\u2022 Can climate change cause earthquakes in the Himalayas?<\/a>
\u2022 Can large infrastructure construction trigger earthquakes?<\/a>
\u2022 How does climate change make earthquakes more dangerous?<\/a>
\u2022 Increasing complex disasters in the Himalayas<\/a><\/p>\n\n\n\n
Are earthquakes becoming more frequent in the Himalayas?<\/h2>\n\n\n\n
An analysis of seismic activity<\/a> in the Himalayas from 1900-2010 found a sharp uptick in the number of earthquakes recorded, particularly after 2000. According to the analysis, the Himalayas experienced fewer than 100 earthquakes per year in the decade 1960-70, but between 2000 and 2010 this had increased to 500-600. The vast majority of these earthquakes were between 2.0 and 6.0 on the Richter scale, ranging in magnitude from tremors that are just about detectable with good equipment to earthquakes that could be felt by anyone and would damage badly built structures (though with zero to light damage to properly built structures). However, the analysis did not draw a link between this rise and climate change.<\/p>\n\n\n\n The Himalayas host some 100,000 km2<\/sup>\u00a0of glaciers<\/a>, making the region the largest ice reserve on Earth outside the two poles. The Himalayas are also warming faster<\/a> than the global average \u2013 in 2022\u00a0the Intergovernmental Panel on Climate Change estimated that under a scenario of moderate carbon emissions, Himalayan glaciers would lose 10-30% of their mass<\/a> by 2030.<\/p>\n\n\n\n This change in glacial mass in the Himalayas could trigger more earthquakes thanks to a process called isostasy, according to Mudassir Bhat, an earth scientist at the University of Kashmir. Isostasy describes how the Earth\u2019s crust rises and settles based on the weight it bears; the impacts of glaciers on this process is known as glacial isostatic adjustment<\/a> (GIA). Since the Himalayan region is crossed by several major faults, Bhat believes that the movement in the earth\u2019s crust caused by loss of glacial mass via GIA could trigger more earthquakes. This process has been demonstrated in other regions<\/a>.<\/p>\n\n\n\n But glaciers are not the only phenomenon exerting pressure on the Earth\u2019s crust in the Himalayas. The monsoon, which provides South Asia with nearly 80% of its annual precipitation in just four months (from June to September), also plays a role.<\/p>\n\n\n\n Research by French and Nepalese scientists into seasonal patterns in 10,000 earthquakes in the Nepal Himalayas concluded<\/a> that \u201cthe seismicity rate [number of earthquakes] in the winter is twice as high as in the summer at all magnitudes above the detection threshold.\u201d They attributed this to pressure placed on the Gangetic basin by the huge weight of water present during the monsoon season suppressing seismicity.<\/p>\n\n\n\n According to Zahid Rafi, chief seismologist and director of Pakistan\u2019s National Seismic Monitoring Centre<\/a> in Islamabad, \u201cThe correlation [with more earthquakes in the winter] is in micro-seismicity \u2013 tiny earthquakes with relatively lesser magnitudes that occur quite frequently.\u201d Nonetheless, he said these small earthquakes could \u201cpotentially be a contributor to triggering a damaging earthquake\u201d.<\/p>\n\n\n\n As climate change makes the monsoon more erratic<\/a>, changing when and where large quantities of water are present on the Indian subcontinent, there could be an impact on this micro-seismicity, with longer drier periods meaning more activity. While most of these tiny earthquakes will not be felt by humans, much less cause any damage, the bigger question is whether smaller earthquakes relieve stress, making larger destructive earthquakes above 6 on the Richter scale less likely, or whether a build-up of small earthquakes may trigger a larger one.<\/p>\n\n\n\n In a 2019 interview, Paul Lundgren of NASA\u2019s Jet Propulsion Laboratory in Pasadena, California, addressed this very question<\/a>. \u201cWe don\u2019t know when a fault may be at the critical point where a non-tectonic forcing related to a climate process [when a fault in the plates is at such a delicate stage that a climate impact could set it off] could be the straw that breaks the camel\u2019s back, resulting in a sizeable earthquake\u2026 We\u2019re simply not in a position at this point to say that climate processes could trigger a large quake.\u201d<\/p>\n\n\n\n Earthquakes can be induced by human activity, and this has been documented since the 1960s<\/a> in the case of hydropower dams, due to the effects of large reservoirs and what is called reservoir-induced seismicity (RIS). This refers to the pressure created by water in a large reservoir on or near a fault line leading to slippage of the Earth\u2019s crust underneath, causing an earthquake.