Going up! To design buildings that can withstand earthquakes, engineers need to know the ‘peak ground acceleration’ - how rapidly the ground will move during the quake, both horizontally and vertically. Instruments called ‘strong-motion accelerometers’ are used to measure movement. In powerful earthquakes the ground may accelerate upward at a rate that is greater than the downward acceleration due to gravity. 2:01 PM
23.6.06
Snow has once again blanketed parts of New Zealand. The South Island received less snow than in the previous storms of 11-12 June 2006, but heavy falls in the central North Island on 22-23 June closed roads, cutting off all routes between the northern and southern North Island except for highways along the Taranaki coast. 1:47 PM
16.6.06
Hazard fact – 16 June 2006 A tornado and lots of snowOn 11-12 June 2006, wild weather brought major problems to New Zealand. On Sunday, 11 June, a small tornado ripped through a Greymouth suburb. Nearly 20 residents, most from a single street, had damage to roofs, sheds, fences and windows. On June 11-12, large areas of the South Island were blanketed by snow, closing roads, bringing down power lines and trees, and shutting schools and airports. Some buildings and verandahs collapsed under the weight of snow. Parts of Canterbury had their deepest snowfalls for more than 30 years. A number of days after the storm, electricity still had not been restored in some isolated areas. In the North Island, rain, gales and overnight freezes also disrupted travel and brought power outages. 2:12 PM
9.6.06
Volcanic earthquakes Volcanic earthquakes are small earthquakes that occur when rocks are broken by molten rock (magma) moving through them. Volcanic earthquakes can be “high frequency” or “low frequency”. If the rocks breaking are relatively cool and brittle the earthquakes will be of a higher frequency than earthquakes caused by the breaking of hotter, and thus softer, rocks. 3:37 PM
2.6.06
Big earthquakes in a typical year According to the United States Geological Survey, during a typical year 18 major temblors (magnitude 7.0 to 7.9) and one great earthquake (magnitude 8.0 or higher) occur worldwide. On average, 10,000 people die in earthquakes annually. 3:08 PM
