The remote Taftan volcano in southeastern Iran has awoken from its 700,000-year slumber, rising by 3.5 inches (9 centimeters) in just 10 months. This seemingly minor shift holds profound significance, prompting scientists to take notice. A recent study, utilizing satellite data, has detected this subtle yet crucial change, suggesting that pressure is building near the summit.
The Taftan volcano, though historically dormant, is now sending out a clear signal that its system is stirring. Scientists have employed InSAR, a radar method that measures ground motion from space, using Sentinel-1 satellites, which can operate day and night and penetrate clouds. The uplift, centered near the summit, has persisted since July 2023, indicating that the pressure has not yet dissipated.
Pablo J. González, from the Spanish National Research Council's Institute of Natural Products and Agrobiology, leads the study. The lack of on-the-ground instruments at Taftan makes space radar the ideal tool for monitoring this remote mountain, despite its proximity to several towns.
The source of the pressure, according to the team's modeling, lies just 1,600 to 2,070 feet (490 to 630 meters) below the surface, suggesting the presence of gases within a hydrothermal system. They ruled out heavy rain and nearby earthquakes as triggers, attributing the rise to internal processes within the volcano's edifice.
Beneath the Taftan volcano lies a magma reservoir, a large underground body of molten rock. The current push is likely caused by gases above it, rather than fresh magma reaching the surface. The pattern of ground rise and stabilization as new cracks open and gas finds exit paths resembles a slow squeeze.
The term 'extinct volcano' can be misleading. Taftan, a 12,927-foot (3,940-meter) stratovolcano, continues to show signs of movement through summit fumaroles. Eruption records for the past 10,000 years are scarce, but silence on paper does not equate to a dead system in rock and gas.
Volcanoes can exhibit long periods of inactivity, followed by sudden changes in months. Scientists consider various factors, including ash plumes, gas, heat, and ground motion, for early warning. Labels are helpful, but measurements are crucial. The new deformation is a measurement, not a label.
Two potential drivers for the uplift are gas accumulation in tight rocks and fractures or a small pulse of melt releasing volatiles into the shallower plumbing. As gas pressure grows, the rock lifts, and the summit area responds first. Both scenarios align with the shallow source and timing.
The main near-term hazards are not lava flows but phreatic blasts, steam-driven explosions that can occur when hot fluids flash to vapor near the surface. Gas bursts can cause eye and lung irritation and damage crops downwind. The city of Khash, located 31 miles away, is susceptible to sulfur odors when the wind aligns.
González emphasizes that the study serves as a wake-up call for authorities to allocate resources for monitoring. The message is to prepare now, as the mountain is whispering, not shouting. The team aims to measure gases at vents and slopes, providing continuous readings of sulfur dioxide, carbon dioxide, and water vapor levels to assess pressure changes.
They also advocate for a basic network of seismometers and GPS units to capture ground shake and slow stretches. Satellites will continue to monitor, with InSAR tracking ground movement from space, enabling rapid detection of small changes for field crews.
Taftan's location in a subduction zone, where one tectonic plate slides under another, contributes to the magma and gas-rich fluids beneath it. The volcano's two main peaks and long-lived gas vents indicate ongoing heat rise from below.
Many volcanoes worldwide exhibit similar slow changes that never culminate in eruptions. Others rapidly escalate after a quiet phase, necessitating swift action. Steady, routine monitoring is crucial for saving lives, transforming surprises into manageable problems with known responses.
Satellites play a vital role in this context, as they can see through clouds and smoke, operating day and night. Sentinel-1's C-band radar, with frequent passes, creates a motion movie, crucial for detecting minor changes. As more satellites launch, revisit times decrease, enabling scientists to receive faster updates when conditions shift.
Combining space and ground-based data provides the most comprehensive understanding. Satellites offer a broad perspective, while ground-based instruments add detailed information. The Taftan volcano's future will depend on continued monitoring, with scientists testing the plumbing's state and assessing the potential size of the next gas pulse.
Nearby residents can take simple precautions, such as understanding wind patterns, keeping masks for sulfur odors, and following official guidance. The study is published in Geophysical Research Letters, and readers can subscribe to Earth.com's newsletter for more engaging articles and updates.
