Showing posts with label Seismic Stuff. Show all posts
Showing posts with label Seismic Stuff. Show all posts

Wednesday, 11 May 2011

Romequake! (Not)


Just took this screengrab of the area surrounding Rome following the scare story that the current alignment of planets (Meaningless apart from it being nice to see a tidy solar system) might cause a large earthquake near Rome. Well, according to all the online resources, no earthquake. So those who left the city and headed for the hills may have been a tad ill advised. Although heading for the hills might have been a teensy error of judgement, considering where the last largish quake occurred. My annotation.

Hi ho, gotta go. Duty calls.

Saturday, 12 March 2011

Christchurch NZ subsidence

One of the things I've been thinking about regarding the recent February 22nd Earthquake in Christchurch, New Zealand, is if there was any collapse of an old magma chamber, surely there should be associated subsidence.

During the quake, according to the satellite image embedded in this article, the ground literally bounced half a metre. The soil underneath parts of the city briefly turned into a virtual liquid, leading to reported subsidence in the area of up to 300mm (1ft). This phenomena is not uncommon during large earthquakes.

Now having looked at the Quake distribution since the first 7.3 and the discovery (Reactivation?) of the Greendale Fault, my thought is that this fault is extending, and that the next 'big one' will occur either off shore or further towards the mountains as part of a more active fault system. Note the depth of the fault on the snagged graphic from the Christchurch Earthquake map site (You have to run the full sequence from Sept 4th). Most of the dots indicate a consistent fault depth of around 5-7.5 km, with a bias pointing towards the end of the Hikurangi trough subduction zone. See this page from the University of Canterbury Geology department.

Geologists of the British Geological Survey discuss the Christchurch Quake distribution in the video below.

Hmm.

Just as an aside; we've been having a lot of Solar flare activity over the past few months. Which allowing for a certain latency in any possible internal heating process, starts to look like there is a degree of real life correlation in the hypothesis. I think there may well be more large seismic events / Volcanic Eruptions to come in the next few months, globally speaking. As we keep on being told, we're in for a 'big one' over here in Southwestern BC, it may be a good idea to keep the old disaster kit on standby. It won't hurt if I'm wrong. Although we've been getting a steady trickle of small seismic shocks which relieve some of the stress building up down below. It could continue like this for another century. On the other hand......

Friday, 11 March 2011

West Coast BC Tsunami watch

In the wake of the big Japanese Earthquake. Environment Canada has issued the following Tsunami warning for the Western BC coast (Their caps);
A LARGE EARTHQUAKE HAS OCCURRED IN THE PACIFIC BASIN NEAR JAPAN. THE WEST COAST ALASKA TSUNAMI WARNING CENTRE HAS RAISED THE ALERT STATUS TO ADVISORY FOR THE FOLLOWING ZONES OF COASTAL BRITISH COLUMBIA:

ZONE A - THE NORTH COAST AND THE HAIDA GWAII ISLANDS

ZONE B - THE CENTRAL COAST INCLUDING BELLA BELLA, BELLA COOLA AND SHEARWATER

ZONE C - THE OUTER WEST COAST OF VANCOUVER ISLAND FROM CAPE SCOTT TO PORT RENFREW

AT THIS TIME IT IS BELIEVED THAT A LOW LEVEL TSUNAMI HAS BEEN GENERATED THAT COULD IMPACT MARINAS AND OTHER COASTAL INFRASTRUCTURE OR CREATE STRONG CURRENTS IN HARBOURS AND ISOLATED COASTAL AREAS. LOCAL GOVERNMENTS IN THESE ZONES HAVE BEEN ADVISED TO ACTIVATE THEIR EMERGENCY PLANS AND TO IMMEDIATELY EVACUATE MARINAS, BEACHES AND OTHER AREAS THAT ARE BELOW THE NORMAL HIGH TIDE MARK.
Here on the Eastern shore of Vancouver Island we shouldn't notice anything, rather like the last Tsunami alert. The people who should pay close attention to the bulletins are those around Port Alberni, Tofino, Uclulet, and Port Renfrew. I can hear those surfboards being waxed from here.

Did go looking for Japanese webcams on the big Japanese quake last night, but the only one I could find was an out of focus view of someone's office wall in the Miyagi district.

Update: Tsunamis of 5-6 ft (1.5-1.8m) high have been reported at the Alaskan end of the Aleutian Islands and at Crescent City, California. Nothing reported from the west coast of Vancouver Island at the time of writing. For Canadian citizens in Japan, there is help available via this site.

Update: As of March 11th at 20:00, the West Coast Tsunami advisory is cancelled.

Sunday, 6 March 2011

Christchurch NZ since 22nd February 2011

Just ran the sequence of quakes since 22nd February and watched the following pattern emerging. Whilst the number of quakes has tailed off, aftershocks are still coming in at 3-4 magnitude, many at between the 5 and 8km depth level. At this point I'm wondering whether the current tremors indicate the formation of a new extension to the Greendale fault.

