The Young Chronicle: For 4th Graders May 3rd, 2015 | Page 4

Page 4 Newsletter Title NEPAL’S EARTHQUAKE CHRONOLOGY Do you know the devastating earthquake that shocked Nepal on Saturday was anticipated over 80 years ago.? This latest quake follows the same pattern as a set of big tremors that occurred over 700 years ago, according to geologists. Laurent Bollinger, from the CEA research agency in France, and his colleagues, uncovered the historical pattern of earthquakes during fieldwork in Nepal last month. Down in the jungle in southern Nepal, Bollinger's team dug trenches across the country's main earthquake fault. where what is now the Indian subcontinent collided 40 million to 50 million years ago with the Eurasian plate, a region that includes most of Europe and Asia. The collision created the Himalayan mountain range, the peaks of which are still rising by around one centimetre a year as a result. As the India plate pushes its way northward into Asia, stress and pressure builds up at the point where the two landmasses meet. When that pressure becomes too much, one landmass slides under another, releasing a shockwave that we call an earthquake. THE PATTERN OF QUAKES AROUND KATHMANDU A fault is a break in the earth's crust along which movement can take place causing an earthquake. They dug at the place where the fault meets the surface, and used fragments of charcoal buried within the fault to carbon-date when the fault had last moved. Bollinger's group was able to show that this segment of fault had not moved for a long time. Previously, the team had worked on the neighbouring segment of fault, which lies to the east of Kathmandu, and had shown that this segment experienced major quakes in 1255, and then more recently in 1934. WHY NEPAL IS PRONE TO EARTHQUAKES Along the southern border of Nepal is the Indus-Yarlung suture zone,      The earthquake on April 25th struck to the north-west f Kathmandu The last time the fault ruptured at this location was back in 1344 It was preceded in 1255 by a big event to the east of Kathmandu The last rupture there was in 1934, hinting strain might accumulate westward 2015's quake follows the pattern with a gap between events of 80 years or so.