Does Climate Change Cause Earthquakes?
How rising water levels and rainfall can trigger earthquakes (and even volcanic eruptions).
We all know that wildfires and floods have become increasingly frequent in recent years. Scientific research now points to climate change being the primary cause. But as if these weren’t enough, a new apprehension is coming forth: does climate change affect earthquakes?
While the research is of course still ongoing, it appears to emphasize that climate change does potentially affect below-the-surface events such as volcanoes and earthquakes via the following mechanisms:
Rising Water Levels
Research published in Nature highlights that our planet lost around 267 gigatonnes of glacial mass between 2000 and 2019. The same study also highlights that this phenomenon contributed to ~21% of the observed rise in sea waters. The rising water levels additionally become the primary reason for increasing flooding and erosional incidents. A 2016 The Guardian article emphasizes a study by Chi-Ching Liu and compeers on the timings of cyclones and earthquakes in Taiwan. They found earthquakes could travel swiftly within the crust due to strong Pacific Ocean typhoons.
But what actually causes an earthquake? The crust of our planet is never motionless. It is always moving. These continuous movements accelerate pressure, the release of which causes tremors on the ground. We call this phenomenon an earthquake.
As glaciers keep melting, the water level continues to rise. This rising water seeps into the crust and widens the existing gaps. Areas with high seismic activities, such as the Ring of Fire (a horseshoe-shaped chain of volcanoes in the Pacific Ocean) and the Himalayas, face the imminent threat. Since the plates of Earth converge at the Ring of Fire, the area already witnesses 90% of all earthquakes. It is possible that increasing rainfall or glacier snow could be the two climate change variables that will trigger more earthquakes around the world.
Himalayas and Earthquake
The Indian Minister of Earth Sciences (MoES), Jitendra Singh, remarked in April that climate change might have marginally increased earthquake frequency in the Himalayas. He pointed out that micro-level earthquakes could occur more frequently as thick ice sheets melt due to climate change. Every year, earthquakes strike in several states of Northern India recurrently, an emerging matter of concern.
The Himalayan region is the most seismically active zone in India. Jean-Philippe Avouac, a noted seismologist at the California Institute of Technology, United States, has linked microseismicity to India’s monsoon, when increased rainfall stabilizes the Himalayan crust horizontally and vertically through compression. While the rainfall increases the stress load in the crust, it also diminishes microseismic activity in the Himalayas. However, in the winter, the water vanishes. It leads to destabilization and recurring earthquakes. In this regard, a 2019 NASA news article also highlights microseismicity.
Microseismicity or microseismic events refers to earthquakes with below zero magnitude, something that cannot be felt by humans. It reaches its climax in the Himalayan region during winter. Nonetheless, some experts also indicate that it is difficult to determine if high-intensity earthquakes are caused by climate change. Yet, they do not exclude the possibility entirely. For now, only microseismic earthquakes due to such events have been recorded in the Himalayan region and several other places around the world.
That said, as Matthew Blackett, Reader in Physical Geography and Natural Hazards, writes, the link is clear: “During the summer monsoon season, the weight of up to 4 metres of rainfall compresses the crust both vertically and horizontally, stabilising it. When this water disappears in the winter, the effective ‘rebound’ destabilises the region and increases the number of earthquakes that occur.”
As per Jitendra Singh’s reply in the lower house of the Indian parliament (Lok Sabha), the National Centre for Seismology plans to set up an early warning mechanism in the Himalayas as a pilot project.
Rainfall and Earthquakes
Can rainfall cause earthquakes beyond the Himalayas? Is Earth’s crust really that fragile? Turns out there’s a possibility. According to a 2008 New Scientist article, researchers have found that earthquakes have followed heavy rains in Germany, France, and Switzerland. However, the earthquakes in these areas were again microseismic quakes. But the places had one thing in common: karst landform with caves and channels. Geologist Steve Miller expained to the New Scientist that Karst landscape features a distinctive topography of soft carbonate rock “riddled with deep fissures, underground channels and cave systems out back then that this landform has water seeping into it instead of running off”. On non-karst land surfaces, rainfall presses down on the Earth in a relatively uniform fashion, carried away by surface rivers and streams, creating little pressure on any underlying fault is small. But in karst, rain pours into the channels and caves, causing pressure as the rain builds up forming “pipes” which, says Miller, can lead to rain triggering earthquakes.
Climate Change and Volcanoes
The volcano is the other below-surface phenomenon that can increase due to the consequences of climate change. How so? According to research published in the journal Geology, “Human-induced climate change is causing rapid melting of ice in many volcanically active regions.” The melting of glaciers then affects the dynamics of the crust and mantle, seen especially around Iceland. The depth of the mantle is affected and thus, the structure of the crust gets changed. Volcanic eruptions are frequent and more often, short. However, the impact is not immediate and takes place with a lag of more than a hundred years. Five thousand years ago, climatic conditions cooled down briefly and the glaciers of Iceland expanded. The study points out that changes in the ice load or deglaciation have caused an increasing uneven volcanic activity. As glaciers retreat and water rises due to climate change events, we can expect more volcanic eruptions in the future. There’s no answer to “when” this will happen.
A WEF write-up links a geological research letter highlighting several earthquake occurrences around 7000 to 10,000 years ago. The study explores how the isostatic rebound in the Last Glacial Period (LGP) induced the upliftment of landforms at various places. Isostatic rebound refers to land rising after heavy pressure, such as glacial, pushing it down for a lengthy period. The elevated landform in Scandinavia, combined with an imbalance of tectonics, induced several earthquakes, some going beyond 7.0 magnitude.
End Note
There is an increasing possibility of more earthquakes occurring in the near future due to climate change. This possibility is sufficient for researchers and scientists to cause concern. As we discovered earlier, the rapid melting of glaciers causes the sea level water to rise, which enters the Earth’s crust and expands it. This phenomenon can trigger more frequent earthquakes and volcanoes. Multiple studies highlight how increasing rainfall also triggers microseismic quakes in certain places like the Himalayas.
The signals of climate change are unmistakable. The impact is becoming more and more evident and urgent. Almost all the articles I’ve cited stress the lack of substantial evidence to say with certainty that climate change will trigger more earthquakes and volcanoes. Yet without us taking significant measures, I am afraid we are heading towards a future where there will be plenty of events for researchers to cite.
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