Giant Volcanic Caldera Discovered Beneath Erzurum Basin in Eastern Türkiye

Giant Volcanic Caldera Discovered Beneath Erzurum Basin in Eastern Türkiye

Geologists have identified a massive volcanic caldera beneath the basin of Erzurum in eastern Türkiye. With an estimated diameter of approximately 60 kilometers, it is now considered the largest known caldera in the eastern part of the country.

caldera – A large volcanic depression formed after a powerful eruption empties the underlying magma chamber, causing the surface to collapse inward.

🔬 Mehmet Salih Bayraktutan – Atatürk University

According to Mehmet Salih Bayraktutan, founder of the Earthquake Research Center at Atatürk University, the discovery fundamentally changes the scientific understanding of the region’s geological evolution. For years, the Erzurum Basin had been classified as a tectonic “pull-apart” basin, although field evidence never fully supported this model.

⚠️ Paradigm shift: tectonic → volcanic origin

The new research demonstrates that the basin was formed through compression-related volcanic processes. The structure has been named the Palandöken Caldera.

A Discovery Decades in the Making

Initial field observations suggesting the presence of the caldera date back to 1985. Over the following decades, satellite imagery, remote sensing analyses, and detailed geological studies consistently revealed a large circular structure surrounding Erzurum, confirming its existence.

📊 Caldera profile

• Age: approximately 6 million years old
• Diameter: 60 km – largest in eastern Türkiye
• Dominant rock types: andesitic and basaltic volcanic rocks
• Key indicator: early lava flows dip inward toward basin center
• Paleoenvironment: deep lake environment developed after eruptions

Researchers estimate that the Palandöken Caldera is around 6 million years old and is dominated by andesitic and basaltic volcanic rocks. Geological data indicate that early lava flows dipped inward toward the basin’s center, where a deep lake environment later developed.

Sediments accumulated progressively from the caldera margins toward the center, while fine volcanic materials spread widely across the basin. Inside the caldera, scientists identified a complex sequence of volcanic and sedimentary rocks, recording a long history of eruptions, lake formation, and sedimentation.

Visible Rim and Seismic Modification

Arc-shaped segments of the caldera rim remain clearly visible on the southern, eastern, northern, and western sides of the basin. When connected, these segments form a nearly complete 60-kilometer-wide ring.

⚠️ Tectonic overprint: earthquakes destroyed western caldera wall

Earthquakes are believed to have destroyed parts of the caldera wall in the west and northwest, allowing flood deposits to enter the lake environments in the region. These sediments accumulated in stacked fan-delta systems and now form the subsurface foundation of the Daphan Plain.

“Despite more than a century of geological research in the region, no previous scientific publication has formally identified or described the Palandöken Caldera.” – Mehmet Salih Bayraktutan

Century of Research, First Identification

Despite more than a century of geological research in the region, Bayraktutan emphasized that no previous scientific publication has formally identified or described the Palandöken Caldera.

⛏️ Next step: deep drilling confirmation

Experts stress that deep drilling at five to six locations across the Erzurum Basin is essential to confirm subsurface structures and fully understand the caldera’s formation.

Scientific Significance

• Revises 100+ years of tectonic interpretation for Erzurum Basin
• First formally identified caldera in this part of eastern Türkiye
• 60 km diameter makes it the largest known caldera in the region
• Provides new framework for understanding volcanic evolution and seismic history
• Opens questions about similar basins previously classified as tectonic

fan-delta systems · andesite · basalt · pull-apart basin · caldera rim

“The Palandöken Caldera is not just a feature — it is a key that unlocks the volcanic past of eastern Anatolia. Deep drilling will write the next chapter.”

Atatürk University · Earthquake Research Center · 2026