Can climate change cause more earthquakes and volcanic eruptions?

Does sea level rise increase the frequency of earthquakes and volcanic eruptions? Or does the melting of glaciers due to temperature rise lead to more volcanic eruptions?

Scientists have long offered this hypothesis, and now they have a chance to test this theory.

“Recent studies have proposed a causal link between rising sea-level during periods of warming climate, and increased frequency of volcanic eruptions and earthquakes,” said Dr Lorna Strachan, a senior lecturer in sedimentology at the University of Auckland (Morton, 2020).

To test the hypotheses, a team of scientists from New Zealand, the UK, the USA, Portugal, Netherlands, Germany, and Australia began multi-year research on the 500-metre long sediment core retrieved from the Hikurangi Subduction Zone, New Zealand’s largest and most active fault.

The East coast lab article “Does climate change influence the frequency of earthquakes and volcanic eruptions?” explains that the sediment core contains a record of all the sediment and material that has been deposited on the seafloor over the last 800,000 years (Does climate change, 2022).

"Does climate change" (2022) explains further:

• “Over time, the material is deposited on the seafloor and builds up in layers. Each layer records a period in time, with the deepest layers containing the oldest material.”
• “Scientists will analyse each of these layers using various dating and analysis techniques such as carbon dating and magnetostratigraphy to piece together a record of large earthquakes and volcanic eruptions. This will create New Zealand’s longest record of earthquake and volcanic history.”
• “Once this record is completed, it will be compared to sea-level change records in a world first, enabling scientists to figure out whether or not there is a causal link between sea level and climate and the frequency of volcanic eruptions and earthquakes.”

Morton (2020) reports that the exquisitely preserved sedimentary record was retrieved from an internal expedition in 2018, allowing scientists to calculate their depositional ages and the sedimentary layers to millimetre precision.

Dr Lorna Strachan, a senior lecturer in sedimentology at the University of Auckland and one of the scientists of the project, says that the sediment record will allow them to identify where the sediments come from and how they were deposited in the deep oceans. These sedimentary deposits can come from events like earthquakes or volcanic eruptions (Morton, 2020).

Morton (2020) says:

• Strachan believes that the record captured at least eight or more glacial and interglacial sea-level cycles across hundreds of thousands of years – or when the planet went through natural cooling and warming periods – these could be compared with volcanic ash, and turbidites from earthquakes, deposited over the same times.
• “While this is linked to changing sea level, the central hypothesis is focused on sea-level change over glacial time scales and at large orders of magnitude of change – or up to 120m of sea-level rise,” she said.
• “In saying that, we are in the upper part of one of these cycles – and therefore, the impact of post-glacial sea-level rise during the last 20,000 years may still be being felt.
• “This deeper time perspective of recurrence, however, may be very useful for future seismic and volcanic hazard analyses.”

The Marsden funded study started in March 2021 and will span three years or until 2024 and involved a team of national and international scientists from the following organisation: the University of Auckland, Victoria University of Wellington, National Institute of Water and Atmosphere Research (NIWA), GNS Science, University of Queensland, GEOMAR Helmholtz Centre for Ocean Research Kiel, California State University, University of Leeds, National Oceanography Centre, Instituto Português do Mar e da Atmosfera, and Utrecht University.

Melting glaciers and volcanic activity

The New Zealand Geographic article “Climate Change = Eruptions, Earthquakes” presents the findings of the University of Arizona study explaining how the land uplift that is occurring in Iceland and Greenland contributes to increased volcanic activity.

According to the study, there is land uplift occurring in the Central Highlands region of Iceland and Greenland of around three or more centimetres a year. The uplift is worrying Iceland’s volcanologists as it can reduce the pressure underneath the glacier and may lead to an increase in volcanic activity (Brenstrum, n.d.).

Brenstrum (n.d.) mentions:

• “Below the lithosphere lies the asthenosphere, which is partly molten and partly solid. The high pressure caused by the weight of the Earth above this layer keeps most of the asthenosphere solid; lower the pressure and more will become liquid and rise towards the surface can increase volcanic activity.”
• The melting of the kilometre-thick ice sheet during the Ice Age in Iceland some 12,000 years ago coincided with increased volcanic activity at 30 to 50 times above the background rate, which has continued for 1500 years, the article says.
• “Once the ice has gone, land uplift can continue for thousands of years as the viscoelastic response of the asthenosphere causes a slow migration of magma sideways to where the ice sheet used to be. Scotland, for example, is still rising about one millimetre each year, while northern Scandinavia is rising 10 times faster. Parts of Scandinavia have risen 300 metres since its ice sheet melted thousands of years ago. Meanwhile, the Earth’s crust immediately adjacent to the vanished ice sheet has been sinking.”
• “Geologists believe these changes have contributed to earthquakes, particularly tremors away from the boundaries of tectonic plates.”

“Learning more about how our environment responds to a changing climate and sea-level rise allows us to understand how these hazards might impact us in the future, and how we might better prepare,” says PhD student Anthony Shorrock who is part of a large team of international scientists, led by Dr Lorna Strachan from the University of Auckland, that investigates the link between long-term sea-level rise due to climate change and the frequency of volcanic eruptions and earthquakes.