Earthquakes Israel worries about its own Big One

Earthquakes Israel worries about its own Big One

Published 29 April 2015

 

The magnitude 7.8 earthquake that struck Nepal, leaving more than 4,000 people dead, has alerted earthquake experts in Israel about the country’s own seismic risk, which could result in a large quake months or a few years from now. Israel, the Palestinian territories, and Jordan are sitting on a major fault line which constitutes “a real, as well as a current, threat to the safety, social integrity, and economic well-being of the people in the region,” reads a 2007 earthquake report.

The magnitude 7.8 earthquake that struck Nepal, leaving more than 4,000 people dead, has alerted earthquake experts in Israel about the country’s own seismic risk, which could result in a large quake months or a few years from now. Israel, the Palestinian territories, and Jordan are sitting on a major fault line which constitutes “a real, as well as a current, threat to the safety, social integrity, and economic well-being of the people in the region,” reads a 2007 earthquake report.
According to the Times of Israel, Israel and the Palestinian territories lie on the top of a tear in the earth’s crust running along Israel’s eastern flank, the margins of two tectonic plates, which experts deem a high seismic risk zone. Jordan sits atop the Arabian plate, which grinds northward at twenty millimeters per year relative to the African plate to its west. At least seventeen historically recorded major quakes have struck Israel in the past 2,000 years, according to a 1994 article published in the Israel Exploration Journal. The last major quake struck on 11 July 1927, killing more than 400 people and leaving “not a house in Jerusalem or Hebron… without some damage,” the Jewish Telegraphic Agency reported.
According to Amotz Agnon, an earth sciences professor at Hebrew University who studies the layers of sediment on the floor of the Dead Sea, magnitude 7 quakes occur along the Jordan Valley roughly once every 1,000 years, with the last major quake occurring in 1033 and smaller quakes like the one in 1927, occurring every eighty to 120 years or so. “Every day that passes without an earthquake brings us closer to a big one,” said Dr. Rivka Amit, head of Israel’s Geological Survey.
The region is currently in a period of frequent tectonic movement. GPS monitoring of tectonic plates that meet in the Jordan Valley indicates that the plates are locked against each other, accumulating elastic energy that will eventually be released in the form of a quake. “When it’s stored on a significant depth range,” Agnon explained, “it will probably be released one day during our lifetimes, or maybe later on, but our buildings will have to sustain significant acceleration.”
Through Tama 38, Israel’s “National Outline Plan” for earthquake reinforcement and retrofitting which was launched in 2005, the Israeli government is encouraging property owners to retrofit their buildings to protect against an impending earthquake (see “Israel considering earthquake-proofing important Biblical-period structures,” HSNW, 27 January 2014).
A Science Ministryreport filed a month ago claims that the program is ineffective. To date, about 2,000 buildings have been or are undergoing retrofits under Tama 38, but roughly 100,000 buildings nationwide remain at risk. Most of the retrofitting has occurred in the greater Tel Aviv area, while cities such as Eilat, Jerusalem, Haifa, Beit Shean, and Tiberias — which lie closer to fault lines — are occupied with vulnerable buildings. According to the ministry report, Israel could reduce earthquake damage by as much as two-thirds, should it budget $430 million toward retrofitting in high-risk areas.
“We are trying to find other ways or other tools to motivate people to go and reinforce their house,” said Dr. Avi Shapira, a seismologist who chairs an interministerial committee on earthquake preparedness. Israel still has “too many residential buildings that are not prepared to sustain a 6.5 earthquake” and “are poorly constructed,” endangering the lives of citizens.
Palestinian cities of the West Bank and Gaza Strip are also vulnerable to seismic activity, mostly because many of their buildings are inadequately constructed. Dr. Jalal Dabbeek, head of the Urban Planning and Disaster Risk Reduction Center at Nablus’s An-Najah University, said more than 70 percent of the buildings in the seven major Palestinian cities in the West Bank were “highly vulnerable.” Even a moderate magnitude-6 earthquake would lead to widespread damage in the West Bank.