moderate earthquake
Technical term used in seismology and disaster reporting for an earthquake of moderate intensity, typically around magnitude 5 to just under 6 on the Japanese seismic scale.
The Japan Meteorological Agency classified this tremor as a moderate earthquake.
小地震 is a small or minor earthquake, weaker than a 中地震.
Compound of 中 (chū, 'medium, moderate') and 地震 (jishin, 'earthquake'). A straightforward technical coinage.