Another Spectrum

Personal ramblings and rants of a somewhat twisted mind


11 Comments

Earthquakes!

First a minute long 7.2 shake just at 2:27 AM this morning. I didn’t bother getting out of bed as it was more of a rolling motion than sharp jolts. New Zealand homes are designed to remain mostly intact during earthquakes. They may may not be habitable afterwards, but their structure does minimise serious injury and death. This particular quake knocked a few items of shelves but nothing was broken.

A few hours later another 7.4 earthquake struck around 900 Km offshore, and in the last hour an 8.1 earthquake struck just of the east coast of the North Island. The third tsunami warning of the day has been issued and evacuation orders have been made for some areas.

And of course so many are evacuating by vehicle causing massive traffic jams, whereas official advice it to walk, run or cycle where possible to avoid congestion. Why are so many people such idiots?

There have also been a number of less intense earthquakes of 5.0 or greater during this morning. Of course the big question in these earthquake swarms is has the biggest shake occurred? Typically the first shake is the largest, but today the strongest was shake was some seven hours after the first. This may even be the first stage of a long lasing swarm. We experienced such a swarm many years ago when we lived in Whanganui. The swarm lasted for around a month and with dozens of shakes, some of which made walking virtually impossible and it was necessary to crawl to cover.

I’ve experienced so many earthquakes during my seventy plus years that I’m rather blasé about them. Having said that, I rather enjoy the ride provided by long or severe shakes – a kind of adrenalin rush. We’ve experienced relatively little damage over the years. Only crockery and ornaments falling of shelves and cracks appearing in our home and in paths around it.

Living in a volcanic, seismically active region, most of us accept the risks of living here. There are a number of regular re-occurring earthquakes that have been documented. Perhaps the most threatening is the Alpine fault that stretches along almost the entire length of the South Island and fractures every 300 to 350 years. The last fracture occurred a little over 350 years ago so it’s not so much a matter of “if” but “when”. Quite likely within my lifetime.

For the moment we have the task of letting friends and family living overseas that we are safe and sound.


1 Comment

Just a little shake

45 minutes ago we experienced a mild earthquake (magnitude 6.2). It was enough to disturb the dog and cause ornaments to rattle and hung picture frames to bang against the wall, but this time only a single item fell over – a top heavy vase holding orchids. It’s funny how different people react. I find them exciting, whereas the wife finds them disturbing.

This one lasted around 45 seconds and came in two distinct waves. The first was a series of vigorous shakes, the second was more of a rolling motion.

Earthquakes are quite common here (around 14,000 each year), although only some 300 are noticeable. NZ lies on the collision zone between the Indo-Australian and Pacific tectonic plates. Visitors to the country often comment on the number of wooden buildings found here. The reason is simple. Wooden framed buildings suffer less damage than masonry and brick structures and are less likely to cause death or serious injury in an earthquake.


7 Comments

Rockin’ rollin’ ridin’

For some reason I’m not able to fathom, extreme forces of nature exhilarate me, never frighten me. As a teenager, I remember watching a violent electrical storm from our front porch when suddenly all I could see was a bright white flash, followed almost immediately by a wave of heat. A second or two later, I was in complete darkness. My first thoughts were “Wow! I’ve been blinded by a lightning strike. What a story to tell!”

Slowly  my vision returned, and I realised that the reason for the darkness was that there were no street lights or any form of lighting from houses in the neighbourhood. I was somewhat disappointed that I wouldn’t have such an amazing story to tell after all.

Lightening had stuck a large step-down transformer that stood about 15 metres from our porch, and the flash and and rush of heat was the result of the transformer exploding from the strike, plunging the suburb into darkness.

In my Early twenties, a brother and I toured the South Island. On the return Cook Straight crossing between Picton and Wellington, The Interislander ferry ran into a violent storm. I was the only passenger to occupy the front observation lounge as the ship’s bow was pointing at the stars one moment, then disappearing beneath dark water the next. Everyone else, including my brother, were huddled in the rear lounge with vomit bags held firmly to their faces, or had developed complexions that ranged from deathly white to assorted shades of green.

I thought the scene was rather funny, although had I been aware that many of the restraints holding the cars, trucks and railway rolling stock on the lower decks had failed, I might have had some concerns for the safety of my car. As it was, I was blissfully unaware of the damage being done below me and enjoyed wandering the top deck promenade while waves several stories high rush past, and the ship pitch violently beneath me.

Earthquakes have the same effect. Living in Aotearoa New Zealand, one gets kind of complacent with short quakes. We’re rather small in geographical terms – only 268,000 square kilometres (103,500 sq mi) in area, about the size of Colorado – but over 20,000 earthquakes are recorded every year. Most pass unnoticed, but there’s usually around 250 each year that are noticeable.

I’ve experienced a number of earthquakes over the years that have caused some damage to our home and contents, although nothing too serious. Each quake is unique and as they come on, I wonder what type of motion will result. Some seem to move in just one plane, for example horizontally or vertically. These, especially the horizontal ones, often have a few violent shakes towards the end, which seem to cause all the damage. The ones I enjoy the most, are those that have a rolling motion and feel as though they are moving in all directions at once. Think of riding a narrow gauge train travelling at very high speed over a poorly laid track with incredibly tight curves, where standing is impossible without holding on tight to the handrails on the seats around you.

Last night’s shake was like that. I was sitting in the lounge watching some late night television, and everyone one else had gone to bed. At 2 minutes after midnight I felt slight sensation of movement, and wondered if an earthquake was about to happen. Very gradually the movement increased, and within 15 seconds, I could see the ceiling fan, and bookcases moving. Shortly after I was watching the walls as they flexed and appeared to have waves moving along them. Doors started slamming shortly afterwards, and by the time a minute had passed, I realised that if I had intended to move to safety, the window of opportunity had probably passed. It would have been impossible to walk upright, and I would have needed to resort to hands and knees to make an escape. So I enjoyed the ride. I realised that with a shake this long, a major shock had occurred within a few hundred kilometres.

At about 5 minutes after midnight, the rocking and rolling had subsided somewhat, and I decided to check on the rest of the family, as I am aware that others do not view earthquakes as I do. I found my wife, daughter and her three children upstairs standing in doorways somewhat shaken. The length of the shake had prompted my daughter to gather her brood around her, and even now, fifteen hours later is reluctant to let them out of her sight.

Strong aftershocks are still being felt, and while only two deaths have been reported, Wellington’s CBD has been closed off due to fallen glass and masonry. Universities and schools have been closed and some roads are impassable. What I find interesting, is that aftershocks have been dispersed over a wide area, from several hundred kilometres south of where I live to over a hundred kilometres north. I wonder if it’s a precursor to the “Big One”. The Southern Alpine fault ruptures approximately every 330 years, the last one occurring in 1717. The fault line extends for over 400 kilometres and is expected to cause a magnitude 8+ earthquake when it ruptures, quite likely, within in my lifetime.

While I know it’s likely to cause widespread damage and possibly fatalities, I really would like to “ride the wave”. I can’t think of anything more exciting.