Time Out


I guess it had to happen eventually and so it has, I am taking some extended time off from the Blogs – aiming to return at the beginning of 2017 (possibly the 1st January 2017). Why? Burnout. Illness – you call it, I probably have it. Seriously though – I’m tired and can’t hold onto to good health, so a longer break is required.

Health Break


Due to continuing bad health I am taking another break from most of my Blogs and will only be posting in an irregular manner over the next few weeks. I think I need to take care of myself a little for the time being. Hopefully, regular service will return before too long. There is nothing too threatening happening, just a long-term issue that flares from time to time.

What happened in New Zealand’s magnitude 7.5 earthquake


Brendan Duffy, University of Melbourne and Mark Quigley, University of Melbourne

At least two people have died in the magnitide 7.5 earthquake that struck New Zealand’s South Island early on Monday, local time.

Preliminary modelling suggests that the earthquake was caused by a rupture of a northeast-striking fault that projects to the surface offshore.

But this may be a complex event, involving several faults on the South Island.

The northern part of the South Island straddles the boundary between the Pacific and Australian tectonic plates.

The jostling between these plates pushes up rocks that create mountains including the Southern Alps and the beautiful Seaward Kaikoura Range, one of New Zealand’s most rapidly uplifting mountain ranges.

The plate motion forces the oceanic crust of the Pacific plate beneath the Australian plate on thrust faults, and also causes the plates to slide laterally with respect to one another on strike-slip faults.

The region affected by the recent earthquake has been one of the most seismically active in New Zealand over the past few years, including earthquakes that occurred as part of the Cook Strait earthquake sequence in 2013. It is likely that these sequences are related given their close spatial and temporal association.

What slipped during the earthquake?

The preliminary analysis strongly suggests that most of the energy release during this earthquake was sourced from the rupture of a roughly 200km-long fault system. This fault system is aligned northeast and dips to the northwest, beneath the northern part of the South Island. It coincides roughly with the subduction thrust in this area.

The potential for large earthquakes on the subduction fault in the lower North Island and upper South Island of New Zealand was recently highlighted by GNS Science, New Zealand’s geological survey. It published evidence for two similar events in the Blenheim area roughly 520-470 years ago, and 880-800 years ago.

Given its setting, this latest earthquake may be structurally complex, involving a mixture of plate boundary thrusting, lateral slip on strike-slip faults, and thrusting within the Pacific plate close to the epicentre, some 15km northeast of Culverden.

The largest aftershocks suggest a mixture of thrusting and strike-slip movements.

The damage caused by the earthquake

Because the fault system was large, and the earthquake apparently started at the southwest end of the fault and propagated to the northeast, the seismic energy was released over a period of up to two minutes.

Large earthquakes produce more long period wave energy than smaller events. The 2011 Christchurch earthquake contained a lot of high-frequency energy and very strong ground accelerations, exposing more than 300,000 people to very strong to intense ground shaking.

In contrast, this recent earthquake was manifested in Christchurch as lower-frequency rolling, and due to the sparse population density in the earthquake region, roughly 3,000 people in the upper South Island experienced strong ground shaking equivalent to the Christchurch earthquake.

Reports are emerging of at least one major fracture in the ground surface that could be related to strike-slip faulting in the Clarence region.

More traces may yet be found given the complexity of the earthquake. Tide gauge analysis will help to understand if a similar trace offshore caused the tsunami.

The earthquake has also triggered liquefaction in coastal areas and in susceptible sediments, and landsliding of up to a million cubic metres along steep susceptible cliffs in the northern South Island.

There are reports of extensive road damage including in the area between Hanmer Springs and Culverden, much of State Highway 1 and even Wellington, on the North Island.

Most of this damage is probably caused by strong ground shaking, which causes weak ground to move en masse and has resulted in numerous slips and road closures in the central and northern South Island.

