|
What happened in Christchurch?On September 4 2010 at 4.35am Christchurch residents were shaken awake by a 7.1 magnitude earthquake that was centred 40 kilometres west of Christchurch at a depth of 10 kilometers. The Epicentre was the small rural town of Darfield. The earthquake caused significant damage to buildings in Darfield and to some buildings in Christchurch City. Thankfully only 2 people suffered serious injury and no deaths occurred from that event. Since September the region has suffered hundreds of aftershocks (smaller earthquakes occurring as a result of the main earthquake).Tuesday February 22 2011. Another earthquake struck Christchurch at exactly 12:51pm - during the busy city lunchtime period. The epicentre of the magnitude 6.3 quake was only 10 kilometers south of east of Christchurch in the historic port township of Lyttelton and was just 5 kilometers deep. The proximity of this quake to Christchurch City coupled with its shallowness meant that its impact was much greater than the September earthquake even though it was smaller in magnitude. This earthquake caused massive damage to the Christchurch’s Central Business District and to Lyttelton and Christchurch's eastern suburbs. In the city centre buildings collapsed as office workers went for lunch and shoppers filled cafes, restaurants and stores resulting in significant loss of life and many people being trapped. Power, water and sewage services were damaged in the city centre and suburbs to the east. Liquefaction also caused significant damage to roads, building and and housing. Liquefaction occurs when a stress such as an earthquake causes the soil to lose it's stiffness and strength and sand and water can force their way to the surface. Cantabrians are known to be a strong and reslient population of people who will with the help of the rest of New Zealand are rebuilding the city. Although parts of the city are still cordoned off Christchurch still has many activities and attractions on offer. The City's airport, which is described as the gateway to the south island, has remained fully functional and at full capacity. One of the best ways in which you can help our city to rebuild is by visiting the region, check out this months edition of the Canterbury Tourist Times to see what you can do here. Confused about earthquakes? Here’s some useful information. New Zealand sits within the “Ring of Fire” an area surrounding the Pacific Ocean where about 90% of the world’s earthquakes occur. Many regions across New Zealand have been affected by earthquakes from time to time. In fact since 1848 there have been at least 30 earthquakes of significant magnitudes (5 and above) around the country and literally thousands occur each year that are too small to feel. An earthquake occurs when blocks of rock sitting on either side of a fault (existing fracture in the earth’s crust) shift abruptly. The result is a sudden release of energy from below the earth’s crust that travels in seismic waves to the surface of the earth. Earthquakes are generally measured by their magnitude – a magnitude 3 earthquake for example is unlikely to cause damage or be felt. The higher the magnitude the more potential it has to cause damage. The intensity of an earthquake and its potential for destruction however are influenced by more factors than simply the magnitude. The depth of the fault as well as factors such as soil type and building codes, and population density all affect the ability of the earthquake to cause damage and possibly loss of life. The Epicentre of an earthquake is the area directly above where the fault ruptures and therefore usually sustains the most damage. |