Currently no system can predict the date or time when an earthquake will occur. But the technology behind earthquake early warning systems can be used to prevent some of the earthquake-related damage by alerting the public when an earthquake occurs close to, or is, approaching their location.
When an earthquake strikes, two types of waves, known as P- and S-waves, are emitted from the point of rupture, often together with a group of waves called surface waves.
The wave which travels fastest and is thus the first to arrive at a particular location is the P-wave. This wave is recorded by seismometers (these measure the strength of an earthquake) but does not normally cause any damage. Damage is caused when the S-wave and surface waves arrive.
The time between the arrival of the P- and S-wave can vary from a few seconds to a couple of minutes, depending on the distance of the location from the epicentre (the location of the earthquake source). Once the P-wave is detected by the instruments at any location, the early warning system sends reports to the public (through mobile applications) and especially to the civil protection departments and emergency responders, alerting them to the impending S-waves, so that any necessary actions can be taken before the destructive shaking starts.
Typical precautionary actions include stopping delicate procedures/operation in the medical services, protecting power stations and stopping train systems and instructing schoolchildren to take cover.
The first public early warning system was used in Mexico in 1991. Today, these systems are increasing their popularity in earthquake-prone countries such as Japan, the US, Taiwan and Turkey.
The picture shows a typical alert message on the app ShakeAlert, which is being developed by the US Geological Survey and other universities for use in the western coast of the US, which is famous for destructive earthquakes.
Some of the information given to the user is the estimated number of seconds left until the earthquake reaches the user’s location and the expected intensity and magnitude of the earthquake.
Did you know…
• 10 per cent of all human beings ever born are alive at this very moment.
• Recycling old aluminum uses only five per cent of the energy used to make new aluminum.
• Footprints and tyre tracks left behind by astronauts on the moon will stay there forever as there is no wind to blow them away.
• The Earth spins at 1,600 km/h but it travels through the solar system at an incredible 108,000 km/h.
For more trivia: www.um.edu.mt/think
Sound bites
• Since the early 1990s, the Malta BioBank has been collecting and storing samples of all Maltese children with the aim of reaching one per cent of the general population. It screens such samples for rare blood disorders such as thalassemia (a locally prevalent blood disorder) and has contributed significantly to the EuroBioBank, which acts as a network between other European Biobanks. The Biobank has also contributed significantly to studies in Type 2 Diabetes Mellitus, Parkinson’s disease and kidney disorders, as well as other illnesses. The current objectives of the unit include the identification of 200 new rare blood disease therapies and ways to diagnose them.
www.um.edu.mt/think/the-malta-biobank-bbmri-mt/
• Now you can turn your mobile phone into a seismometer! The application MyShake (by Berkeley Seismological Laboratory) may be downloaded for free onto your Android smartphone. One of its features is the plotting of the three-component acceleration seismogram (vertical and two horizontal components) that utilises the phone’s inbuilt accelerometer device. Put your phone on a table and watch it record up-down and lateral shocks that you give to the surface. When phones are idle, these recordings can help to build a worldwide seismic network. The system detects and gathers collective signals which are recognised as earthquake accelerations using innovative network algorithms and can provide useful data about the earthquake, as well as contribute to earthquake early warning.
http://myshake.berkeley.edu/