Earthquakes, tremors and quakes are terms that describe movements within the Earth's crust. However, the term "earthquake" is primarily associated with major seismic events and is the most commonly used.
In this article we are going to tell you What is seismicity and why is it important to study it?.
What is seismicity?
Seismicity It is a measure of seismic activity at a specific location based on frequency and intensity over time.A place or region may have high or low seismic activity, which is related to the frequency with which earthquakes occur in that place.
These phenomena, which originate inside the Earth, propagate outwards in all directions in the form of waves. Earthquakes, which occurThey are characterized by their short duration and variable intensity, they are the result of the abrupt release of energyInterestingly, they also have a beneficial aspect, as they provide valuable information about the Earth's interior. Today, the technique known as seismological or seismic tomography allows for a broad understanding of the internal structure of our planet.
Causes of earthquakes
While the main cause of earthquakes is the interaction between tectonic plates, it is not the only contributor. Any process capable of accumulating significant energy within rocks has the potential to produce earthquakes, the magnitude of which is influenced by several factors, including the extent of the area of stress concentration. The most important causes can be listed in order of importance as follows:
- Tectonic: These earthquakes arise from the movement of the tectonic plates that make up the Earth's crust, impact large regions and are the main cause of most seismic events.
- Volcanic: This phenomenon is rare; when an eruption occurs with great intensity, it produces significant shocks that impact mainly the surrounding areas; however, its area of influence is limited compared to those caused by tectonic activity.
- Sinkings: The erosive effects of groundwater acting within the crust create voids, which eventually collapse under the weight of the overlying material. This collapse gives rise to vibrations known as earthquakes, which are infrequent and of minimal extent.
- Landslides: The immense weight of mountains exerts a significant force that can cause them to flatten and can trigger earthquakes through the occurrence of landslides along faults, however, these events are not usually of considerable magnitude.
Why is it important to study seismicity?
An earthquake produces a range of effects, including earth tremors, fires, seismic waves at sea and landslides, as well as disrupting essential services, inducing panic and causing psychological trauma. The extent of the damage is influenced by several factors: the time of the earthquake, its magnitude, proximity to the epicenter, the geological characteristics of the region, the types of construction of the different buildings, the population density and the duration of the tremor.
Earthquakes are quantified and measured using intensity and magnitude scales. The Mercalli scale, also known as the intensity scale, is tied to a particular location and is determined based on the damage or effects experienced by people and their structures. Instead, The Richter scale, which measures magnitude, refers to the energy released during an earthquake and is represented numerically through data collected by seismographs. This classification method is the most recognized and widely used to categorize earthquakes.
It is important to study seismic activity in order to reduce the impacts caused to the population and reduce the risk of damage to people and infrastructure.
Types of earthquakes and their impacts
Foreshocks are typically characterized by smaller magnitude tremors that occur before significant seismic events, marking the initial stages of fracturing in the area that will become the focal point of the major earthquake. Identifying these foreshocks presents challenges, as they cannot be easily distinguished from the typical seismic activity of a region. Consequently, It is usually only after subsequent seismic events that an earthquake can be classified as foreshock.
Aftershocks are a phenomenon observed by seismologists after a significant earthquake, characterized by lower magnitude tremors that occur in the vicinity of the focus of the main earthquake. These aftershocks are likely to arise from the mechanical readjustment of the affected area, which does not return to its equilibrium state immediately after the primary tremor, as they occur within the rupture zone of the main event. Initially, the frequency of these aftershocks is high, but gradually decreases over time.
Analysis of aftershocks from a major earthquake It has been essential to estimate the dimensions of the rupture zone and contribute to various scientific investigations.From a societal perspective, understanding their occurrence is essential to adopting a proactive approach. Aftershocks, which are smaller in magnitude, can occur minutes, days, or even years after the initial event, with a frequency ranging from a handful to hundreds of occurrences.
Seismic predictions are essential to understanding the recurrent nature of earthquakes. The energy that builds up in a given location must eventually be released, leading to the occurrence of new seismic events. These phenomena tend to manifest periodically in the same geographic areas, so in those regions where If a major earthquake has not occurred for a long period, the probability of such an event occurring increases.
It is reasonable to expect that areas that have already experienced strong earthquakes will experience similar events in the future. Achieving prediction through a thorough understanding of natural processes is a fundamental goal of all scientific disciplines, and seismology is no exception to this quest.
Can earthquakes be predicted?
Until now, There is no reliable method for predicting earthquakes, not even in technologically advanced countries like the United States and Japan. However, the progress made and the knowledge acquired allow us to confidently affirm that the time will soon come when anticipating the occurrence of an earthquake will become a common reality.
The Seismic Alert Systems (SAS) Established in various nations, they offer the ability to detect the onset of a major earthquake in the vicinity of its epicenter, taking into account the different speeds of propagation of seismic and electrical waves, as well as the distance from the seismic epicenter to the place where its impacts are intended to be mitigated.
I hope that with this information you can learn more about what seismicity is and why it is important to study it.