Making Waves

When a tsunami hits, there is nothing in the world that can stop the powerful wave from destroying everything in its path. If you've watched the news at all in the last ten years, you'll know what a tsunami looks like, and just how destructive it can be. But do you know how they begin?

A Tsunami can be caused by natural occurrences, whether that be a submarine landslide, the impact of an asteroid or meteorite, an earthquake that causes the shifting of the seafloor, or an underwater volcano (Keller and Devecchio, 102-109.)

A tsunami in Great Britain is very unlikely 

thanks to its position on the Eurasian plate.

(photo: Britishnationalparty.com)

The Lisbon tsunami and fire, 1755
(Glogster.com)

When reading about Great Britain, I was unsurprised to find that the British Isles are not really at risk of tsunamis, once again thanks to their placement on the Eurasian tectonic plate. According to the British Geological survey, there is evidence that Great Britain did suffer at least one tsunami about 8000 years ago. Thanks to geological records, scientists believe that a submarine earthquake off the coast of Norway sent waves toward the shores of Britain.

According to the Encyclopedia Brittanica, a magnitude 8 earthquake originating along the Atlantic faultiness created a tsunami powerful enough to destroy the city of Lisbon, Cornwall in 1755. With 20 foot waves, the tsunami destroyed 12,000 buildings and killed 60,000 people in the city alone.

Today, we know it is unlikely that Great Britain would be at risk of an earthquake for a few reasons. First, that the earthquakes which take place along the nearest plate boundary (the Atlantic Ridge) are too small and too far away to cause any peril. Second, that Britain hardly experiences earthquakes large enough to cause harm, given that the largest one recorded in British history was a 6.1  magnitude. It is for these reasons that there is currently no national tsunami warning system.

It's Nobody's Fault

Because of it's location on the Eurasian plate, Great Britain does not experience volcanic activity. However, Britain is home to many beautiful but dormant volcanoes, most of which are located in Scotland. Most of these volcanoes are ancient. In fact, the "super volcanoes" of Moore, Skye and Run  in western Scotland are estimated to be about 60 million years old.

Arthur's Seat, located at the highest
 point in Edinburgh is one of the most visited
volcanoes in Great Britain.
[http://www.dailymail.co.uk/travel
/travel_news/article-2853274/Scotland-
boasts-HALF-UK-s-best-volcanoes-none-
budge-stunning-Giant-s-Causeway-spot.html]

Why exactly does Great Britain have zero volcanic activity? It happens to do with it's exact location on the Eurasian tectonic plate. When tectonic plates come together, if one plate is denser than the other it will move under the lighter one. In this process of subduction, the high temperature melts rocks and creates magma. According to the British Geological Survey, when the magma comes up through the earth, it creates a volcano. However, since Great Britain is nowhere near the edges of a tectonic plate, new volcanoes don't occur.

Since volcanoes happen quite frequently in Iceland, the UK air traffic control service NATS occasionally issues "ash warnings" to help protect the European aviation industry. from massive ash clouds.

All Shook Up

Wouldn't it be great if all it took to measure earthquakes was a sheet of paper and a couple of googley eyes? In reality, measuring seismic activity (especially in the UK) is complicated, yet absolutely fascinating!

Source

According to the British Geological survey, an earthquake occurs when a fault ruptures, releasing a burst of energy. The bursts of energy create ripples called seismic waves.  When these waves travel on the surface, they are naturally called "surface waves." On the other hand, waves called "body waves" travel in the body of the earth, and are split into two groups: S waves, which travel through solids only, and P waves, which travel through solids, liquids and gasses. (Keller and DeVecchio, 59-60)

Like any country, Britain;s earthquakes are caused by the movement of tectonic plates. Because it does not lie above a major boundary line, Britain experiences mainly minor earthquakes that are relatively frequent. In Great Briatian, out of the average 50 to 60 quakes taking place, only 20 to 30 earthquakes are felt each year, and most of which are never seen as posing any kind of threat. On to the Richter scale, the tool we use to measure the magnitude of an earthquake, earthquakes ranging below the level 4 mark are considered insignificant. Each year, most of Great Britain's earthquakes are felt at 5.

British Geological Survey provides
seismic activity stats regularly!

The British Geological Survey is a great resource which actually puts out a regularly updated list containing seismic events in the British Isles from the past 50 days. (Website can be found here!)

According to the survey, the most recent quake in Great Britain happened in Bromyard, Herefordshire. At a magnitude of 2.3, it's no wonder no one has yet reported feeling this small quake to the BGS.













Note to classmates reading this: anyone have any idea how to get rid of accidentally hi lighted portions of text?

Catch my Drift?

Map shows major plates, boundaries, and plate
movement (whybecasuescience.com)

Have you ever wondered why Earth's continents look like they should fit together, almost like a puzzle? Thanks to Geologist Alfred Wegener's, we now know that each continent is embedded in one of  the earth's tectonic plates, and that these plates are constantly moving. We call these broken up plates the lithosphere. According to Keller and DeVecchio, (Natural Hazards, 33-34), the lithospheric plates move over another layer called the asthenosphere.

In a Divergent boundary, two plates are moving away
from each other, while hot mantle is rising up from the center
forming a rift. (Keller and DeVecchio)

Great Britain is located on the Eurasian plate, yet it is not close to the division of the plates. To its right lies a Divergent boundary line (pictured right), which according to the British Geological Survey is responsible for creating more lithosphere as plates move away from each other.

However,  because it does rest on some fault lines, Great Britain experiences a few minor earthquakes each year. The earthquakes are caused by stress in the crust below Britain, which is caused by the shifting of the Eurasian plate.

Yours, Mines, and Ours

From the jewelry we wear to the salt on our table, we use rocks and minerals in our everyday lives. But where are these resources from? Great Britain happens to be a major contributor to the world's rock and mineral supplies, and has been since around 2,300 BC. In fact, according to George Ryback, author of Eighth Supplementary list of British Isles Minerals (1988) claims that 580 species of minerals have been found in England, and 850 found in the entire British Isles.

 According to the University of Manchester, Great Britain's rocks and minerals are mainly mined within three districts: Cumbria, Caldbeck Falls, and the Pennine Orefield.

In Cumbria, mines calcite and barite, while in Caldbeck Falls, lead, copper and zinc are commonly mined. The Pennine Orefield brings in the fluorite, barium, barytocalcite and alstonite. 

Photo (calcite) : http://www.rock-site.co.uk/cms.php?id_cms=15

Photo (copper) : http://www.rocksforkids.com/R&M/copper.htm

Hazards, Disasters, Catastrophes, oh my!

Located in the North Atlantic ocean just west of the European continent lies the island of Great Britain. Although the country's history of disasters isn't quite as dramatic as some, Great Britain has still had its share of naturally occurring mishaps over the years, including massive storms, floods and earthquakes.

The natural processes which occur in Britain can be categorized into three groups: Hazards, disasters, and catastrophes. 

A natural hazard can be defined as that which threatens the lives and property of people on a small scale. Natural hazards, such as floods, cyclones and volcanic eruptions only have the potential to become dangerous. When a natural hazard actually causes physical damage to human lives or the environment for a limited amount of time, we call is a natural disaster. When a disaster requires large portions of money and greater amounts of time to heal, we call it a catastrophe.