Something I don’t think I’ve ever mentioned, but that many of you may have encountered in the course of reading about Japan, is that the Japanese don’t use the Richter scale when describing the intensity of an earthquake. They do use it to measure it for geological purposes (as in, to record how much energy was released), but for the purposes of broadcasting how strong it was, they use a system developed by the Japan Meteorological Agency. The scale is interesting because it’s calibrated by what most of us really want to know: How was it experienced by people?
7 – In most buildings, wall tiles and windowpanes are damaged and fall. In some cases, reinforced concrete-block walls collapse.
6 upper – In many buildings, wall tiles and windowpanes are damaged and fall. Most unreinforced concrete-block walls collapse. 315 — 400 gal
6 lower – In some buildings, wall tiles and windowpanes are damaged and fall. 250 — 315 gal
5 upper – In many cases, unreinforced concrete-block walls collapse and tombstones overturn. Many automobiles stop due to difficulty in driving. Occasionally, poorly installed vending machines fall. 140 — 250 gal
5 lower – Most people try to escape from danger, some finding it difficult to move. 80 — 140 gal
4 – Many people are frightened. Some people try to escape from danger. Most sleeping people awake. 25 — 80 gal
3 – Felt by most people in the building. Some people are frightened. 8 — 25 gal
2 – Felt by many people in the building. Some sleeping people awake. 2.5 — 8 gal
1 – Felt by only some people in the building. 0.8 — 2.5 gal
0 – Imperceptible to people. Less than 0.8 gal
They use a pendulum to measure how much the ground moves at locations around the country. (At least, they used to–it’s entirely possible they have electronic sensors now.) As you can see, the quake in Niigata a few minutes ago, being a strong 6, may have caused considerable damage. NHK still, of course, doesn’t have much word. I’m not sure whether building codes there are similar to those in Tokyo. One of the problems in Kobe during the Great Hanshin Earthquake ten years ago was that, in Japanese terms, that region is not a major earthquake zone, so most buildings weren’t built quake-proof and older buildings were not retro-fitted. They’re reporting an explosion at a gas station and 3 cars buried under a cliffslide (I’m only half-hearing–it doesn’t sound as if anything major collapsed or anyone was killed).
Another shake at the NHK studio in Niigata. It started 30 seconds ago, and now we’re feeling it. Big-time. Whew. This one’s at least as big as the one a half-hour ago. The newscaster’s telling people to open a door or window (that way if the frame’s distorted you can still get out if there’s a fire), so they may be expecting more aftershocks. Okay, it was a weak 6 in Niigata, and another 3 or 4 here. It’s in rural areas that the biggest worry of falling roof tiles and collapsing wooden buildings exists; it’s a good sign that they’re not reporting much damage from areas outside Niigata cities, but it’s too soon to say for sure.
18:45: And now they’re correcting that one to another strong 6.
18:55: Or wait, they’re saying it was a weak 5. That one was spooky for me because you could see the newsroom in Niigata start to shake, and then we felt it half a minute later. It’s interesting to note that, while everyone’s afraid of another big quake here in Tokyo, the major ones we’ve had over the last ten years have all been in other regions: Kobe, of course, but also Sendai and Hokkaido (always a hotspot, I think).
Looks as if there was a train derailment and there were a few people injured in falls, but fortunately nothing major. BTW, there was another one in the middle there at 18:15 that I didn’t get around to mentioning. The Nikkei has its first report up and says that the magnitudes (this is different from the JMA scale–“magnitude” still isn’t the Richter scale in Japan, but it’s more comparable) were 6.8, 5.9, and 6.3.
23:09: Three deaths have been reported, and inevitably there were some houses that collapsed. Something else Reuters mentions, which I’d wondered about, is that in places where the ground is already soaked and destabilized from this year’s barrage of typhoons, even low-intensity shaking could be enough to cause more mudslides. That doesn’t apply to Niigata, I don’t think. But since the center of the quake was pretty close to the geographical center of mainland Japan, it could apply to some of the prefectures in southern Honshu.