Sinkholes have opened across multiple regions in recent years, collapsing roads, swallowing vehicles, and in some cases damaging buildings. The holes form when underground rock slowly dissolves, usually because water is wearing away soft rock such as limestone. Once the underlying support weakens, the surface can give way suddenly.

Around 700 sinkholes have been documented in Turkey’s Kaş region, according to local officials. A recent example measured roughly 100 feet across and about 50 feet deep. Officials installed warning signs and fencing around the site, noting that the area could still collapse further.

Geologists say the region’s groundwater levels have fallen as farms pump out large volumes of water and rainfall has declined. Underground cavities that were once filled with water are emptying, leaving the ground with less structural support. Turkey’s location within a fault-controlled basin means that shifting ground can also contribute to collapses.

A similar event occurred at a copper mine in Chile’s Atacama Desert. A sinkhole about 105 feet wide appeared near an underground mine operated by a Canadian company. Workers cordoned off the area, and no injuries or equipment damage were reported. Mining operations below ground were halted while geologists investigated.

In 2010, a sinkhole opened in Guatemala City, roughly 60 feet wide and about 20 stories deep. A three-story building was reported to have fallen into the crater. The collapse followed Tropical Storm Agatha, which brought heavy rain to the city. Investigators suspected that a damaged sewer or storm drain may have weakened the soil before the storm provided the final trigger.

China’s Xiaozhai Tiankeng, often called the Heavenly Pit, is one of the largest known sinkholes. Located in southern China, it reaches a maximum depth of about 2,000 feet and is roughly 1,760 feet across. Vegetation, including large ferns and ancient ginkgo trees, grows at the bottom, and researchers have documented more than 12,200 plant species there. Clouded leopards have also been observed in the forest below.

Sinkholes vary considerably in size. Some are only a few feet deep, while others can reach the depth of a skyscraper. Human activity, including construction, drilling, and groundwater pumping, can increase the risk of collapse. Heavy rainfall frequently serves as the final trigger.

The Dead Sea region has become particularly prone to sinkholes because its groundwater contains high concentrations of salt, which dissolves quickly and weakens the ground. Some holes in the area have been large enough to injure people standing nearby.

A separate geology mystery in Peru involves thousands of small pits along a rocky ridge known as the Band of Holes. The pits stretch about a mile across the mountainside. For decades, researchers offered various theories, including water collection, crop cultivation, defensive trenches, or graves. None of these explanations matched the evidence.

Archaeologists later found traces of corn and wild plants used for basket weaving in the pits, along with pottery dating to the 15th century, when the Inca civilization conquered the Chincha people. The Incas did not use currency, but they collected tribute from conquered groups. Researchers now believe the pits functioned as a measurement system. Local families filled each pit with goods such as corn, cotton, or peppers, and Inca officials later collected and transported the goods to a nearby administrative center.

The Nazca Lines, located elsewhere in Peru, remain harder to explain. The geoglyphs include hundreds of geometric shapes, straight lines, and images of animals and plants, some large enough to be seen from altitude. Commercial pilots spotted them in the 1930s. The Nazca people are generally credited with creating the figures between roughly 1 and 700 CE. Some archaeologists have suggested the lines were connected to rituals intended to bring rain, since the region receives very little precipitation, but no consensus has been reached.

The Vredefort Crater in South Africa, created by an asteroid impact about two billion years ago, is currently about 99 miles wide. Scientists estimate it was once considerably larger, possibly around 174 miles across, making it the largest known impact crater on Earth. Erosion and newer rock layers have worn down the original structure. Researchers studied fractured minerals such as quartz and zircon to estimate the force of the impact, concluding the asteroid may have been up to 15.5 miles wide and struck at speeds reaching 56,000 mph.

The impact occurred at a time when Earth was inhabited only by single-celled organisms, so no mass extinction followed. The event may, however, have had a significant effect on the planet’s climate.

A smaller but better-known impact event took place in Siberia in 1908. The Tunguska event flattened about 80 million trees across roughly 830 square miles. Because the object exploded in the air rather than striking the ground, no crater was formed. Witnesses described a bright flash and a powerful shock wave that broke windows hundreds of miles away. Scientists later concluded that an asteroid about the size of a 25-story building exploded between three and six miles above the surface.

In 1994, fragments of the comet Shoemaker-Levy 9 crashed into Jupiter over six days. The impacts, which involved chunks up to half a mile across, heated Jupiter’s atmosphere to extreme temperatures and left dark scars visible for months. The event helped scientists track winds in Jupiter’s stratosphere and study how chemicals mix in the planet’s atmosphere. It also reinforced the importance of monitoring objects that could threaten Earth.

More recently, craters have appeared in the Arctic permafrost. The first was discovered in 2014 by a helicopter pilot. In the years that followed, additional craters emerged in the same region. Researchers found elevated methane concentrations around the holes and concluded that pressure from methane gas had caused underground explosions. The gas accumulates in the frozen ground and builds up until the surface splits open.

