The Most Common Causes Of Tsunamis Are Underwater Earthquakes. To Understand Underwater Earthquakes, You Must First Understand Plate Tectonics. The Theory Of Plate Tectonics Suggests That The Lithosphere, Or Top Layer Of The Earth, Is Made Up Of A Series Of Huge Plates. These Plates Make Up The Continents And Seafloor. They Rest On An Underlying Viscous Called The Asthenosphere.

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The most common causes of tsunamis are underwater earthquakes. To understand underwater earthquakes, you must first understand plate tectonics. The theory of plate tectonics suggests that the lithosphere, or top layer of the Earth, is made up of a series of huge plates. These plates make up the continents and seafloor. They rest on an underlying viscous called the asthenosphere.

Think of a pie cut into eight slices. The pie crust would be the lithosphere and the hot, sticky pie filling underneath would be the asthenosphere. On the Earth, these plates are constantly in motion, moving along each other at a speed of 1 to 2 inches (2.5-5 em) per year. The movement occurs most dramatically along fault lines (where the pie is cut). These motions are capable of producing earthquakes and volcanism, which, when they occur at the bottom of the ocean, are two possible sources of tsunamis.

When two plates come into contact at a region known as a plate boundary, a heavier plate can slip under a lighter one. This is called subduction. Underwater subduction often leaves enormous “hand prints” in the form of deep ocean trenches a long the seafloor. In some cases of subduction, part of the seafloor connected to the lighter plate may “snap up” suddenly due to pressure from the sinking plate. This result in an earthquake. The focus of the earthquake is the point within the Earth where the rupture first occurs, rocks break and the first seismic waves a re generated. The epicenter is the point on the seafloor directly above the focus.

When this piece of the plate snaps up and sends tons of rock shooting upward with tremendous force, the energy of that force is transferred to the water. The energy pushes the water upward above normal sea level. Th is is the birth of a tsunami. The earthquake that generated the December 26, 2004 tsunami in the Indian Ocean was a 9.0 on the Richter scale – one of the biggest in recorded history.

The main idea of this text is that …

a. A deep ocean trench is a result of an earthquake
b. The energy of subduction can lead to earthquakes
c. Plate tectonics lead to an earthquake and volcanism
d. Tsunamis in Indian Ocean are biggest in the history
e. Strong movements of undersea fault lines cause tsunami


Jawaban untuk soal di atas adalah e. Strong movements of undersea fault lines cause tsunami.

Soal ini menanyakan ide pokok dari teks.

Pada paragraf pertama terdapat kalimat “The most common causes of tsunami are underwater earthquakes” yang artinya “Penyebab tsunami yang paling umum adalah gempa bumi bawah laut.”

Selain itu pada paragraf kedua terdapat pernyataan pendukung paragraf sebelumnya, yaitu “The movement occurs most dramatically along fault lines” yang artinya “Pergerakan terjadi paling dramatis di sepanjang garis patahan.”

Kemudian pada paragraf selanjutnya adalah pendukung tentang terjadinya tsunami akibat pergeseran kuat di laut.

Berdasarkan kalimat tersebut, dapat disimpulkan bahwa teks ini berbicara tentang “Strong movements of undersea fault lines cause tsunami” yang artinya “Terjadinya tsunami akibat pergeseran kuat patahan bawah laut.”

Jadi, jawaban yang tepat adalah e. Strong movements of undersea fault lines cause tsunami.


Semoga jawaban diatas dapat membantu kawan belajar ya. apabila ada pertanyaan silakan berkomentar dibawah ini.


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