What Is Earthbag Construction?

In 1910, a former Yugoslav seismologist Moholovich discovered that the seismic wave was refracted 50 kilometers below the ground. He believes that this zone of refraction is the interface between the crust and the different substances below it. In 1914, the German seismologist Gutenberg found that there was another interface of different materials at a depth of 2900 kilometers underground. Later, to commemorate them, they named the two faces "Moho" and "Gutenberg", and divided the earth into three crusts, the crust, the mantle and the core. The structure of the earth is similar to that of other terrestrial planets. It is layered, and these layers can be determined by their chemical and rheological properties. The earth has a silicon-rich crust, a very viscous mantle, a liquid outer core and a solid inner core. This knowledge of the Earth's internal structure comes from physical evidence and some inferences, including volcanic material and seismic waves.

Earth structure

From inside to outside: core-mantle-crust. From outside to inside: crust-mantle-core.

The internal structure of the earth refers to the layered structure inside the earth. According to the change of the propagation speed of seismic waves at different depths in the ground, the interior of the earth is generally divided into three concentric spherical layers: the core, the mantle, and the crust. The central layer is the core; the middle is the mantle; the outer layer is the crust. The crust and mantle are separated by the Moho boundary, and the mantle and core are separated by the Gutenberg boundary. Earthquakes generally occur in the crust. The inside of the crust is constantly changing, and thus the force is generated, which deforms, fractures, and displaces the crust rock layer, and an earthquake occurs. Super earthquakes refer to large earthquakes with extremely strong seismic waves. However, its occurrence accounts for 7% ~ 21% of the total earthquake, and the damage degree is several times that of the atomic bomb. Therefore, the impact of super earthquakes is very extensive and destructive.

Earth tectonic earthquake

An earthquake is a phenomenon in which the local medium inside the earth ruptures sharply and generates shock waves that cause ground vibrations within a certain range. Earthquake is the rapid vibration of the earth's surface. It was also called ground motion in ancient times. Like wind, rain, and lightning, it is a natural phenomenon that often occurs on the earth. Earthquake vibration is the most intuitive and common manifestation of earthquakes. Strong earthquakes that occur on the sea floor or in coastal areas can cause huge waves, called tsunamis. Earthquakes are extremely frequent, with about 5 million earthquakes occurring worldwide each year. Today the probe can travel in the outer space of the solar system, but has no reach for the interior of the earth under human feet. At present, the deepest borehole in the world is only 12 kilometers, and the crust has not penetrated. Scientists can only hint at the secrets of Earth by studying earthquake waves, geomagnetic waves, and volcanic eruptions.

Earth's tectonic crust

The crust is the surface layer of the earth, and it is also the place where humans live and engage in various production activities. The crust is actually composed of multiple groups of fractures and many sized blocks. The exterior of the crust is undulating, so the thickness of the crust is not uniform: the average thickness of the crust below the continent is about 35 kilometers. The thickness of the crust on the plateau is more than 65 kilometers; the thickness of the crust under the ocean is only about 5 to 10 kilometers; the average thickness of the entire crust is about 17 kilometers, which is only a thin layer compared with the average radius of the earth at 6371 kilometers. The upper layer of the crust is a granite layer (magmatic rock), mainly composed of silicon-aluminum oxide; the lower layer is a basalt layer (magmatic rock), mainly composed of silicon-magnesium oxide. Theoretically, the temperature and pressure inside the crust increase with the depth, and the temperature increases by 1 ° C every 100 meters. Drilling results in recent years have shown that the temperature rises by 2.5 ° C for every 100 meters of depth when it reaches a depth of more than 3 kilometers, and the temperature reaches 200 ° C at a depth of 11 kilometers. The vast majority of crustal rocks known to date are less than 2 billion years old, and even the oldest stone in Greenland, Denmark, is only 3.9 billion years old; astronomers have verified that the earth has a history of about 4.6 billion years, which indicates that the earth s crust The layers of rock are not the original crust of the earth, but are later formed by the material inside the earth through volcanic and orogenic activities.

Earth tectonic mantle

Below the crust is the middle layer of the earth, called the "mantle", with a thickness of about 2865 km. It is mainly composed of dense rock-forming materials. This is the layer with the largest volume and the largest mass inside the earth. The mantle can be divided into upper and lower mantles. It is generally believed that there is a soft stratosphere on the top of the upper mantle, which is presumably due to a large concentration of radioactive elements, which is transformed and exothermic, and the rocks are melted, which may be the source of magma. The mantle above the stratosphere and the crust together form the lithosphere. The temperature, pressure and density of the lower mantle increased, and the material was in a plastic solid state.

Earth tectonic core

Under the mantle is the core, which has an average thickness of about 3400 kilometers. The earth core can be divided into three cores: the outer core, the transition layer and the inner core. The outer core is about 2080 kilometers thick, and the material is generally liquid and can flow. The thickness of the transition layer is about 140 kilometers. The inner core is a ball with a radius of 1250 kilometers. Mind, the substance is probably solid, mainly composed of metal elements such as iron and nickel. The temperature and pressure of the Earth's core are very high. It is estimated that the temperature is above 5,000 ° C, the pressure is above 132 million kPa, and the density is 13 grams per cubic centimeter. Some American scientists have experimentally calculated that the temperature at the junction between the mantle and the core is 3500 ° C Above, the temperature at the junction of the outer core and the inner core is 6300 ° C, and the core temperature is about 6600 ° C. The average density of the earth is 5,515 kg / m3. Since the average density of surface matter is only about 3000 kg / m3, we can know that there is more dense matter in the core area of the earth. More information about the Earth's core comes from seismological research.

Seismological measurements show that the earth's core consists of two parts: a solid core with a radius of 1220 kilometers and a liquid outer core wrapped around it, with a total radius of 3400 kilometers. The solid core was discovered by Inge Lehmann in 1936 and consists mainly of iron and nickel.

In the early Earth, 4.5 billion years ago, the high-temperature melting state caused heavier matter to sink to the center of the earth, and lighter matter to float to the crust. This process is called planetary differentiation. The composition of the earth's core can therefore be inferred to be 80% iron, as well as nickel, and some light elements. Other heavy elements, such as lead and uranium, are either too low or combined with other light elements and remain in the earth's crust. The inner core is even thought to be composed of iron crystals. [2] [3]

The outer core of the liquid is wrapped around the inner core and is also composed of iron and nickel, with a small amount of light elements.

Recent studies have shown that the innermost part of the Earth's core may be rich in gold, platinum, and other iron-philic elements. [4]

The composition of the earth has a lot to do with the composition of ordinary chondrites and the exterior of the sun [5] [6]. The composition of the earth is similar to ordinary chondrites, but completely different from another refractory pyrophyllite chondrites. In the early 1940s, many scientists, including Francis Birch, built geophysics on the basis of this research. The reason why the two meteorites are so different is that the environment in which the refractory pyrophyllite meteorite is generated must be an extremely hypoxic environment. This allows some or all of the oxygen-loving elements to remain in the same alloy as the core.

Generator theory holds that convection in the outer core and the Coriolis effect create a magnetic field for the earth. The inner core cannot maintain a stable magnetic field because it is higher than the Curie temperature, but it may stabilize the magnetic field generated by the outer core.

Recent studies have shown that the kernel may turn faster than other parts of the earth [7]. In August 2005, some geophysicists published a paper in Science, claiming that the inner core of the earth turns 0.3 to 0.5 degrees more than the surface every year [8] [9].

Modern research suggests that there are three sources of geothermal gradients: waste heat during the formation of the earth, decay of radioactive elements, and solidification within the core of the earth.