On 11 May 2011 a magnitude 5.1 earthquake struck the town of Lorca in Murcia, south-east Spain, killing nine people and injuring more than 300. Although modest in magnitude, it was one of the most destructive Spanish earthquakes in decades.
The reason was its extremely shallow depth — only about 1 km — and its location directly beneath a populated town on the Alhama de Murcia fault. Shallow quakes concentrate their energy near the surface, so even a moderate magnitude can bring down older masonry buildings, which is what happened in Lorca's historic centre.
The disaster reshaped how Spain thinks about seismic risk in its south-east, the country's most seismically active region. It is the reference event for earthquake preparedness in Spain and a reminder that magnitude alone does not determine how dangerous a quake is — depth and location matter just as much.