About 200 kilometres south of Delhi lies the mostly forgotten town of Bayana in Rajasthan. Once celebrated for producing perhaps the world’s first and finest clear crystalline sugar, Bayana rivalled Agra and Delhi in wealth and grandeur. What made Bayana’s sugar special was something to do with its wells and their water. Then, suddenly, Bayana’s prestige waned. And finally vanished altogether. What had happened?
Environmental historians believe that the cause of the town’s decline was a distant earthquake in 1505 and the gradual diminishing of available water. Bayana lies on the Bayana Basin, in the eastern part of the North Delhi Fold Belt within an ancient chunk of the earth’s crust known as the ‘Aravalli Craton’. The town sits atop undeformed sedimentary rocks that were formed from sand brought down by rivers that mixed in a shallow sea, filling it over millions of years. Over time, under high pressure and aided by pulses of immense heat from below, these sediments turned into rocks roughly between one to two billion years ago. What set in Bayana’s decline is perhaps one, or perhaps even two, earthquakes that shook its ambition. The quake or quakes did not occur beneath Bayana but quite far away. The first one most likely happened in Afghanistan. The Baburnama, the memoirs of the first Mughal emperor, records an earthquake that ruptured the ground below Paghman and Bektut, west of Kabul. It caused the river Kabul to swerve tens of metres away from its old course. Another site, or perhaps a second, discrete earthquake, occurred in Kumaon and the Western Himalaya of Nepal. Paghman is nearly two thousand kilometres away northwest and Kumaon-West Nepal's epicentre is at least 400 kilometres north of Bayana, as the crow flies. The city, which was perched atop the heat and pressure-tempered sandstone-and-quartzite shoulders of the Aravallis, perished not because a quake occurred under it, but at a considerable distance away.
Earth scientists who study earthquakes — seismologists — rely on plate tectonics and the make-up of the earth’s crust to understand how quakes impact a region. They begin with the oldest rocks that much of India straddles, which are by and large stable. It is the rocks lying above them, the ‘younger’ layers, which are restless.
This is where the Aravallis enter the picture. These hills began to assemble above the basement rocks soon after they had become stable. The Aravallis were not created all at once but in several distinct phases. Its oldest rocks are tens or a hundred million years younger than the ancient basement upon which they sit. Seismologists recognise four distinct major rock terrains in these hills. The oldest rocks are gneiss (pronounced ‘nice’) in the region around Bhilwara, a staggering 3 billion years old. The next spurt of mountain-building happened between 2 to 1.8 billion years ago across the Aravallis, giving it its characteristic glassy quartzite. The rocks around Delhi are relatively recent, around 1.1 billion years old. These ‘babes’ of the Aravallis rocks were formed when magma from volcanoes recooked older rocks between 850–750 million years ago to make new ones.
This is what geologists call the ‘post-Delhi magmatic event’.
A significant part of the Aravallis lies unseen beneath the surface. It is only relatively recently that we discovered that the Aravallis don’t terminate in north Delhi as was thought but run considerably beyond — albeit underground — to come to an end near Hardwar. Anyone who doubts the significance of this rocky extension of the Aravallis needs to know that it forms the divide for the Ganga and Indus’s watersheds.
The Aravallis have played a role in shaping every landscape that emerged after it — the Vindhyas, Satpuras, Sahyadris, even the geologically ‘recent’ Himalaya and Thar. But the singular feature that seismologists like to keep abreast of today is the restless Delhi fold belt.
Earthquakes, like the one in Bayana in 1505, do not have to occur directly below or even close by to have major and lasting effects. Here’s a bit of physics and geology for the scientifically inclined: Seismologists peer with great interest at crustal reflectivity variation or CRV, which expresses the difference in how seismic waves ‘bounce’ off and travel through different layers of rock within the Earth’s crust. Imagine you are at a pond with lotuses, lilies, and other floating plants. If you create a wave, you will notice that the waves are intercepted, deflected and buffered by these impediments on the surface. What you see is only on a horizontal plane on the surface of the pond. Seismologists need to ‘look’ deep within the earth and study past earthquakes to build models about how waves travel and bounce through layers of rock, both vertically and horizontally. They study the crust’s architecture and the density and composition of its rocks. They study at what depth these tremors occur and how far they are transmitted. Waves behave differently as they travel across rocks of different densities. Some rocks reflect it, a few cancel it, and some — only a very few — amplify it. Tiny differences in rock types or the presence of ‘fluids’ can make one place more susceptible to earthquakes than the other.
The tectonic history of each region exerts a deep influence on it. For example, where land parted in the past and created rifts, and zones where landmasses collided and rubbed against each other that created mountains, react differently to near and distant quakes. Each rift and hill is different from another. Hence, when seismic waves pass through them, they behave differently. Some rocks in fault and shear zones also contain fluids, such as tiny amounts of water. Often previous seismic episodes have produced heat to ‘liquefy’ some rocks, which behave like liquids. Every rock layer alters the velocity of seismic waves. Some rocks become subterranean ‘tsunamis’ and transmit tremors further.
The Aravallis by themselves do not encounter earthquakes from below but receive shockwaves, chiefly from the hills of the Af-Pak border or the northwestern Himalaya (the horizontal waves in our makebelieve pond!).