Earthquakes, aftershocks and the pull of the moon

Given the earthquake happened on the eve of a supermoon full moon, and the closest the Earth and moon will be since 1948, it wasn’t long before some tried to make a connection.

But the tidal triggering of earthquakes has been investigated since the 19th century and remains a challenging and controversial field.

Small amplitude and large wavelength tidal deformations of the Earth due to motions of the sun and moon influence stresses in Earth’s lithosphere.

It is possible that, for active faults that are imminently close to brittle failure, small tidal force perturbations could be enough to advance rupture relative to the earthquake cycle, or to allow a propagating rupture to travel further than it might otherwise have done.

But the specific time, magnitude and location of this or any other large earthquake has not been successfully predicted in the short-term using tidal stresses or any other possible precursory phenomenon.

Deliberately vague predictions that provide no specific information about the precise location and magnitude of a future earthquake are not predictions at all. Rather, these are hedged bets that get media air time due to the romantic misinterpretation that they were valid predictions.

Most earthquake scientists, including those that research tidal triggering of earthquakes, highlight the importance of preparedness over attempts at prediction when it comes to public safety.

To this end, GNS Science uses a system of operational earthquake forecasts to communicate earthquake risk to concerned New Zealand residents during an aftershock sequence such as we are now entering.

These forecasts are based on earthquake physics and statistical seismology. The current operational forecast indicates an 80% probability of:

A normal aftershock sequence that is spread over the next few months. Felt aftershocks (e.g. M>5) would occur from the M7.5 epicentre near Culverden, right up along the Kaikoura coastline to Cape Campbell over the next few weeks and months.

This aftershock sequence will probably (98%) include several large aftershocks (some greater than magnitude 6 have already occurred), and for each magnitude 6 aftershock we expect 10 more magnitude 5 aftershocks over the coming days and weeks.

The Conversation

Brendan Duffy, Lecturer in Applied Geoscience, University of Melbourne and Mark Quigley, Associate professor, University of Melbourne

This article was originally published on The Conversation. Read the original article.

Newspoll: Labor gains to lead 53-47


Adrian Beaumont, University of Melbourne

Tuesday’s Newspoll, conducted 3-6 November from a sample of 1850, had Labor leading 53-47, a one point gain for Labor. Primary votes were 39% for the Coalition (steady), 38% for Labor (up 1) and 10% for the Greens (steady).

30% were satisfied with Turnbull’s performance (up 1), and 58% were dissatisfied (also up 1), for a net approval of -28. It is the first time since the election that Turnbull’s net approval has not declined in Newspoll. Shorten’s net approval was an unchanged -15.

To the extent that Donald Trump’s shock victory has an effect on Australian politics, it will probably help One Nation, the most Trump-like party in Australia. Most supporters of the three established parties will not change their votes, but One Nation could consolidate some of the Others vote.

Last week’s Essential, conducted over two weeks from a sample of 1800, also had Labor leading 53-47 from primary votes of Coalition 38%, Labor 37%, Greens 10%, One Nation 6% and Nick Xenophon Team 3%. Turnbull’s net approval was -8, down from -3 in October. Shorten’s net approval was -9, down from -3.

23% thought the Coalition government was too tough on asylum seekers, 24% too soft and 37% about right; in August, these percentages were respectively 21%, 29% and 31%. 56% approved of the government’s proposed legislation to ban asylum seekers from ever coming to Australia, and 29% disapproved.

59% would have supported Clinton if they could vote, with 19% supporting Trump. In June, respondents favoured Clinton 71-15; the 12 point drop for Clinton was driven mainly by Coalition and Other voters. Australian voters far preferred Clinton to handle important issues. 52% thought that US influence in the world is becoming weaker, with 19% for stronger.

An Ipsos online panel poll of 921 respondents, conducted Thursday and Friday, found that 66% of Australians opposed Trump’s election as US President. Similar percentages (58-63%) thought he would be bad for the US, the world economy, the Australian economy, world security and relations between the US and Australia. 45% thought the Coalition would be most capable of managing Australia’s relationship with the US under Trump, with 22% selecting Labor and 14% One Nation.

