Earthquakes & Volcanoes
Tracking Earthquakes
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1. (Divergent Boundary)
On Saturday, October 22, 2011, a 4.8 magnitude earthquake, with a focus depth of 10km (6.2 miles), struck just north of the Africas Horn, in the Gulf of Aden. This is a divergent boundary because it's located in one of the areas where the African plate and Arabian plate spread away from eachother, continually creating new material. Divergent boundaries also create shallow focused earthquakes such as this one. Interestingly enough, just west of this earthquake alonge the same divergent boundary, is the great East African Rift Valley (USGS).
On Saturday, October 22, 2011, a 4.8 magnitude earthquake, with a focus depth of 10km (6.2 miles), struck just north of the Africas Horn, in the Gulf of Aden. This is a divergent boundary because it's located in one of the areas where the African plate and Arabian plate spread away from eachother, continually creating new material. Divergent boundaries also create shallow focused earthquakes such as this one. Interestingly enough, just west of this earthquake alonge the same divergent boundary, is the great East African Rift Valley (USGS).
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2. (Continental-Continental Convergent Boundary)
A 7.1 magnitude eathquake, struck Eastern Turkey on Sunday, October 23, 2011 at 10:41:21 UTC. With a focus depth of 16 km (9.9 miles) this earthquake ruptured on the Eurasian plate, close to where the Arabian Plate converges and subducts into it. Given the distance from the surrounding Seas', the focus depth and the many mountain ranges nearby; all evidence supports, that this earthquake was caused by a continental-continental convergent boundary. Not only the depth of the earthquake, but also the large amount of Mountains that usually accompany continental-continental convergent boundaries. Continetal versus continental crust is too hard to perform subduction, so instead mountains rise up (USGS).
A 7.1 magnitude eathquake, struck Eastern Turkey on Sunday, October 23, 2011 at 10:41:21 UTC. With a focus depth of 16 km (9.9 miles) this earthquake ruptured on the Eurasian plate, close to where the Arabian Plate converges and subducts into it. Given the distance from the surrounding Seas', the focus depth and the many mountain ranges nearby; all evidence supports, that this earthquake was caused by a continental-continental convergent boundary. Not only the depth of the earthquake, but also the large amount of Mountains that usually accompany continental-continental convergent boundaries. Continetal versus continental crust is too hard to perform subduction, so instead mountains rise up (USGS).
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3. (Oceanic-continental convergent boundary)
A 6.9 magnitude earthquake struck near the coast of Central Peru, on Friday, October 28, 2011 at 1:54 PM. The focus depth reached 23.9 km (14.9 miles). This earthquake is on an oceanic-continental convergent boundary. Along this coast of South America, the denser ocean floor sinks below the continental crust in a process called subduction(USGS). Nearly the entire westcoast of S. America is a convergent boundary, where the Nazca plate converges into the S. American plate, and formed the Andes (largest mountain range in the world).
A 6.9 magnitude earthquake struck near the coast of Central Peru, on Friday, October 28, 2011 at 1:54 PM. The focus depth reached 23.9 km (14.9 miles). This earthquake is on an oceanic-continental convergent boundary. Along this coast of South America, the denser ocean floor sinks below the continental crust in a process called subduction(USGS). Nearly the entire westcoast of S. America is a convergent boundary, where the Nazca plate converges into the S. American plate, and formed the Andes (largest mountain range in the world).
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4. (Oceanic-oceanic convergent boundary)
A 5.0 magnitude earthquake (represented by the orange dot), with a focus depth of 26.9 km (16.7 miles), ruptured south of the Mariana Islands on thursday, November 10, 2011 at 8:17 AM. The earthquake happened nearly on top of the oceanic-convergent boundary (USGS). The white arrow represents where the Pacific plate is subducting below the Philippine plate continuing to form an oceanic trench. In fact this same process produces volcanic activity and eventually creates a volcanic island arc, such as the Mariana Islands you see in the picture (Mcknight p. 384).
A 5.0 magnitude earthquake (represented by the orange dot), with a focus depth of 26.9 km (16.7 miles), ruptured south of the Mariana Islands on thursday, November 10, 2011 at 8:17 AM. The earthquake happened nearly on top of the oceanic-convergent boundary (USGS). The white arrow represents where the Pacific plate is subducting below the Philippine plate continuing to form an oceanic trench. In fact this same process produces volcanic activity and eventually creates a volcanic island arc, such as the Mariana Islands you see in the picture (Mcknight p. 384).
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5. (Transform Boundary)
A 5.6 magnitude earthquake, located in the Balleny Islands region, just north of the South Pole and south of New Zealand, ruptured on Tuesday, November 8, 2011 at 3:51:24 AM. With a depth focus of only 0.1 km (-0.1 miles), providing evidence that this is a transform boundary earthquake. Sitting on top of an oceanic-transform-fault, where the Antarctic Plate and Pacific Plate run parallel. Neither new crust, or old crust is being created, everything stays "conservative", but still produces a lot of shallow focused earthquakes such as this one (USGS).
