TAU geology researchers got more than they bargained for on an expedition to Turkey

A TAU team of seismic experts found themselves bang in the middle of a major earthquake measuring 6.3 on the Richter scale in Turkey this summer. The 40-strong delegation of researchers and students from the Departments of Geophysics and Planetary Sciences and Plant Sciences at TAU were in Turkey to study the "triple junction"- the meeting point of several large and seismically-active geological fault systems near the city of Karaman-Marash in southeastern Turkey. The team's objective was to make a geological study of the northernmost point of the Dead Sea Rift, a large fault system, where it ends and meets with the Taurus Mountains.

The earthquake occurred while members of the delegation were examining one of the rift systems - leaving the researchers shaken but excited. "It's an extremely rare event for a quake to take place exactly at the time of a scientific expedition," said TAU geophysicist Prof. Zvi Ben-Avraham, a member of the delegation. "Especially since we were examining the most active part of the fault system at the moment the quake struck."

It was only when the team got back to their base in the city of Adana, however, that they discovered the full extent of the disaster. Part of the city was plunged into darkness. All of its residents had abandoned their homes and prepared to spend the night in parking lots, on sidewalks, in public parks and on traffic islands. In the nearby city of Jihan, houses had collapsed like a stack of cards. More than a hundred people were killed and close to a thousand were injured.

A safe place for the night?

"We arrived at the hotel, which thankfully was still standing," said Prof. Ben-Avraham and colleague Prof. Akiva Flexer. "Plaster and paint had fallen in the rooms and hallways, but we decided that since the hotel appeared stable after such a major tremor, it would probably hold up during the aftershocks - which are usually weaker. We decided to remain there for the night. There were two aftershocks - one at midnight and one early in the morning, which drove some of our team outdoors. The water supply was disrupted."

The earth's surface is made up of plates which interlock like a mosaic, say Professors Flexer and Ben-Avraham. Between the plates are large faults - giant cracks in the earth's crust - along the length of which the plates move in several different ways: they either collide, press against one another, slide against one another, or tear apart from one another.

The Dead Sea Rift, which extends for a thousand kilometers from the southern part of the Gulf of Eilat to the Taurus Mountains in Turkey, constitutes a boundary between the Arabian plate and the African plate. Along the length of this rift there is a horizontal sliding movement between the plates, as the Arabian plate, situated east of the Rift (i.e. Saudi Arabia, Jordan and Syria), moves northward at a faster rate than the African plate, situated west of the Rift (i.e. Sinai, Israel and Lebanon). The Rift ends in the immediate area of the Taurus Mountains at the meeting points of three plates, the Arabian and the African with another northern plate, the Euro-Asian plate, known locally as the Anatolian plate. These so-called "triple junctions" are a rare phenomenon on land, since most are situated out at sea. They are very active from a seismic point of view.

Despite the enormous amount of research invested, especially in California and China, it is still not possible for scientists to predict large earthquakes. "The earthquake process is complex and takes place deep under the earth's surface: The radius of the earth is about 6,400 km. and the deepest boring that has been conducted to date by the Russians has been to a depth of 12 km," said the TAU professors.