This beautiful image is of Mount Redoubt - a stratovolcano hailing from the Aleutian Range, a fairly IMPRESSIVE mountain range in Alaska. I use the word IMPRESSIVE because as far as I can tell HEAPS of really tall mountains and active volcanoes live there. The volcanoes in the range are officially a part of the Aleutian Arc - which formed as a result of the SUBDUCTION of the Pacific Plate under the North American Plate.
Mount Redoubt has erupted 5 times!! since 1900 - who wouldn’t redoubt it (see what I did there).This image is taken from a 1989-1990 eruption (that’s right, went down in TWO decades - there is certainly no cause to redoubt its eruptive PROWESS). In fact, the eruption lasted for SIX months - on a geological level it was AWESOME - on a financial level, damage was estimated at $160 million. Because of this costliness, I will now stop basking in the beauty and wonder of this dangerous yet beautiful and wondrous tectonic beast.
Earthquakes - most tectonological and yet I haven’t blogged about them very much - perhaps because they can be so thoroughly devastating - I do not want to undermine this fact with the lighthearted tone I tend to take.
Having said that, the processes by which earthquakes occur, are, like most things geological, pretty AMAZING. Basically, when two huge chunks of rock rub up against each other (so to speak), things don’t always go smoothly (so to speak) - indeed there tends to be some friction (so to speak) and said friction results in a huge build up of pressure (so to sp…ok this has gone on long enough now). Eventually this pressure causes a fracture in the rock, releasing a whole HEAP of energy in the form of an EARTHQUAKE.
The severity of an earthquake is measured by the Richter scale, the moment magnitude scale or the Modified Mercalli scale (now apparently (according to wiki) rebranded as the Mercalli intensity scale - oh how times have changed). The Mercalli scale measures the effects of an earthquake on human’s, structures etc. from 1 (not felt) to 10 (total destruction).
The Richter scale quantifies the energy contained in a single earthquake on a scale of one to ten. The Richter scale used to be THE man about town when it came to the scale social ladder but apparently (unbeknownst to me - I bow my head in shame - indeed i’m pretty sure Richter is still the go to guy in Australia) something called the moment magnitude scale is far more commonly used to measure earthquakes in terms of energy released (let’s be honest though, it doesn’t roll off the tongue quite as nicely as RICHTER which sounds truly gritty and earthquake-y).
Earthquake’s often have disastrous consequences - and can act as the catalyst for other devastating natural phenomena (namely tsunamis and sometimes volcanic eruptions). Sometimes our Earth thrusts its demand for respect upon us - it is so important that we respond with preparedness and LEARN as much as we can about its awesome (in the truest sense of the word) power.
Mt Rainier- a huge stratovolcano in the US (Washington state to be exact - to be honest before I saw this picture all I knew about Washington state was something to do with Twilight…also, it does NOT house Washington D.C - I know right, most confusing…cut me some slack, I’m Australian for chrissakes). Anyway, from here on out I will associate Washington state with this BEHEMOTH instead - and boy is she beautiful.
Apparently said behemoth is part of the Cascade Volcanic Arc, which formed as a result of SUBDUCTION - Involved is a the low key so-called ‘minor’ plate, known as the Juan de Fuca Plate (frankly the most interestingly named of ALL the tectonic plates and one which I don’t know much about - probably because it sounds like it was named after a gallant, handsome and mysterious Spanish explorer (quite coincidentally, Juan de Fuca WAS a gallant, handsome and mysterious Spanish explorer - I know right, what are the chances).
The Juan de Fuca Plate was slowly SUCKED underneath the larger North American Plate - most of the Juan de Fuca Plate now resides permanently subducted beneath the North American Plate - which must be nice because I’ve heard it’s a lovely place for a holiday home…
Mt Ranier is known to be a particularly DANGEROUS volcano. It has a large amount of glacial ice, which, when melted by lava, can produce huge volcanic mudflows known as lahars. Said lahars have the consistency of concrete and can flow at up to 100km/h.
