Off Topic: The Good Stuff, Calderas, Volcanos, Faults, Tsunamis And 'simple' Earth Quakes

[AriLea]

You are my favorite people for off Elio AND on-Elio talk. We got talking about Yellow Stone geology in other threads, so I just thought you might like to read these clips from the web I found. It did straighten out a couple things I thought I knew.
-quote/clips-
The Yellowstone caldera the existence of which is attributed to the "Yellowstone Hotspot", exists with all modern historical features covering an area of 1575 sq miles in North America. It has hosted the biggest known event in the world, the last eruption 760,000 years ago which unleashed 8,000 times as much lava and ash as Mount St. Helens. It actually includes several large features from diverse events, including 3 calderas with other remnants including at least 3 Tuffs, these are Island Park Caldera, Huckleberry Ridge Caldera, Henry's Fork Caldera, Huckleberry Ridge Tuff, Mesa Falls Tuff, and Lava Creek Tuff.
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Second only to Yellowstone in North America is the Long Valley caldera, in east-central California. The 200-square-mile caldera is just south of Mono Lake, near the Nevada state line. The biggest eruption from Long Valley was 760,000 years ago, which unleashed 2,000 to 3,000 times as much lava and ash as Mount St. Helens, after which the caldera floor dropped about a MILE, according to the U.S. Geological Survey. Some of the ash reached as far east as Nebraska. What worries geologists today was a swarm of strong earthquakes in 1980 and the 10-inch rise of about 100 square miles of caldera floor. Then, in the early 1990s, large amounts of carbon dioxide gas from magma below began seeping up through the ground and killing trees in the Mammoth Mountain part of the caldera. When these sorts of signs are present, it could mean trouble is centuries, decades, or even YEARS away, say volcanologists.
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The Lake Toba caldera in North Sumatra, Indonesia, Yellow stones big sister, 1080 square miles, blew 74,000 years ago. Ejecting many cu miles of material, (3000 Mt St Helens) and according to scientists seems responsible for bottlenecking the human RNA genome into just 12 women survivors during that world-time.
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Tupo Caldera in New Zealand, 485 square miles in area, 26,500years ago and 2200years ago. 22cu miles (75 St Helens)
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Aira Caldera in southern Japan. 22000years ago with 14cu miles ejected. (50 Mt St Helens)

I must surmise something here, it's not the calderas that are scary to me but the underlying 'hotspots'. These cause the formation of strings of caldera which have formed at the onset of the biggest events. The Caldera themselves continue to be active for a long time, but initially they have formed in previously featureless land.

Now, wasn't that fun?

 

[AriLea]

So then, to continue on with the 'disaster series'. . (Keep in mind with these things, life may not be safe, it never was, and never will be, but it is worth the risk, IMHO!)

-compiled from web clips-
Tsunamis have a small amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometres long, whereas normal ocean waves have a wavelength of only 30 or 40 metres), which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 millimetres (12 in) above the normal sea surface. They grow in height when they reach shallower water, in a wave shoaling process ....

A typical wave period ( which can vary! ) for a damaging (ocean transversing) tsunami is about 12 minutes. This means that if the drawback phase is the first part of the wave to arrive ( note: the rise could come first! ) , the sea will recede, with areas well below sea level exposed after 3 minutes. During the next 6 minutes the tsunami wave trough builds into a ridge, and during this time the sea is filled in and destruction occurs on land. During the next 6 minutes, the tsunami wave changes from a ridge to a trough, causing flood waters to drain and drawback to occur again. This may sweep victims and debris some distance from land. The process repeats as the next wave arrives.

The Greek historian Thucydides suggested in his late-5th century BC History of the Peloponnesian War, that tsunamis were related to submarine earthquakes, but the understanding of a tsunami's nature remained slim until the 20th century and much remains unknown.

The Roman historian Ammianus Marcellinus (Res Gestae 26.10.15-19) described the typical sequence of a tsunami, including an incipient earthquake, the sudden retreat of the sea and a following gigantic wave, after the 365 AD tsunami devastated Alexandria.
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2004 Indian Ocean tsunami was among the deadliest natural disasters in human (recorded) history with at least 230,000 people killed or missing in 14 countries bordering the Indian Ocean.

Of historical and current (with regard to risk assumptions) importance are the 1755 Lisbon earthquake and tsunami (which was caused by the Azores–Gibraltar Transform Fault), the 1783 Calabrian earthquakes, each causing several ten thousand deaths and the 1908 Messina earthquake and tsunami. The tsunami claimed more than 123,000 lives in Sicily and Calabria and is among the most deadly natural disasters in modern Europe.