Webcams are still down in the centre of Christchurch, although most of the local traffic cams seem to be operative.

I'm still waiting for some moron highly qualified non-scientist / government adviser to blame the Christchurch quakes on 'Man made global warming'. Just so I can play 'spot the looney', and I'm not talking about the Canadian one Dollar coin.

Sunday, 27 February 2011

Christchurch webcams

In case anyone wants to see what's happening in Lyttleton Harbour and Christchurch, there are available webcams. A couple in the town are out of action, but others are still up and running.

Lyttleton Harbour here.

Christchurch here. Although it looks like a bunch of stills have been put in as a placeholder while the main cameras are down. They do show the damage done by the shocks though.

Traffic cam links around Christchurch here.

Donation link to help the Kiwis is on the sidebar at the top.

Krisuvik swarm: count 356....er 425

In the screengrab, which is representative rather than definitive, as I couldn't be sure I was getting the whole lot on. The tremor count at the time of observation was 356 at 13:25 GMT in the last 48 hours. That is a hell of a busy weekend. I make it over 228 since midnight, local time and rapidly increasing. For preliminary data, that's going to keep someone busy.

Range of tremors is mostly 2+km depth on the third day of near continual swarm activity. No idea what this portends, apart from I'd still like some idea of what the water levels of Kleiforvatn are doing. It's still jaw meets desk territory.

More later today. This bears watching.

All data from Icelandic Met Office Earthquakes page.

Update: My goof. Count is 356, not 367. Revised.

Update: As of 15:00GMT 394 Tremors. That's a whole lot of shaking.

Added to top of sidebar: Christchurch Earthquake Appeal. Thanks to Small Dead Animals for highlighting the link.

Update: 425. Also peaking and shallowing. See data grab below.
Sunday
27.02.2011 17:27:36 63.928 -22.034 1.1 km 4.1 90.07 4.8 km NNE of Krýsuvík
Sunday
27.02.2011 17:25:21 63.920 -22.030 1.6 km 3.4 90.07 4.0 km NNE of Krýsuvík

Will be very surprised if something doesn't blow in the next 24-48 hours at this rate.

Update: 514 tremors in the Reykjanes peninsula area in the last 48 hours as of 22:25 GMT. Most close to Krisuvik.

Saturday, 26 February 2011

Christchurch again

Just been reviewing data nabbed from the Christchurch Quake site. Seems to me that as the most recent activity is easing, returning gradually towards pre big hit levels. Magnitudes are mostly between 2-3, and some of it is going deeper. Way deeper. From around the 2-9km depth mark on Tuesday (The biggest quakes epicentres were about 5km down), to as deep as 38km at 04:45 (NZ time) 26/2/2011. Almost all in that narrow band just south of town. Wonder what's going on down there?

Hmm. My logic tells me there's nothing to worry about as the worst is past. My instinct is telling me not to take any holidays in Christchurch NZ for the next week or so.

I'm sure a proper volcanologist will tell me I'm being a bit paranoid. Yet having looked at this University of Arizona website, the Christchurch area was 'aseismic' from 1990-99. The Te Ara site tells a similar (but not quite) story. As always, the problem is insufficient information.

New link for British Columbia tremors

Via Environment Canada, this link contains details of earth tremors in South Western BC. Added to Volcano links on the sidebar.

If anyone is interested there was a 4.3 magnitude 300km WNW of WhiteHorse in the Yukon at 3:08 PST this morning, but there have been no reports that anyone 'felt' it.

Friday, 25 February 2011

When is an eruption overdue?


A theme picked up from this post on Erik Klemetti's 'Eruptions' blog.

We keep on hearing in the media that this or that volcano is overdue, and that consequently "We're all doomed!". Yellowstone is 'overdue', Mt Baker, Mt Rainier, and just about every currently quiet volcano on the planet is 'overdue'.

The problem is that we still don't seem to understand more than the basics of what makes a volcano go 'foom!' We understand the what, but as to the underlying when and where, we're pretty much adrift, making half educated guesses. We are told that we're 'overdue' for a 'big one' (Earthquake) in this area, but the problem is that there is too little information available on the stresses building up in the crust below us. Ergo we get caught out when something like the Christchurch disaster hits. Millions, billions even are wasted on 'preventing' phantasms like (I really do get tired of the whole circus) man made global warming when there are far greater local risks from unmapped seismic activity. Then a cynical voice pops into my head saying "Ah, but you can't tax volcanoes and earthquakes, can you?"

A minor breakthrough in predicting volcanic activity has been published over at UBC Vancouver, where certain kinds of eruptions can be predicted by their sound signature. Specifically those with 'stiff' magma. Yet we're no closer to predicting when or if a Volcano will erupt, or a major earthquake will occur. Yes we can monitor swarm activity, but the information we get from that is currently very superficial.

