Hi everyone,
I haven't posted lately because of the need to deal with various issues IRL here -- flu, then work! (So, nothing drastic.) Also, because I couldn't
perceive anything much happening quake-wise. However, now I feel we might have something major coming up. Problem is, I can't figure where. Not even
any firm regional indicators.
There are the usual suspects, like the west coastal Sth American region, Indonesia and the nearby island groups in that part of the Ring of Fire and
of course the Kamchatkas, all of which have had quakes in the mag 8-plus range in the not-too-distant past, but I think we might need to look for
possible indicators in other places.
The following regions I'm about to mention are not for prediction. As noted above, I can't pin this down. They're just observations:
Turkey: had a couple of very bad quakes in the last few years, the worst being the one in Van in 2011. However, Istanbul itself has gone a good while
without anything major and the faults there are capable of producing very powerful events, including regional tsunamis.
Southern Italy, beneath the Mediterranean Sea: there is a significant fault line there and the last very big quake it generated is commonly known as
the 1908 Messina earthquake. Its estimated mag 7.1 (Mw) event caused major destruction in the nearby regions and also triggered a tsunami that came
ashore up to almost 40 ft high in places. (Yes, nearly 40 feet. About 12 metres.) This event was considered to be the deadliest single-day natural
disaster in European history.
Pacific NW, USA into BC, Canada: nearly everyone reading this knows about this one. The Cascadia Subduction Zone (CSZ) running along the coast there
is capable of producing a quake far more powerful than the San Andreas one that destroyed San Francisco in 1906. Many people expect "the big one" will
be the next California quake, and they may well be right -- but sooner or later the CSZ will let go again. You'd be hard pushed to find any expert
study that denies this.
However, with luck the CSZ will wait a good while yet but geologically, it is "in the zone" for another major movement -- meaning that allowing for
the variations in time between big events, another one could happen any time. The problem is that according to the geological evidence, especially
from deposits left by the previous huge quakes' tsunamis (called "turbidites"), the times between events have varied a great deal, from maybe a
century or so up to around 1,000 years. So, when geologists say the next event is "imminent" (and some use exactly that term), they do
not mean
it's going to happen any day now. They mean that based upon the regional seismic history, it
could.
And, as I've said several times in this thread already, regional preparedness for the eventual (likely) PNW mag 9.0-plus and its accompanying
tsunami(s) is nowhere near as good as it could be or should be. Nothing approaching the broad-based Japanese model of quake and tsunami awareness and
defenses has been implemented; it is undeniable that their huge anti-tsunami walls alone helped to save lives. Yes, many of those 30-foot-plus walls
got overtopped and destroyed, but they gave many people time to escape and survive.
Japan: so, let's look at this nation. Japan has numerous significant earthquake regions, mostly along its eastern coast. The Tōhoku quake in March
2011 was something of a surprise for many experts as they were expecting the next major event further south, with the Tōkai region (closer to Tokyo)
high on the list of likely places. Large Tōkai region quakes (mag 8 Mw or bigger) occur roughly every 100 to 150 years and the last one there of that
scale was in 1854. Prior to that, they were recorded in 1707 (147 years prior), 1605 (102 years prior) and 1498 (107 years earlier). It's now been 159
years since the 1854 event.
Purely on the basis of those intervals we can see why many experts have serious concerns about the Tōkai region. However, trying to predict these
events is never that simple. We can look back at the previous four Tōkai events over more than half a millennium, but we are only really observing a
virtual eyeblink of time from the planet's perspective. So, even if it is another few decades or so before the next Tōkai event, it still won't
affect the long-term average very much. But just like Cascadia, the Tōkai region is now "in the zone".
I'd really appreciate it if anyone wishes to voice their own concerns or observations. We're not in the "doom and gloom" business -- there are plenty
of threads for that -- I simply see part of our task as keeping tabs on what might be in the offing. The more we know about the very fundamental
realities of what is and isn't likely, the better.
So I'll leave it with you and look forward to whatever you might want to add.
edit on 30/11/13 by JustMike because: (no reason given)