<\/p>\n\n\n\n There are currently about 100 operational hydropower dams<\/a> across the Himalayan region, with an additional 650 planned or under construction, including in China, India, Pakistan, Nepal, and Bhutan. If all these projects are completed, the Himalayas will become the most dam-dense region in the world, especially in particular areas such as the Chenab region in Jammu and along the Brahmaputra in Arunachal Pradesh<\/a>.<\/p>\n\n\n\n According to Ayaz Mahmood Dar, an integrated researcher of earth sciences and director of Tehkeek International, a research institute based in Srinagar, Jammu and Kashmir, \u201cThe Chenab valley [in Jammu] is a case study of reservoir-induced seismicity.\u201d In addition to four existing mega hydroelectric power projects in the Chenab valley, at least six other mega projects<\/a> are currently in various stages of development.<\/p>\n\n\n\n In August 2022, 13 earthquakes struck the valley in less than five days<\/a>. \u201cThe valley rests on the Kishtwar Fault, and it\u2019s apparent that the construction of mega dams is the main reason behind the increased seismicity in the region. However, more research needs to be put in to get a holistic picture,\u201d Dar says.<\/p>\n\n\n\n The destructive impact of major earthquakes can become magnified in what is called a \u2018complex disaster\u2019 \u2013 one in which one disaster, such as an earthquake, sets off another, such as a landslide or glacial lake outburst flood (GLOF).<\/p>\n\n\n\n A GLOF occurs when a lake formed by meltwater from a glacier breaches its banks. Glacial lakes are rarely stable, and when a GLOF occurs, the debris that held the water back is often carried by the outburst, with potential for massive damage. Globally, over 15 million people<\/a> are at risk of GLOFs, with a third of all those at risk located in India (3 million) and Pakistan (2 million).<\/p>\n\n\n\n Rakesh Kayastha, a seismologist working at the Himalayan Cryosphere, Climate and Disaster Research Center at Kathmandu University, Nepal, tells The Third Pole that an earthquake in the Himalayas that measures above 5 on the Richter scale carries a heightened danger compared to an earthquake of similar magnitude elsewhere, because it may also trigger a GLOF.<\/p>\n\n\n\n Rising temperatures driven by climate change are causing Himalayan glaciers to melt at an increasing rate, creating more and more glacial lakes in the process. Researchers have identified more than 8,000 glacial lakes<\/a> in the Himalayas, of which up to 200 may be potentially dangerous. Between 2003 and 2010, 85 new glacial lakes<\/a> formed in the Indian Himalayan state of Sikkim alone. Dark pollutants<\/a> from sources like open burning and coal plants in lowland areas also settle on glaciers in the Himalayas, causing them to absorb more energy and thereby accelerating glacial melt, exacerbating the impacts of temperature rise.<\/p>\n\n\n\n Another way in which climate change-induced warming could trigger earthquakes in the Himalayas is that when a large section of a melting glacier breaks off and falls, this can lead to cryo-seismicity \u2013 or an \u2018icequake\u2019, a seismic event caused by breaks in ice or ice-saturated ground, as seen in the polar regions<\/a>. \u201cThe breakage of glaciers can trigger cryo-seismicity [measuring] up to 7 on the Richter scale,\u201d says Ayaz Mahmood Dar. \u201cThis threat is real in the Himalayas because with glaciers absorbing more heat, the possibility of cracks and therefore, icequakes, is more than ever.\u201d<\/p>\n\n\n\n So far, the breakage of glaciers has not led to large cryo-seismic events in the Himalayas. What we have seen are complex disasters, with breaking glaciers leading to floods and landslides. In February 2021, this is exactly what happened<\/a>, when a large chunk of a glacier broke off in the Indian state of Uttarakhand, triggered by an avalanche rather than an earthquake, setting off a flash flood and damaging an under-construction dam.<\/p>\n\n\n\nCan climate change cause earthquakes in the Himalayas? <\/h2>\n\n\n\n
![\"\"\/](\"https:\/\/dialogue.earth\/content\/uploads\/2023\/05\/2A9W31W_Gorkha-earthquake-aftermath-explainer_BODY1.jpg\")
<\/div>Can large infrastructure construction trigger earthquakes?<\/h2>\n\n\n\n
![\"Baglihar](\"https:\/\/dialogue.earth\/content\/uploads\/2021\/11\/2FMJ3YA-scaled.jpg\")
<\/div>How does climate change make earthquakes more dangerous?<\/h2>\n\n\n\n
![\"The](\"https:\/\/dialogue.earth\/content\/uploads\/2021\/08\/F50CR5.jpg\")
<\/div>Increasing complex disasters in the Himalayas<\/h2>\n\n\n\n