3.7 Quake on Washington Coast a Cause For Concern?

First off; NO...a 3.7 quake is NOT a big quake. However, we need to remember that these smaller quakes are most likely the only warning we are going to get before the 'big one' hits, so we need to pay attention to them. Yes, we get quakes here in Washington but not as many as you might think and very few in this size range. What concerns me a bit about this one is the size, the location, the depth and also a bunch of smaller 'micro' quakes taking place near it.

I will try to present my thoughts as clearly as possible. Please forgive me if I jump around a bit, there is always a lot rolling around in my head.

The quake:

Magnitude 3.7
Date-Time Sunday, July 24, 2011 at 12:19:28 UTC
Sunday, July 24, 2011 at 05:19:28 AM at epicenter
Time of Earthquake in other Time Zones

Location 47.708°N, 123.178°W
Depth 42.3 km (26.3 miles) set by location program
Region OLYMPIC PENINSULA, WASHINGTON
Distances 20 km (12 miles) WNW (284°) from Brinnon, WA
26 km (16 miles) WSW (238°) from Quilcene, WA
35 km (22 miles) W (268°) from Bangor Trident Base, WA
49 km (30 miles) SSE (156°) from Port Angeles, WA
64 km (40 miles) W (278°) from Seattle, WA

Location Uncertainty horizontal +/- 0.3 km (0.2 miles); depth fixed by location program
Parameters NST= 93, Nph= 95, Dmin=11 km, Rmss=0.26 sec, Gp= 22°,
M-type=duration magnitude (Md), Version=1
Source Pacific Northwest Seismograph Network

Event ID uw07241219


The other, smaller micro quakes. Please note what may be a micro swarm developing near Friday Harbor:


MAP 3.7 2011/07/24 12:19:28 47.708 -123.178 42.3 20 km ( 12 mi) WNW of Brinnon, WA
MAP 1.0 2011/07/24 12:07:13 46.763 -121.940 5.2 6 km ( 4 mi) E of Ashford, WA
MAP 1.4 2011/07/24 10:33:53 48.619 -123.040 15.1 9 km ( 6 mi) N of Friday Harbor, WA
MAP 1.6 2011/07/24 08:27:40 47.435 -121.819 20.4 6 km ( 4 mi) SW of Riverbend, WA
MAP 1.5 2011/07/24 07:37:39 48.604 -123.045 13.1 8 km ( 5 mi) N of Friday Harbor, WA
MAP 1.9 2011/07/24 07:15:13 48.612 -123.043 13.9 9 km ( 5 mi) N of Friday Harbor, WA
MAP 1.1 2011/07/24 04:47:18 48.615 -123.038 13.6 9 km ( 6 mi) N of Friday Harbor, WA
MAP 1.6 2011/07/24 03:04:41 48.227 -121.640 5.2 4 km ( 2 mi) SW of Darrington, WA
MAP 3.4 2011/07/23 08:03:40 47.645 -121.728 17.1 14 km ( 8 mi) E of Carnation, WA


The Source


So for those familiar with the area, my concern is probably obvious. For the larger group that is NOT familiar, let me give you a bit of a background lesson on the geology of this area.

The Coast of Washington State sits on top of a subduction zone, where the North American plate is moving over top of the Pacific Plate. This type of tectonics is what creates the mega quakes. Our last large quake (similar to the one that hit Japan earlier this year) was about 300 years ago. They (the scientists) say we are long over-due and the latest best-guess says it will happen whithin the next 20 years. This is nothing, geologically speaking. Me, living here I figure it can happen today, next week, next year or never. But I am as prepared as possible and pay attention. I want as much warning as possible.

Here are a couple of great maps showing these plates (courtesy USGS)











Now, looking at the above two maps, you need to look at where this 3.7 is and the other, smaller quakes (all occuring today)

Todays map



So we have a 3.7 quake (moderate size) right where the subduction zone is and at that depth, it's a bit more concerning. Add to it the micro quakes occuring nearby at a more shallow depth, may (and I stress may) indicate the stress and dynamics going on bellow. I am NOT a geologist. I am just an avid quake watcher. I have watched my area for nearly 15 years now so I know what is unusual.

