Which phenomenon can result when the pressure of magma builds up in a volcano?

When the pressure of magma builds up in a volcano, it can lead to intense seismic activity. This occurs because the accumulation of magma generates pressure within the surrounding rock formations. As this pressure increases, it can create fractures and movement in the Earth's crust, which results in earthquakes or other seismic events. The sudden release of this built-up pressure during a volcanic eruption can also contribute to significant seismic activity, indicating a dynamic relationship between magma movement, pressure, and the tectonic environment.

The other options do not accurately describe the likely outcomes of pressure buildup. For instance, no volcanic activity or a stable state would not align with the high-pressure conditions typically leading to eruptions. Similarly, gradual land uplift may occur under certain geological conditions, but it does not specifically correlate with the immediate and intense seismic effects that result from magma pressure buildup. Hence, the correct connection between magma pressure and seismic activity underscores the dynamic nature of volcanic systems.