teori plat tektonik

Teori Plat TektonikTeori Plat Tektonik

Teknik GempaTeknik GempaDIII Teknik SipilDIII Teknik Sipil

Jurusan Pendidikan Teknik Sipil dan PerencanaanJurusan Pendidikan Teknik Sipil dan PerencanaanFT UNYFT UNY

20092009

Fisiografi : bentuk permukaan planet Fisiografi : bentuk permukaan planet

• Divisi dasar permukaan bumi memperlihatkan Divisi dasar permukaan bumi memperlihatkan bahwa permukaan bumi dibagi atas daerah bahwa permukaan bumi dibagi atas daerah kontinental dan daerah lautan, dimana daerah kontinental dan daerah lautan, dimana daerah lautan mengambil sekitar 60% luas daerah lautan mengambil sekitar 60% luas daerah permukaan dan 40% diambil oleh kontinental. permukaan dan 40% diambil oleh kontinental.

• Sebuah Sebuah transecttransect, atau potongan melintang, , atau potongan melintang, memotong di sepanjang kontinen hingga ke lautan memotong di sepanjang kontinen hingga ke lautan memperlihatkan sebagian divisi-divisi fisiografi memperlihatkan sebagian divisi-divisi fisiografi utama. utama.


• Gunung-gunung merupakan bagian yang Gunung-gunung merupakan bagian yang terelevasi naik dari kontinen dan terelevasi naik dari kontinen dan membentuk daerah yang relatif kecil di membentuk daerah yang relatif kecil di permukaan bumi di atas permukaan laut. permukaan bumi di atas permukaan laut.

• Kebanyakan daerah luasan kontinental Kebanyakan daerah luasan kontinental berada di elevasi di bawah 1000 kaki (300 berada di elevasi di bawah 1000 kaki (300 m), dengan gunung yang tertinggi mencapai m), dengan gunung yang tertinggi mencapai hampir 30000 kaki (8854 m). hampir 30000 kaki (8854 m).


• Pada sisi yang berkebalikan dari spektrum, dasar lautan Pada sisi yang berkebalikan dari spektrum, dasar lautan memiliki kedalaman tipikal antara 2,5 – 3 mil (4 – 5 km) memiliki kedalaman tipikal antara 2,5 – 3 mil (4 – 5 km) dengan transisi yang kasar ke atas hingga ke garis pantai dengan transisi yang kasar ke atas hingga ke garis pantai dan transisi ke bawah hingga ke beberapa palung yang dan transisi ke bawah hingga ke beberapa palung yang sangat dalam dengan kedalaman lebih dari 36000 kaki sangat dalam dengan kedalaman lebih dari 36000 kaki (11040 m). (11040 m).

• Garis pantai merupakan daerah-daerah yang sangat Garis pantai merupakan daerah-daerah yang sangat dinamis dimana daratan bertemu dengan lautan dan secara dinamis dimana daratan bertemu dengan lautan dan secara konstan bergeser ke belakang dan ke depan terhadap waktu konstan bergeser ke belakang dan ke depan terhadap waktu geologis sebagai sebuah respon terhadap perubahan-geologis sebagai sebuah respon terhadap perubahan-perubahan ketinggian air laut. perubahan ketinggian air laut.

Tipe-tipe pergerakan lempeng plat Tipe-tipe pergerakan lempeng plat tektoniktektonik

• Divergent Plate BoundaryDivergent Plate Boundary• Convergent Plate BoundaryConvergent Plate Boundary• Transform Plate BoundaryTransform Plate Boundary

Divergent Plate BoundaryDivergent Plate Boundary

• Divergent plate boundaries are axes of Divergent plate boundaries are axes of spreading where a plate splits and is spreading where a plate splits and is pulled apart. These boundaries are pulled apart. These boundaries are uplifted by upwelling heat and uplifted by upwelling heat and characterized by tensional stresses that characterized by tensional stresses that produce block faulting, fractures and produce block faulting, fractures and open fissures. Basaltic magma derived open fissures. Basaltic magma derived from partial melting of the mantle is from partial melting of the mantle is injected into the fissures and extruded injected into the fissures and extruded to form new seafloor. to form new seafloor.

