A sleeping giant's heartbeat
Mount Ararat, a compound stratovolcano reaching 5,137 meters (16,854 feet), appears quiet. For centuries, its twin snow-capped peaks, Greater and Lesser Ararat, have stood silent over the plains of eastern Turkey. The last confirmed magmatic eruption occurred around 2,500 years ago, with pyroclastic flows burying Early Bronze Age settlements. A more recent event in 1840 was a steam-driven phreatic eruption, triggered by a massive magnitude 7.4 earthquake. This event caused a gigantic landslide on the northern flank, obliterating the village of Akori and killing up to 10,000 people in the region.
Despite this long magmatic silence, modern geophysical techniques suggest the volcano is dormant, not extinct. Seismic tomography, a method that uses earthquake waves to create a 3D image of the Earth's subsurface, has detected a low-velocity anomaly beneath the massif. This zone, centered at a depth of around 15 kilometers, indicates the presence of partially molten rock. The seismic waves slow down as they pass through this material, showing a potential magma chamber that could be the source of future eruptions. The findings challenge the perception of Ararat as a permanently inactive feature and place it back on the list of potentially hazardous volcanoes.
Reading the waves
Seismic tomography works much like a medical CT scan. Just as X-rays travel at different speeds through bone and tissue, seismic waves (P-waves and S-waves) generated by distant earthquakes travel at different velocities through materials of varying temperature and density deep underground. By measuring the arrival times of these waves at multiple seismograph stations surrounding a volcano, scientists can map out areas where the waves are delayed.
Beneath Mount Ararat, the identified low-velocity zone is a region of crystal mush—solid crystals and liquid magma. While the exact percentage of melt is difficult to determine, its presence indicates a thermally active magmatic system. The volcano itself is a massive edifice, with a base 35 kilometers (22 miles) wide, built up over 1.5 million years through four major phases of activity. These phases ranged from initial fissure eruptions to the later cone-building events that formed the modern peaks of Greater and Lesser Ararat. The detection of a magma body deep beneath this extensive volcanic complex provides a physical basis for its long and powerful history, and a warning that this history may not be over.