Staying a little longer on fluids, there’s another area that may have an impact on the region. A 2023 study found that massive overextraction of groundwater both in the Punjab and California have indirectly caused the Earth’s axis to tilt a tiny bit. In groundwater-deficit regions, the effect of an earthquake may get amplified should one occur. What has water got to do with earthquakes, you may ask? Here’s one way in which it occurs: on October 20th 2011, a rare phenomenon occurred in Talala, Gujarat, famous for being the home of the Asiatic lion and kesar mangoes. At 10:42 AM, an earthquake with a magnitude of 5.1 on the Richter scale struck, creating cracks in houses, collapsing walls and causing panic. Unlike very large earthquakes, it did not destroy an entire town but reminded people of the region’s seismic risk. Some researchers studied the Talala earthquake and found that the quake was caused by movement along shallow faults. These faults were already weak and fractured. Heavy rainfall during the monsoon may have played a part. Seismologists suspect that rainwater may have seeped deep into the cracks of rocks. This would have increased the pressure underground and made it easier for the rocks to slide and slip, sending a tremor. As rocks under Talala continued to give way, the region experienced several aftershocks. Unlike the more powerful and devastating Bhuj earthquake of 2001 which was caused by the shifting of deep-seated faults in Kutch, Talala’s tremors were more local and influenced by surface processes like rainfall. Fortunately, the Punjab region does not sit on such a seismic tripwire. But could the hollowed out groundwater ‘channels’ reverberate and amplify incoming shockwaves? Can rainwater fill empty channels and create Talala-like tremors in the Punjab?
One study suggests that Talala-like tremors may already be occuring in the Delhi region. It also notes that cities situated close to the Aravallis such as Delhi, Jaipur and Udaipur are ‘poorly-studied’ and ‘unknown sources of seismic hazard is a concern and warrants further scientific and policy intervention’.
Tremors and quakes are a reality in north India. Delhi straddles zone IV which has fairly high seismicity. On 24th December 2025, the Delhi Disaster Management Authority updated its website which says that the state commonly encounters ‘earthquakes of 5-6 magnitude, a few of magnitude 6-7 and occasionally of 7-8 magnitude’. Mild tremors are common on either side of the Aravallis, but rarely are there strong ones above its quartzite or basement rocks. But here is a reminder from India’s National Centre for Seismology to shake you up further. On 12th December 2025, a little before 2 o’clock in the afternoon, Baghpat in Uttar Pradesh, east of the Aravallis, was jolted with a tremor. Nine days later, at noon, a mild quake was felt in Rohtak in Haryana, which is west of the Aravalli range.
Tremors and quakes are no longer only a natural phenomenon but can also be human-made. We don’t know nearly enough about how landscapes and their processes work and how each is connected to the other. We don’t know when a landscape will collapse. The example of the December 1967 Koyna dam disaster comes to mind. That dam, when completed, was built with the latest science in hand. Geotechnical studies, monsoon and river flow analyses, topography, and geology—all aspects were covered. The region was classified as being geologically stable and judged to be far from known tectonic faultlines. The disaster was triggered by the weight of the water in the dam’s reservoir, which pressed upon hidden geological faultlines. As water filled and drained from the reservoir, it changed the pressure in the rock’s layers and pores. This could have reactivated ancient faults and widened fractures underlying the volcanic Deccan rocks. The 6.3-magnitude earthquake killed nearly 200 people and left tens of thousands homeless. The dam developed minor cracks that were quickly repaired. This new, geo-anthropogenic disaster was labelled as ‘reservoir-induced seismicity’— an earthquake where none should have occurred. The government at the time remained in denial that the quake had anything to do with the dam.
If not for science’s sake, perhaps policymakers should pore through ancient scriptures and historical texts for guidance. Not surprisingly, history validates what scientists have been hinting at: that the Aravalli–Delhi Fold Belt region has experienced earthquakes since recorded history and mythology! Here’s a summary. Around 3,000 BCE, during the Mahabharata war, an earthquake shook the ground near Kurukshetra. Between the 6th and 11th centuries BCE, tremors were reported from ancient kingdoms like Arbuda, Kuru, Malwa, Maru, Matsya and Salwa. The destructive Delhi earthquake of 26th July 1720 damaged areas from Kabuli Gate to Lal Darwaza and the Fatehpuri Masjid partially collapsed. The next big earthquake to hit Delhi was in 1835. The 1848 Mount Abu and 1882 Deesa earthquake caused damage to the Dilwara and Gaumukh temples and shook Delhi. Earthquakes in north Gujarat (1875) and Sindh (1906) were felt strongly in Delhi. I will spare you the morbid details about death, disability and destruction.
The question we must ask about the ‘mining and development proposal’ in the Aravallis is not only about groundwater, tree cover, dust transport or the monsoons alone, but also the possibility of a distant — or worse, a ‘man-made’ — earthquake that can ravage the region. Chances are that gouging out the Aravallis will increase the risks of earthquakes which otherwise may not occur.
Are we willing to wager on this? Are we willing to obliterate the world’s oldest mountain — a potential world geoheritage site — for granite to line our courtyards and the floors of homes and hotels? Such erasure is permanent. The Aravalli or the ancient mountain ‘Arbuda’ as it was called in the Rigveda and Puranas, was welded by Lord Indra. On it rest several sacred Hindu and Jain temples and paths that lead to pilgrimage sites. It is the fount of the rivers Banas, Luni, and Mahatma Gandhi’s beloved Sabarmati. Saline lakes formed from trickles that came out of its hills provided salt when the first humans arrived in the subcontinent. Can so much history be erased? What gives us this hubris?
Pranay Lal is a natural history writer who is currently working on a book on how nature shaped the subcontinent’s history