The deadly earth

Volcanoes are spread all over the Earth, mostly located at the boundaries between the tectonic plates that make up the Earth’s surface. One of the last major eruptions to cause significant loss of life was in 1991 when over 800 people died when Mount Pinatubo in the Philippines erupted; this figure would have been much larger if it had not been for volcanologists predicting the eruption and the early evacuation of people that resulted. In 2010, the eruption of Eyjafjallajokull in Iceland shut down most of Europe’s airspace. Recently, the Icelandic government has begun a program to use more sensors and better real-time data analysis in order to monitor volcanoes and give earlier warnings of possible eruptions. Sensors that can help in the prediction of volcanoes include:

• Seismometers look for ground motions that would indicate if there are seismic waves from either a quake or eruption
• Multi-gas meters look at changes in the composition of gas coming from the ground that could show signs of magma
• GPS sensors detect movement in the Earth's crust which could come from magma build-up below, by using use satellite technology
• Infrasound microphones array record shock waves in the atmosphere which are generated by eruptions or quakes
• Volumetric strainmeters are large canisters of liquid that are located in holes in the ground – rocks that press on these canisters can cause the liquid inside to move and be displaced.

Earthquakes are caused mostly by the rupture of geological faults and similarly to volcanoes, they usually occur at the boundaries between the tectonic plates. Californians live in awareness of the “big one”, whilst the 2011 Tōhoku earthquake and subsequent tsunami caused the failure of the Fukushima Daiichi nuclear power plant and resulted in over 15,000 deaths.  Seismometers are the key in earthquake prediction, but there are also several other methods including the study of anomalous animal behaviour, electric field and magnetic field variations, and radon emissions.

Tsunamis are caused by the displacement of a large volume of water and are often the result of underwater earthquakes. However, even if the magnitude and location of an underwater earthquake is known, it is difficult to accurately predict if tsunamis will occur; instead, a tsunami warning system is used. This system is based on a sensor network to detect the tsunamis and a communication system to issue alarms to get people evacuated. The sensors themselves are either shore-based tide gauges or DART (Deep-ocean Assessment and Reporting of Tsunamis) buoys out at sea. They look for changes in the observed sea level height and are used to verify the existence of a tsunami.

Hurricanes or tropical cyclones are storm systems that form in the tropical regions of the world and produce strong winds and heavy rain. Hurricane Sandy which hit the United States east coast in late October 2012 caused unprecedented damage and claimed more than one hundred lives. Hurricane prediction is based on weather forecasting and looks at the strength of high- and low-pressure areas in order to see where the path of a hurricane will be.  The average wind through the entire depth of the troposphere is considered to be one of the best tools in determining the track direction and speed of hurricanes. Forecasters use high-speed computers and sophisticated simulation software to produce computer models that will predict the path of hurricanes based on the future position and strength of high- and low-pressure systems. These forecasting techniques, combined with data from Earth-orbiting satellites and other sensors, have increased the accuracy of tracking hurricanes over recent decades.

Tornadoes are a particular problem in the so-called ‘tornado alley’ in Central USA, located between the Rocky Mountains and the Appalachian Mountains. Recently, a Category EF5 tornado with winds of over 200 mph hit Moore, Oklahoma killing at least 24 people. The main method of detecting tornadoes is weather forecasting and the use of Doppler weather radar stations. These measure the velocity and radial direction of winds in a storm and use this information to look for evidence of rotation in storms from more than a hundred miles away.  To improve weather forecasting, students from Oklahoma State University’s Department of Mechanical and Aerospace Engineering have created storm-penetrating unmanned aerial vehicles (UAVs) that may help increase warning times for tornadoes by collecting better meteorological data. These UAVs will penetrate thunderstorms, including the supercells that spawn tornadoes and obtain the data vital for weather forecasting. The information collected can be used for both immediate forecasts of the storm’s path and strength and for predictive models. The data can also be used in numerical simulations to aid meteorologists in their understanding of tornado genesis.

As well as being used to predict natural disasters, technology can be used to help cope with their aftermath and lessen their effects. Earthquake engineering is one such technology; it is concerned with limiting the risk from earthquakes to life and the natural and man-made environment.  Seismic vibration control is one part of earthquake engineering that aims to mitigate seismic impacts in building and non-building structures. Methods of seismic vibration control include: lead rubber bearings; tuned mass dampers; friction pendulum bearings; building elevation control; simple roller bearing; springs-with-damper base isolators and hysteretic dampers. There are various modern technologies which are important for managing the aftermath of, and recovery from, disasters.  These include the use of remote sensing satellites to provide up-to-date images of the disaster regions to enable the appropriate rescue resources to reach the areas involved, and the use of mobile radio technology for communications (voice, messaging and internet). Power supplies may also need to be brought in.

Earth will continue to be the home of man for the foreseeable future so technology that allows us to predict natural disaster events and cope with them will continue to evolve and become increasingly more valuable as population growth means we spread across more of the Earth’s surface.

Inspec has many control terms and classifications to cover the topics discussed, control terms include:

• atmospheric acoustics
• autonomous aerial vehicles
• cellular radio
• diesel-electric generators
• disasters
• earthquake engineering
• earthquakes
• electronic messaging
• emergency management
• emergency power supply
• geochemistry
• geomagnetism
• geophysical equipment
• geophysics computing
• Global Positioning System
• Internet
• meteorological radar
• mobile radio
• oceanographic equipment
• radon
• real-time systems
• remote sensing
• sea level
• seismometers
• storms
• terrestrial electricity
• troposphere
• tsunami
• vibration control
• volcanology
• weather forecasting
• wind

and classifications include: