Minor Quake Swarm Shakes Israel's Sea of Galilee
No damage known from series of small quakes starting at 4:50; last swarm to jolt northern Israel in 2013 lasted a month, geologists tell Haaretz
A swarm of small earthquakes jolted the area of the Sea of Galilee on Wednesday morning, causing no damage. Eleven quakes have been detected so far this morning, Yariv Hamiel, head of Geological Hazards at the Israel Geological Institute told Haaretz.
At least some people noticed the strongest two. One measured 4.1 on the Richter scale and was detected at 4:50 in the morning. The other measured 3.8 on the Richter scale.
"I felt the bed shaking. It took me a few moments to realize it was an earthquake," says Yasmin of Nazareth of the predawn tremor.
The hypocenter of today's swarm was north of the city of Tiberias, meaning that is where the tremors originated. The epicenter, which is where the quake is most strongly felt (above the hypocenter), was the northern Sea of Galilee area roughly across the lake from Kibbutz Ginosar.
Each of the 11 quakes happened at different depths, up to about 10 kilometers, Hamiel explained.
"We had a similar swarm in October 2013 that continued for a month in exactly the same place – north Kinneret," he said. "The intensities were a little less then – the strongest then was above 3 but didn't reach 4."
He added that there had been a tremor just two days ago, on Monday, but it only measured 2.1 on the Richter scale.
Running for shelter
Earthquakes still cannot be predicted, though work is being done around the world with that aspiration in mind. However, in the case of powerful quakes, lives can be saved by taking shelter if people are warned the second the quake begins.
Around the world, systems have been developed to detect quakes as soon as they start in order to send alerts. The idea is that people can rush to take means to protect themselves before the seismic motion reaches them.
The caveat is that the faster the systems sending the alerts is, the more that will be at the expense of analyzing the event and "judging" - even using automated systems - whether the incident warrants alerting the population. In other words, the faster the system, the more likely it is to send people scrambling when the danger is negligible.
But one can choose to be alerted quickly and hide when unnecessary, or be alerted once the danger is clear – but is more imminent.
Israel is in the process of installing a quake-alerting system called Tru'a, at a cost of about 35 million.
The Tru'a system will be fed information from 120 seismic sensors placed along the Dead Sea Valley to the Sea of Galilee, in the Jordan Valley and on Mount Carmel. So far 40 sensors have already been installed, Hamiel told Haaretz. The work is expected to finish in May 2019, after which it can be made operational.
When a shake begins and is sensed by the system, alerts will be sent to the Home Front Command and disseminated among the general public.
Asked whether Tru'a will be programmed to be more "fast" or more "accurate", Hamiel explained that this is a decision yet to be made, by the geologists in cooperation with the army (Home Front Command).
Shaken to bits
Quakes around the Sea of Galilee and in the region in general are not rare. The sea, actually a freshwater lake, sits smack on the Dead Sea Fault (which people call the Great Rift Valley), stretching thousands of kilometers from Africa to Turkey, Hamiel says.
The Dead Sea is also in that vast fault line, which has also produced serious temblors from time to time.
The quakes in Israel are of the type called slide-slip. Israel sits on the Sinai plate, which rubs against the Arabian plate to our east. The Arabian plate is moving north relative to the Sinai plate, and the result is the occasional very big quake.
In recent history, Israel suffered powerful temblors in 1927, in the northern part of the Dead Sea, and another in 1995, centered in the Gulf of Eilat. Doing the math over about 2,000 years, says Hamiel, we see powerful quakes roughly every 80 to 100 years. So yes, Israel is overdue for a big one, which could happen at any part of the Dead Sea fault. "We know where, but we don't know when," Hamiel spells out.
How big? We can't say, but we can say that earthquakes have destroyed cities throughout history.
Leaving aside the propensity of the local peoples to invade each other's territory and wreak ruin, the region's peoples have suffered from quakes throughout recorded history because of the Dead Sea Fault.
Archaeologists have found stark evidence of past temblors in all the ancient cities around the Sea of Galilee, including Tiberias itself and Hippos-Sussita on the other side of the lake, and Beit She'an a bit to the south of them both, to name just three. All were destroyed by temblors in the year 363 C.E. Tiberias and Beit She'an recovered. Hippos, finally leveled by the moving earth in the year 749, was never rebuilt.
Experts warn of more major quakes in Israel's future but of course, they cannot say when, as prediction remains impossible.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.