Immediately after an earthquake occurs, the hypocenter and magnitude are analyzed using preliminary data from seismographs near the hypocenter. Based on such data, the seismic intensity and time of arrival of any larger tremors are estimated for early notification through the media. If warnings of a major quake can be made even seconds in advance, railways and roads can be shut down, airplane takeoffs and landings avoided, and measures to protect against tsunamis can be taken. General households can also turn off the gas.