One thing I noticed is that when the US talks about earthquakes, it often only notes the seismic magnitude value of the quake and doesn't always mention the seismic intensity scale values of the affected locations. This is in contrast to Japan where quakes are almost always mentioned in both magnitude and the Japan Meteorological Agency's "shindo" intensity scale [1], eg. "The 2011 Tohoku Earthquake was a M9.0 quake with a maximum intensity of shindo 7." The US does have the equivalent of the JMA shindo scale - the Modified Mercalli (MM) scale [2], and they do seem to be used, but I see the MM values mentioned much less frequently than how both the Japanese agencies and the general public refers to shindo values.

While the magnitude value signifies the overall energy of the quake, intensity scale values indicate the shaking intensity of a given location; hence, it feels more grounded in one's daily life experiences. Many Japanese individuals have developed an approximate sense of how strong a quake is - conversations like "That was a bit big, somewhere around shindo 4?" are common after quakes. People do of course care about magnitude, but the thing they care most about after a big quake is more likely "what was the seismic intensity in the worst-hit area?"

Any idea why intensity scales seem to be much less common in the US?

[1] https://en.wikipedia.org/wiki/Japan_Meteorological_Agency_se...

[2] https://en.wikipedia.org/wiki/Modified_Mercalli_intensity_sc...