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The recent magnitude 4 earthquake that struck Delhi before dawn on Monday, February 17, 2025, highlighted the unique seismic characteristics of the region, differentiating it from the earthquake activity prevalent in the Himalayan region. While Delhi experiences tremors frequently, often originating from distant locations like Afghanistan, this particular earthquake was unusual because its epicenter was located within Delhi itself, near Dhaula Kuan. This marked the strongest earthquake originating in Delhi in at least five years, according to data from the National Centre of Seismology. The event prompted widespread alarm, with residents rushing out of their homes as tremors shook the Delhi-NCR region. Importantly, despite the alarm, the magnitude 4 earthquake caused no reported damage, underscoring the relatively low intensity despite the proximity of the epicenter to a densely populated urban area. A similar magnitude earthquake occurred hours later near Siwan in Bihar, further emphasizing the seismic activity in the region.
Delhi's location within a seismically active zone, the Aravalli-Delhi Fold Belt, explains its susceptibility to earthquakes. This geological belt stretches from southern and eastern Rajasthan to Haryana and Delhi, characterized by deformed rock layers that were folded and bent due to geological processes millions of years ago. These deformities have created stress that is occasionally released in the form of earthquakes. This mechanism is distinctly different from the process causing earthquakes in the Himalayan region, a globally recognized highly seismically active area. The Himalayan earthquakes are primarily triggered by the subduction of the Indian tectonic plate under the Eurasian plate, leading to significant stress buildup. In contrast, the Aravalli-Delhi Fold Belt was significantly more seismically active in the past but has experienced a considerable slowdown in tectonic activity over time, resulting in increased geological stability. However, existing faults within this belt continue to cause occasional mild earthquakes, described by expert Vineet Gehlot as 'old scars flaring up once in a while'. A 2022 research paper co-authored by Gehlot, Rajeev Yadav, and Stacey Martin detailed the annual seismic activity in and around Delhi, reporting approximately 25 earthquakes of magnitude 2.5 or higher, with about five of these reaching magnitude 3.5.
The Delhi earthquake also drew attention due to reports of a peculiar sound accompanying the tremors, a phenomenon not previously associated with earthquakes felt in the capital. While earthquakes can indeed produce sounds, these are often low-frequency and inaudible to humans. Larger earthquakes may produce audible sounds, but these are rare. Expert Gehlot clarified that most reported sounds during earthquakes are likely misinterpretations of other sounds produced by building vibrations or other sources caused by the shaking. The sound reported in Delhi is likely such a case and not indicative of a unique earthquake characteristic. This distinction is crucial, as it helps to avoid undue speculation about the nature of the earthquake based on the unusual sound.
The probability of a large, damaging earthquake originating in Delhi is deemed low by experts. Although historical records mention significant earthquakes in or near Delhi around 1720 and 1803 (the latter possibly mislocated and now believed to have been in Uttarakhand), the current geological understanding suggests a minimal risk of a major earthquake. The tectonic setup, subsurface structures, and energy levels within the Aravalli-Delhi Fold Belt are not conducive to generating large earthquakes. While a large earthquake would undoubtedly cause significant destruction in Delhi's densely populated and built-up areas, the likelihood of such an event is considered extremely low. This assessment is based on a comprehensive understanding of the region's seismic history and geological characteristics. Continuous monitoring and research are essential to enhance our preparedness and understanding of seismic activity in the region, allowing for informed risk mitigation strategies.
Source: The dawn quake: How tremors in Delhi are different from earthquakes in the Himalayan region