Saturday, February 4, 2012

The Cumbre Vieja Volcano

One of the more interesting verses in Revelations are verses 8 and 9 of Chapter 8, stating:
And the second angel sounded, and as it were a great mountain burning with fire was cast into the sea: and the third part of the sea became blood;

And the third part of the creatures which were in the sea, and had life, died; and the third part of the ships were destroyed.
I have long presumed that "a great mountain burning with fire" must be a meteor. However, I came across a web-site (I don't remember which one now) that speculated that it referred to a volcano in the Canary Islands that would collapse into the sea causing a massive tidal wave. I had never heard of this possibility before. In further researching the subject, it is evident that the web-site was referring to the Cumbre Vieja volcano in the Canary Islands.

According to Wikipedia, Cumbre Vieja "is an active volcanic ridge on the volcanic ocean island of Isla de La Palma in the Canary Islands." In 2001, CNN published an article, stating:
They fear that the mega-wave -- know as a tsunami -- could be generated by part of a mountain twice the size of Britain's Isle of Man crashing into the sea following an eruption of the Cumbre Vieja volcano on La Palma, in the Canary Islands -- part of the Spanish island chain off West Africa.

Travelling at speeds of up to 500mph, the tsunami would be an unstoppable force and would be the biggest-ever recorded in history.

Previous research by Dr Simon Day, of the Benfield Greig Hazard Research Centre at University College London predicted that a future eruption of Cumbre Vieja was likely to cause the western flank of the mountain to slide into the sea.

The energy released by the collapse would be equal to the electricity consumption of the entire U.S. in six months.

With Dr Steven Ward, from the University of California, Dr Day has produced a new model that predicts more accurately how big the tsunami will be and where it will strike.

Immediately after the landslide, a dome of water almost 900 metres (3,000 ft) high and tens of kilometres wide will form, only to collapse and rebound.

Its first target was expected to be the West Saharan coast of Morocco, where the wave would measure a devastating 330ft from crest to trough.

Propelled by a series of crests and troughs, the tsunami would travel a distance of almost 155 miles in just 10 minutes, the model predicts.

Racing at the speed of a jet aircraft, it would reach Florida and the Caribbean in eight or nine hours.

A wall of water 164ft high -- higher than Nelson's column in London's Trafalgar Square -- would smash into the coasts of Florida and the Caribbean islands, the forecast predicts.

The northern coast of Brazil would be hit by a wave more than 130ft high.

The wave would travel four or five miles inland, flattening everything in its path.
(See also the Viable Opposition blog's discussion). However, other web-sites claimed that the destruction would extend further north, possibly affecting New York and Boston. (See, e.g., here).

