The correct statement about the earthquake is:
"The earthquake was caused by plates moving together. It released a lot of energy, but the observer did not see much damage."
In this context, a high magnitude indicates that the earthquake released a significant amount of energy. However, the low intensity as reported by the observer suggests that there was not much damage observed, possibly due to the location of the observer or the depth of the earthquake. Earthquakes at convergent boundaries are typically associated with high magnitude.