Accomodating Recent Increase in Earthquakes 1

[EngineerofSteel]

How are you accounting for the global increase in seismic activity?

Earthquakes have increased. Has anyone modified their design procedures to account for the increased probability of seismic events?

I am being extra cautious in considering building design, and especially connections. I've been reading and improving my design process.

I've been looking at buildings that failed.

What are others doing?

 

[msquared48]

Constantly updating my disaster pack.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[EngineerofSteel]

Mike,

By disaster pack, do you mean copies of ATC-20 and other evaluation materials?

What is your disaster pack?

 

[msquared48]

I am ATC-20 trained and prepared, but, no, I mean my personal and family disaster plans and survival supplies.

Living where I do, it's just a matter of time before we will be seeing what a lot of other locations in the world already have.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[bridgebuster]

In the northeast, DoT's have been requiring ince the mid-90s that we design for seismic. The NYC Building Code adopted seismic requirements around 1990.

I don't necessarily agree with an "increased probability of seismic events"; does anyone really know why EQs happen? I'm being philosophical not technical.

 

[bimr]

Please provide your source of information on the "global increase in seismic activity"?

 

[EngineerofSteel]

Well, here is an article from USGS saying there is NO increase:

http://www.washingtonpost.com/wp-dyn/content/discussion/2010/03/08/DI2010030802570.html

The measuring of earthquakes has changed. Prior to the 70's, the Richter scale was used. Today, the "moment magnitude" scale is used. (Excuse the wikipedia link... its a good summary)

http://en.wikipedia.org/wiki/Moment_magnitude_scale

Here is Time's list of the top 10 quakes of all times. Printed in 2010, it omits the Honshu quake. Add that in, and 4 of the top 10 are in the last decade:

http://www.time.com/time/specials/packages/completelist/0,29569,1953425,00.html

Ah. Here is the winner: USGS compiled quake totals worldwide. The increase is obvious:

http://earthquake.usgs.gov/earthquakes/eqarchives/year/eqstats.php

The table at the above link is best. All the measurements are on the same Mw scale.

 

[cvg]

there is no significant increase in earthquakes (only in deaths) shown in the USGS table. In fact according to this table, it appears there may be a worldwide decreasing trend. 2010 appears to be a bad year for the US, however it appears that 2011 is on track to be at or below average. I am not convinced that 10 years of data is sufficient for valid statistical analysis regardless of what Time Magazine says.

 

[msquared48]

Somehow, with all the recent activity on the Pacific rim of fire, I highly doubt that there is has not been an increase. I have never seen such activity, particularly with the larger quakes.

Just don't buy the no increase scenario...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[cvg]

don't take my word for it, USGS is more credible (unless you believe in conspiracy theories, than they must be covering something up...)

http://earthquake.usgs.gov/learn/topics/increase_in_earthquakes.php

 

[msquared48]

I am not a conspiracy theorist, but I do keep my eyes open.

My guts, and I do trust them, tell me the number and magnitudes are increasing, and I'll just leave it at that.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[hokie66]

As well as having the ability to detect more earthquakes, we receive much more information about them from the media. I put it in the same category as climate change...runs in cycles.

 

[rconner]

I guess it won’t be long before it will be claimed that Man is somehow causing said increase, if there is one, and that with adequate/necessary funding (of course ultimately with increased rates, taxes, fees, or regulations yaddah yaddah yaddah) some study or theoretical mitigations/remediations to react to all this can be done by our omniscient powers-at-be.

A read and look at the pictures etc. in the thread

http://cr4.globalspec.com/blogentry...-Engineering-and-the-Illusion-of-Total-Safety

may however be worthwhile(if you have not seen). While it is true of course that smart and persuasive Engineers and politicians are capable of great things, I fear sometimes however that we may sometimes overestimate our own knowledge, capabilities/Power and influence. I particularly like the quote of xanasax in this referenced thread,

“If man made it, then God can tear it down"

[Everyone have a good weekend, and msquared48, you may want to pack a slide rule like I have in my little disaster kit, as you may find they run a little better than electronic calculators and computers when there is no power!]

 

[Qshake]

I agree with Hokie66, this is a natural phenonmenom that will run in cycles.

Regards,
Qshake

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