The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken up into tectonic plates. The Earth's lithosphere is composed of seven or eight major plates (depending on how they are defined) and many minor plates. Where the plates meet, their relative motion determines the type of boundary: convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The relative movement of the plates typically ranges from zero to 100 mm annually.[2]
Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the lithosphere remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories, since disproven, proposed gradual shrinking (contraction) or gradual expansion of the globe.[3]
Tectonic plates are able to move because the Earth's lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by tidal forces of the Sun and Moon. The relative importance of each of these factors and their relationship to each other is unclear, and still the subject of much debate.
Answer:
Mantaro River
Explanation:
The source of the Amazon River has been attributed to the headwaters of three different Peruvian rivers in the high Andes: the Marañón, the Apurímac, and the Mantaro. Explorers and scholars have identified each of the three rivers as being the source of the Amazon under one of the three definitions.
The water cycle or hydrologic cycle is the continuous movement of water between the earth's surface and the air. Water molecules move from the atmosphere (or air) to the earth's surface and back again. Water moves from the atmosphere to the earth's surface via rain, snow, sleet or hail. It moves back to the atmosphere via evaporation. The sun's energy is the catalyst for the movement of water between the atmosphere and the earth's surface.
Answer:
The podcast addresses secondary risks in the aftermath of an earthquake. These risks include damaged structures, the disruption of rivers due to debris buildup, and changes in groundwater. The podcast also points out that landslides are a common secondary effect of earthquakes. The podcast can help inform Japanese leaders of such risks so that they might successfully develop policies and procedures for handling future earthquakes and the recovery from their ensuing damage.
Explanation: Exact answer from Tutorial
