Environmental Geology Assignment Example | Topics and Well Written Essays - 500 words

Environmental Geology - Assignment Example motions between the larger Pacific, North America and Eurasia plates; these include the Okhotsk and Amur microplates that are respectively part of North America and Eurasia. (b) The Japan Trench subduction zone has hosted nine events of magnitude 7 or greater since 1973. The largest of these is a M 7.8 earthquake approximately 260 km to the north of the March 11 epicenter, caused 3 fatalities and almost 700 injuries in December 1994. In June of 1978, a M 7.7 earthquake 35 km to the southwest of the March 11 epicenter caused 22 fatalities and over 400 injuries. Large offshore earthquakes have occurred in the same subduction zone in 1611, 1896 and 1933 that each produced devastating tsunami waves on the Sanriku coast of Pacific NE Japan. (c) The coastline here is particularly vulnerable to tsunami waves because it has many deep coastal embayments that amplify tsunami waves and cause great wave inundations. The M 7.6 subduction earthquake of 1896 created tsunami waves as high 38 m and a reported death toll of 22,000. The M 8.6 earthquake of March 2, 1933 produced tsunami waves as high as 29 m on the Sanriku coast and caused more than 3000 fatalities. The March 11, 2011 earthquake far surpassed other earthquakes in the southern Japan Trench of the 20th century, none of which attained M8. A predecessor may have occurred on July 13, 869, when the Sendai area was swept by a large tsunami that Japanese scientists have identified from written records and a sand sheet. Ans. Eyjafjallajà ¶kull, also known as Eyjafjà ¶ll, lies south of the intersect between Icelands East Volcanic Zone (EVZ), a NE-SW trending rift system, and the E-W trending South Iceland Seismic Zone (SISZ). The EVZ is currently the main zone of divergence between the North American and Eurasian plates on the Icelandic landmass, with slightly less divergence currently occurring at the parallel Western Volcanic Zone. Eyjafjallajà ¶kull is an elongated structure somewhat resembling a shield volcano, which is