A related formation, the Batagaika Crater in Siberia, is a large depression that formed when part of a frozen slope collapsed. It has expanded over time and has exposed ancient soil and fossils. In 2018, researchers found the remains of a 42,000-year-old foal preserved in the permafrost. Scientists study the site for what it reveals about past climates and ecosystems.

In Greenland, a 1993 ice core sample was reexamined in 2023 and found to contain fossils of moss, willow, and an Arctic poppy. The discovery indicates that the center of Greenland’s ice sheet melted completely at some point in the past, allowing vegetation to grow. Researchers note that if Greenland’s ice melted once, it could happen again, with potential consequences for global sea levels.

Giant viruses have also been found in Greenland’s ice. These viruses, which are larger than typical viruses, infect algae. By darkening the ice, they may reduce how much light is reflected and slow melting. The discovery was the first time giant viruses were found in Greenland’s ice and snow.

Researchers have also investigated a gravity anomaly under East Antarctica. The Wilkes Land anomaly shows signs consistent with a large impact crater, possibly up to 30 miles wide in terms of the meteor that created it. If confirmed, it would be one of the largest known impacts on Earth. The crater is buried beneath thick ice, making direct study difficult, and scientists have not ruled out alternate explanations such as volcanic activity or erosion.

A separate gravity anomaly near Hudson Bay in Canada has been explained by two factors. The region sits over mantle convection that drags the crust downward, and the land is still recovering from the weight of the Laurentide ice sheet, which melted about 10,000 years ago. The ground in the region continues to rise slowly, and sea levels there are dropping as a result.

In 1980, a drilling accident at Lake Peigneur in Louisiana caused the lake to drain into an underground salt mine. The drill punctured the mine walls, and millions of gallons of water poured into the tunnels. Fifty miners escaped before the flooding became severe. The lake, which had been about 11 feet deep, collapsed into the mine, creating a temporary waterfall about 164 feet high. Eleven barges, a tugboat, and the drilling rig were pulled into the crater. The mine flooded completely within two days, and the lake took on a new depth of about 200 feet. The drilling company paid $45 million in compensation, and an investigation found that the engineer had used incorrect maps when selecting drilling coordinates.

California’s Lake Berryessa features a large concrete drainage structure known as a glory hole. Built by engineers, it functions as an overflow mechanism, directing excess water from the lake into a nearby bay during heavy rain. The structure has also become a tourist attraction.

In Yemen, a large hole in the desert known as the Well of Barhout has remained poorly understood. Locals have described unusual sounds and a strong odor coming from the pit. In 2021, a group of cavers descended to the bottom and found stalactites, waterfalls, and snakes. No scientific consensus has been reached on how the hole formed.

The Mariana Trench in the western Pacific is the deepest known location on Earth, with a depth that could accommodate one and a half Everests. The trench is home to species adapted to extreme water pressure, including microorganisms, transparent fish, and other creatures not found elsewhere. Diving to the bottom requires specialized equipment designed to withstand the pressure.

Geologists are also studying the North Anatolian Fault beneath the Sea of Marmara near Istanbul. The fault has produced large earthquakes in the past, and pressure has been building along a locked section for centuries. Researchers used electromagnetic imaging to create a three-dimensional map of the fault’s structure. Some models suggest a major rupture of magnitude 7 or higher could occur in the coming decades. Turkey has worked to upgrade its earthquake early warning system, which can now detect initial seismic waves within seconds, though gaps remain in seabed sensor coverage.

The Cascadia Subduction Zone, stretching from Northern California to Vancouver Island, is capable of producing a megathrust earthquake of magnitude 9 or greater. The last such event occurred in 1700 and generated a tsunami that reached Japan without warning, recorded by local communities as an orphan tsunami. Scientists have found evidence of ghost forests along the Northwest coast, where trees were killed by saltwater after the land dropped during that earthquake. GPS monitoring has also detected silent earthquakes, slow movements that release energy without causing shaking. Experts estimate roughly a one-in-eight chance of a megathrust event within the next 50 years.

The Seattle Fault Zone, which runs beneath the city, produced an earthquake around the year 923 estimated at magnitude 7.5. That event lifted parts of the seafloor and triggered a tsunami. More recent research suggests smaller earthquakes occur about every 350 years, more frequently than previously believed. These smaller quakes are capable of damaging buildings and infrastructure, and scientists have recommended updating building codes to account for them.

Japan’s Nankai Trough has also drawn attention as a potential source of a large earthquake. The last major ruptures occurred in 1944 and 1946, both around magnitude 8.1. In 2024, a magnitude 7.1 quake on the trough’s edge prompted Japan’s first-ever megaquake advisory, though most warnings were later lifted. Scientists estimate a 70 to 80 percent chance of an earthquake between magnitude 8 and 9 in the region within the next few decades.

