Earthquakes occur when two blocks of the Earth’s crust suddenly slip past one another. This meeting point is called the fault or fault plane. The sudden release of energy, caused by the rapid motion along a fault, generates seismic waves that make the ground shake. During and after the earthquake, the plates or blocks of rock start moving and continue to move until they get stuck again.
Earthquakes can occur in any part of the Earth’s crust and even deeper in the Earth’s mantle; no one is safe from seismic activity and earthquakes. However, areas located near tectonic plate boundaries are more prone to ground shaking. Over 80 percent of large earthquakes occur around the edges of the Pacific Ocean, an area where the Pacific plate is being subducted beneath the surrounding plates. This location is known as the “Ring of Fire”, which is the most seismically and volcanically active zone in the world. Antarctica has the least earthquakes of any continent.
Foreshocks are smaller earthquakes that happen close to the nucleation point of the larger earthquake that follows. Until the larger earthquake occurs, it is not possible to tell if an earthquake is a foreshock or not. We use the term mainshock for the largest earthquake in the sequence.
Aftershocks are relatively smaller earthquakes that follow the mainshock. They are smaller than the main earthquake and occur in the vicinity of the mainshock rupture. They can continue for weeks, months, or even years after the mainshock, depending on the mainshock magnitude.
The most active areas in terms of earthquake activity lie within the “Ring of Fire”, a region where Pacific plate is being subducted beneath the surrounding plates. Here, 80 percent of large earthquakes occur. Similarly, this is the most active volcanic region globally.
Most catastrophic earthquakes, with most damage and fatalities are China and Iran, mostly due to the fact, that many large cities are built along the active faults.
The five most known earthquake precursors are:
- A swarm of small earthquakes;
- Increasing amounts of radon in local water;
- Increasing size of magnitudes in moderate size events;
- Groundwater level changes…
At Quantectum, we use scientifically proven and reliable ways to forecast earthquakes.
Earthquakes can cause damage to the infrastructure which can affect people’s life both on a personal as well as professional level. Moreover, an earthquake may disrupt public services like transport systems and communication infrastructure, which can isolate people from the world, damage health facilities, and transportation, disrupting service delivery and access to health care. Worst of all, a lack of food and drinking water may occur.
The consequences of earthquakes do not end here. Long after an earthquake, some people can experience trauma and post-traumatic stress disorder. Due to the damage to public roads and facilities, businesses can temporarily lose the ability to generate income, as most of the finances go into recovering from the damage. Moreover, contents, documents, computers, as well as other office material can be lost for good.
MegaQuake is an earthquake of exceptional destructive power, with a magnitude of 8 or greater. The largest earthquake ever recorded was a magnitude 9.4-9.6 on May 22, 1960 in Chile that ruptured a fault for almost 1,000 miles.
It is believed that earthquakes of magnitude 10 or larger cannot happen because the magnitude of an earthquake is related to the length of the fault system on which it occurs. This means that the longer the fault, the larger the earthquake. We do not know of any fault long enough to generate a magnitude 10 earthquake. However, if an earthquake of magnitude 10 or more would occur, it would extend around most of the planet.
Strong earthquakes with magnitudes of 8 and more occur several times a year on a global average. On average, 15 quakes ranging in magnitude between 7 and 8 strikes on an annual basis. These can all have devastating effects on people and the environment. Moreover, up to 1,300 moderate earthquakes with a magnitude between 5 and 6 take place worldwide every year, while even smaller earthquakes with magnitudes of 3 to 4 occur, roughly speaking, 130,000 times a year. Magnitude 3 earthquakes are usually still noticed by people if they are in the vicinity of the epicenter, but in most cases, they do not cause any damage.
The most damaging earthquake ever recorded was the Shaanxi earthquake in China in 1556. It is considered the most devastating earthquake in human history, with a death toll of approximately 830,000 and an estimated magnitude of 8.
The strongest instrumentally recorded earthquake in the last hundred years took place in Chile on 22 May 1960 with a (moment) magnitude between 9.4 and 9.6.
Even though forecasting and prediction both relate to similar future-oriented concept, there is a fine line that differentiates them.
A forecast is a calculation or an estimation of probability estimate for a certain magnitude earthquake to happen in a specific area.
In contrast, a prediction refers to an actual act of indicating that an event might take place in the future with or without prior collected data and information. It tries to explain a possible outcome or future event. They can be highly risky, and the actual results may deviate from the predictions made.
On the whole, all forecasts are predictions, but not all predictions are forecasts. Basically, anyone could do a prediction, since it does not require any special skills, but for a person to do forecasting, he/she requires a lot of educational background, special skills, and in-depth research.
Quantectum uses several models for earthquake forecasting. For each model, numerous forecasts are produced, all activated from the same starting time, but with slightly different starting conditions, and by using slightly different physical parameters. In this way, computers produce ensembles of forecasts for each model. Ensemble forecasting is a type of probability forecasting. It conveys a message, which explicitly reminds the user about the forecast uncertainty that should be considered when making any practical use of the forecast. The uncertainty associated with every forecast means that different scenarios are possible, and the forecast should reflect that. Single deterministic forecasts can be misleading as they fail to provide this information. In this way, Quantectum can produce daily charts of synchronization clouds, which indicate regions of increased probability for moderate to strong earthquakes, up to 64 days ahead.
Classically, numerical earthquake prediction was supposed to be based on a single, ‘deterministic’ prediction with an increasing model accuracy and decreasing initial condition errors. This approach is, however, not used by Quantectum. Seismic systems are chaotic. Quantectum uses the same approach as is used in meteorology (see ECMWF).
ECMWF on ensemble forecasting: Looking at the problem from a slightly more fundamental point of view, a forecast explicitly cast in probability terms is better; not only because it provides the user with an estimate of the error, but because it is more ‘truthful’. So, a probability forecast conveys a message which explicitly reminds the user that there is always a forecast uncertainty that should be considered, computed, and taken into account when making any practical use of the forecast. In fact, even ‘deterministic’ forecasts are in reality probability forecasts in disguise, since an error bar can and should always be associated with it. That error bar implies a probability distribution of forecasted future states around a central value.
The uncertainty associated with every forecast means that different scenarios are possible, and the forecast should reflect that. Single ‘deterministic’ forecasts can be misleading, as they fail to provide this information.
The input data are the EMSC, USGS, or CMT seismic catalogs (freely available on the Internet), which contain information on timing, magnitude, and the epicenter of past earthquakes in the region. To forecast the next earthquake(s), we need a maximum of 50 past earthquakes in the chosen region.
By generating a range of possible outcomes, the method can show how likely different scenarios are in the days ahead, and also how long into the future the forecasts are useful. The smaller the range of predicted outcomes, the ‘sharper’ the forecast is said to be. Good ensemble forecasts are not just as sharp as possible but also reliable.
Yes, our lack of knowledge does significantly increase uncertainty in the forecast to some extent. This is why there is much work going into improving our knowledge of initial conditions and of seismic processes that computer models need to mirror. In addition, Earth is a chaotic system. This means that it is sensitively dependent on initial conditions. In a chaotic system, a slight change in the input conditions can lead to a significant change in the output forecast. In a non-chaotic system, small differences in initial conditions only give small differences in output. Hence, it is important in earthquake forecasting to investigate how sensitive the seismic systems are at any stage to initial conditions. Ensemble forecasting does this by looking at the spread of possible outcomes.