Publications

In recent weeks the media has run an information campaign on behalf of the National Emergency Management Authority (NEMA), the Home Front Command (HFC), and the Geological Survey of Israel (GSI) about the Tru'ah system, which provides early warnings of earthquakes – very short advance warnings (a few seconds or tens of seconds) – and is now operational.

The significance of this announcement must be clear. Scientists are still unable to foresee earthquakes, and it is therefore impossible to provide people with sufficient lead time to evacuate buildings and move to open areas to prevent, or at least reduce, the number of casualties. Damage to infrastructures, buildings, and property is inevitable. It is, however, possible to save people’s lives through early warning. It takes a few seconds from the onset of the earthquake until the arrival of the damaging seismic wave in vulnerable populated areas. This may be sufficient time for a few immediate rescue operations such as the rapid evacuation of low-rise buildings at risk.

An earthquake creates seismic waves of various types, two of which are pertinent to the need for warnings. The faster wave – the first to reach any relevant site – is the P (Primary/Pressure) wave; it does not cause damage. The slower wave that arrives later is the S (Secondary/Shear) wave, which shakes the ground and can thus damage buildings. There is a lapse of a few seconds from the arrival of the P wave until the arrival of the S wave, depending on the distance from the earthquake’s epicenter. The closer the epicenter is to any at-risk area, the shorter the time between the two waves. The farther from the epicenter, the longer the lapse of time.

There is an available, relatively inexpensive option of installing sensors in homes or in public institutions that can identify the P wave to enable lifesaving actions – mainly the evacuation of buildings – before the S wave hits. For some years, such sensors have been installed in most Israeli schools as mandated by the Ministry of Education. Some public institutions and private companies have voluntarily installed them as well. These systems provide a certain amount of warning, depending on the distance from the quake’s epicenter.

In addition, for several years warning systems utilizing sensors located close to anticipated earthquake epicenters have been installed. The objective is to identify the P wave close to the epicenter and send an immediate warning signal. The advantages of these systems are their accuracy, the avoidance of false alarms caused by shaking that is not due to an earthquake, and above all, their ability to send a rapid electromagnetic wave to populated areas, giving them a few more seconds of warning. The system is also able to identify the magnitude of the earthquake and thus avoid sending warnings for weak or harmless tremors. Such systems are already in use in 15 countries worldwide, including Japan, Mexico, South Korea, Turkey, Italy, Chile, and the United States.

The idea of setting up a similar system was recommended to Israeli decision makers back in 2007. Implementing the recommendation took almost 15 years, but Israel finally has a vital system, Tru’ah, that has been adapted to conditions in Israel, installed and operated by the GSI. This system, which became operational in recent weeks, consists of 120 sensors scattered along the Dead Sea Rift and other active sites, and has a data processing center that can assess within seconds the strength and danger of an earthquake and send instant warnings. For example, if an earthquake occurs at the Dead Sea, Jerusalem will get a 3-second warning, Tel Aviv about 18 seconds, and Haifa about 30 seconds. In addition, the system will identify the earthquake’s magnitude and determine which towns should receive a warning. The stronger the quake, the larger the area to be warned.  With an earthquake of a magnitude 6 or higher, the whole country will receive a warning (for details [in Hebrew], see the GSI seismology website).

Clearly the warning will be more significant for buildings closer to the quake’s epicenter, where the tremor will be stronger. Yet at those sites, the time lag between the P wave and the S wave will be shorter, sometimes too short for the warning to save lives. If the interval between the waves is longer, there is more time for rescue operations; since the seismic wave’s intensity declines with distance, the likelihood of damage decreases as it moves away from the quake’s epicenter. This means that the warning will be most effective in areas that are neither very close to the epicenter nor very far from it. All depends on the earthquake’s magnitude; the stronger the quake, the greater the damage.

Recent earthquakes felt in Israel came from two sources: the Dead Sea Rift (most recently in the Beit She'an region), and the Mediterranean (around Cyprus and Crete). The Tru'ah system, deployed mainly along the Dead Sea Rift, will be able to warn of quakes in that area but it will not be effective for quakes originating in the Mediterranean unless there are connected systems in the coastal area.

Tru'ah currently sends an alert to the Home Front Command, which immediately informs the public through notifications on cellular devices, a specialized app, alarms, loudspeaker systems, and more. The existence of this warning system is essential, but it is still limited in its effect and does not fully utilize the available technological potential:  at this stage, the only realistic responses in the few seconds following a Tru'ah warning before the S wave arrives are to leave the building (if you are on the ground floor) or reach the air-raid shelter or the stairwell, and nothing more. While this is helpful, it is possible to enhance the system’s scope by improving and automating existing national and local systems that can interface with the Tru'ah system. Such enhancements could trigger a number of life-saving automatic actions in the short time available. For example, it could be possible to stop an elevator at the nearest floor and instruct its occupants to exit; aircraft approaching an airport could be prohibited from landing; electrical circuits and turbines could be shut down based on preexisting plans; pipes carrying gas and hazardous materials can be shut down to prevent leaks; vehicles could be warned not to drive onto bridges that might collapse; and backup generators could be turned on in essential facilities to take over during blackouts. Israel is far from implementing these vital strategies. The first barrier to overcome is in the domain of regulation, which requires various agencies (through legislation, protocols, and organization) to create efficient interfaces among themselves.

“A strong earthquake is not a question of if; it’s only a question of when.” This headline appeared 20 years ago and is still valid. Israel has done, and continues to do, too little to minimize the potential damage from anticipated earthquakes. The most urgent tasks can be divided into two sets: the first – reinforce public buildings, with priority for schools and hospitals plus essential infrastructures like bridges, as well as residential buildings. The second – improve public awareness and readiness for earthquakes. The goal is to prepare the citizenry for the possibility that in the event of a severe quake, help from central government agencies (HFC, the fire department, Magen David Adom first responders, the police) and from local agencies will be delayed and thus unable to provide immediate rescue operations and subsequent logistical support.

The installation of the Tru'ah system is a very important first step in the long process of preparing Israel for earthquakes. The current media campaign helps to increase awareness – in the public and in government – of the danger and the need to prepare accordingly. However, the campaign’s messages might create a false image of an effective comprehensive response and adequate preparations in the event of a catastrophic earthquake. Moreover, the unnecessarily long time it took to set up this limited system and the fact that even today, little is being done to reinforce buildings and to implement the relevant recommendations presented in the 2018 State Comptroller’s report attest to the decision makers’ low level of attention and to Israel’s poor preparations for this anticipated mass disaster.

Implementation of the Tru'ah system is a welcome measure. That said, the road ahead to nationwide preparedness is still very long.