Why Japan Mega-Quake Causes So Many Aftershocks – And How Long Aftershocks May Continue

You’re looking at my bsussman@koin.com inbox from Saturday night March 12, 2011.

Take a close look.

Except for one email from American Express and another from www.koinlocal6.com — it’s all from the USGS. That is, the scientists who track quakes around the world.

Each USGS email is letting me know about an aftershock 4.5 or bigger off the coast of Japan.

72 Hours After Japan 9.0 Quake – Aftershock Breakdown – See Updated Totals 

I did a quick search to count how many aftershocks we’re talking about after one of the world’s most powerful quakes and here’s what I’ve come up with:

• more than 225 aftershocks, magnitude 4.5 or larger
• the largest was magnitude 7.1 (as of this writing)
• 23 of these aftershocks were magnitude 6.0 or greater
• Updated: find the number of aftershocks as of the Japan quake’s 1 month anniversary

Why Big Quakes Create So Many Aftershocks – In Human Terms
Have you ever lost a job? A person you loved and relied on? Or a pet that was your constant companion? It’s a shock, isn’t it. It takes a long time to adjust to your ‘new normal’ without them. Eventually you’re doing pretty well but then something reminds you of what you lost and it jolts you all over again although usually this is not as bad as the initial loss you experienced. That’s the human analogy for a mega-quake and the resulting aftershocks.

Why Big Quakes Create So Many Aftershocks – In Scientific Terms
The other night on the news I answered this question on the news: How big was the rupture in the earth from the Japan mega-quake of 2011?

In northwest terms,  it’s about Eugene, Oregon to Kelso, Washington–150 miles long.  The width of this rupture is about Tillamook, Oregon to Portland–about 60 miles wide.That’s a lot of earth releasing unbelievable pressure and energy and leaving behind a brand new shape at the fault under the Pacific Ocean. Now, bit by bit, the subduction zone where this happened must adjust to the ‘new normal’ shape and pressures left by the quake. Each aftershock is an attempt at settling in and settling down.

So, the overall trend will be for the majority of these quakes to get smaller and fewer in number. Although aftershocks will likely continue for a year, at least–most will not be felt on land. And of those that are, many will not do additional damage.

But there will be exceptions to the trend and that’s what worries me for the people of Japan. After the Sumatran quake of 2007 the aftershocks got smaller and smaller as is typically the case. Then came a 7.7 magnitude aftershock–3 years later. It lead to more death and destruction.

One Final Thought On The Japan Mega-quake and Tsunami

We all were shocked at the video of the tsunami and quake when it happened. But for the first couple of days the death toll hovered around 1,000. I even had some people tell me they were surprised it wasn’t worse. Well, it is worse. Much worse than most of us can imagine.

As searchers get to areas totally cut off from communication and as they dig through apartment buildings in rubble and clean up tsunami debris, the death toll will skyrocket. And we’re going to see the full scope of how tragic this event has been. This is what played out in Indonesia after the great Sumatran quake. It’s what played out in New Orleans after Hurricane Katrina. We knew it was bad–but had no idea how bad–until days after the event.

If you’re a praying person, please join me in saying a prayer for strength for the people of Japan. They’re going to need lots of that.