It isn’t every day that one is in the middle of an earthquake and grateful for it. Arch Johnston, a seismologist with the University of Memphis, and a team of other specialists were in the Rann of Kutch, studying the aftermath of the 2001 earthquake in Bhuj, Gujarat, when another quake struck. “We saw Arch struggling to balance his tall frame, yet clapping his hands and laughing aloud and shouting ‘thank you’,” recount the scientists C.P. Rajendran and Kusala Rajendran in their book, The Rumbling Earth: The Story of Indian Earthquakes. Such anecdotes pepper this accessible, concise history of earthquakes, which is exceptional in that it comes from an Indian vantage.
A homeless family at a makeshift tent in Bhuj, Gujarat. | Photo Credit: Getty Images
Combining their decades-long scholarship, the book attempts to demystify earthquakes: What makes them hard to predict? Why are some regions more likely to be jolted than others? Is the loss of life and property inevitable in the wake of a tremblor? Can knowing the history of earthquakes in a region make forecasts of future ones more accurate? What are aftershocks, foreshocks, plate tectonics, P-waves and S-waves?
Students in Amritsar light candles to pray for Turkey following the 2023 earthquake. | Photo Credit: Getty Images
Mysterious ways
Answers to these questions are the meat of the book, dispelling some of the intrigue surrounding earthquakes. The basic principles of astronomy, biology, chemistry can be comprehended as their dramatis personae — the sun, moon, stars, plants animals, metals — are visible. The earth sciences are relatively mysterious because the action is underground and invisible and involves gargantuan bodies moving incrementally over aeons and prodding cataclysmic changes.
A woman collecting water from a tap near a collapsed wall of an apartment building in Guwahati, after a strong earthquake hit Assam in 2021. | Photo Credit: Getty Images
The unexpected jolt that can strike anytime, accompanied sometimes by death and devastation, is linked to the same forces that slowly nudged a large independent island near Antarctica, that we know today as the Indian subcontinent, to eventually ram into Eurasia and create the Himalayas.
Indian sand artist Sudarshan Pattnaik’s sand sculpture on Puri beach, Bhubaneswar, following the earthquake in Turkey in 2023. | Photo Credit: Getty Images
Only in the decade that men landed on the moon did earth scientists conclusively establish the theory explaining these links. Continents and the oceans weren’t immobile and rested on ‘plates’ which were in constant motion and floating on a layer of molten rock. Plate tectonics, as this theory is called, also explains the formation of continents, volcanic activity, tsunamis and the intensity and timing of earthquakes. It is due to plate tectonics that India expects, with a sense of dread, a massive, Himalayan earthquake (or a couple of them) but whose exact timing and location unfortunately cannot be predicted. This was after a 2001 paper in the journal ‘Science’ by scientists Roger Bilham, Vinod Gaur and Peter Molnar calculated that there is a long 700 km segment along the Himalayan plate boundary that hasn’t produced a major earthquake in the last 500 years. Therefore, all the strain accumulated over the centuries will inevitably result in a displacement that will wreak “unparalleled damage” in several parts of north India, particularly the Gangetic plains. The Rajendrans describe their own excursions into the Himalayas to decipher evidence of past earthquakes.
A survivor searches for belongings amid the ruins of her damaged house following an earthquake in Nepal in 2023. | Photo Credit: Getty Images
Archaeoseismology, as this endeavour is called, involves studying ancient structures such as old temples or land formations that may reveal signs of past earthquakes and help estimate the probability of future ones.
The earthquake at Killari, Maharashtra, in 1993. | Photo Credit: Getty Images
Damage control
While the overwhelming number of earthquakes globally occur along the zones where the plates meet, there are other kinds too. For instance, the 1993 Killari earthquake in Maharashtra, or the Koyna earthquake in 1967, which has been linked to the filling up and emptying of a reservoir, are examples of significant earthquakes that are not linked to plate-boundary dynamics. While predicting major quakes remains a mystery globally, what’s better known is ways to minimise the scale of the damage.
Signs in Dichato, Chile, direct residents to tsunami evacuation routes. | Photo Credit: Getty Images
Chile, the book notes, is a country that is frequently rocked by massive earthquakes but reports minimal damage, thanks to the strict enforcement of building codes — a lesson that is by and large ignored in India’s construction ethos. India’s varied geography, geology and history suggests that many mysteries remain. Dr. Johnston, the Rajendrans say, probably jumped for joy because he got to experience a quake at the Rann of Kutch, a place significant in geological history. Not only was this great desert once a sprawling sea but in 1861 it was the site of an unusual earthquake that created a 2-4 km high bund, called the Allah bund, that till date stretches all the way to Pakistan.
Charles Lyell, the 19th century founding father of geology, described the discovery that a land surface could be deformed by earthquakes a “watershed moment in the history of geology.” Earth science practitioners must take up the task of sensitising the community about new developments in the field, the Rajendrans point out.
The Rumbling Earth: The Story of Indian Earthquakes; C.P. Rajendran, Kusala Rajendran, Vintage/Penguin, ₹699.
jacob.koshy@thehindu.co.in
Published - August 02, 2024 09:01 am IST