NSW by-elections: huge swing against Nats in Orange

Yesterday, by-elections were held in the NSW lower house seats of Orange (National-held), Wollongong (Labor-held) and Canterbury (Labor-held). In Orange and Canterbury, the sitting members successfully contested Federal seats at the recent election, while Noreen Hay resigned as Wollongong member after many scandals.

In Orange, the Nationals won 31.1%, down a massive 34.5 points from the 2015 election. Perhaps reflecting a Trump surge, the Shooters, Fishers & Farmers were second with 24.3%, followed by Labor at 18.6% (down 4.7). The rest of the vote mainly went to Independents with the Greens at 5.8%.

There is no preference count yet for the Nationals vs Shooters contest. NSW uses optional preferential voting, which will make it harder for the Shooters. However, unless the Nationals can greatly extend their lead on the remaining votes, the Shooters are likely to win their first ever single member electorate.

The Orange result has been blamed on the proposed greyhound racing ban that has now been withdrawn, and on forced council amalgamations.

The other two by-elections were less dramatic. In Wollongong, Labor defeated Independent Gordon Bradbery 58-42, a one point swing to the Independent who had contested the 2015 election. In Canterbury, Labor was opposed by only the Greens and Christian Democrats, and romped home with 66% of the primary vote.

WA Newspoll: 52-48 to Labor

The Western Australian election will be held in four months on 11 March 2017. A WA Newspoll, conducted from August to October with a sample of 860, has Labor leading by 52-48, a 2 point gain for the Liberal/Nationals since the March to May WA Newspoll.

Primary votes are 41% for Labor (down 1), 40% for the combined Liberals and Nationals (steady) and 9% for the Greens (down 2). These primary vote changes imply that the 2 point two party change is partly a result of rounding.

Despite the improvement on voting intentions, Premier Colin Barnett’s ratings slumped. His satisfied rating was down 3 to 28% and his dissatisfied rating up 3 to 61%, for a net approval of -33. Opposition leader Mark McGowan’s net approval fell 10 points, but he is still at a +13 net rating.

This poll is in agreement with a recent ReachTEL poll that also had Labor ahead 52-48. The ReachTEL poll was conducted on 27 October, so it is much more recent and useful than this Newspoll, conducted over three months.

Queensland Galaxy: 51-49 to Labor

A Queensland Galaxy poll has Labor leading by 51-49, a one point gain for Labor since August. Primary votes are 37% for the Liberal Nationals (down 1), 35% for Labor (up 2), 16% for One Nation (steady) and 8% for the Greens (steady). Premier Annastacia Palaszczuk’s approval was down two to 44% and her disapproval was up eight to 39%, for a net approval of +5. I expect this poll was conducted Wednesday and Thursday from a sample of about 900.

US Presidential election: Clinton won popular vote

Donald Trump will be the next US President after winning the decisive Electoral College by a likely 306-232 margin. However, according to Cook Political Report analyst David Wasserman, Hillary Clinton is currently leading in the national popular vote by 47.7% to 47.1%, and that lead is certain to increase as most of the remaining votes are from strong Democratic territory. Clinton is likely to win the popular vote by about 2%.

The popular vote/Electoral College discrepancy occurred because Clinton performed much worse in the swing states than overall. The swing states had a higher proportion of non-university educated whites than nationally, and this group was easily Trump’s best demographic. This will be the fifth time in US history that the popular vote winner has not won the Presidency; 2000 was the most recent occurrence.

My last two articles on the US election for Election Watch may help to understand why this result happened. This tweet below from New York Times analyst Nate Cohn shows how rural America swung big to Trump (red is the Republicans’ colour).

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The Conversation

Adrian Beaumont, Honorary Associate, School of Mathematics and Statistics, University of Melbourne

This article was originally published on The Conversation. Read the original article.