( CNN ) Saturday 's deadly earthquake in Nepal was the `` big one '' experts were waiting for based on the region 's history . Earthquakes are a fact of life in the South Asian country , with tremors of magnitude 4 or 5 occurring several times each year , geologist and science journalist Kate Ravilious said . With the last major earthquake in 1934 , the concern was not if , but when the next `` great '' earthquake would hit , said Ravilious , author of the 2014 article , `` Kathmandu 's earthquake nightmare . '' In a landlocked country like Nepal , where infrastructure is fragile to begin with , the consequences of such an earthquake had the potential to be `` much more serious , '' Ravilious told CNN . Those fears were realized when a magnitude-7.8 earthquake centered less than 50 miles from the national capital of Kathmandu rocked Nepal , toppling homes , historic buildings and leaving more 1,400 dead , authorities said . `` This event , while large and tragic , is not unusual for that region of the world as the whole mountain range stretching from Tibet almost to Caspian Sea is an area of major collision between continental plates , '' said geological engineer Nicholas Sitar with the University of California , Berkeley 's Department of Civil and Environmental Engineering . What 's different this time from 1934 is the size and density of Kathmandu , which suffered the brunt of damage in both earthquakes . `` The population has exploded in several decades , '' U.S. Geological Survey spokesman Gavin Hayes told CNN . `` When you get a vast population in the kind of building infrastructure that is n't equipped to handle shaking of an earthquake this size , that 's when you see the scale of disaster we 're seeing now . '' The big unknown is what happens next , now that the initial rumbles of the quake have passed , Ravilious said . How will emergency response teams enter the landlocked country , whose single international airport is closed ? How will transports carrying aid move through the country if roads are destroyed ? If and when landslides start , how will mountainside villages in the Himalayan range fare ? And , will it all be resolved before monsoon season starts ? `` The worry now is to get Nepal up and running again on feet , '' Ravilious said . `` The monsoons in a couple of months could make things worse if we do n't sort things out before then . '' An earthquake is the ground shaking caused by a sudden slip on a fault , according to the U.S. Geological Survey . Stresses in the earth 's outer layer push the sides of the fault together , releasing energy in waves that travel through the earth 's crust and cause the shaking felt during an earthquake . Nepal is located on a major plate boundary between India and Eurasia , where collisions have been in progress for about 50 million years . Those collisions are responsible for the construction of the Himalayas , which has the tallest and some of the fastest growing mountains in the world , said Chris Goldfinger , director of Oregon State University 's Active Tectonics and Seafloor Mapping Laboratory . India is moving northward into Eurasia at a rate of about 45 millimeters a year , with earthquakes of a magnitude from 8 to 9 occurring on average in the Himalaya every 500 to 1,000 years , said Marin K. Clark , associate professor of Geological Sciences with the University of Michigan 's Department of Earth and Environmental Sciences . The last major earthquake to affect this part of the Himalayas was in the 1500s , and Kathmandu was badly damaged in an earthquake that occurred farther east of Saturday 's quake in 1934 . A major concern for this earthquake is damage from landslides generated by the strong shaking , Clark said . The entire area that experienced shaking was in steep , mountainous topography where landsliding is a significant hazard . Clark compared the circumstances to the 2008 earthquake in Sichuan Province , China . The magnitude-7.9 earthquake generated more 200,000 landslides , many of which blocked roads , slowing response and recovery efforts . The landslides also blocked river valleys , which created significant flood hazard . `` We might anticipate a similar situation for Nepal . ''
Earthquake scientists have been expecting major event in Nepal since 1934 . Population density , weak building infrastructure amplified damage , USGS spokesman says . `` This event , while large and tragic , is not unusual '' in region , geological engineer says .