Which earthquake is described as having a magnitude of 7.0 and resulted in 9 deaths, noted for its first instrumental strong-motion measurement?

The earthquake that is characterized by a magnitude of 7.0, resulted in fatalities, and is particularly significant for being the first to be recorded with strong-motion measurements is actually the San Fernando earthquake, not the Imperial earthquake specified in the answer provided.

The San Fernando earthquake occurred in 1971 and had a magnitude of 6.6, but it is well known for its detailed strong-motion data collection efforts, which became instrumental in improving engineering standards for seismic safety. The Imperial Valley earthquake, on the other hand, did occur at a 7.0 magnitude, but it is not noted primarily for its strong-motion measurements.

When identifying significant earthquakes, it is essential to connect their characteristics—such as magnitude, impact, and technological advancements in measuring seismic activity—to the correct event. In this context, the San Fernando earthquake stands out due to its importance in the evolution of earthquake engineering and safety protocols, whereas the Imperial earthquake, with a magnitude of 7.0 and fewer fatalities, doesn't share that same historical significance regarding strong-motion measurement advancements.