Earth's Deformation and Volcanic Eruptions

Question

Scientists can predict volcanic eruptions by monitoring certain surface changes on an active volcano. One type of change they can monitor is called deformation. Scientists can measure deformation by measuring the tilt (angle) of land in relation to the horizon. Magma chambers exist below the surface of a volcano. When a chamber fills with magma it inflates and the land surrounding the chamber is pushed out, in a process called inflation. After an eruption, the chamber deflates, or drops down, in a process called deflation. In the deformation model shown below, the balloon represents a magma chamber.

From left to right, the model titled 'Figure 1. Deformation' shows a volcano just before eruption and a volcano just after eruption. The left volcano shows a large balloon below the surface, labeled 'Inflation', with arrows pointing up labeled 'volcanic eruptions', and the surface is curved up. The right volcano shows a small balloon below the surface, labeled 'Deflation', with arrows pointing down and the surface is curved down.

The graph below represents tilt measurements and eruption data for an active volcano in Hawaii called the Kilauea Volcano. The arrows in the graph represent eruptions.



Constructed Response Question
In Figure 2, the change in tilt measurements before a volcanic eruption is thought to be a result of magma quickly rising to Earth’s surface.

A. Using Figure 1, explain the change in tilt measurements shown in Figure 2 AFTER a volcanic eruption.

B. Explain how scientists can use the tilt measurement data to predict future volcanic eruptions and to help protect people living near the volcano.

Answer 1

A. Explanation of Tilt Measurements After a Volcanic Eruption

In Figure 1, after a volcanic eruption occurs, the magma chamber below the surface of the volcano undergoes deflation. This means that the large balloon representing the magma chamber shrinks as the magma is expelled from the chamber during the eruption. The surface of the volcano, which had been curved upward due to the inflation from the accumulating magma, begins to curve downward.

As a result, the tilt measurements reflect this change in the surface of the land. After the eruption, the tilt would show a decrease, indicating that the surface is sloping back down toward the horizon, consistent with the deflation of the magma chamber. This decrease in tilt measurements is due to the reduced pressure exerted by the now smaller magma chamber and the downward movement of the land as it returns to its original state.

B. Predictive Use of Tilt Measurement Data for Future Eruptions

Scientists monitor tilt measurement data to observe changes in the shape of the volcano. Before an eruption, the tilt measurements often indicate inflation of the volcanic surface, signifying that magma is rising toward the surface and adding pressure to the surrounding rock, which leads to an increase in tilt. When a sustained trend of increasing tilt is observed, it is a strong indicator that an eruption may be imminent.

By analyzing historical data and patterns of tilt changes associated with past eruptions, scientists can establish a correlation between tilt measurements and eruption activity. If significant inflation is recorded, it may inspire scientists to issue alerts and take preventative measures to protect people living near the volcano, such as evacuations or safety drills.

Additionally, continuous monitoring allows for real-time data collection, which helps scientists refine eruption models and provide warnings. Overall, the tilt data acts as an essential tool for volcano monitoring, enabling quicker response times and potentially saving lives by ensuring that communities are prepared for future volcanic eruptions.