My hometown of Los Angeles is home to the earliest reported earthquakes, dating back to 1769 (and, of course, many more since). The world’s largest recorded earthquake occurred in Chile in May 1960 and measured a moment of magnitude 9.5. Just one earthquake can cause destruction that costs hundreds of millions of dollars to repair and, more importantly, can cause death.
In 2009, Italian scientists were found guilty of manslaughter for failing to foresee the L’Aquila earthquake that killed more than 300 people. But how successful can we expect our earthquake prediction to be?
In the United States, all scientific experts in geology are with the United States Geological Survey. Their webpage on earthquake prediction begins with: I don’t know how, and I don’t expect to find out anytime in the foreseeable future. ‘ Well, that’s pretty clear!
But why? Even if we could predict hurricanes, floods, and tornadoes, with varying degrees of confidence, why can’t we know when the next “big thing” in terms of earthquakes will occur?
What is an earthquake?
To understand the challenges in predicting earthquakes and what is lacking in current efforts to make those predictions, we need to know what causes them.
Our understanding of what causes earthquakes is based on the theory of plate tectonics, or the idea that the Earth’s outer crust is made up of moving slabs of rock called plates. These plates can move around on an underlying rocky but more malleable inner layer called the Earth’s mantle, which sits above the molten material in the Earth’s core.Modern theories of plate tectonics has existed since the 1950s and is believed to have nine major plates. There are many fault lines along the boundaries of each of these plates, where most of the planet’s earthquakes are known to occur.
While moving relative to one another, these tectonic plates may attempt to slide off and collide with each other. The jagged border edges of these plates are immobilized, but the rest of the plate continues to move, storing energy along the plate boundaries in the process. When the inner portion of the plate moves enough that the edges overcome friction and do not stick together, the stored energy is radiated in ripples to the rocky surface of the Earth. As these waves pass through the ground, they shake the ground and cause earthquakes.
Why can’t we predict earthquakes?
If we know how earthquakes occur, why can’t we predict when they will occur? Contains four elements. To determine how possible early warning signs (or signs) translate into these four factors, scientists look for patterns in earthquakes that have already occurred, or refine known tectonic plate movements. You need to create a modified mathematical model.
In the first case, scientists have linked multiple natural factors that preceded earthquakes in the past, such as increased radon abundance in local water sources, rising groundwater levels, changes in electromagnetic activity, and even strange animal behavior, to the earthquakes themselves. I tried to connect with For example, small fissures, called microfissures, form in underground rocks before major ruptures that ultimately cause earthquakes. These small cracks change the rock’s permeability. In other words, it allows water to pass through rocks more easily. Highly permeable rocks can lead to changes in groundwater levels. This same change in permeability can also lead to the release of radon, which is formed by radioactive decay of elements in certain minerals.
But even if scientists were able to draw a geological link between these natural changes and earthquakes, there is little evidence that one must occur in conjunction with the other. may occur without subsequent earthquakes, or quakes may occur without these precursory events. Earthquakes occur miles below the surface of the earth, so other early indications are of course possible, but you won’t be able to easily detect them at the surface, especially if you don’t know what you’re looking for.
Without empirical evidence to associate possible specific warning signs with earthquakes, scientists can instead try to model specific fault lines. However, building these models is extremely difficult due to the considerable difficulty of studying how rocks and minerals behave at elevated temperatures and pressures towards the Earth’s core. Such conditions are difficult to reproduce in the laboratory, and geologists have drilled boreholes to study the condition of the San Andreas Fault Zone, but such efforts are costly and difficult. .
Another difficulty in earthquake prediction is that small quakes that are barely or not recorded on the surface of the earth are thought to start the same way, despite ultimately having different intensities and durations. A big earthquake. So there may be no easy way to tell whether an early warning sign is a precursor to a more devastating big earthquake or a small tremor.
»Read more “Can we predict earthquakes?” at QuickAndDirtyTips.com
