My city Christchurch was fucked by a 6.2 or 6.3 - but it was both (a) shallow (5km) and (b) close to dense residential areas.

Christchurch was near to the 7.1 Canterbury earthquake but that did much less damage as it was 10km deep and Christchurch wasn't on top of it (it mostly affected less dense rural properties in the region near Christchurch).

Be careful not to think of earthquakes as a point - talking about epicentres and precise depth is very misleading. Earthquakes are a fault-sheet or wrinkles. Surface fault lines only show where the 3D rips through the solid earth meet the surface. Fault lines matter a bit especially since they indicate local shallowness, but I suspect we get distracted by them because they make spectacular news reports. Reality is complex.

My parents house was right above the fault plane of the Canterbury fault - and their house came though mostly okay. I know lots of people very near the Christchurch quake and many of their houses were unrecoverably damaged.

7.4 @ 300km deep you just yawn and roll over. @10km deep you pray your concrete roof tiles don't come through the ceiling and kill you in your bed... you basically just lie on top of your wife, give thanks for the time you did have, and hope for the best.

[0] https://postimg.cc/HckCRn1m

It started near Hualien City with the magnitude 7.4 and then if you folow the blue lines you can see how it rattled NE-SW mostly along the coast for the first hour (6 events) then following the pink line you can see it popped at the NE end along the coast before a series of events that curved out into the sea to the E-SE for the next hour (5 events). That was followed during the third hour by 4 events oriented roughly NE-SW in green with all but one offshore to the NE. The fourth hour saw 4 more events almost complete the square in yellow. Things were quieting by then and the fifth hour only saw two events, both offshore in light blue with the series ending red with a single event offshore.

I have a graph of activity showing the magnitude and depth versus the time of the event. You can see that the later events trend deeper and lower magnitude making them unlikely to be felt as much as the initial event and less likely to cause as much damage. [1]

[1]https://postimg.cc/zyfdWhNT

To understand the timing of the events I have displayed them in an elapsed time versus magnitude display based on the initial event timing. [2]

[2] https://postimg.cc/68w81VqG

You can see how the magnitude of the events tails off and they become less frequent with time. In the map view you can get a feel for the region's relaxation after the main quake and the other graph allows you to see how the event magnitudes decreased while the later events tended deeper.

And the deeper it is, the further it is away from the ground, where humans are.

Of course transitioning to a new standard would be even more confusing for a while.

Edit: apparently there are many different scales in wide use already. https://en.wikipedia.org/wiki/Seismic_magnitude_scales