Scientists Discover New Way to Identify Earthquake Strike Zones

Scientists at the University of California, Riverside (UCR) have developed a new method to identify parts of earthquake faults that may be more likely to rupture. The study was led by Gareth Funning and Axel Periollat and published in Geophysical Research Letters.

What is the New Method for Identifying Earthquake Strike Zones?

The new method helps scientists identify parts of major faults where tectonic strain is accumulating and where a future earthquake rupture may be more likely.

• Tectonic plates are constantly moving, but some sections of a fault can remain locked for decades or even centuries. Although these sections do not move freely, pressure continues to build as the plates push against each other. These locked sections are called asperities. They can store large amounts of tectonic strain, which may be released suddenly during a major earthquake.
• The researchers identify such sections by studying very small movements of Earth’s surface. This provides information about where strain is building up along a fault and helps identify areas that may be vulnerable to future rupture.

The method is therefore focused on identifying potential earthquake strike zones, rather than predicting the exact timing of an earthquake.

How Does the Method Work?

The researchers use GPS observations to detect extremely small movements of Earth’s surface. Although these movements are difficult to notice directly, they reveal how tectonic plates are moving and interacting beneath the surface.

• An algorithm analyses these observations to identify fault sections that are not moving freely and are therefore effectively locked. These sections are where tectonic strain can continue to build over time.
• The approach was tested in Russia’s Kamchatka Peninsula. Before a major earthquake occurred, the researchers had identified a locked section beneath the peninsula where strain was concentrated. The earthquake that followed ruptured through the same area identified by the model.

This provided an important real-world test of the method. However, the researchers could identify the likely area of rupture, not the time at which the earthquake would occur.

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Implications for Disaster Preparedness

• Better risk assessment: Identifying fault sections with high tectonic strain can improve long-term assessment of earthquake-prone areas.
• Targeted preparedness: Authorities can give greater attention to areas where major fault ruptures may be more likely.
• Improved earthquake planning: Information on strain accumulation can support better planning for future earthquake risks.
• Better tsunami assessment: Identifying vulnerable fault sections can also improve understanding of tsunami risks, particularly in subduction zones.
• Early identification of vulnerable zones: The method can identify potentially high-risk fault sections before a major earthquake, supporting long-term disaster preparedness.

However, better identification of high-risk fault sections does not mean that earthquakes can now be predicted. The method remains a tool for hazard assessment, not precise earthquake forecasting.

What are the Limitations?

• A major challenge is the difficulty of studying faults located beneath the ocean. GPS stations on land can provide detailed information about surface movement, but many potentially dangerous faults are offshore. This creates gaps in monitoring earthquake and tsunami risks.
• Another difficulty is that not all faults behave in the same way. Some faults release tectonic energy through slow movement instead of a sudden major earthquake. This makes it harder to assess their long-term behaviour.

Researchers are therefore exploring other ways to monitor these areas. In Japan, acoustic instruments are being deployed on the seafloor to measure slow changes in the Earth’s crust. Similar projects are being considered in Chile and the Pacific Northwest. Satellite observations may also help provide information from areas where ground-based measurements are difficult.