ruled out. Chatgaon (now Chittagong), Bangladesh was famous for the Mint. Chittagong was devastated by an earthquake in 1762 which also made some nearby islands rise above the sea level.

A powerful earthquake struck the Ganga plains in eastern India on 4 June 1764 and losses were tremendous in terms of loss of lives and property. More than 400 million people now live in the Ganga plains.

On September 1, 1803 , Mathura-Delhi area was rocked at 3AM. Mathura suffered the maximum damage. Open fissures were formed on the ground from which water gushed out with force. Scores of buildings were ruined within seconds. Domes of all the mosques constructed by Ghazi Khan tumbled down. One of them fell in to a fissure on the ground and vanished. Delhi was also severely affected and top portion of famous Kutub Minar tumbled down. Thomas Oldham of Geological Survey Of India (GSI) believed that this earthquake must have been 6.5 on Richters scale.

Kutch (Bhuj) earthquake of 26 January, 2001 is still fresh in the memory. It is worth recalling that the earthquake on June 16, 1819, in Kutch was no less devastating. So intense was the earthquake that eight kilometers north of Sindri, in the Rann of Kutch a three metre high and 65 km long ridge of clay and shell was formed. The local population named it 'Allah Bund'. Bhuj a major town then, had perished in this earthquake. About 2000 people lost their lives. This earthquake took a toll of 500 lives during a religious congregation in a mosque at Ahmedabad. So powerful was the earthquake that shocks were felt in the far north at Sultanpur, Jaunpur, Mirzapur in U.P. and Kolkata.

Thomas Oldham of GSI calculated the intensity of this earthquake on Richter scale as 8.3. The gravity of the situation can be understood by the fact that an earthquake beyond the intensity 8 causes total devastation.

The night of 26 August, 1833 was an unforgettable nightmare for the people of Kathmandu in Nepal . The earthquake razed to ground more than 100 houses. The intensity of the earthquake could be gauged from the fact that water from lakes and ponds was seen to rise in sort of tidal waves, birds left their nests and human beings were petrified with terror.

Northwest India was rocked in the afternoon of February 19, 1842. The epicenter of the earthquake was in Jalalabad (Pakistan) and almost one third of this town was razed to ground. The effect was terrible in Kabul and Peshawar and many lives were lost. Firozepur and Ludhiana were badly affected.

The temperature of the hot spring at Sohna (Haryana) became normal. Oldham in 1893 worked out that this earthquake had affected an area of about 216,000 sq km.

The Cachar earthquake of 1869 was the worst felt by the people of Kolkata. The epicenter of the earthquake was in the North Cachar district of Assam. Silchar town was the worst affected. Water in the lakes and rivers rose like tidal waves overflowing at several places. Near Pola, Barak and Dhulesar rivers, cracks and fissures were formed on the ground, through which fountains of water and sand spurted. Studies of Thomas Oldham indicated that the earthquake affected an area of 6,47,500 sq km. Including Hajaribagh in the Northwest, Patna in the North, Darjeeling and north of Lakhimpur. Incidentally this event initiated a systematic study of earthquakes in India. Findings of Thomas Oldham, the founder of Geological Survey Of India on Cachar Earthquake were published by his son R.D. Oldham in 1882 in the Records of the GSI. In the same volume he also published, 'A Catalogue of Indian Earthquakes from earliest time to the end of A.D. 1860'.

Geological Survey Of India is one of the pioneering surveys of the world to have prepared an earthquake intensity map in 1885. On 30 May that year Kashmir was shaken violently by a quake. E.J. Jones of the GSI surveyed the area and established that the epicenter of the quake was at a depth of 12 km in Kashmir.

Yet another great earthquake shook the northeastern states and west Bengal on 12th June, 1897. Known as the Great Assam Earthquake, it was investigated by R.D. Oldham of GSI and his team. They estimated that the earthquake had affected an area of 1,275,000 square miles. The seismological survey carried out by R.D. Oldham was published as a Memoir of the GSI.

Around that time towards of end of the 19th century at some places in the world use of Seismograph had started. They became more popular after the seismological station came up at Istanbul, Turkey. Network of seismographs came into being in the early 20th century. Prior to establishment of seismograph network the seismologists had to depend upon actual survey of earthquake affected areas and records of damages. Such records are essential even now, but seismograph has made a world of difference.

The database generated from the study of the past earthquake damage helps in compiling a Seismotectonic Atlas. It is an invaluable tool in the hands of planners, developers and major civil construction projects.

Earthquakes are part of the earth's environment. They are generated within the earth. Read about some more about some recent damaging earthquakes in the next issue.