A 5.6 magnitude earthquake, located in the Balleny Islands region, just north of the South Pole and south of New Zealand, ruptured on Tuesday, November 8, 2011 at 3:51:24 AM. With a depth focus of only 0.1 km (-0.1 miles), providing evidence that this is a transform boundary earthquake. Sitting on top of an oceanic-transform-fault, where the Antarctic Plate and Pacific Plate run parallel. Neither new crust, or old crust is being created, everything stays "conservative", but still produces a lot of shallow focused earthquakes such as this one (USGS).
Tracking Volcanoes
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1. (Shield Volcano)
Haleakala volcano forms nearly the entire eastern portion of Maui island, with a summit of 9.5 km. Inside the crater of Haleakala is a young chain of cinder cones. Located near the middle of the Pacific Plate, Haleakala and all of the Hawaii volcanoes are being fed by a huge Hot Spot far below the surface, where magma continually pressurizes up and out of the volcanoes (Smithsonian).
Haleakala volcano forms nearly the entire eastern portion of Maui island, with a summit of 9.5 km. Inside the crater of Haleakala is a young chain of cinder cones. Located near the middle of the Pacific Plate, Haleakala and all of the Hawaii volcanoes are being fed by a huge Hot Spot far below the surface, where magma continually pressurizes up and out of the volcanoes (Smithsonian).
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2. (Composite Volcano)
Mount Fuji-san is a composite volcanoe located in Japan. With a summit reaching 3776 m, Mt Fuji is the tallest and most noted volcano in Japan. Fuji is barely located on the Eurasian plate, with the Pacific plate subducting underneath it, and possibly the Philippine plate as well. With estimated subduction speeds of 92mm per year, making it a relatively active convergent boundary. Basaltic lava flows from the summit helped to form the Five Fuji Lakes on the north side. Last erupting in 1707, launching ash clear to Edo, Tokyo, giving the volcano a crater on its east side (Smithsonian).
Mount Fuji-san is a composite volcanoe located in Japan. With a summit reaching 3776 m, Mt Fuji is the tallest and most noted volcano in Japan. Fuji is barely located on the Eurasian plate, with the Pacific plate subducting underneath it, and possibly the Philippine plate as well. With estimated subduction speeds of 92mm per year, making it a relatively active convergent boundary. Basaltic lava flows from the summit helped to form the Five Fuji Lakes on the north side. Last erupting in 1707, launching ash clear to Edo, Tokyo, giving the volcano a crater on its east side (Smithsonian).
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3. (Lava Domes)
Mono-Inyo Craters, CA forms a 17-km-long group of mostly lava domes, lava flows, and tephra rings. Mono Craters were formed by the bulging up of viscous lava. Lying on the east side of the Sierra Nevada between Long Valley caldera and Mono Lake, these volcanoes stay "plugged" up by Pyroclastics usually and grow viscous lava from within, usually ending in explosive eruptions. These lava domes are part of the Sierra Nevada batholith which form many of the mountain ranges in this region. Believed to be associated with the former subduction boundary of the North American Plate (Smithsonian).
Mono-Inyo Craters, CA forms a 17-km-long group of mostly lava domes, lava flows, and tephra rings. Mono Craters were formed by the bulging up of viscous lava. Lying on the east side of the Sierra Nevada between Long Valley caldera and Mono Lake, these volcanoes stay "plugged" up by Pyroclastics usually and grow viscous lava from within, usually ending in explosive eruptions. These lava domes are part of the Sierra Nevada batholith which form many of the mountain ranges in this region. Believed to be associated with the former subduction boundary of the North American Plate (Smithsonian).
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4. (Cinder Cone)
Sunset Crater, is a Cinder Cone Volcano located north of Flagstaff, AZ. Usually, no higher than 500 m, cinder cones are the smallest volcano's. Sunset Crater is also referred to as a Fissure vent, and is the youngest vent out of the 550 in this highly volcanic region. Although, Sunset Crater is located on the North American Plate, it's most likely to far inland from the subduction of the Pacific Plate to be associated. This volcano is probably being fed by a Hot Spot deep in the earths surface (Smithsonian).
Sunset Crater, is a Cinder Cone Volcano located north of Flagstaff, AZ. Usually, no higher than 500 m, cinder cones are the smallest volcano's. Sunset Crater is also referred to as a Fissure vent, and is the youngest vent out of the 550 in this highly volcanic region. Although, Sunset Crater is located on the North American Plate, it's most likely to far inland from the subduction of the Pacific Plate to be associated. This volcano is probably being fed by a Hot Spot deep in the earths surface (Smithsonian).
