Quick Answer
Look for bulging or swelling in the area around volcanic vents, increased seismicity and tremors, and steam venting with a peculiar odor. Changes in the color and temperature of steam vents can also signal an impending lava flow. A decrease in temperature and an increase in steam output may indicate the approach of lava.
Signs of Lava Flow Preparation
When a volcano is preparing to erupt, magma moves upward through the vent system, causing the ground to inflate and swell. This is known as a “bulge” and is an early warning sign of an impending lava flow. The bulge forms when magma accumulates beneath the surface, causing the ground to rise.
Recognizing the Warning Signs
Increased seismicity and tremors are also signs that magma is moving beneath the surface. As lava moves closer to the surface, steam venting becomes more intense and may take on a peculiar odor. Changes in the color and temperature of steam vents can also signal an impending lava flow. A decrease in temperature and an increase in steam output may indicate the approach of lava.
Predicting Lava Flow Speed and Direction
The speed and direction of a lava flow can be predicted by observing the slope and gradient of the surrounding terrain. Lava flows tend to move faster and farther down steeper slopes. The viscosity of the lava is also an important factor in determining the speed and direction of the flow. Thicker, more viscous lava flows tend to move more slowly and may change direction more frequently than thinner, less viscous flows.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.