• The initial rift zone in the disruption of The initial rift zone in the disruption of a continent is marked by the a continent is marked by the introduction of oceanic crust between introduction of oceanic crust between continental crust blocks and a general continental crust blocks and a general uplift. These oceanic-to-continental uplift. These oceanic-to-continental crust boundaries are passive margins crust boundaries are passive margins and tectonic activity is minor once and tectonic activity is minor once separation is achieved. separation is achieved.

Divergent Plate BoundaryDivergent Plate Boundary

• At the present time, East Africa is bowed upward in a At the present time, East Africa is bowed upward in a broad arch which is splitting at the crest, forming a linear broad arch which is splitting at the crest, forming a linear rift valley marked by volcanic activity and the formation rift valley marked by volcanic activity and the formation of pillow lava . This is a first step in the passive margin, of pillow lava . This is a first step in the passive margin, divergent boundary. As the process continues, the rift floor divergent boundary. As the process continues, the rift floor will sink and oceanic crust will grow. will sink and oceanic crust will grow.

• There is already oceanic crust in the Afar region of the There is already oceanic crust in the Afar region of the African rift valley. As the margins spread, the flow will African rift valley. As the margins spread, the flow will cool and subside, forming an oceanic area like the Red cool and subside, forming an oceanic area like the Red Sea. The passive margins are relatively free of mountain Sea. The passive margins are relatively free of mountain chains and tectonic activity since they lie within a plate.chains and tectonic activity since they lie within a plate.

Convergent Plate BoundaryConvergent Plate Boundary

• Plate convergence, where plates collide, are tectonically Plate convergence, where plates collide, are tectonically active with complicated geological processes, including active with complicated geological processes, including igneous activity , crustal deformation, and mountain igneous activity , crustal deformation, and mountain building (orogeny). The collision and subduction of plates building (orogeny). The collision and subduction of plates may follow many patterns, but several basic responses can may follow many patterns, but several basic responses can be related to modern tectonic situations.be related to modern tectonic situations.

• When oceanic crust meets continental crust, the oceanic When oceanic crust meets continental crust, the oceanic plate subducts. As the Nacza plate moves under South plate subducts. As the Nacza plate moves under South America, earthquakes and volcanic activity are associated America, earthquakes and volcanic activity are associated with the Andes. Subduction destroys oceanic crust and with the Andes. Subduction destroys oceanic crust and reduces the oceanic area.reduces the oceanic area.

Convergent Plate BoundaryConvergent Plate Boundary

Transform Plate BoundaryTransform Plate Boundary• Transform Plate Boundaries are locations where two plates Transform Plate Boundaries are locations where two plates

slide past one another. The fracture zone that forms a slide past one another. The fracture zone that forms a transform plate boundary is known as a transform fault. transform plate boundary is known as a transform fault. Most transform faults are found in the ocean basin and Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges. A smaller number connect offsets in the mid-ocean ridges. A smaller number connect mid-ocean ridges and subduction zonesconnect mid-ocean ridges and subduction zones

• Transform faults can be distinguished from the typical Transform faults can be distinguished from the typical strike-slip faults because the sense of movement is in the strike-slip faults because the sense of movement is in the opposite direction (see illustration above). A strike-slip opposite direction (see illustration above). A strike-slip fault is a simple offset, however, a transform fault is fault is a simple offset, however, a transform fault is formed between two different plates, each moving away formed between two different plates, each moving away from the spreading center of a divergent plate boundary. from the spreading center of a divergent plate boundary. When you look at the transform fault diagram above, When you look at the transform fault diagram above, imagine the double line as a divergent plate boundary and imagine the double line as a divergent plate boundary and visualize which way the diverging plates would be visualize which way the diverging plates would be moving.moving.

Transform Plate BoundaryTransform Plate Boundary

teori plat tektonik

Documents