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.
This is because earthquakes at convergent boundaries (where tectonic plates move toward each other) typically release a large amount of energy, which can result in a high magnitude. However, the intensity reported by the observer can be low if the earthquake occurred in a remote area, if the building infrastructure was resilient, or other factors that may have mitigated damage despite the energy release.