To this day, Israel has not managed to follow in the footsteps of countries like Japan or the United States in constructing buildings and various infrastructures that can withstand powerful earthquakes. Geologists are currently presenting the National Infrastructures Ministry with a study on a sophisticated system that - while not preventing destruction - may help the civilian population reach safety during an earthquake and aid the public and private sectors to institute functioning emergency systems and essential infrastructures.

In recent weeks, the Geological Survey has completed a report detailing a preliminary assessment of an earthquake early warning system. Geologists and seismologists are unable to predict earthquakes, but today there are systems that make it possible to transmit a warning of a powerful earthquake before its destructive waves spread. This warning time, which ranges from a few seconds to a few dozen seconds, depending on the distance from the epicenter of the quake and the way the system is operated, could suffice to carry out a series of basic safety measures in the event of an earthquake.

Range of destruction - 70 kilometers

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The idea of establishing an early warning system in Israel was first promoted three years ago by Dr. Danny Wachs, a former senior researcher at the Geological Survey. His colleagues at the Survey decided to carry on with the project and Survey director Dr. Benny Begin delegated the task to Dr. Ariel Heimann.

Heimann has examined the state of existing warning systems abroad and has analyzed the possibility of establishing such a system in Israel. He has also estimated the warning time it could provide the Israeli population at between a few seconds and nearly half a minute, based on a model of the speed of seismic waves in Israel that was prepared at the Geophysical Institute. "Our initial conclusion is that an early warning system could reduce the damage expected in the wake of a destructive earthquake in Israel, and we are proposing an in-depth examination of the possibility of setting up such a system," asserts Heimann.

In Israel there are several centers of seismic activity, first and foremost the area of the Dead Sea Rift. In the past, destructive earthquakes have occurred there and it is clear that they will also happen in the future. Heimann notes that in an earthquake of the magnitude of 7.5 that occurred in Turkey in 1999, the radius of significant damage was about 70 kilometers.

"If we relate to this distance as a reasonable distance for the production of significant damage in a powerful earthquake, and we examine the area of the effects of such a future earthquake along the Dead Sea rift, the picture that emerges is threatening," writes Heimann. "The northern population centers will be affected by earthquakes that have their epicenter in the Jordan Valley or the Sea of Galilee, whereas the population centers in the center of Israel and Jerusalem will be affected by earthquakes that have their epicenters in the Jordan Valley and the Dead Sea."

Early warning systems are based on an apparatus that identifies the characteristics of the quake and transfers such information within a few seconds. In case the system is located at a site that needs to be protected, such as a building, the initial identification of seismic waves, called P-waves, warns of the later destructive waves called S-waves. The amount of time the warning takes depends on the time gap between the different kinds of waves. Therefore, the further a certain site is from the epicenter of an earthquake, the longer the warning time.

Another way of operating a warning system is to locate a large number of sensors in an area where quakes are expected. This system identifies P-waves and performs various calculations to create a map of earth movements in various places. In accordance with this data, a warning signal is sent using a technique that is faster than seismic waves. The map is supposed to prevent the incidence of warnings to places where destructive damage is not expected and, in so doing, prevent false alarms.

"Multi-sensor systems that are located at earthquake epicenters are capable of providing the longest warning time for an earthquake," notes Heimann. "They make use of the rapid data-processing and the location of the sensors close to the earthquake epicenter and far from population centers."

The information from the warning system is transferred to reception systems that are capable of carrying out a long series of pre-programmed actions. For example, such a system will set off an alarm in schools and offices, allowing students and workers time to enter a reinforced room or at least take shelter under tables.

A warning system can bring about a long series of additional actions, including disconnecting electricity and gas systems to prevent fires, stopping elevators, closing valves and pipes of hazardous materials, preventing planes from taking off and performing rapid backup for computers.

Heimann notes that early warning systems are already operating in a number of countries that have learned from their earthquake experiences, first among them Japan, Turkey and the United States. In Japan the water system has its own sensors that close off containers and prevent leaks. Another Japanese system switches off electricity generators and turbines. Since the beginning of the past decade, a system of sensors located along the seashore has been in operation in Mexico, several hundred kilometers away from the capital, Mexico City. Thus far, this system has sent about 60 warnings, and only in one case was it a false alarm. Heimann notes that in recent years, not a single earthquake death has been registered in Mexico City even though there have been powerful earthquakes in the country, and one of the reasons for this is the warning system.

Minimizing the damage

In Israel's case, the potential earthquake epicenters are not far from the large population centers. In the case of an earthquake in the area of the Sea of Galilee, Tiberias, for example, will receive no warning at all and if the quake is in the northern Dead Sea, Jerusalem will receive a warning of only three seconds. However, a sensor system could provide a warning of nearly 20 seconds to the large population centers in the coastal area if the earthquake occurs in the Dead Sea Rift, and nearly 30 seconds if the epicenter is in the Sea of Galilee. Jerusalem, too, will be able to receive a warning of about 30 seconds if the epicenter is in the Sea of Galilee. In the case that the warning systems are located at sites that will be damaged by the earthquake, the warning times are far shorter and come to 10.5 seconds at most.

Heimann notes that Israel has the technological ability and the infrastructure of seismic information to set up such a warning system. However, the cost of a system could amount to tens of millions of dollars and it will have to be maintained constantly. From the social and psychological perspective, he says a paradoxical situation may arise, in which the presence of such a system, which is supposed to prevent casualties, only increases the sense of vulnerability among the population.

"This report will be presented to the decision-makers, and in our opinion it would be a mistake on their part if they do not decide to carry out a thorough feasibility study that takes into account the budgetary and economic aspects as well as the social aspects," says Dr. Rivka Amit, head of the department of engineering of geology and geological hazards at the Geological Survey. "The decision-makers will have to decide whether this is what the country needs at this time, when there are also other threats with which it must deal. Powerful earthquakes in our region do not occur with great frequency, but it has to be internalized that it will happen and it will be a painful blow."