On April 1, 1946, a magnitude-7.8 (Richter Scale) earthquake occurred near the Aleutian Islands, Alaska. It generated a tsunami which inundated Hilo on the island of Hawai'i with a 14-metre high (46 ft) surge. The area where the earthquake occurred is where the Pacific Ocean floor is subducting (or being pushed downwards) under Alaska.

The 1964 Alaskan earthquake, also known as the Great Alaskan earthquake and Good Friday earthquake, occurred at 5:36 P.M. AST on Good Friday, March 27. Across south-central Alaska, ground fissures, collapsing structures, and tsunamis resulting from the earthquake caused about 139 deaths. A 27-foot (8.2 m) tsunami destroyed the village of Chenega, killing 23 of the 68 people who lived there; survivors out-ran the wave, climbing to high ground. Lasting four minutes and thirty-eight seconds, the magnitude 9.2 megathrust earthquake was the most powerful recorded in North American (known/recorded - modern) history, and the second most powerful recorded in world history.

Examples of tsunami originating at locations away from convergent boundaries include Storegga about 8,000 years ago, Grand Banks 1929, Papua New Guinea 1998 (Tappin, 2001). The Grand Banks and Papua New Guinea tsunamis came from earthquakes which destabilised sediments, causing them to flow into the ocean and generate a tsunami. They dissipated before traveling transoceanic distances.

The cause of the Storegga sediment failure is unknown. Possibilities include an overloading of the sediments, an earthquake or a release of gas hydrates (methane etc.).

The 1960 Valdivia earthquake (Mw 9.5), 1964 Alaska earthquake (Mw 9.2), 2004 Indian Ocean earthquake (Mw 9.2), and 2011 Tōhoku earthquake (Mw9.0) are recent examples of powerful megathrust earthquakes that generated tsunamis (known as teletsunamis) that can cross entire oceans. Smaller (Mw 4.2) earthquakes in Japan can trigger tsunamis (called local and regional tsunamis) that can only devastate nearby coasts, but can do so in only a few minutes.

In the 1950s, it was discovered that larger tsunamis than had previously been believed possible could be caused by giant submarine landslides. These rapidly displace large water volumes, as energy transfers to the water at a rate faster than the water can absorb. Their existence was confirmed in 1958, when a giant landslide in Lituya Bay, Alaska, caused the highest wave ever recorded, which had a height of 524 metres (over 1700 feet). The wave did not travel far, as it struck land almost immediately. Two people fishing in the bay were killed, but another boat amazingly managed to ride the wave.

Another landslide-tsunami event occurred in 1963 when a massive landslide from Monte Toc entered the Vajont Dam in Italy. The resulting wave surged over the 262 m (860 ft) high dam by 250 metres (820 ft) and destroyed several towns. Around 2,000 people died. Scientists named these waves megatsunamis.
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OK, that all seems like the source of any number of 'survivorship' story lines we find entertaining. IMHO, being attracted to such stories are part of our survival instinct. Acquiring too much fear is one possible casualty for being a little too interested.

 

[NSTG8R]

I don't know if this counts, but a science show I was watching recently said that the largest volcanic event in geological history create the Siberian Traps. It pumped out 720,000 cubic miles of lava [basalt], and lasted around 1 million years. The program postulated that a meteorite or comet impact on the exact opposite side of the planet may have set it off. The theory is that the seismic waves created by the impact would concentrate on the other side of the planet. The crater, they theorize, is under the Antarctic ice cap. A satellite, that records gravitational anomalies, found a huge gravitational anomaly over Antarctica they suspect may be from an gigantic iron meteorite.

I'll have to see if I can locate the show that it was on.

 

[AriLea]

If you are interested in tsunami, IMHO, you must also consider this one... (hopefully such a thing is never encountered as standing waves or as a non-dispersal 'plane wave')
Rogue waves (also known as freak waves, monster waves, episodic waves, killer waves, extreme waves, and abnormal waves) are large and spontaneous surface waves that can be extremely dangerous, even to large ships such as ocean liners.

In oceanography, rogue waves are more precisely defined as waves whose height is more than twice the significant wave height (Hs or SWH), which is itself defined as the mean of the largest third of waves in a wave record. Therefore, rogue waves are not necessarily the biggest waves found on the water; they are, rather, unusually large waves for a given sea state. (Hopefully never encountered as standing waves or as a non-dispersal 'plane wave')

The wave that caught the attention of the scientific community was the digital measurement of the "Draupner wave", a rogue wave at the Draupner platform in the North Sea on January 1, 1995, with a maximum wave height of 25.6 metres (84 ft) (peak elevation of 18.5 metres (61 ft)) . During that event, minor damage was also inflicted on the platform, far above sea level, confirming that the reading was valid.

