The ground beneath Cornwall contains more than 20,000 abandoned mine shafts, relics of the region’s 18th- and 19th-century mining boom. Many were never properly mapped or secured, and some have begun to fail. In February 2020, a section of garden in Camborne collapsed after a storm toppled a tree. The hole initially measured about three feet wide but grew over the following days to the size of a small house, damaging a nearby road and disrupting local utilities.
The collapse followed heavy rain that had weakened the soil, and the fallen tree added extra weight to ground that had grown unstable. Engineers determined that an abandoned mine shaft from roughly 200 years ago sat beneath the property. Similar incidents have occurred elsewhere in Cornwall. In St Austell, a resident reportedly died in the 1990s when an old shaft opened up on private property. A 30-foot-deep shaft also appeared near the second fairway at Par Golf Club after extreme rainfall. In November 2025, a parked car sank into a hole about six and a half feet deep behind a bakery in Redruth. No one was injured, but witnesses reported rubble continuing to fall into the opening afterward.
These collapses are not typical sinkholes. A sinkhole forms when water dissolves rock underground, but the problem in Cornwall is different. Old mine tunnels lose structural support and collapse. Wooden supports, some in place for more than 150 years, have rotted to the point where they can be pulled apart by hand. When one shaft fails, nearby unstable areas can fail as well. Near Perranporth Beach, three additional holes appeared in sand dunes above the abandoned Wheal Ramoth mine, which once extended about 300 feet underground.
Repairing these sites is expensive and complicated. Engineers must first map the underground voids using drill holes, cameras, and scanning equipment. Heavy machinery can make the problem worse by placing pressure on weak ground. Common repairs involve digging down to the shaft, installing a concrete cover, and filling the space with engineered material before rebuilding the surface. Costs range from around $6,000 to more than $300,000, depending on the size and complexity of the collapse. Homes built over old mines can also be difficult to insure and sell. Checking for old mine workings is a standard part of the property-buying process in the region.
Mining remains part of Cornwall’s future as well as its past. There are plans to reopen South Crofty, the last large tin mine in the area, which closed in 1998. Cornwall has also become significant for lithium production, a material used in rechargeable batteries.
Scientists studying the fault system beneath the Sea of Marmara, south of Istanbul, have developed a detailed three-dimensional map of the North Anatolian Fault using electromagnetic imaging. The technique measures how rocks resist electric current and has helped identify sections where stress has been building. One locked section near Istanbul last produced a major earthquake in 1766, more than 250 years ago. Historical records suggest that large earthquakes in this region have occurred roughly every 250 years, leading researchers to describe the fault as late in its seismic cycle.
A major earthquake near Istanbul would affect a city of about 15 million people that generates close to 40 percent of Turkey’s economic output. Turkey has been upgrading its earthquake early warning system, which detects the initial, less destructive waves of an earthquake and sends alerts before the stronger waves arrive. The upgraded system sent its first alert in October 2025, about eight seconds after a magnitude 5 quake struck the Sea of Marmara. Scientists are working to add more sensors to the seafloor to extend warning times.
Computer simulations covering more than 10,000 years of earthquake cycles suggest that the fault does not behave as one continuous rupture point. The models indicate that sediment thickness and temperature differences limit how far a rupture can travel. Simulated events did not exceed magnitude 7.3. The western sections of the fault produce more regular earthquakes, while eastern sections generate smaller paired events. Some parts of the fault creep slowly, releasing tension without producing major earthquakes.
In early 2025, more than 28,000 earthquakes struck near the Greek island of Santorini. Most were small, but some reached magnitude 5, strong enough to fracture walls and close schools. The epicenters moved gradually northeast toward the Kolumbo submarine volcano, about five miles offshore. Researchers estimated that roughly 80 billion gallons of magma moved upward from about 11 miles beneath the surface, then stalled about two miles below the seafloor. The swarm subsided after several months, but scientists continue to study the data. Seismic swarms of this kind have also occurred in Japan, Iceland, the Caribbean, and Italy. Researchers are using machine learning to detect patterns in the tremors and map the most active parts of the crust.
The Cascadia Subduction Zone, which runs more than 600 miles from Northern California to Vancouver Island, has produced at least 10 major earthquakes over thousands of years. The last known event occurred in 1700 and sent a tsunami across the Pacific that reached Japan. The zone is currently quiet, but the plates are locked and building pressure. If the fault ruptures, it could produce an earthquake of magnitude 9 or higher and a tsunami that would reach parts of the coast within 15 to 30 minutes. Emergency guidelines advise residents in coastal areas to move to high ground immediately after strong shaking rather than waiting for alerts.
The United States Geological Survey estimates a 10 to 15 percent chance of a major Cascadia earthquake within the next 50 years and a one-in-three chance of a smaller but still significant event. Studies of the seafloor have found evidence of repeated ruptures, with some sections dropping vertically by six to eight feet during past earthquakes. Preparation efforts include better monitoring of the fault and updated building standards.
Australia, despite being far from tectonic plate boundaries, has been identified in a global stress map as one of the most internally stressed landmasses on Earth. Researchers mapped more than 100,000 stress measurements and found that the Australian continent is being squeezed from multiple directions. Some areas, such as the Bowen Basin, show stress directions that rotate unpredictably. Scientists say this does not mean Australia faces an imminent major earthquake, but it suggests that the idea of geologically safe areas may need revision.
The East African Rift System offers a visible example of how continents can stretch and split over time. The Nubian and Somalian plates are drifting apart at a rate of less than an inch per year. If the process continues, the crust could thin enough for seawater to enter, forming a new ocean basin over millions of years. In 2018, a large crack in Kenya received widespread attention, but it was a surface-level sign of a process that has been underway for about 25 million years.
Deep-drilling efforts have provided limited information about the Earth’s interior. The Kola Superdeep Borehole in Russia remains the deepest artificial hole ever created, reaching about 7.6 miles below the surface. The project encountered increasing temperatures, porous rock, and equipment failures before it was shut down in 1992. Samples recovered from the hole contained ancient single-celled marine fossils and water-filled fractures, changing understanding of the crust.
Scientists have detected large underground water reservoirs in several locations. In 2014, researchers found water trapped inside the mineral ringwoodite about 400 miles beneath North America. The amount of water contained in the mineral could be several times greater than the volume of all surface oceans combined. The water is not in liquid form but is bound within the mineral’s crystal structure. This discovery supports the theory that much of Earth’s water may have originated deep underground and gradually moved to the surface over billions of years.
In the Oregon Cascades, researchers have identified a volcanic aquifer holding at least 19.4 cubic miles of water, more than twice the volume of Lake Mead. Scientists measured rock temperatures at different depths and found that temperatures remained constant in several areas, indicating that water was flowing through the rock and cooling it. The aquifer is part of the Cascade mountain range, which was formed by volcanic activity linked to the Cascadia Subduction Zone. Understanding how much water is stored in volcanic rock also helps predict how future eruptions might behave, since water that reaches magma can create pressure that triggers explosive activity.
Abandoned underground mines have also caused problems in residential areas beyond Cornwall. The same geological processes that created the region’s mineral wealth have left a complicated legacy beneath the surface, one that continues to require monitoring and maintenance.