Viable Opposition referenced a paper in the American Geophysical Union Journal by Dr. Steven Ward and Dr. Simon day, entitled “Cumbre Vieja Volcano – Potential collapse and tsunami at La Palma, Canary Islands.”The authors of that paper state: "This line of reasoning leads us to believe that a future eruption near the summit of the Cumbre Vieja will likely trigger a flank failure." The describe the possible size of the block what will slide:
The best geological evidence that we have paints a Cumbre Vieja collapse sending down a slide block 15-20 km wide and  15-25 km long. The thickness of the slide block is not easily fixed. Mapping the depth to the detachment surface by locating earthquakes that occur on it has not been possible. No records exist of seismic activity associated with the 1949 eruption, or the subsequent 1971 eruption at the island's southern tip. No other tectonic earthquakes of consequence have struck under La Palma in the last three decades either. Nevertheless, characteristics of past collapses point to a listric detachment 2 to 3 km below the summit of the volcano. Toward the west, the surface dips seawards at a shallow angle to intersect the offshore toe. Toward the east, the detachment steepens sharply to intersect the surface within a few km of the
mountain's crest. In consideration of everything, we believe that a future flank failure of Cumbre Vieja volcano will dislodge a broadly wedge-shaped slide block as cartooned at the bottom of Figure 2. The volume and mean thickness of rock participating in a flank failure depends upon the detailed shape of the basal surface, but they should fall in the range of 150 to 500 km 3 and 1 to 2 km respectively. The inferred geometry and volume of the expected failure coincide closely with features of the previous La Palma collapse (~566 ka), remains of which are still visible to the north on Cumbre Nueva.
They also describe the resulting tsunami:
Within 2 minutes of the initial failure (Figure 4a), a water dome has built atop the sliding block to 900 m height -- only somewhat less than the thickness of the block. Within 5 minutes (Figure 4b), the fast-traveling initial wave crest has outrun the now disintegrating
landslide front. The leading wave height has dropped to 500 m after 50 km of travel. Large negative waves now appear behind the leading crest. These are due partly to rebound of the initial dome and partly due to the passing of the back of the slide block that drops the water column (dark gray squares to light gray squares in Figure 3). At 10 minutes (Figure 4c), the slide has run its course. The tsunami disturbance has grown to 250 km in diameter and several hundred-meter high waves have rolled up the shores of the three westernmost islands of the Canary chain. Note the relatively non-directional character of the wave pattern and that already, the leading positive wave (200 m) is no longer the largest. Several negative and positive ones 2-3 times larger trail behind. From 15 to 60 minutes (Figure 4d-f), waves sweep eastward through the rest of the Canary Islands and 50-100 m waves make first landfall on the
African mainland. Upon nearing the West Saharan shore, the tsunami waves slow, and crush together (Figure 4f). In contrast, toward the west, a great train of dispersed waves 500 km across, develops as the tsunami moves into the Atlantic basin. Peak wave heights (60 m) there show up in the second crest. From 3 to 6 hours (Figure 4g,h), the tsunami expands across the Atlantic retaining palpable amplitude in an arc subtending more than 180 degrees. Toward the northeast, Spain and England experience 5 to 7 m waves. La Palma Island itself blocked most of the radiation in this direction. Vanguards of the tsunami (10 m) first brush North America near Newfoundland. Simultaneously, larger (15-20 m) waves arrive at the north shore of South America. At 9 hours (Figure 4i), Florida faces the tsunami, now parading in a dozen cycles or more. In 50 m of water offshore Cape Canaveral, even after being weakened by geometrical spreading and frequency dispersion, tsunami from lateral collapses of the volume, dimension, and speed of that expected at La Palma could retain 20-25 m height. Shoaling waves do not continue to grow much in water shallower
than their height, so 20-25 m probably reflects the terminal height of the waves expected on Florida's beaches.
Here is video interview with the authors:

 Here is a video simulation of the tsunami:

However, there has been some push back from other scientists that maintain that the claims of the size of the block are exaggerated and the risk is small. (See article here; and here). However, a subsequent paper concluded:
We conclude that although uncertainties still exist regarding the timing of a future flank collapse of the Cumbre Vieja volcano, the various lines of evidence presented here provide strong indications that when such collapses do occur at La Palma and other oceanic islands in the geologically near future, the resultant tsunamis will have the potential to remain highly destructive at oceanic distances.
This posting from the Maine Geological Survey also states:
Although the flank instability of Cumbre Vieja is noted, many scientists tend to disagree with massive failure of the western flank of the volcano; rather, they think it would happen in smaller separate events that would not be capable of triggering a mega-tsunami (Wynn and Masson, 2003). There is much scientific debate over the timing of an eruption that would trigger such events (considered to be decades to thousands of years), whether or not a massive failure of Cumbre Vieja's flank would occur during an eruption, or even if a mega-tsunami could possibly result (and reach the United States with such projected wave sizes). Mader (2001) used different wave modeling and determined that the resulting tsunami waves that reached the U.S. east coast and Caribbean would be on the order of 3 meters. The International Tsunami Information Center provided the following information in regards to the creation of a mega-tsunami by massive flank failure:
  • While the active volcano of Cumbre Vieja on Las Palma is expected to erupt again, it will not send a large part of the island into the ocean, though small landslides may occur.
  • No such event - a mega tsunami - has occurred in either the Atlantic or Pacific oceans in recorded history.
  • The colossal collapses of Krakatau or Santorin (the two most similar known happenings) generated catastrophic waves in the immediate area but hazardous waves did not propagate to distant shores. Carefully performed numerical and experimental model experiments on such events and of the postulated Las Palma event verify that the relatively short waves from these small, though intense, occurrences do not travel as do tsunami waves from a major earthquake.
A more general discussion of past, and possible future, mega-tsunami can be found here.

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