Tectonic plate

• Tectonics refers to the changes in the Earth’s crust due to the movement of tectonic plates.
• Earth’s crust process includes mountain formation, changing process of the shape of the earth’s crust, earthquake, and volcanism.
• Donkey Ear's Peak, prior to earthquake damage which reduced the size of the prominences.
• The 2015 Sabah earthquake (Malay: Gempa Bumi Sabah 2015) struck Ranau, Sabah, Malaysia with a moment magnitude of 6.0 on 5 June, which lasted for 30 seconds.
• The earthquake was the strongest to affect Malaysia since the 1976 Sabah earthquake.
• The lithosphere is the solid upper mantle and crust broken into plates that move over the asthenosphere.
• The asthenosphere is part of the upper mantle that behaves plastically and slowly flows.
• The lithospheric plate is the ~100-km-thick surface of the Earth that contains crust and part of the upper mantle, is rigid and brittle, and fractures to produce earthquakes.
• The asthenosphere is the hotter upper mantle below the lithospheric plate that can flow like silly putty and is a viscoelastic solid, NOT liquid.
• The Earth’s crust is divided into plates which are moved in various directions, causing them to collide, pull apart, or scrape against each other.
• Earthquake magnitude: scales based on rupture dimensions (equivalent to energy released) M o = seismic moment, which is calculated as m * A * d, where m is the shear modulus of rock; A is the rupture area, and d is displacement.
• More ground shaking occurs in poorly consolidated (loose) sediments than solid bedrock.
• Buildings need to be constructed to withstand earthquakes in areas where they are prevalent.
• Ruptured gas lines from earthquakes is one of the major hazards.
• Power outages, water shortages and interruptions in communication can also be caused by earthquakes.
• Seiches are the rhythmic sloshing of water in lakes, reservoirs, and enclosed basins.
• Use seismograms from at least three geographic locations to locate epicentre by triangulation.
• The construction design and resonance frequency can have a major impact on the amount of damage.
• Ground rupture refers to areas where the land splits apart causing a rupture, often long linear features.
• Landslides and ground subsidence occur when the land moves quickly, potentially causing a lot of damage and potential loss of life.
• Tsunamis, or seismic sea waves, are waves that occur in the open ocean, with heights usually less than 1 meter, but can exceed 30 meters when they reach shallower coastal waters.
• Use nomogram to estimate distance from earthquake (S-P interval) and magnitude (join points on S-P interval scale and S amplitude scale).
• Land shift is an example of a change in the land, such as the uplift of the sea floor, which has been known to occur during an earthquake.
• Divergent plate boundaries are marked by the mid-ocean ridge where new oceanic lithosphere forms.
• When two oceanic plates collide, the older denser slab will sink back into the mantle forming a subduction zone.
• The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench.
• The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.
• Trench systems occur for both continent-ocean and ocean-ocean boundaries.
• During the process of elastic rebound, slippage at the weakest point (the focus) occurs after buildup of strain.
• Examples of divergent plate boundaries include Iceland and the East African Rift System.
• Earthquakes can be caused by faults, the motion of magma, and explosions (e.g volcanoes or nuclear bombs).
• Plates are made of rigid lithosphere which is composed of the crust and the upper part of the mantle.
• Continent-oceanic crust collision, also known as subduction, forms mountains, for example, the Andes.
• Secondary (S) waves travel through solids.
• Minor plates include Nazca, Indian, Arabian, Philippine, Caribbean, Cocos, Scotia, Juan de Fuca.
• Accumulated strain leads to fault rupture.
• The world's deepest parts of the ocean are found along trenches, for example, the Mariana Trench is 11 km deep.
• Energy released radiates in all directions from its source, the focus (see below).
• Ocean-ocean collision forms mountains, for example, Mount St. Helens.
• At plate boundaries, volcanic activity occurs and earthquakes occur.