Forests as Earthquake Buffers: When Roots Are Stronger Than Concrete

In a country such as Indonesia, which lies on the Ring of Fire, earthquakes are not merely a possibility but a certainty. We live above converging tectonic plates, where the Earth’s energy is periodically released in tremors that shake the foundations of life. The usual response has been largely technocratic: strengthening buildings, designing earthquake-resistant foundations and raising construction standards. All of these are important. But one element is often overlooked—quietly growing and working without a sound: forests.

A 2018 popular science article entitled “How Forest Could Limit Earthquake Damage to Buildings” puts forward a thought-provoking thesis: forests are not simply guardians of water and barriers against landslides, but may also naturally reduce the impact of earthquakes. The idea may seem unconventional, but that is precisely its strength: it encourages us to consider more fully the relationship between ecology and disaster mitigation.

Earthquakes generate seismic waves that travel through layers of soil. When these waves reach the surface, they interact with local geological conditions. Loose, water-saturated soil, or soil that has lost its natural structure, tends to amplify shaking. In extreme circumstances, soil can lose its strength and behave like a liquid, a phenomenon known as liquefaction.

This is where forests play a key role. Tree-root systems work like a network of bindings that reinforce soil structure. Roots increase cohesion and stability, making the soil less susceptible to disruption by seismic waves. Geotechnical studies indicate that vegetation can significantly increase soil shear strength, particularly in surface layers (Stokes et al., 2009).

In other words, forested soil is better prepared to withstand shaking than land that has lost its vegetation cover. Forests also affect how earthquake energy is distributed. Vegetation—through its trunks, branches and leaves—has mass and flexibility, allowing it to damp vibrations by absorbing and reducing their energy. Although this effect is not as great as structural engineering in buildings, it can be significant at landscape scale. Forests act as complex systems that break up, disperse and weaken energy, preventing it from concentrating in one place.

A conceptual pillar: forests as natural infrastructure

Infrastructure has traditionally been understood as something built: roads, bridges and buildings. A newer approach, however, recognises forests as green infrastructure and natural seismic buffers. Their functions in an earthquake context include reinforcing soil through roots, regulating water and reducing liquefaction, reducing wave energy through damping and scattering, and stabilising slopes and microtopography. A series of studies conducted between 2014 and 2018 by Sébastien Guenneau, Agnès Maurel and Jean-Jacques Marigo also indicates that vegetation patterns can act like metamaterials, influencing the propagation of seismic waves.

Forests are also linked to the hydrological cycle. Soil that is excessively water-saturated is at greater risk of liquefaction during an earthquake. Through their capacity to absorb water, forests help maintain a balance in soil moisture. Rather than allowing water to pool or excessively fill the soil’s pores, they absorb, store and distribute it naturally. This can reduce the risk of soil turning “liquid”.

The implications for buildings and settlements are tangible. Areas that retain forest cover tend to experience less damage than degraded areas—not because the earthquakes are weaker, but because the soil is more stable, energy is more effectively damped, and the risks of secondary disasters such as landslides and liquefaction are lower. Forests are not a rival to technology, but a partner that has long been overlooked.

Unfortunately, modern development often moves in the opposite direction. Deforestation, land conversion and resource exploitation erode the environment’s natural capacity to mitigate disasters. We replace roots with concrete, forgetting that concrete stands on increasingly fragile soil. We strengthen buildings while weakening their ecological foundations. This is the paradox of modern civilisation: the more advanced our technology becomes, the more vulnerable the systems supporting it can be.

A wiser approach is to integrate engineering with ecological management, in what is now known as ecosystem-based disaster risk reduction. Under this framework, forests are positioned as natural infrastructure working alongside built infrastructure. Protecting forests is no longer merely a conservation issue, but part of a national disaster-mitigation strategy.

More profoundly, this perspective invites us to recover a more fundamental awareness: nature has mechanisms of balance that have been precisely calibrated. In spiritual terms, this can be understood as mizan—the balance that sustains harmony among the different elements of life. When forests are protected, soil becomes stronger, water is regulated and energy is controlled. When forests are damaged, we lose not only trees but also an irreplaceable system of protection.

Earthquakes may ultimately be impossible to prevent, but their impact can be managed. In that effort, forests offer a simple yet profound lesson: strength does not always come from what is hard and rigid. Sometimes what is flexible, living and rooted is what endures longest. It is time to ask ourselves again: when facing the Earth’s tremors, will we rely solely on concrete, or begin planting roots again?

It is therefore important to provide green open spaces dominated by trees in urban and rural settlements, as well as in office and business areas. These should serve as green infrastructure, with locations combining centralised and distributed spaces.

The advantage of a central forest area is its strong ecological effect, including biomass, roots and microclimate. It is more effective in stabilising soil, absorbing water and buffering energy. In an earthquake context, it can serve as a primary buffer zone.

A distributed green network, meanwhile, spreads benefits throughout an area, reduces damage hotspots and creates ecological connectivity. In an earthquake context, it can help break up the spatial distribution of vibrations. Ideally, an area should have both centralised and distributed forests.

Rural areas could also further develop talun—mixed forest and garden areas—as green mosaics in the countryside.