Over the life of our planet the construct and shape of its surface has changed repeatedly. But this has been no passive activity; it has been accompanied by volcanic eruptions, floods and massive shifting of continental plates. As the plates are forced together, the earth trembles and shakes and mountain ranges are formed, chasms are opened, whole oceans move and continents are born. These processes began at the beginning of time and continue today.
When I was an undergraduate in 1965, the nascent theory of continental drift was being argued with the evidence mounting in its cause. The whole idea of continents moving about had reached introductory geology classes. What a fascinating idea! Over the following half century it has moved from theory to established fact as geologists traced the geological time line in very disparate continents separated now by huge oceans of water.
These massive plates of land continue to move, to form mountains, to slide down under the sea. But not without complaint. Inertia and friction resist movement and thus they occur in sudden jolts -like trying to move heavy furniture. These jolts are what we call earthquakes.
Typically, earthquakes occur along the edges of the continental plates, along fault lines (we have all heard of the San Andreas fault in California). In new Zealand, the Pacific plate is sliding southward along the Australian plate with the fault line running along the mountainous west coast of South Island. As you look northward, the fault line extends through Wellington and continues to the center of North Island. There are over 14,000 earthquakes in New Zealand per year although only about 200 are strong enough to be felt. New Zealand is sometimes called the Shaky Islands.
However, the final chapter on seismic activity in New Zealand had not yet been written. A previously unknown fault has been described and named the Greendale fault, which runs on an east-west line west of Christchurch and is the location of much of the activity over the past several months.
The size of an earthquake, while significant in its damaging force, is not the sole determining factor. Like real estate, it is "location, location, location". The 2010 Haiti quake was 7.0 M, 1989 the San Francisco, 7.1 M, the current Christchurch quake only 6.3 M on the Richter scale but the property damages estimated at US$12 billion the highest from a natural disaster since Hurricane Ike in 2008.
Certainly the loss of life is low when compared to a disaster like Haiti, but much of that can be attributed to awareness and preparedness and a wealthier economy. The losses to the economy do no, however, stop at current property losses. The economy depends heavily on tourism and many of the seriously damaged buildings in the city are the old historic buildings that attract tourists, like the cathedral, and it is questionable if they can be restored. And, of course, 5000 earthquakes (201 of the over magnitude of 4.0) in the last six months isn't exactly a big draw for tourists.
Christchurch cathedral before quake:
Christchurch cathedral after quake Feb 22, 2011:
When I was an undergraduate in 1965, the nascent theory of continental drift was being argued with the evidence mounting in its cause. The whole idea of continents moving about had reached introductory geology classes. What a fascinating idea! Over the following half century it has moved from theory to established fact as geologists traced the geological time line in very disparate continents separated now by huge oceans of water.
These massive plates of land continue to move, to form mountains, to slide down under the sea. But not without complaint. Inertia and friction resist movement and thus they occur in sudden jolts -like trying to move heavy furniture. These jolts are what we call earthquakes.
Typically, earthquakes occur along the edges of the continental plates, along fault lines (we have all heard of the San Andreas fault in California). In new Zealand, the Pacific plate is sliding southward along the Australian plate with the fault line running along the mountainous west coast of South Island. As you look northward, the fault line extends through Wellington and continues to the center of North Island. There are over 14,000 earthquakes in New Zealand per year although only about 200 are strong enough to be felt. New Zealand is sometimes called the Shaky Islands.
However, the final chapter on seismic activity in New Zealand had not yet been written. A previously unknown fault has been described and named the Greendale fault, which runs on an east-west line west of Christchurch and is the location of much of the activity over the past several months.
The size of an earthquake, while significant in its damaging force, is not the sole determining factor. Like real estate, it is "location, location, location". The 2010 Haiti quake was 7.0 M, 1989 the San Francisco, 7.1 M, the current Christchurch quake only 6.3 M on the Richter scale but the property damages estimated at US$12 billion the highest from a natural disaster since Hurricane Ike in 2008.
Certainly the loss of life is low when compared to a disaster like Haiti, but much of that can be attributed to awareness and preparedness and a wealthier economy. The losses to the economy do no, however, stop at current property losses. The economy depends heavily on tourism and many of the seriously damaged buildings in the city are the old historic buildings that attract tourists, like the cathedral, and it is questionable if they can be restored. And, of course, 5000 earthquakes (201 of the over magnitude of 4.0) in the last six months isn't exactly a big draw for tourists.
Christchurch cathedral before quake:
Christchurch cathedral after quake Feb 22, 2011:
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