Thread: Disaster preparedness - annual vs episodic

For the Pacific Northwest, the greatest threat to public safety is known as "the big one", a megathrust earthquake which occurs about every 500 years. Though historically we had no idea when earthquakes might strike, recent studies of the fault reveal the quake to operate like bad clockwork, so it's somewhat predictable. The "sticky" subduction produces a sort of ratcheting effect called Episodic Tremor and Slip. The episodes last about two weeks, but most importantly they're consistently spaced 14 months apart. Thus we can confidently predict windows of risk. Additionally, ETS amplitude is modulated by tides, which, being predictable as the lunar cycle, means we can foresee far into the future which episodes will coincide with tidal forces (including ocean load) for more or less risk of fault failure (the big one).

Practically, one may circle some days on a 2014 calendar for ETS, draw a possibly overlapping circle for spring tide, and decide if that's really such a good time to host a big international event.

Present awareness of ETS and its implications is practically zero both in the general public and agencies responsible for disaster preparation and response. I think this fosters complacency and poor planning because "an earthquake can strike at any time" and we're looking at an earthquake that's unlikely to strike in our own lifetimes.

Emergency Preparedness Week

May 4 to 10, 2014

Emergency Preparedness Week (EP Week) is an annual event that takes place each year during the first full week of May. This national event is coordinated by Public Safety Canada, in close collaboration with the provinces and territories and partners.

Wouldn't it make better sense to hand out free survival kits, conduct drills, etc. the week before disaster is more likely? I understand that making such a local change is really my responsibility, so no good whining across the internet about it. I can't expect cooperation from the folks in Ottawa on this one either. Better I should persuade provincial officials to adopt an inconvenient schedule tailored to the inconvenience of our approaching earthquake.

Is ETS recent discovery?

Never heard of it, I live here and have even spoken with Dr. Atwater a couple times on the banks of the Copalis river some years ago when he was putting together how the last big event happened.

Can you post a link?

I would be interested in a link to the citations also, as this is pretty odd sounding. Yes the slip/trust quakes are episodic, but the two week gap and spring tide assertions need sourcing.

For the basic scoop, see the graph on this page .

More at Episodic tremor and slip - Wikipedia, the free encyclopedia , then click any of 23 references if you're curious.

Correlation with tides: Modulation of Tremor Amplitudes by Tidal Stresses . This one makes me hunger for more, because no clarification is made between land tides and ocean tides (i.e. the pull on mantle vs. the pull on water), and though a 1.5 hr lag is noted, there's no attempt to relate this to the well-known lag of sea height as it follows gravity. I'm guessing we will soon work out the opposing vertical stresses on plates by sea weight and mantle lift caused by tide, and have a model that helps predict subduction tremors all around the ring of fire.

So your trying to correlate several different things for your assertion?

I'm not proposing an hypothesis. I'm proposing that preparations for earthquake be scheduled around predictable tremor/slip events, not arbitrarily because "it can happen any time".

Thanks for the info.

Is there a good relationship between ETS and major subduction quakes other places?

The 0.2 anti-correlation between tidal stress and ETS events is not really very predictive. I'm sure enough to change major planning events to improve people's public awareness of disaster preparedness.

I'm not proposing an hypothesis. I'm proposing that preparations for earthquake be scheduled around predictable tremor/slip events, not arbitrarily because "it can happen any time".

Personally speaking, I tend to favour regular, predictable disaster preparation and warnings. People seem to respond best when they know this stuff as a routine.

Fire safety drills are best held reasonably often and - usually - scheduled, so that people learn to behave in a controlled and appropriate way if ever they need to.

Same thing here for bushfire safety. The country fire units go around during spring and early summer reminding people to clear their gutters and update their fire safety plans. The television ads for updating fire safety plans should start soon here. (A bit late for NSW this year, but hey ho.)

Nowadays they're also advising some people that there is no way a fire truck or crew will ever be endangered to fight a bushfire affecting their house - whether it's their horrible access road or some other feature of the terrain, it's too risky. They'll also advise whether the house/ property is un/suitable for a stay and fight strategy or get outta here first thing in the morning strategy on high fire danger days.

Originally Posted by adelady

I tend to favour regular, predictable disaster preparation and warnings. People seem to respond best when they know this stuff as a routine.

here for bushfire safety. The country fire units go around during spring and early summer reminding people...

That's my point. Wisely, Australians time preparations in anticipation of the risk window. Scheduling bushfire awareness campaigns for after bushfire season would be stupid.

Meanwhile in BC we have these regular, predictable earthquake risk windows, as regular as Australian fire seasons; and officials stepping up often after to remind us of an earthquake risk that just passed. That's known as comic timing.

PNW is pretty good at planning for a lot of long term contingencies actually, and if you look between the lines in a lot of policies you'll see it. But the Big One can only be addressed through 2 things: building codes and personal emergency preparedness kits. Progress has happened on building codes with new buildings, but Seattle still allows a lot of old buildings that will cause a lot of death when it happens. Ready.gov has been good at advocating the needed emergency kits, but in my opinion some striking, doom oriented TV ads to bring people to their site to make a plan would be tax dollars well spent. We all should have the kits needed to survive a week with everything shut down.