It was a bad week for severe earthquakes. That’s not to say that we don’t see dozens of earthquakes most weeks, but most of them are of low magnitude, and cause minimal damage.
But the week started off with a Magnitude 5.4 quake in Indonesia on Monday the 21st at 06h21 UTC, in the province of Jawa Barat, population about 3 million people, and, as of late Friday night, the death toll stood at over 270 souls, of whom one third are children. The most recent victim found had been a 7 year old girl rescuers had spent 3 days searching for. She was eventually found under three collapsed layers of concrete, and had unfortunately not survived. Another 40 persons are still missing, over 2000 injured, and 62000 displaced. Search and rescue operations are ongoing, amidst many aftershocks, and heavy rain is hampering efforts.
On Tuesday the 22nd, a magnitude 7.2 quake struck just off the coast of the Solomon Islands, slightly east of Papua New Guinea, at a depth of 10km under the ocean, and generating a very small tsunami. There were about 2000 people within the radius of danger, and I’m glad to say there have been no reports of loss of life there, but damage to buildings and an airport and some power cuts have been reported.
And then, on Wednesday the 23rd, a 6.1 magnitude earthquake struck Turkey slightly east of Istanbul and close to the coast of the Black Sea, at a depth of 10km. About 197000 people were exposed to very strong shaking, and at least 93 persons injured. By yesterday no reports of deaths had been received, though the earth is still settling down in the area, as small aftershocks are felt. Again, heavy rainfall makes rescue efforts difficult.
Our Regional Director Michael ZS1MJT tells me that he and Pierre ZS1HF travelled up to Mossel Bay last weekend to meet the group of enthusiastic Radio Operators who come from that Southern part of the Cape Coast, and who asked for more information, and the right process for becoming HAMNET members and integrating themselves into HAMNET Western Cape.
Eighteen Southern Cape Amateurs joined for the session at 09h00 on Saturday, held at the new Joint Operations Centre in Mossel Bay. Pierre and Michael covered subjects like who should join HAMNET, why you should become a member, what is WSAR and how we fit in with the other organizations; discussions on antennas, propagation, NVIS, vehicle antenna placement: the pros and cons, deployment do’s and don’ts, ethics, the SARL, tactical call signs and recruitment.
During the course of the morning, they were visited by the deputy mayor of Mossel Bay and the JOC manager. They welcomed HAMNET and explained the purpose of the new JOC and also how it is going to be managed.
Michael says it was a very informative morning and a lot was learned, and I thank him for this report.
Those of you living in lightning-prone parts of the country will be interested in an article coming from the University of South Australia. This says that the chances of being struck by lightning are less than one in a million, but those odds shortened considerably this month when more than 4.2 million lightning strikes were recorded in every Australian state and territory over the weekend of 12-13 November.
When you consider that each lightning strike travels at more than 320,000 kilometres per hour, that’s a massive amount of electricity.
Ever wondered about lightning? For the past 50 years, scientists around the world have debated why lightning zig-zags and how it is connected to the thunder cloud above.
There hasn’t been a definitive explanation until now, with a University of South Australia plasma physicist publishing a landmark paper that solves both mysteries.
Reporting in Phys.org, Dr. John Lowke, former CSIRO scientist and now UniSA Adjunct Research Professor, says the physics of lightning has stumped the best scientific minds for decades.
“There are a few textbooks on lightning, but none have explained how the zig-zags (called steps) form, why the electrically conducting column connecting the steps with the cloud remains dark, and how lightning can travel over kilometres,” Dr. Lowke says.
The answer? Singlet-delta metastable oxygen molecules.
Basically, lightning happens when electrons hit oxygen molecules with enough energy to create high energy singlet delta oxygen molecules. After colliding with the molecules, the “detached” electrons form a highly conducting step—initially luminous—that redistributes the electric field, causing successive steps.
The conducting column connecting the step to the cloud remains dark when electrons attach to neutral oxygen molecules, followed by immediate detachment of the electrons by singlet delta molecules.
Why is this important?
“We need to understand how lightning is initiated so we can work out how better to protect buildings, airplanes, skyscrapers, valuable churches, and people,” Dr. Lowke says.
While it is rare for humans to be hit by lightning, buildings are hit many times, especially tall and isolated ones (the Empire State Building is hit about 25 times each year).
The solution to protect structures from lightning strikes has remained the same for hundreds of years.
A lightning rod invented by Benjamin Franklin in 1752 is basically a thick fencing wire that is attached to the top of a building and connected to the ground. It is designed to attract lightning and earth the electric charge, saving the building from being damaged.
“These Franklin rods are required for all buildings and churches today, but the uncertain factor is how many are needed on each structure,” Dr. Lowke says.
There are also hundreds of structures that are currently not protected, including shelter sheds in parks, often made from galvanized iron, and supported by wooden posts.
This could change with new Australian lightning protection standards recommending that these roofs be earthed. Dr. Lowke was a committee member of Standards Australia recommending this change.
“Improving lightning protection is so important now due to more extreme weather events from climate change. Also, while the development of environmentally-friendly composite materials in aircraft is improving fuel efficiency, these materials significantly increase the risk of damage from lightning, so we need to look at additional protection measures.
“The more we know about how lightning occurs, the better informed we will be in designing our built environment,” Dr. Lowke says.
This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.