Assignment Reflection
The correlation between earthquakes and volcanoes is extremely connected. Almost every single place I was tracking down one, the other was always nearby it seemed. Beings that earthquakes can even play an active role in volcanoes erupting, they seem to almost be brother and sister of natural disasters. On page 381 of the textbook, you can literally follow where all of the tectonic plates meet up and there’s guaranteed action. As far as volcanoes are concerned, these usually happen along convergent boundaries where denser rock gives way by subduction. Either ocean crust or continental crust will be pulled underneath the older crust by way of “slab pull” (Mcknight p. 382). This sub-ducting movement can either push existing magma up further into the volcanoes, creating tons of internal pressure of trapped gasses, and can also release more magma to also be pushed up. Either way, this exact same process that feeds and creates volcanoes is causing earthquakes continually whether we feel them or not.
We can’t consider all earthquakes bad, according to the USGS text, Calaveras Fault in the city of Hollister, CA has some 20,000 earthquakes a year, but many are never even felt because this stress is continually being released (USGS para. 10). Earthquakes that take lives and cost billions in damage are the ones that accumulate this stress and pressure until finally breaking and causing 6+ magnitude earthquakes. Another factor that can play into the amount of damage theses forces can produce, is by looking at their distribution. The difference between an east-coast quake and a west-coast quake is almost night and day. According to the plate tectonics research done by USGS, the continental crust on the east-coast of N. America is older rock and has not been continually cracked and fractured by earthquakes. However, stronger rock is not better when earthquakes are involved. All these cracks and fractures caused by continual earthquakes on the west-coast break up the rocks and absorb tons of the seismic energy, which means the earthquake will not travel as far or do as much damage (USGS para. 12). An east-coast earthquake of the same magnitude can almost travel 3 xs the distance of a west-coast earthquake, but in this case quantity does beat out quality and if you’re scared of dying from an earthquake, it’s much smarter to move east.
First off, I had no idea how closely related volcanoes and earthquakes actually are to each other. One thing that really got my attention about both forces was how common and frequent they are around the world, especially earthquakes. Nearly every place where ocean meets continent, there’s guaranteed to be some action. It was an eye opener to realize how frequently active our earth is, besides the constant weather and temperature changes we physically notice every, there is actually a lot of natural disasters constantly happening around the globe. The earth is cracking off yellow dots left and right, like their “going out of style”.
I understand that plate tectonics is a theory, but to me, it’s seems like a pretty reliable science in how much evidence has been gathered on it. The fact that a divergent boundary runs completely down the middle of the Atlantic Ocean, separating the Americas from Africa and Europe it pretty compelling evidence. Anybody can see how these continents could easily fit together, and I learned without a doubt in my mind that they were once together, forming the supercontinent Pangaea (McKnight p. 376). Just from studying plate boundaries and how they cause massive damage through volcanoes and earthquakes without breaking a sweat; it seems that given geological time, it was no big effort to break off the continents. You also have to wonder why the Pacific Ocean borders nearly all of the worlds’ convergent boundaries and the Atlantic Ocean carries nearly none.
One world view that definitely changed for me in learning this area of natural sciences’ is religion. Growing up in a very religious family, I mean no disrespect by believing without a doubt, that earth is billions of years old, all proven by simply understanding plate tectonics and how they move. Doesn’t have to mean that religion is wrong, but unfortunately it does prove that they seriously messed up a few dates on the creation of things. Before this course, I would have never entered a debate about the age or dates correlated with earth, but now I’d argue that confidently with science backing me up.
Another world-view I gained from studying these natural disasters was an “Oprah” bleeding heart for poor Japan; I can’t believe how many volcanoes they have on that one big island. A wiki research said that Japan is home to 120 volcanoes, which is 10% of all land volcanoes on earth. Nearly every type of boundary line is running through or around Japan. Two different subduction boundaries, both at the speed of 90+ mm/yr., are converging in towards Japan at different angles. No more wondering why they constantly get hit with every type of natural disaster on a regular basis, it makes perfect sense to me now. This assignment was definitely extensive, but I feel much more informed now, that when I hear about different natural disasters happenning all around the world, I practically have the boundaries types and plates memorized and could give a general explaination to how and why certain disasters occured.
*Work Cited
-“USGS” Earthquake Hazards Program. Google Earth website. http://earthquake.usgs.gov/earthquake.
-"USGS". Plate tectonics and people. http://pubs.usgs.gov/publications/text/tectonics.html
-“Smithsonian” . Smithsonian Institution Global Valcanism Program. Google Earth website. <http://www.valcano.si.edu/info>
-Mcknight. Physical Geography 10th ed. Pearson Education, Inc. ed. Christian Botting. Upper Saddle River, NJ, 2011.
-“USGS” Earthquake Hazards Program. Google Earth website. http://earthquake.usgs.gov/earthquake.
-"USGS". Plate tectonics and people. http://pubs.usgs.gov/publications/text/tectonics.html
-“Smithsonian” . Smithsonian Institution Global Valcanism Program. Google Earth website. <http://www.valcano.si.edu/info>
-Mcknight. Physical Geography 10th ed. Pearson Education, Inc. ed. Christian Botting. Upper Saddle River, NJ, 2011.