Volcano monitoring technique indications that a volcanic eruption could be poised to explode can be detected only if the volcano is carefully and consistently monitored. The volcanic monitoring technique aims at finding the precursory phenomenon that is described and observing the movements of magma under volcanoes.
The United States Geological Survey is responsible for complete volcano monitoring programs throughout regions like Pacific Northwest, Alaska, and Hawaii. The most precise methods to determine the location and motion of magma in volcanoes are by using seismology and studying the flow of seismic waves in the volcano.
These could be generated naturally by earthquakes that occur beneath the volcano, or by the seismic energy generated by scientists who trigger explosions and observe how the energy travels throughout the volcanic ash. Certain kinds of seismic waves pass through magma-like fluids (compression alp-waves, also known as compression) while other kinds of seismic waves are not (shear and S-waves).
The magma’s position underneath a volcano is established by triggering an explosion on the other end of the volcano, and using seismic receivers placed within the volcanic area to determine the location of a “shadow zone” where P-waves are detected, however, Swaves aren’t.
The magma-rich body that forms the shadow zone is traced to three-dimensional space making use of data from the various earthquake receivers. The repeated experiments over time could follow the movements that the magma is making. Precursory phenomena like lava flows are also tracked to monitor their evolution in time, which will improve estimates of upcoming eruptions.
The temperature changes of the surface are monitored by satellite thermal images and also other changes, including changes in the structure of released gases, are also monitored. Other potential precursors could be observed in changes to physical properties, for instance, magnetic and electrical fields surrounding volcanic prior eruptions.
Therefore, the changes in the geochemical properties of the gases and fluids that come from volcanic vents and fumaroles are indicators of activity under volcanoes. The changes are largely influenced by the speed of degassing of magma under the volcano, as well as interactions between the magma and water systems underground.
Gas monitoring is generally focused on looking for extreme changes or non-equilibrium conditions in the sulfurous and hydrochloric acid, carbonic acids nitrogen, and oxygen and hydrogen sulfur. Convergent margin andesitic varieties of explosive volcanoes exhibit the most variation in the composition of the gases prior to eruption because the magma from these volcanoes is mostly derived from the fluids transported deep by submarine oceanic slabs.
The details of geophysical volcanic monitoring are complex and have experienced explosive growth in technology over the last few years. One of the most common techniques used for monitoring volcanoes nowadays is to use a large array of extremely sensitive seismographs referred to as broadband seismometers, which can detect many different types of earthquakes.
Broadband seismometers are able to detect seismic waves at frequency ranges that range from 0.1-100 seconds, which is a significant improvement over previous seismometers with short periods of time that could detect only frequencies of 0.1-1 second. Small earthquakes in swarms, also known as harmonic tremors can be associated with the eruption of magma that moves upwards or laterally under the volcano. They typically increase in frequency prior to an eruption.
They are distinct from tectonic seismic events that typically have a predictable pattern of primary shock and aftershocks. Based on the analysis of seismic data collected from a variety of seismographs, geologists can create three-dimensional images of the region beneath the volcano, similar to a topographic scan or CAT scan, and thus monitor the distribution and movement of magma under the volcano. As the magma moves close to its surface eruptions are most likely.
The magma’s movement is sometimes accompanied by explosion-type earthquakes that are easily distinguished from earthquakes that are triggered by the movement of faults. The majority of eruptions that cause volcanic explosions are caused by bulging, swelling or any other deformation of the earth’s surface of the volcano. One method to anticipate eruptions is the measurement and monitoring of this bulging.
Ground deformation is typically determined using a variety tools. Certain instruments are able to precisely measure the shift on the level surface and others track tilt while some make electronic distance measurements. These kinds of measurements have been increasing in accuracy because of precision Global Positioning System instruments that permit measurements of latitude, longitude, and elevation which are precise to less than a half inch (1 centimeter) even in the most remote areas.
A few observations have been observed regarding events that are a precursor to eruptions, even though the causes aren’t fully recognized. Magnetic and electrical fields have been found to exhibit changes at a variety of volcanoes, particularly those with basaltic magma with an extremely high amount of magnetized minerals. These changes could be related to the motion of magma (and magnetic minerals) or changes in the gas’s movement, heating as well as other reasons.
Recent research has linked small shifts in the microgravity fields surrounding active volcanoes, specifically explosive andesitic volcanoes to changes in the magma flow underneath the cones. Satellite images are currently used to trace features and volcanic deposits as well as to observe eruptions.
There’s a vast variety of different kinds of features satellites can detect and observe, which includes many of the visible and other areas that comprise the spectrum electromagnetic. Variations in the volcanic surface as well as the development of domes and the opening and closing of fissures within the volcano are visible through satellites. Certain satellites employ radar technology that allows seeing through clouds as well as certain ash. They are especially useful in studying volcanoes located in far locations and in adverse weather conditions at night, or during eruptions.
Additionally, a volcano monitoring technique known as radar interferometers is able to detect ground deformation on a smaller than an inch (cm) dimension, and show the appearance of bulges and swelling due to the enlargement of magma under the volcano. Satellites are able to detect and monitor the surface temperature, and some can also monitor eruption cloud formation, ash plumes, and other atmospheric phenomena at a global level.
This volcano monitoring technique provides seismologists and geologists the tools to be able to make better predictions about when eruptions could occur, thereby saving lives and properties. When all the methods are integrated into a single monitoring program, scientists can better determine when the next eruption will occur.
Many volcano monitoring technique is used in America. The United States uses many different kinds of observation to ensure security for citizens. They include the Alaskan Volcano Observatory, the Cascades Volcano Observatory, and the Hawaiian Volcano Observatory.