Final answer:
The significant event on June 2nd leading to an eruption could be increased seismic activity, thermal changes, changes in gas emissions, or the emergence of ash plumes. These events are typically initial signs or precursors to a major volcanic eruption.
Step-by-step explanation:
The question refers to a significant event that occurs on 2nd June in the build up to a volcanic eruption. The first significant event in this context could be several things based on your study materials. Examples may include increased seismic activities, changes due to thermal anomalies, alterations in volcanic gas emissions, or the emergence of ash plumes as seen in the structure of the Cleveland volcano.
Particularly, referring to the figures provided, one could infer that this event could be something like an eruptive prominence or solar flare as mentioned in Figure 15.20. These activities are generally the presursors of a significant volcanic eruption. These are followed by an eruption which is the most violent event on the surface of the Earth.
The nature of such significant event really depends on specific cases and factors, therefore the precise answer might vary based on further context. But in general, these are the initial signs that geologists and scientists look for when predicting a volcanic eruption.
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