Answer: The Northridge quake was greater than Nisqually's because of the sequels the former had after the actual event.
Explanation: The aftershock of the 2 earthquakes were significantly different, marking Northridge as the place with more repercussion in the aftermath of the tremor itself: it can be remarked that hundreds of small quakes were recorded during the week after, causing a lacking possibility to start moving forward in order to start the rebuilding process.