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Nestled along the eastern coastline of South Korea’s Gyeongsangbuk-do, the city of Pohang presents a fascinating, and at times stark, juxtaposition. To the world, it is a synonym for cutting-edge steel production, home to the global giant POSCO. To South Korea, it is a vital industrial heart and a rising hub of education and technology. Yet, beneath this facade of human engineering and economic prowess lies a dynamic and often unforgiving geological reality. The story of Pohang is not just one of industrial triumph; it is a profound narrative about humanity’s complex relationship with the Earth’s subterranean forces—a relationship thrown into sharp relief by contemporary crises from renewable energy ambitions to the stark realities of seismic hazard.
Pohang’s geography is a dramatic product of its location. It sits within the Yeongil Bay, a wide, sheltered inlet of the East Sea (Sea of Japan). To the west and north rise the rugged folds of the Taebaek Mountains, their weathered slopes acting as a natural backdrop. The Hyeongsan River cuts through the city, delivering sediments from the interior to form a fertile, alluvial plain that has supported agriculture for centuries before industry arrived. This combination of a protected deep-water port, flat land, and proximity to resources made it an ideal site for heavy industry.
But the true character of this land is written in its rocks. Pohang is the crown jewel of the Gyeongsang Basin, a massive geological feature that dominates southeastern Korea.
During the Cretaceous period, over 66 million years ago, this basin was a vast, active depocenter. It was a world of fiery volcanoes, sprawling river systems, and shallow lakes. The evidence is everywhere. The city and its surrounding areas are famous for their spectacular sedimentary formations—layers of shale, sandstone, and conglomerate that are tilted, folded, and exposed along the coast in textbook-perfect outcrops. These are not just rocks; they are pages from a deep-time history book. They contain one of the most abundant and well-preserved dinosaur footprint trackways in the world, along with fossilized plants and fish, painting a picture of a lush, vibrant ecosystem.
This sedimentary sequence is interbedded with volcanic rocks—ashes and lavas from the intense volcanic activity that accompanied the basin’s formation. This Cretaceous cauldron was fundamentally shaped by tectonic forces related to the subduction of ancient oceanic plates, a prelude to the tectonic drama that continues today.
For decades, South Korea was considered a region of relatively low seismic hazard, especially compared to its neighbors Japan and China. Pohang, like the rest of the country, built its dense infrastructure and industrial complexes with this assumption in mind. That illusion was shattered on November 15, 2017.
A magnitude 5.4 earthquake struck directly beneath the city. It was the second-strongest instrumentally recorded earthquake in Korean history and the most destructive. Buildings cracked, infrastructure failed, and thousands were displaced. The psychological shock was profound. But the scientific and ethical aftershocks were even greater. Intensive international investigations concluded that the earthquake was likely induced by human activity—specifically, the high-pressure injection of water into a deep geothermal energy well at a pilot project site.
This event catapulted Pohang from a footnote in tectonic textbooks to a global case study. It exposed a hidden geological truth: the Korean Peninsula, particularly the Gyeongsang Basin around Pohang, is crisscrossed with numerous pre-existing faults. These faults are not as active as the subduction zones ringing the Pacific, but they are critically stressed. The 2017 earthquake demonstrated that they are capable of slipping catastrophically if perturbed by anthropogenic activity.
Here, Pohang’s story collides head-on with a critical global hotspot: the urgent transition to renewable energy. Enhanced Geothermal Systems (EGS) represent a tantalizing prospect—a way to generate clean, baseload power by fracturing hot rock deep underground. The Pohang Geothermal Project was a flagship effort to pioneer this technology in Asia.
The 2017 quake, however, revealed the immense and often underestimated risks. Injecting fluid into the complex, fault-ridden basement rock of the Gyeongsang Basin acted as a lubricant, unlocking tectonic strain. The event forced a global reckoning within the geoscience and energy communities. It raised urgent questions: How do we rigorously assess subsurface risk before greenlighting such projects? How do we balance the desperate need for carbon-free energy with the imperative to not trigger human disaster? Pohang stands as a permanent cautionary tale, emphasizing that the Earth’s subsurface is not a passive laboratory but an active, poorly mapped system that can bite back.
While the ground beneath Pohang tells one story of hazard, the waters at its doorstep tell another. The city’s coastline is a dynamic interface, now on the frontline of the climate crisis. Yeongil Bay, while sheltered, is not immune to the effects of sea-level rise and intensifying storm surges. Coastal erosion, saltwater intrusion into freshwater aquifers, and the vulnerability of low-lying industrial and residential areas are growing concerns.
Furthermore, Pohang’s identity is tied to the sea. Its fisheries and its port, crucial for both steel exports and imports of raw materials like iron ore and coal, are susceptible to climate disruption. Changing ocean temperatures and acidity can impact marine ecosystems, while more extreme weather events threaten port operations and supply chain resilience. The city’s economic fate is thus doubly tied to geophysical forces: the solid rock below and the rising seas around it.
In the aftermath of the 2017 earthquake, Pohang has been forced onto a new path. It is no longer just a city that extracts from and builds upon the Earth, but one that must engage in a far more nuanced dialogue with it.
The response has been multifaceted. Scientifically, South Korea has dramatically intensified its seismic monitoring network. Fault mapping has become a national priority. The legal and regulatory framework for subsurface projects has been overhauled with much stricter protocols for risk assessment and public consent.
Technologically, Pohang’s expertise is being redirected. The same engineering prowess that built a steel empire is now being applied to seismic retrofitting, developing more resilient building codes, and advancing subsurface imaging technologies. Pohang University of Science and Technology (POSTECH) has become a central hub for cutting-edge research in geohazards, sustainable energy, and climate adaptation.
The city’s narrative is evolving. It is leveraging its painful experience to position itself as a global knowledge center for geological hazard mitigation and sustainable subsurface management. The goal is to transform a legacy of industrial risk into one of planetary resilience.
Pohang’s landscape—from its dinosaur-bearing cliffs to its fault-lined foothills to its engineered shoreline—is a palimpsest. It bears the imprints of ancient ecosystems, tectonic violence, agricultural society, and staggering industrial transformation. Today, it bears the scars of a misunderstood subsurface and the gathering threats of a warming climate. Its ongoing story is a powerful microcosm of the 21st century’s greatest challenge: learning to harness the Earth’s resources and powers not with brute force, but with profound humility, deep understanding, and an unwavering commitment to coexisting with the dynamic planet we call home. The future of Pohang, and perhaps a model for many industrial cities worldwide, lies in listening closely to the whispers and rumbles from the ground upon which it stands.