It is now proven via satellite radar studies that waves with crest to trough heights of 20 metres (65.6 ft) to 30 metres (98.4 ft), occur far more frequently than previously thought. It is now known that rogue waves occur in all of the world's oceans many times each day. In 2004 the ESA MaxWave project identified more than ten individual giant waves above 25 metres in height during a short survey period in a limited area of the South Atlantic. The ESA's ERS satellites have helped to establish the widespread existence of these 'rogue' waves.

The basic underlying physics that makes phenomena such as rogue waves possible is that different waves can travel at different speeds(and directions), and so they can "pile up" in certain circumstances - known as "constructive interference". However other situations can also give rise to rogue waves, particularly situations where non-linear effects or instability effects can cause energy to move between waves and be concentrated in one or very few extremely large waves before returning to "normal" conditions.

Rogue waves have now been proven to be the cause of the sudden loss of some ocean-going vessels. Well documented instances include the freighter MS München, lost in 1978 and the MV Derbyshire lost in 1980, the largest British ship ever lost at sea. A rogue wave has been implicated in the loss of other vessels including the Ocean Ranger which was a semi-submersible mobile offshore drilling unit that sank in Canadian waters on 15 February 1982. In 2007 the US National Oceanic and Atmospheric Administration compiled a catalogue of more than 50 historical incidents probably associated with rogue waves.

Rogue waves may also occur in lakes. A phenomenon known as the "Three Sisters" is said to occur in Lake Superior when a series of three large waves forms. The second wave hits the ship's deck before the first wave clears. The third incoming wave adds to the two accumulated backwashes and suddenly overloads the ship deck with tons of water. The phenomenon was implicated in the sinking of the SS Edmund Fitzgerald on Lake Superior in November 1975.

Rogue waves present considerable danger for several reasons: they are rare, unpredictable, may appear suddenly or without warning, and can impact with tremendous force. A 12-metre (39 ft) wave in the usual "linear" model would have a breaking force of 6 metric tons per square metre [t/m2] (8.5 psi). Although modern ships are designed to tolerate a breaking wave of 15 t/m2 (21 psi), a rogue wave can dwarf both of these figures with a breaking force of 100 t/m2 (140 psi).

Researchers at the Australian National University have also recently (2012) proven the existence of rogue wave HOLES, an inverted profile of a rogue wave. In maritime folk-lore, stories of rogue holes are as common as stories of rogue waves. They follow from theoretical analysis but had never been proven experimentally. In 2012 the ANU published research confirming the existence of rogue wave holes on the water surface observed in a water wave tank.

 

[Rob Croson]

A 1,700 foot wave?! Holy crap....

 

[Rob Croson]

I don't know if this counts, but a science show I was watching recently said that the largest volcanic event in geological history create the Siberian Traps. It pumped out 720,000 cubic miles of lava [basalt], and lasted around 1 million years. The program postulated that a meteorite or comet impact on the exact opposite side of the planet may have set it off. The theory is that the seismic waves created by the impact would concentrate on the other side of the planet. The crater, they theorize, is under the Antarctic ice cap. A satellite, that records gravitational anomalies, found a huge gravitational anomaly over Antarctica they suspect may be from an gigantic iron meteorite.

I'll have to see if I can locate the show that it was on.

Go, go, Google!

GRACE gravity evidence for an impact basin in Wilkes Land, Antarctica - von Frese - 2009 - Geochemistry, Geophysics, Geosystems - Wiley Online Library

[1] New details on the east Antarctic gravity field from the Gravity Recovery and Climate Experiment (GRACE) mission reveal a prominent positive free-air gravity anomaly over a roughly 500-km diameter subglacial basin centered on (70°S, 120°E) in north central Wilkes Land. This regional inverse correlation between topography and gravity is quantitatively consistent with thinned crust from a giant meteorite impact underlain by an isostatically disturbed mantle plug. The inferred impact crater is nearly three times the size of the Chicxulub crater and presumably formed before the Cretaceous formation of the east Antarctic coast that cuts the projected ring faults. It extensively thinned and disrupted the Wilkes Land crust where the Kerguelen hot spot and Gondwana rifting developed but left the adjacent Australian block relatively undisturbed. The micrometeorite and fossil evidence suggests that the impact may have occurred at the beginning of the greatest extinction of life on Earth at ∼260 Ma when the Siberian Traps were effectively antipodal to it. Antipodal volcanism is common to large impact craters of the Moon and Mars and may also account for the antipodal relationships of essentially half of the Earth's large igneous provinces and hot spots. Thus, the impact may have triggered the “Great Dying” at the end of the Permian and contributed to the development of the hot spot that produced the Siberian Traps and now may underlie Iceland. The glacial ice up to a few kilometers thick that has covered the crater for the past 30–40 Ma poses formidable difficulties to sampling the subglacial geology. Thus, the most expedient and viable test of the prospective crater is to survey it for relevant airborne gravity and magnetic anomalies.​

