Mexico’s Popocatépetl volcano has long drawn attention for its size, constant activity, and glowing plumes of smoke and ash, yet for decades scientists did not fully understand what was happening deep inside it. Rising more than 17,800 feet between Mexico City and Puebla, the volcano looms over an area where around 25 million people live, placing homes, schools, hospitals, roads, and airports within potential danger. While most high-risk volcanoes around the world already have detailed maps of their interiors to show how magma moves and eruptions begin, Popocatépetl remained an exception, as earlier studies produced unclear and sometimes conflicting results that failed to reveal how the volcano was built from within or where molten rock was collecting.
A rare look beneath the crater
After five years of work, scientists have created the first clear three-dimensional image of Popocatépetl’s interior. This image shows what lies up to 18 kilometers below the crater. It reveals several pools of magma at different depths instead of just one large chamber. These magma pockets are separated by layers of rock and other materials.
The findings show that the inside of a volcano is far more complex than the simple drawings many people learn in school. Instead of one pipe leading from a single magma chamber to the surface, Popocatépetl has a layered and active interior. Magma, gas, water, and rocks are all moving at the same time.
This movement creates small earthquakes called seismic signals. These signals travel through the ground and carry clues about what is happening below. By listening carefully to these signals, scientists can learn where magma is located, how hot it is, and how deep it sits.
To capture these signals, the research team placed seismographs all around the volcano. These machines measure ground vibrations up to 100 times every second. At first, there were only 12 instruments. That was enough to warn of danger, but not enough to fully understand the volcano. The team increased the number to 22, covering the entire volcano.
Each device collected massive amounts of data. Sorting through it by hand would have taken years. Instead, the scientists used artificial intelligence. The computer system was trained to recognize different kinds of tremors. Slowly, patterns began to appear. These patterns helped scientists map what materials were inside the volcano and where they were located.
Climbing into danger to gather data
Collecting this information was not easy. Scientists had to climb high up the volcano, often before sunrise. They carried heavy backpacks filled with computers, batteries, gas sensors, and tools. The air was thin, and every step required effort.
The terrain changed quickly. Pine forests at lower levels gave way to ash-covered slopes. At higher points, the ground felt warm underfoot. They crossed dried lahar paths. These are channels formed by dangerous mudflows of ash and rock during heavy rains. Even when dry, these areas showed how powerful the volcano can be.
At night, the volcano sounded alive. Explosions echoed across the slopes. Ash sometimes fell like rain. On darker nights, the crater glowed orange. These sights and sounds reminded everyone that Popocatépetl is always active.
The scientists regularly dug up seismographic stations to collect stored data. Sometimes the equipment was damaged. Batteries died. Animals chewed wires. Explosions shook stations loose. Every working device felt like a small victory.
Near the upper slopes, massive rocks lay scattered across the ground. Some were volcanic bombs, thrown out during past eruptions. These rocks showed how dangerous the area can be. In recent years, people have been injured or killed by falling debris after ignoring safety restrictions.
Despite the risks, the team continued. Direct contact with the volcano helped them understand its behavior better. Being on the mountain gave context to the data on their screens. The volcano was no longer just lines on a graph. It was a living system.
A volcano shaped by time and activity
Popocatépetl formed more than 20,000 years ago inside the remains of older volcanoes. It has been active since 1994 and releases smoke, gas, and ash almost every day. From time to time, lava builds a dome inside the crater. Eventually, the dome collapses and triggers an eruption. The most recent major eruption happened in 2023.
The new 3D image shows that magma is more concentrated on one side of the volcano. This matches areas where tremors are more frequent. Understanding this uneven structure helps explain why certain eruptions behave the way they do.
The volcano has shaped human history as well. Long ago, entire villages were buried in ash during eruptions. In the early 1900s, human activity inside the crater caused an eruption. Even today, the volcano releases large amounts of natural greenhouse gases, though far less than nearby cities produce.
The interior map does not answer every question. Instead, it provides a clearer picture of what is happening beneath the surface. It allows scientists to track changes over time. By comparing future data with this baseline, experts can better understand when the volcano is becoming more dangerous.
For the millions living nearby, this knowledge matters. Better understanding means clearer warnings and faster responses during eruptions. The mystery inside Mexico’s majestic giant is no longer completely hidden. Step by step, layer by layer, science is revealing what lies beneath Popocatépetl’s powerful presence.
