Question

Explain suitability of different basalts for tunneling?​

Answer 1

Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flows that can spread over great areas before cooling and solidifying.[11] Flood basalts are thick sequences of many such flows that can cover hundreds of thousands of square kilometers and constitute the most voluminous of all volcanic formations.[1