While I do NOT think it time to raise any alarms....I can guarantee you there are a number of geologists right now scrutinizing this rash of quakes today and the ones of this past week. I always think it prudent to be on top of this, so this is a big heads up to any of my neighbors....and this inculdes those South of me in Oregon and California. Everything that happens along the subduction zone I believe involves you too. I won't get into that here, but I cover all my thoughts in my 'putting it all together' thread (see tag line). Simpy put: I don't think the subduction zone stops at Northern California, but extends all the way THROUGH California and down into mexico. SO...when I look at the dynamics here,I also look in those areas. A quick look HERE shows you there is a TON of action down where i think the other end of the zone is. Yin-yang.

Here are a few other quake watching site for this region for those who are interested:

REQ2 recent earthquakes (be sure to select the 'depth' option...paints a picture)

Cascade Tremor Activity


I will update if there are any new developments. Hopefully this was a nice release of energy and nothing more.

I don't get out of bed for anything less then a 5.0

C'mon man you know as well as anybody that this doesn't mean jack.

You trolling for flags or something today

reply to post by kro32


Yah kro, because I 'troll' for flags all the time. It's like my main goal here at ATS.

Did you read the thread (It is finished now, if you care to read it)

I realize that a 3.7 is NOT a big deal. I explain in the thread why I think we need to pay attention to it though and the other quakes occuring today and the past few days around it. Geology isn't about 'only getting excited about the big ones'. It is about looking at ALL the SMALL indicators, and then the smaller ones.

I have been watching these indicators for years. Yes, sometimes I get 'excited' about nothing. But at least I am paying attention. Most people are clueless. This one just got my attention. The location, depth, size and other things I talked about in the OP.

I am Not trolling or fear-mongering. I am doing what I feel ATS is about. Sharing my thoughts to network and learn from each other.

Well you never know I guess. I don't think anything will happen myself as flurries of small quakes are not proven to be reliable indicators of anything however I suppose it's reasonable to assume something could happen so doesn't hurt to keep an eye on it.

Good research on your thread though.

reply to post by westcoast


People can say that earthquakes of this size are insignificant, but, as I know you understand perfectly well, having earthquakes of this size alone is a different issue entirely. We know the earthquake was at the subterranean boundary between the two plates - around 40 km. We know that area is a megathrust zone. We also know that, as such, the area is capable of massive releases of energy.
This earthquake may seem small, and therefore insignificant, to some, but I believe that's the point. It's a quake large enough to indicate a build-up of energy, but it's not large enough to represent a full release of that energy. The swarm of smaller quakes also testify to this, meaning energy is being built-up and not released. Considering this, we could see the 3.7 as being a hint at a much greater build-up of energy within the megathrust zone.

Anyone who doesn't understand the potential significance of a "minor" 3.7 in a megathrust zone don't understand the concept of preshocks. These are the same people who would've disregarded the 7-range quakes that preceded the 9.0 off Japan.

It's certainly worth watching. And keep an eye on those dogs, as well

I live in Seattle and I really don't think there is much to be concerned about. Washington state has small earthquakes quite often.

Also....(for your information)......www.kirotv.com... ....and....

www.pnsn.org...



Hi...everyone....it just goes to show...that I should of read through all of the other posts...before I posted the above....(I am learning.....) I think maybe mother earth may be warning us.

Very good summary - I found the information
very helpful as i forget sometimes about certain
locations. Good work Westcoast - will be keeping
a sharp eye now on this location.

Believe me when I say Westcoast is definitely
not a troll!!

reply to post by CLPrime


Thank you for your comments, I think you said it better than I did in my OP.

As to the dogs....yes. Hard to explain to people and I don't want to say anything about it in the OP and make people discredit the info. My one dog has been driving me crazy this week. She has proven reliable when it comes to quakes. Her behavior has ben different though this week and with the two 3+ quakes near darrington, now this one and the micro quakes in Friday Harbor....it adds to my 'gut' feelings. Some people may not rely too much on that but for me...it's about instinct.

As to the comment that Washington gets small quakes every day; actually, we don't. We go through periods of not have ANY for weeks at a time. More often, we will have small micro quakes a few times a week, usually at Mount Rainier or Mount Saint Helens. Lately (last few months) we have some odd areas with micro quakes...whithin 30 miles or so of my home. These are the ones affecting my dog. These are new. I haven't been too concerned about them though since they are small and shallow. If anything, I would say these stem from a volcanic seismic zone for Glacier peak (just my theory). These quakes in the past 24 hrs though out on the peninsula and the sound...these are different. YES..we get micro quakes out in the area, but not a lot of them. We certainlt don't get 3+ quakes every day. We get them....but only occasionally and not normally out on the peninsula at that depth. That is what CLPrime is saying. It is not just about the size.

reply to post by westcoast


Hi..thank you for your post....live and learn! My cat has been acting (out of the norm) for about a week now...and I am wondering...is he warning me?

reply to post by caladonea


I meant to thank you for those links! I use the PNSN one daily. Some great stuff in there if you know where to look...the other two links I provided stem from there.

