We didn't feel it at all. In fact, we didn't know anything about it until the afternoon when went into town for some errands and happened to pass a TV display in a store that was showing news pictures of the damage.
We did feel an aftershock last night which awakened us sometime before midnight and sent Momo out of her house, barking.
Since I grew up in California, earthquakes are not new to me. In fact, during the Kern County earthquake of July 1952, which at 7.3 on the Richter, was the largest in the conterminous United States since the San Francisco shock of 1906, since I was just a baby, my father grabbed me out of the crib and rushed outside with my mother and three older siblings. Only when everyone was safely assembled in the yard did someone point out that he was holding me upside down.
In college I spent a year in a field geology class mapping the Mill Creek Canyon fault - an offshoot of the famous San San Andreas fault - in the San Bernardino Mountains. I had a great teacher - Dr. Dana - who had studied directly under Dr. Charles Richter.
On September 12, 1970, a 5.2 earthquake -the Lytle Creek - struck in nearby San Bernardino and literally threw me out of bed that morning (at 7:31 am if you're wondering). At a nearby community college, the library was unscathed except for the geology section which was thrown to the floor in the quake. The following year, a 6.6 quake on the San Fernando fault in Sylmar did $500 million in damage and killed 65 people. Tectonic plate theory was fairly new stuff back then. I was definitely in the right place at the right time for studying seismology.
The map above shows the tectonic plates around Japan. The red lines are faults. ISTL is the Itoigawa-Shizuoka Tectonic Line, MTL is the Median Tectonic Line.
Earthquakes are a common occurrence in Japan - it's on same "ring of fire" as California, just the other side of the Pacific plate. Niigata itself was previously hit just two days after my arrival here in Ocotober of 2004, causing death and destruction that continued to affect the region for some time. Since Japan sits at the juncture of the Pacific, Philippine, and Okhotsk (or North American) tectonic plates, where the Pacific plate subsumes under the Eurasian plate, it offers front row seats for earthquake and volcanic activity. As for volcanoes, I lived on one in Hawaii which is a much more active area for that, so that's not new to me either.
Niigata and Kobe are located at either end of what is called the Niigata-Kobe Tectonic Zone. Kobe of course had a terrible temblor in 1995 which registered 7.2 and took 1,800 lives.
Surprisingly perhaps, the NKTZ is not the most active area. Most earthquakes here occur under the sea between the coastline and the Pacific plate starting just to our north - that's because it's where the Pacific plate goes under the Eurasia plate.
Luckily for us, Kashima City is located on an alluvial plane with, as you can see from the maps, few faults in the immediate area. We do feel quakes, but they usually just rattle things a bit.
I thought I might explain the Richter scale and other scales (there are lots) used around the world for comparing earthquakes, but this post is long enough already I think and don't want to risk it becoming a "bloggopotamus".
Some people wonder if living with typhoons and earthquakes and volcanoes is stressful. Well, since we're in a spot that doesn't take the brunt of any of those, I'm fine with it.
Now my mother grew up in Kansas which in my mind is spelled T-O-R-N-A-D-O, and I would much rather deal with volcanoes, typhoons and earthquakes, thank you very much! "Aunty Em, Aunty Em..."