Sometimes it strikes me just how POWERFUL our Earth is and I am amazed by how little respect we treat it with. Surely with the knowledge we have about the havoc that can be wreaked by…well…GEOLOGY…it pays to learn as much as we can about it!
Photo by Alex Anderson
Soooo…igneousrocklobster…it may surprise you to know that this is NOT in fact my name (the DELIGHTFUL character featured in my profile picture is not me either - though we have a similar look around the eyes). igneousrocklobster is simply an exceptionally clever play on the name of a CLASSIC B52’s song (if I do say so myself). I thought for today’s post I might EXTRAPOLATE (if you will) with regards to the individual components of my pseudonym.
I suppose we had better proceed in order of geological relevance - first up: IGNEOUS, one of the three main BREEDS of rock (word breed potentially misleading - NB no procreation required), the other two being SEDIMENTARY and METAMORPHIC.
Igneous rock is formed when MAGMA or LAVA solidifies, which, to my mind, makes it the most ENGAGING rock variety. Along with that pesky metamorphic rock it makes up 90-95% of the top 16km of the Earth’s crust.
Igneous rock is either INTRUSIVE or EXTRUSIVE.
Intrusive igneous rock meddles through all of your stuff, reads your diary, invades your personal space…it’s a nightmare. It is formed when magma cools and solidifies WITHIN the crust - i.e. under the surface of the Earth. It can be EXPOSED by erosion and thus takes up vast expanses of the Earth’s surface.
Extrusive igneous rock is formed from the cooled lava which has been JETTISONED out of a volcano - it’s freaking awesome. (NB: Magma = molten rock still beneath the surface of the Earth, Lava = molten rock which has been set free from the SHACKLES of its subterranean prison via a volcanic eruption).
I think it’s time I shifted this post in the direction of my true PASSION – crustacean-al biology. LOBSTERS are orange when you cook them, they’re quite delicious…and they have claws. That is all.
Quality folding at Cape Liptrap - a magical place cemented solidly in the hearts of all Melbourne-based geology undergrads.
This is an image of Mount Cleveland, one of the most ACTIVE volcanoes in the Aleutian Arc (that’s Alaska for those out of the loop…I may or may not have been out of said loop until 10 minutes ago)- it has erupted at least 21 times in the last 230 years - indeed this NASA generated image captures one of those times (in May 2006) rather nicely.
Apparently a wily group of astronauts were the first to observe the eruption (they must have been having work drinks nearby or something) and alerted the Alaska Volcano Observatory whose technicians had knocked of early for the day (that’s what I heard anyway).
The Aleutian Arc formed as a result of the SUBDUCTION (that old chestnut) of that pesky Pacific Plate under the North American Plate.
(Image courtesy of NASA)
The San Andreas Fault - a 1, 300 km long incision GOUGED into the Earth’s surface, as if some sort of omnipresent OVERLORD performed a complex surgery wearing an oversized pair of gloves - that is what’s happening right…wait…what?
Come on now…the reality is far more AWESOME. You see the San Andreas Fault forms the TRANSFORM tectonic boundary between the two chunks of rock known as the Pacific Plate and the North American Plate; between them they cover…oh…just the PACIFIC OCEAN and North America-Greenland-Cuba-the Bahamas-Siberia-Japan-and-Iceland (or parts thereof)…and we wonder why the North American Plate acts kinda high and mighty.
To put it somewhat simply, all land to the WEST of the INCISION (I suppose should probably refer to it as the FAULT from now on to avoid befuddlement (though given the awesomeness of the word befuddlement do we really want to avoid it? I think not…)) is located on the Pacific Plate and is moving northwest, whilst all land to the EAST located on that MONSTER of a North American Plate and is moving (relatively) in a southeasterly direction.
All this is happening at the (almost) BLISTERING speed of 35 - 37 millimeters per year. When two huge slabs of rock take it upon themselves to SCRAPE past each other in this manner - you know things are going to get ugly - and by ugly I obviously mean the sort of rock formation captured in the DELIGHTFUL satellite image I have posted above (and, jokes aside, earthquakes, which actually can get ugly - keep safe everybody).