The 1964 Great Alaska Earthquake, with a magnitude of 9.2, remains the most powerful earthquake recorded in North American history. It lasted more than four minutes, triggered tsunamis, and caused land shifts that raised some coastlines by 30 feet and lowered others by 8 feet. The earthquake destroyed buildings across Anchorage and wiped out the village of Chenega.

Japan has developed advanced earthquake-resistant construction methods. Buildings use thicker beams and pillars, and some are fitted with base isolation pads that separate them from the ground. Dampers, which work like oversized hydraulic pumps, absorb shaking energy in tall buildings. After the 1995 Kobe earthquake, which killed more than 5,000 people and caused an estimated $200 billion in damage, Japan overhauled its building codes and disaster management systems. The earthquake early warning system that came into use afterward has since provided residents with advance notice before strong shaking arrives.

The New Madrid seismic zone in the central United States produced a series of large earthquakes between December 1811 and February 1812. The quakes were felt across a wide area, caused the Mississippi River to temporarily flow backward, and destroyed the town of New Madrid, Missouri. Modern researchers have debated whether recent small earthquakes in the region are aftershocks of those events. Estimates vary, with some studies suggesting that anywhere from 10 to 65 percent of recent quakes may be related to the 1811–1812 sequence.

Mount Yasur in Vanuatu has been erupting continuously since at least 1774, when explorer James Cook observed it. Stromboli in Italy has held the Guinness World Record for the longest continuously erupting volcano, with activity spanning more than 2,400 years.

Scientists have also studied the relationship between volcanic activity and extinction events. The largest mass extinction in Earth’s history, the Permian-Triassic extinction about 252 million years ago, coincided with massive volcanic eruptions in Siberia that released large quantities of gas and likely disrupted the climate.

A coal seam fire at Burning Mountain in Australia has been smoldering underground for at least 6,000 years. The fire moves slowly through a coal layer, and experts say it is unlikely to be extinguished naturally anytime soon.

The most powerful earthquake ever recorded measured magnitude 9.5 in Chile in 1960. It triggered a tsunami that affected areas across the Pacific and temporarily shifted Earth’s rotation by about two milliseconds. Any earthquake above magnitude 25 is not considered a realistic concern because Earth’s crust does not contain enough energy to produce one. An asteroid impact has the potential to generate far more powerful shaking, with the event associated with the dinosaurs’ extinction estimated to have produced effects equal to roughly magnitude 11.

Residents in earthquake-prone regions are generally advised to drop, cover, and hold on during shaking, to stay away from windows and unstable objects, and to remain sheltered for a short period after the shaking stops in case of aftershocks.

Researchers have found evidence that the San Andreas Fault and the Cascadia Subduction Zone may be mechanically linked. Marine sediment cores suggest that paired earthquakes occurred at least ten times in the last 3,100 years, with ruptures on one fault potentially triggering the other through stress changes at the Mendocino Triple Junction. If a large earthquake on one fault were followed shortly by a rupture on the other, the combined effects could affect infrastructure and shipping hubs across the West Coast and beyond.

Yellowstone, often described as a supervolcano, has shown signs of activity in recent years. The ground near the Norris Geyser Basin rose by about an inch beginning in July 2025, similar to previous uplift events in the 1990s and 2010s that did not lead to an eruption. Geyser activity, including an eruption of the acidic Echinus Geyser in February 2026, has drawn public attention, though scientists regard such events as typical. The magma chamber beneath Yellowstone is estimated to be only 5 to 15 percent liquid. The last major eruption occurred about 631,000 years ago, leaving behind the caldera that now forms part of the park.

Larger volcanic systems, known as large igneous provinces, can produce repeated lava flows over long periods. The Columbia River Basalt Group in the Pacific Northwest, which formed about 17 million years ago, covers roughly 42,000 cubic miles. Some geologists have suggested a connection between that lava flood and the Yellowstone hotspot, though the relationship remains an area of ongoing research.

Taftan Volcano in southeastern Iran has shown renewed activity. Satellite images indicate that its summit rose by about 3.5 inches over ten months. Scientists believe the movement is related to pressure from gas or magma below the surface. The volcano has been reclassified from extinct to dormant, which means it will now receive closer monitoring. Volcanic emissions from an active period could affect air quality or flight paths in the region, though no eruption has occurred.

The Campi Flegrei caldera near Naples, Italy, has experienced ground uplift and earthquake swarms for years. Recent studies suggest that much of the shaking comes from a sealed underground water and steam reservoir rather than rising magma. The area remains capable of producing steam-driven explosions, and scientists have adjusted their hazard assessments accordingly. Supervolcano eruptions remain rare. The most recent confirmed super-eruption occurred about 26,500 years ago in New Zealand, and the average interval between such events is roughly 100,000 years.