Earthquake Precursors in the Ocean, Essay Example

Better Understanding of Earthquake Precursors in the Ocean

As per the extensive researches done in earth and mineral science department, it has indicated that the properties of fluids, which are circulating in submarine fault zones, are changing over time in a process called seismic cycle. Seismic cycle is a cycle in which the strain accumulates slowly along the fault until it exceeds beyond the frictional forces, which prevent the fault from slipping. An earthquake will take place at the moment of rapture when the accumulated strain is suddenly released. A new cycle begins by accumulating strain, and it continues until the occurrence of the next rapture. The fluids circulating in the faults will undergo extremely high temperatures and tremendous pressure due to their proximity to the mid-ocean ridges. At a certain point, the fluids might reach a supercritical state. Physical properties of the supercritical state like diffusivity, density, and viscosity are intermediate to those of gases and liquids. Pressure is the determinant of variance incompressibility of supercritical fluids. As per the analysis of the studies, these changes in compressibility might trigger an earthquake. After a short period of foreshocks, an earthquake will occur[1].

As per the research conducted by the students of earth and mineral science department, before an earthquake occurs, there are early warning signs, which indicate that an earthquake will occur anytime. The warning signs are known as the seismic precursors. There are many types of earthquake precursors, which have been studied and proved by the scientists. The earthquake precursors include; animal behaviors, gas or fluid emissions, thermal signals, seismic signals, electrical signals, and ground movements. According to a geological study in United States, it indicated that animals relocated several days before the earthquake occurred in Greece. Animals are very sensitive to earthquakes more than human beings are because they feel the first tremors in seconds. All these are signs, warnings, and signals indicating that an earthquake will occur in a very short time. The signals and signs are very important it enable human beings to predict the occurrence of the earthquake and remain prepared for the disaster. The preparedness includes moving to save areas, together with movable properties to save lives, and avoids the destruction of properties. In addition, the results of the model help in guiding future researchers in detecting seismic precursors. Seismic precursors will be applied in earthquake predictions and advises to the community residents and the public. Supercritical fluids require only specific conditions. Supercritical fluids are encountered on land in volcanic and hydrothermal areas like Iceland.

Near the transform faults, two antagonistic effects usually play under the effect of tectonic forces. The first one is an increase in the shear stress, which tends to weaken resistance and break rocks in the transform fault. The second one is the decrease in pressure of the fluid in the fault resulting to a major increase in the volume of pore space between the rock beds. The effect will act as the stabilizing suction cup which counterbalance the weaken rock beds. As a result, it will delay the triggering of the earthquake. For the counterbalancing mechanism to be efficient, it will depend on the fluid compressibility[2]. When the fluid compressibility is high, counterbalancing mechanism will be more efficient. In addition, it will be higher when the fluids are present in the liquid state because of low compressibility causing a dramatic decrease in fluid pressure. The decrease will be as a result of the smaller increase in volume. For the gas type fluids, which have higher compressibility, its suction cup effect will be nearly inexistent.

Earth and mineral science has been very important in understanding how counterbalancing mechanism will fail during the fault slip when a change in the liquid gas state of the fluid occurs. Failing of counterbalancing mechanism will allow the triggering of a major shock. The transition occurs in several days with numerous signs, which include many small foreshocks. Subsea observatories can be compared with the laboratory in the seafloor. Since they are equipped with a series of instruments, they can record various types of data, which can be used in studying geophysical events occurring in the ocean[3]. Before the seismic waves are released, they are in different levels underground. The point at which the seismic waves originate is the earthquake focus. The earthquake focus is also referred to as the hypocenter. The foci that cause the natural earthquakes are found in different depths in the underground surface. The shallow is located at between 1-100 kilometers, intermediate is between 70 – 300 kilometers and a deep one is at 300 kilometers or below. Shallow earthquakes cause serious damages because it releases three-quarter of the total energy of earthquakes in the world. As compared to the deep and intermediate earthquakes, shallow earthquakes occur at any type of plate boundaries like subduction zones or the ocean trenches[4].

According to college of earth and mineral science, earthquakes cause serious damages to human beings, animals, plants, and property destruction. It has been a serious disaster in many countries, and it needs advanced preparation such that destructions and loss of lives can be controlled or avoided. This can be done only by monitoring the seismic precursors signs and warnings shown by animal movement, thermal signals, ground movements and many others.

Fault system can be created to estimate the fault creep and reduce the potential size of the next rapture. It is because the earthquake is a continuous cycle of accumulation, release and re-accumulation. Fault creep will be introduced, which is the slip and slow release of strain on the upper part of the earth’s crust. A great greater will be released in seconds, and no fault creeps will occur because the fault will be locked, and the stress will build until an earthquake occurs.

References

Géli, L., & Henry, P. (2014). Seismic precursors linked to super-critical fluids at oceanic transform faults. Nature Geoscience, 7(10), 757-761.

Blackett, M. & Malamud, B. D. (2011). Exploring land surface temperature earthquake precursors: A focus on the Gujarat (India) earthquake of 2001. Geophysical Research Letters, 38(15).

Chmyrev, V. & Vallianatos, F. (2013). Detection and monitoring of earthquake precursors: TwinSat, a Russia–UK satellite project. Advances in Space Research, 52(6), 1135-1145.

[1] Blackett & Malamud (2011). Exploring land surface temperature earthquake precursors: A focus on the Gujarat (India) earthquake of 2001. Geophysical Research Letters p. 15.

[2] Chmyrev & Vallianatos (2013). Detection and monitoring of earthquake precursors: TwinSat, a Russia–UK satellite project. Advances in Space Research, p. 1139.

[3] Blackett, M. & Malamud, B. D. (2011). Exploring land surface temperature earthquake precursors: A focus on the Gujarat (India) earthquake of 2001. Geophysical Research Letters, 38(15).

[4] Géli, L. & Henry (2014). Seismic precursors linked to super-critical fluids at oceanic transform faults. Nature Geoscience, p. 760