Geological events like an earthquake, volcano eruptions, and tsunamis can wreak havoc whenever they hit. Many times, they hit without warning because they are difficult to predict. However, researchers are trying to develop accurate geological event prediction systems to help people prepare to evacuate an area and save lives
Worst World Earthquakes
There have been several powerful seismic events over the past century that have to lead to widespread devastation. The most powerful earthquake in the world was one the measured 9.5 on the Richter scale, which took place in Chile in May 1960.
The results of the Valdivia earthquake left an estimated 2 million people homeless and cost about $400 to $600 million. Those costs equate to about $3 to $6 billion today after adjustments for inflation. The death estimates ranged between 460 to 6,000 people, but most of the victims died due to the following tsunami, not the earthquake.
The consequences of the 2011 Honshu earthquake, also known as the Great Sendai earthquake, are still being felt today. The 9.0 earthquake was the largest in Japan’s history, and it took place along the country’s northeast coast, about 80 miles from Sendai.
The quake was followed by a tsunami traveling at speeds of 435 miles per hour. The size of the waves ranged from about 10 to 125 feet tall. The earthquake was so powerful that it triggered tsunami waves as far away as the west coast of the United States and aftershocks could be felt from Norway to Antarctica.
Not only was it Japan’s worst earthquake, but it was the costliest as well, with damage estimates of $310 billion. The area is still recovering, and it could take years before it gets back to normal. The earthquake also caused untold ecological damage because the Fukushima Nuclear Power Plant was disabled by the tsunami.
The reactors melted or exploded, sending radiation pouring into the waters of the Pacific Ocean and the air. Dozens of people were also exposed to the radiation, with over 1,600 “disaster-related” deaths in areas surrounding the plant.
Indian Ocean Tsunami
When an earthquake occurred in the Indian Ocean in 2004, it triggered a tsunami that caused hundreds of thousands of people to die. Damage from the quake was estimated at over $10 billion, it displaced 1.7 million people in 14 countries, and the tsunami killed approximately 228,000 people.
It was a magnitude 9.1 earthquake, which was the strongest in 50 years, and the tsunami was the worst one in recorded history. Due to the devastation, the United Nations began developing an early warning system for tsunamis.
Japan has an early warning system for earthquakes, which may have saved some lives in Tokyo during the 2011 event. The system warned citizens about the quake about one minute before it occurred. While they couldn’t be predicted in the past, improvements in technology have allowed scientists to begin creating systems to forecast and warn communities about seismic activity. However, nature, like toads, are often better predictors of these events.
Researchers studied the habits of the common toad and found that the males left their breeding grounds five days before an earthquake hit the area. The 2010 study found that toads abandoned their habitats five days before the L’Aquila Italy earthquake in 2009, which was about 46 miles from their location.
Due to the movement of tectonic plates and the locations of faults, scientists can estimate when an earthquake will occur. To do so, they also study the history of earthquakes in the area and find out where the pressure is increasing on the fault lines. Unfortunately, earthquake predictions, or in this case forecasts, are often vague.
A geological event prediction requires knowing the exact time and the exact location of an earthquake, which can be difficult to do. The closest that can be done is to calculate the data and forecast the probability of an earthquake.
For instance, the US Geological Survey (USGS) has studied seismic activity in the San Francisco Bay Area and have calculated that a major event could take place in the next 30 years. However, that information isn’t precise, so it cannot be called a prediction.
Why Earthquakes are Unpredictable
Although geologists can estimate when an earthquake may occur, they cannot pinpoint exactly when. Signals associated with an earthquake do not exist, so there is no way to determine when one will occur.
While there are usually smaller tremors before a major quake, it could be days or months before a one takes place. Sometimes the vibrations occur right before the earthquake, so there isn’t any time to warn people about an event before it happens.
Studying the events have been made more difficult because they take place far below the Earth’s surface. Their location can prevent scientists from gathering all the data they need to make accurate predictions about their occurrence.
Japan’s Early Warning System
Even though most researchers have not come up with a way to pinpoint where or when an earthquake will occur, Japan was able to design an accurate early warning system. Their system was put online in 2007 and kept people from being injured during the Honshu quake.
It works by detecting tremors, which often occur before an earthquake, locates its epicenter by calculating data, and then sends out a warning over a network of seismographs located across the country. Satoko Oki, a seismologist for the Earthquake Research Institute at the University of Tokyo, uses P-waves and S-waves to detect earthquake activity.
The P-waves, which stands for Primary waves, is the initial indication of an impending quake. The waves, which do not cause much damage, appear as short, fat wavelengths. The S-waves, the S is for Secondary, are longer and can be significantly more destructive.
Since the P-waves are almost always first, they can be used to calculate the occurrence of an earthquake and give people time to prepare for it. The warnings for the national system is sent out by the Japan Meteorological Agency. Private systems exist in offices, factories, and Japanese Railways added a system when the Nozomi Bullet Train started operations about 20 years ago.
Tsunami Warning System
Along with the earthquake early warning system, Japan also developed a warning system for tsunamis. Destructive tsunamis can cause more damage and take more lives than an earthquake, and they are usually triggered by seismic activity. A tsunami is usually triggered by an earthquake on the sea floor or one close to a coastline, like the Honshu quake.
Japan placed detection, or Deep-ocean Assessment and Reporting of Tsunami (DART) buoys, in the Pacific Ocean to help warn people about the water events. The DART system was created by the National Oceanic and Atmospheric Administration in 2001.
This system includes bottom pressure recorders placed on an ocean’s floor and a surface buoy. When activity is detected by the recorder, it relays the information to the buoy, which in turn sends it to a satellite, and it is transmitted to a control station.
Most of the buoys have been placed in the Pacific Ocean, which is where most tsunamis occur, but they are also found in the Atlantic and the Caribbean Sea as well. Most tsunamis occur within about 15 to 20 minutes after an earthquake, which provides some warning for islands near the earthquake’s epicenter.
However, they work better for islands or countries that are hundreds or thousands of miles from the main event. For instance, after the Honshu earthquake, the system was able to predict and send out warnings about tsunami waves to the Hawaiian Islands and the west coast of the US and Canada.
Neural Networks and Earthquake Predictions
Scientists haven’t given up on creating an accurate geological event prediction system and are trying to develop one using neural networks. An artificial neural network is loosely based on the brain’s ability to learn, so to forecast an earthquake, a computer is fed the data it needs and is able to calculate it to pinpoint a seismic event.
The parameters of the input information correlate to seismic activity, which helps to forecast an earthquake. This system can provide two predictions:
- The probability of an earthquake that is larger than the size of the preset magnitude value.
- The probability of an earthquake of a smaller magnitude than the preset value.
This type of system has been put into place in Chile, which is one of the most active seismic regions. The system was able to forecast and warn Chileans about earthquake activity in the region, so they could prepare to evacuate the area before it hit.
The continued development of an earthquake and tsunami prediction system would have the ability to warn countries and save thousands of lives. However, due to the limited data, the use of new technology, and the unpredictability of seismic activity, it could be some time before an accurate prediction or early warning system can be developed and starts operations.
Since thousands of lives are at stake, the work on developing early warning systems continue.