An Experiment in Alternative Methods of Earthquake Prediction

reply to post by caitlinfae

As I was away for a few days I've had to catch up.

It seems that several members are getting antsy/nervous at around the same time and when this has happened in the past it has sometimes indicated something major in the offing. (Anyone who wants to dig back through this thread will find that this has tended to be the case.)

So, although your post focuses on the PNW, and today we are seeing a significant swarm of quakes in SoCal, it's worth considering what this may all mean.

I doubt that anyone has ever established causative links between PNW quake events and those in SoCal -- and perhaps there aren't any -- but all the same we can wonder.

Mike

reply to post by rbkruspe

I appreciate your comments as I'm sure we all do; I think it's also interesting that although you've not made or claimed a specific prediction, in the greater scheme of things the quake swarm in SoCal (which has really picked up in just the past few hours) is significant and could tie in with what you have sensed (or intuited, if we prefer that term).

Mike

reply to post by rbkruspe

It happened, all right... And maybe it wasn't just the SoCal swarm:

Magnitude 7.3 - OFFSHORE EL SALVADOR

2012 August 27 04:37:20 UTC

Details
Summary
Maps
Scientific & Technical
Tsunami

Earthquake Details

This event has been reviewed by a seismologist.

Magnitude 7.3
Date-Time

Monday, August 27, 2012 at 04:37:20 UTC
Sunday, August 26, 2012 at 10:37:20 PM at epicenter
Time of Earthquake in other Time Zones

Location 12.278°N, 88.528°W
Depth 20.3 km (12.6 miles)
Region OFFSHORE EL SALVADOR
Distances 111 km (68 miles) S of Puerto El Triunfo, El Salvador
118 km (73 miles) S of Usulutan, El Salvador
123 km (76 miles) S of San Rafael Oriente, El Salvador
133 km (82 miles) S of Santiago de Maria, El Salvador
Location Uncertainty horizontal +/- 16.1 km (10.0 miles); depth +/- 4.2 km (2.6 miles)
Parameters NST=345, Nph=345, Dmin=130.2 km, Rmss=1.21 sec, Gp= 65°,
M-type=(unknown type), Version=D
Source

Magnitude: USGS NEIC (WDCS-D)
Location: USGS NEIC (WDCS-D)

Event ID usc000c7yw

Source: USGS

This is especially significant because of its location relative to the SoCal swarm:


(Map source at this USGS page Note that this page is regularly updated and the above-shown quakes will "drop off" within seven days.)

There could be a causative link between the SoCal events and the El Salvador quake, as they are situated along one of the same, greater fault lines in the region. In fact it seems likely, purely on the grounds that the SoCal swarm was very intense in the hours just prior to the El Sal event but has now quietened down.

Last night I surmised on the QuakeWatch thread here that the SoCal events might cause activity further N to NW, but neglected to state that it could also happen further S to SE.

Naturally it could, but I overlooked it as my focus was on the SoCal region. My error.

It now just remains to be seen if this is all, but that El Salvador quake was very strong and also quite shallow, so I'm fearful for the effects it might have had on nearby towns.

But in summary and just for future reference, I want it on record that the concerns being strongly voiced by rbkruspe and others in the past few days seem to have been justified.

By the way, rbkruspe, could you just remind me of roughly where you are? Don't need to be specific but a general region would help.

Mike

Originally posted by MamaJ
reply to post by JustMike

 

Good morning Mike! I'm just getting done with my first cup of coffee and it seems as if Cali is still ok, never the less still a lot of activity over there including the off shore big one.

Earthquake Report is reporting the off shore quake was coming in so conflicted, even with tsunami info because the quake happened on the oceanic plate and not the North American plate.

Do you mind explaining this in detail for me.

Hi Jenn,

looking at the reports on the Earthquake-Report website here, I can follow what they're talking about in terms of "confusion".

It seems that there was some delay in reports coming in from the near-regional networks and this puzzled the E-R people because at the strength they were noting from sites like USGS, it seemed amazing that local people didn't feel it and log on in large numbers to get more info.

The reason they allegedly didn't feel it (much) was because the quake was supposedly not on the plate that part of the Sth American land mass sits on, but rather:

...the hypocenter of the earthquake was located in the oceanic plate and not in the North American plate. This event was in other words an intra-plate event and not a subduction earthquake like most of the earthquakes are in the area.

If the quake did in fact occur intra-plate on the oceanic plate (ie away from an edge of it), then its effects on people on land (and on another plate) would be far less than if it were on a subduction zone boundary -- meaning on or near the edges between two colliding plates where one edge is pushing down under the other.

So, their explanation makes sense. However, they later posted another update:

USGS has located the epicenter of all events in the subduction zone below the continental plate while snet was putting it more into the ocean.

(Both of the above quotes from Earthquake-Report.com at the link given above.)
The current map from USGS shows that they do, indeed, have the quake located on the "land" plate and in the subduction zone:

Source: USGS at this link (Note that this map will change over time.)

Problem: if the USGS has the quake in the right place -- namely on a subduction zone boundary and on the same plate as the nearest land is on -- then why didn't many people feel it at all?

I suspect that the E-R people were right: it's possible the quake was not so close to a subduction zone boundary and was perhaps further west of where USGS has it. If this is the case it would explain the very limited effects on the nearby regions. And yes, even USGS can get things slightly wrong. No-one's infallible in the seismic sciences, after all.

Also, do you think it's possible this is volcanic related, I know we were throwing the idea around yesterday and TA made a thread, but it seems likely to me even more this morning. It's just soooo active and California is basically a huge volcanic state, is it not?? Advise me please. Lol

Thanks!

Jenn

Volcanic related? Jenn, I have no idea, really. I've mentioned that there could be volcanic influences in some quakes which otherwise seem "normally" tectonic, but without detailed analyses of seismo traces (wave forms) we're in the dark on this score.

As for Cali, yes, it's volcanic and besides the ongoing hot springs and so forth, there's the Long Valley Caldera and other evidence of much greater volcanism in the past.

Considering the theory that the Pacific plate is colliding with the Nth America plate all along the western side of the continent, and also that this action is believed to have partly formed the Cascades and its volcanoes (but not Long Valley), then major movement of the Pacific plate (and related subduction) could lead to volcanic activity. That's not my opinion, just what I've gleaned from reading reports from those who study these things.

However that doesn't mean that anything cataclysmic is imminent. These changes have been going on for millions of years and what we've observed "live" is not even an eyeblink. Geological records suggest that things have not fizzled out completely yet, though.

Best regards and sorry for the lonng reply!

Mike

reply to post by Doodle19815

I sincerely hope and pray that the New Madrid Seismic Zone (NMSZ) stays nice and quiet and if it can do that for a good few decades at least then that would be a blessing.

If we consider how poorly prepared people in California really are (eg only about 20% have quake insurance), and that the people in the PNW are even less prepared -- in spite of the fact that sooner or later they're going to have another quake on a scale like Japan's big one last year -- they are still way ahead of most people and govt authorities in the NMSZ region.

While the next "big one" in Cali is going to be very bad and a megathrust event in the PNW could (potentially) be even worse, I shudder to think what will happen if the NMSZ experiences an event around magnitude 8 like they did 200 years ago. I expect very few people there have more than the vaguest notion that it's even possible, let alone have read the reports from FEMA about the potential effects.

If wishes can make it so, then I wish a thousand times that the NMSZ stays quiet. The alternative is just too horrible to fully contemplate.

Mike