Read the following passage about and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions.
Early Warning Systems
People may take steps to reduce the impact of a natural hazard when they are aware that it is likely to occur. But how can people recognize they are in danger? Scientists use many methods to help predict when natural hazards are likely to happen.
Seismometers measure earthquake activity. An increase in small earthquakes can mean a larger earthquake is about to happen or a volcano is becoming more active. If a volcanic eruption is predicted, people can evacuate, or move to safer areas. Governments can prepare emergency supplies, such as food and water. Emergency workers can be ready to help with injuries. All of these steps reduce the impact and help save lives.
Scientists use several devices and methods to constantly collect information about a volcano's activity. Radio transmissions allow the data to be sent instantly to a monitoring system. Scientists can tell what is happening with a volcano almost as soon as it happens. They can also use that information to predict what is likely to happen next.
Besides tracking seismic activity, scientists also monitor gases, temperature and water at a volcano site. A change in the amount of carbon dioxide and others given off by the volcano can be measured to comprehensive analysis of these factors helps scientists improve eruption predictions and enhance public safety.