About the cats: hard to say! I think anything is possible though and animals certainly sense stuff we don't. I don't know if we can say it's been scientifically proven that animals sense quakes, but there is definately enough info out there and with my own personal experience, I am a believer!


FYI...USGS has changed the info on the quake a couple of times now. Down to a 3.4 but now back up to a 3.7 and listed as the olympic peninsula instead of just Washington. Also of note; I think it telling there are listing those micro quakes in Friday Harbor so fast. It's a sunday. Usually, it takes until Monday afternoon for them to go through the info and back-fill it. Someone is working over-time this weekend.

Good points Westcoast! Def another area to keep an eye. Thanks for your time putting this together

reply to post by westcoast


all us locals know about the big one about to come.

i just want to know,
what kind of tsunami would the puget sound have and what would it do?

The Cascadia plate as it is often referred to is probably one of the least understood fault boundries. Scientists have calculated a 37% chance that it will rupture within the next 50 years. Magnitude? Cannot say. But magnitude is only part of it.

Magnitude
Period
Distance Ruptured
Geology

These all add up to make an earthquake deadly. Here's hoping it doesn't rupture until the world economy is alot happier so to speak as it could cripple the us and asia.

Stay safe all

Do you also look at the upper part of the plate, in Canada? I was just wondering, or is that a different section of the plate? Asking because I am not really sure.

Either they do not update this on weekends, or it is extremely quiet in B.C.

Link

Thank you for the update, I had not noticed these new quakes.
Oh and westcoast does not troll for flags and stars, anyone saying that should take the time to read some of westcoast's other threads before making that kind of assumption.

reply to post by PacificBlue


In general, I think the 'officiall' Northern end of the Cascadian Subduction zone is near Vancouver Island. But I think there is a strong argument for it going further. I haven't ever really given an opinion though, because I simply haven't looked into the history, geology and tectonics at play there close enough.

I was actually surprised earlier this year when someone here at ATS introduced me to the link you just provided. I had no idea that area was so active and felt pretty stupid. I had assumed (big mistake) that the USGS and PNSN monitored the Vancouver Island region also, since it is clearly included in the cascadian subduction zone region. However....it is not. The only quakes showing up on the USGS list are those over 3.5 mag. Quite surprising. Interesting to note, that the cascade tremor array DOES extend up there...and that is where a lot of the action is. I think it important to keep this region in mind when looking at the subduction zone, thank you for the reminder. I have no idea as to whether it is updated over the weekend, so all I can really say is that there haven't been any over 3.5 there.

No further quakes listed today so far, but I have GEE up with several stations around the area and there seems to be a constant 'background' rumble or micro quakes.

There has been notable increase of 5 and 6+ mag. quakes over the last week all around the pacific plate. All except the US west coast

Definately some more activity near Friday Harbor right now on GEE (even through all the P waves from the two 6.2's elsewhere). I'll take a screen-shot and upload it in a few. Looks like a series of micro quakes.

ETA: Here is the screen shot. And I take that back....looks like it might be bigger than a micro quake. Perhaps around a 2 mag

Thats normal dude. happens all the time over there.

Seriously guys, if you are gonna report a quake in an area, dont look it up on the internet, but BE THERE, live there, so you would know how normal it is. There are TONS of places in the world where quakes happen several times a weak, they got used to it 200 years ago. They still live there cause the weather is great.

No use reporting all those small ones, basically stick to 7+, or preferably 8+

Originally posted by NeoVain
Thats normal dude. happens all the time over there.

Seriously guys, if you are gonna report a quake in an area, dont look it up on the internet, but BE THERE, live there, so you would know how normal it is. There are TONS of places in the world where quakes happen several times a weak, they got used to it 200 years ago. They still live there cause the weather is great.

No use reporting all those small ones, basically stick to 7+, or preferably 8+

Try READING the OP and the thread! She DOES live there!

I love how newbies come into threads and spout off like they know everything. "Deny Ignorance" is the motto of ATS. But feel free to continue living the "ignorance is bliss" lifestyle. Obviously judging a thread based on it's title and not actually paying attention to it, is what you did.