 

[AriLea]

I don't know if this counts, but a science show I was watching recently said that the largest volcanic event in geological history create the Siberian Traps. It pumped out 720,000 cubic miles of lava [basalt], and lasted around 1 million years. The program postulated that a meteorite or comet impact on the exact opposite side of the planet may have set it off. The theory is that the seismic waves created by the impact would concentrate on the other side of the planet. The crater, they theorize, is under the Antarctic ice cap. A satellite, that records gravitational anomalies, found a huge gravitational anomaly over Antarctica they suspect may be from an gigantic iron meteorite.

I'll have to see if I can locate the show that it was on.

Sooooo then onto meteor impacts..
(First these 3 links...too much to cut and paste)
Impact event - Wikipedia, the free encyclopedia
List of impact craters on Earth - Wikipedia, the free encyclopedia
Asteroid Impacts:10 Biggest Known Hits

Aside from the Antarctic impact noted(which doesn't even plot on the charts below), in contrast to the past, the subject is very well address at this point, (see links), so lets just look at some sobering points in these three chart images below. Definitely gave me a wow moment. Not a big a wow as hearing about the black-hole 18 !billion! times the mass of our sun, (and xx million/or/billion light-years away!) but still, this affects us much closer to home.

Chelyabinsk meteor: Chelyabinsk meteor - Wikipedia, the free encyclopedia
(15 February 2013) Measuring about 20 metres in diameter (see 'every 60 years' below), estimated initial mass of about 12,000–13,000 metric tonnes, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km. It is the largest known natural object to have entered Earth's atmosphere since the 1908 Tunguska event.

The bulk of the object's energy was absorbed by the atmosphere, with a total kinetic energy before atmospheric impact equivalent to approximately 500 kilotons of TNT (about 1.8 PJ), 20–30 times more energy than was released from the atomic bomb detonated at Hiroshima.

Its explosion created panic among local residents, and about 1,500 people were injured seriously enough to seek medical treatment. All of the injuries were due to indirect effects rather than the meteor itself, mainly from broken glass from windows that were blown in when the shock wave arrived, minutes after the superbolide's flash. Some 7,200 buildings in six cities across the region were damaged by the explosion's shock wave.
(note 10,000GJ = 2.39kt TNT exposive )

 

[NSTG8R]

Sooooo then onto meteor impacts..
(First these 3 links...too much to cut and paste)
Impact event - Wikipedia, the free encyclopedia
List of impact craters on Earth - Wikipedia, the free encyclopedia
Asteroid Impacts:10 Biggest Known Hits

Aside from the Antarctic impact noted(which doesn't even plot on the charts below), in contrast to the past, the subject is very well address at this point, (see links), so lets just look at some sobering points in these three chart images below. Definitely gave me a wow moment. Not a big a wow as hearing about the black-hole 18 !billion! times the mass of our sun, (and xx million/or/billion light-years away!) but still, this affects us much closer to home.

Chelyabinsk meteor: Chelyabinsk meteor - Wikipedia, the free encyclopedia
(15 February 2013) Measuring about 20 metres in diameter (see 'every 60 years' below), estimated initial mass of about 12,000–13,000 metric tonnes, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km. It is the largest known natural object to have entered Earth's atmosphere since the 1908 Tunguska event.

The bulk of the object's energy was absorbed by the atmosphere, with a total kinetic energy before atmospheric impact equivalent to approximately 500 kilotons of TNT (about 1.8 PJ), 20–30 times more energy than was released from the atomic bomb detonated at Hiroshima.

Its explosion created panic among local residents, and about 1,500 people were injured seriously enough to seek medical treatment. All of the injuries were due to indirect effects rather than the meteor itself, mainly from broken glass from windows that were blown in when the shock wave arrived, minutes after the superbolide's flash. Some 7,200 buildings in six cities across the region were damaged by the explosion's shock wave.
(note 10,000GJ = 2.39kt TNT exposive )


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Scariest part about it, was that no one saw it coming!