The Earth under our feet talks, it resonates, it shouts. Humankind's problem is that we firstly have a poor understanding of what the earth's crust is trying to tell us, and secondly trying to listen is a little like having an in depth conversation in a Disco. There's a too much background noise, not just from human but from other activity. Isolating and eliminating various sound signatures is stuff that until recently was the purely the domain of military sonar specialists. Yet like trying to chat up an attractive person of gender choice (let's not be sexist here- meh), sound is only part of the communication. Relying on sound alone easily gets you into situations with metaphorical undergarments round knees and real red face. Depending upon the situation and whether you're having fun, or perhaps not.

Carrying on with the chatting up in Disco conceit, there's far more to detecting eruptions than simply sound. There's motion, expression, and perceived mood. Sometimes these moods are hard to divine, but they are there. So maybe sound detection alone is only a part of the answer.

It has been posited that changes in geomagnetism or even changes in the solar magnetosphere may have a subtle impact on volcanism, rather like Svensmark's cloud climate hypothesis; where increased particle bombardment from cosmic rays when the solar wind is low increases cloud formation, increasing albedo and thus reflecting sunlight away from the Earth's surface. Thus making the Earth cooler.

Study of other planets in the solar system tells us that volcanic activity can be driven by energy generated by a body moving through a magnetic field. Published work by Russian researchers Sergey Pulinets and Kirill Boyarchuk, amongst others, point in this direction. As Earth is known to have a nickel iron core, so it is suspected does Io, one of Jupiters Inner moons. Now Io, the moon in question, is a highly volcanically active place, and has a curious phenomenon suspected to be due to magnetic activity, a ‘flux tube’ of highly charged electrical activity connecting Io and Jupiter. It is thought that this produces an inductive heating effect in Io’s nickel iron core, driving the observed high level of volcanic activity. This is perfectly in line with accepted electromagnetic theory where a metallic body moving through a magnetic field will induce electromagnetic activity in said body.

It may interest anyone who gets this far in my often poorly structured posts, that similar 'flux ropes' between the Sun and Earth have been observed by NASA's THEMIS mission.

Ergo, it may be argued that observed changes in the interaction between the Sun and the Earth’s magnetic fields may have some effect upon the heating effect of the Earth’s core, thus providing a driver of volcanic activity. Local changes can be measured with magnetometers. Whilst this type of measurement alone may not be sufficient to act as a volcano / earthquake early warning device, in combination with stress meters, additional observations should be sufficient to build up a better picture of what the Earth is telling us, deep down.

Going back to the chatting up in the disco conceit, thus may we be able to see what the object of our intentions (Seismic activity) is going to do by joining up the dots of sound, electromagnetism and observed local physical changes. Thus easing the task of knowing what 'mood' our potential date is in. Then we may have a better idea of what any given volcano or earthquake fault is liable to do, and perhaps get the hell out of Dodge before a Pompeii happens.

Thursday, 24 February 2011

Christchurch Quake distribution.

Regarding my post on the Christchurch Earthquakes. Here is a screengrab of published seismic activity during the last seven days in that area. From the 18th to the 25th February, New Zealand dates and times.

As I posited earlier, the majority of the activity, including the big ones, have all been located in a fairly tight geographical area in the north caldera wall of an extinct volcano. The dots show the epicentre of each tremor, colour coded for depth.

The thought occurs that if one side of a caldera shifts, that moves the stresses around, and it's only a matter of time before more tremors hit around the rest of the perimeter. When and where appear to be the only issues outstanding.

Wednesday, 23 February 2011

Christchurch, NZ

My comrade in words the Angry Exile brought this site to my attention which kind of tells a greater story about the Christchurch Earthquake than the one currently being covered in the mainstream.

Often when an Earthquake is reported, all you see are the headlines, like '200 people killed in quake horror' for example. When you read the associated articles, they skim over the surface, glossing over important details that might be actually useful, apart from generating mere sympathy for the victims. The really interesting thing about the Christchurch tremors is the concentration of seismic activity and where it is happening.

What really did the damage was not one big quake, like the 7.1 magnitude on the picture from 4th September 2010, but a series of rapid hammer blows of 3-4+ magnitude after the main shocks of 6.3 and 5.7, which occurred within twelve minutes of one another. They were followed by a 5.9 magnitude quake less than two hours later. If you run through the sequence of tremors, you can see that the vast majority of the recent shocks recorded are in what is known to be the northern caldera wall of an extinct volcano. Having run through the recent sequences, I'd hazard a guess that what is happening under the Southern edge of Christchurch is a widespread collapse of the old volcanic vent system and magma chambers in the 2-12km depth range. Perhaps even slippage in the faults within the caldera walls as they 'settle'. Not directly related to the nearby Greendale fault at all.

I'm only an amateur observer of such phenomena, but that's what it looks like to me. Go look for yourselves. Run the sequence of 22nd February and you'll see what I mean.
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