You've probably heard about the earthquake in Hawaii today. I had some ideas for a blog post today, but they have been preempted. Big things happen early Sunday mornings in Hawaii. At least the earthquake didn't happen on December 7th.
A little after 7 am Hawaii time a magnitude 6.6 earthquake struck off the Kona coast of the big island of Hawaii. The word from emergency services was that no tsunami was generated. That turns out to have been incorrect, but the tsunami was only 4 inches high, so no big deal.
There was a lot of damage on the big island, but no serious injuries. Considerably less damage on the other islands, and again no serious injuries. But electricity was knocked out pretty much statewide for most of the day. So no blogging for most of the day.
No major damage on Oahu. The shaking lasted for almost a minute, but to the earthquake experienced it was obviously not close by. Enough to be really scarey for the earthquake-inexperienced. Having lived most of my life in California on or near the San Andreas and Hayward faults, I've been through enough to tell. It felt to me like about a 4.4-ish quake. I was a little concerned because I've never been through a quake in the building we're living in, but it's a wood-frame structure, and they're generally pretty good in quakes.
It shook for a while after the quake was over. A little disquieting but not unexpected. But the worst was no electricity, which meant no coffee and no computer. So no internet, no news, no blogging. We tuned the little hand-crank emergency radio to a working station for our news.
Your basic earthquake has two major shaking components: the p-wave and the s-wave. The p-wave travels faster, but looses strength more quickly. The s-wave travels more slowly and holds its strength longer. So if you're really close to the epicenter, they both arrive at about the same time. If you're further away, the p-wave gets there first, then the s-wave. Far enough away they arrive separately, and you can tell the difference. The p-wave is vertical: it lifts you up, then drops back down, sometimes sharply. The s-wave is the horizontal , with the shaking most people associate with an earthquake. Even further away, the p-wave is too weak to feel, and you only get the s-wave. That's what we had when the earthquake struck us.
So it was obviously not too close. A reassuring thought when the first aftershock hit a few minutes later. There was a reportedly a third aftershock soon after as well but we didn't feel it. Nor any of the other later aftershocks.
Now you know how to tell how close you are to an earthquake epicenter from the way the earthquake feels. And remember, if you are able to pay attention to those details, it's probably not a serious earthquake where you are (although it could be serious somewhere else).
There was no significant surf today, but it wasn't really a beach day anyway. Before and after the earthquake, it was overcast, rainy, windy at times, and just to add extra incentive to avoid the beach, a box jellyfish warning also in effect.