In this week’s geoscience roundup (12-18 July, 2018) in addition to the regular update on the Kilauea eruption, we have a peep at the activities of another two other big names — one of them a very big name — among volcanoes, and some thoughts about how cold it can get in a warming world.
Two Sleeping Giants May Be Back…Quietly
I include a supplementary volcano or two more or less every week (in addition to the update on the rumblings of Kilauea) and it’s deliberate. I want readers to be aware that volcanic activity, like earthquake activity, is a normal part of the Earth’s activity and goes on all the time, though largely unremarked upon.
Two sleeping giants are stirring this week. One of them you’ll almost certainly have heard of, and the other you almost certainly won’t. It’s 135 years since Krakatau, in Indonesia, erupted with catastrophic results — killing at least 36,000 people and possibly many more, scoring a rating of 6 on the Volcanic Explosivity Index, which puts it among the largest known, and generating what is thought to be the loudest sound ever recorded (it was heard 4,800 km away).
The 1883 eruption literally blew the volcano away, leaving behind three small islands. But removing a volcano doesn’t take away the supply of magma and since then, the volcano has been rebuilding. The new cone is probably more correctly known as Anak Krakatau (Son of Krakatau) and is now a respectable 813 metres high.
And it’s rumbling on. The Global Volcanism Program database lists 45 eruptions since 1883, all relatively small. The most recent of them began on 18 June this year and is continuing. It’s characterised by a series of ash-producing events and increased seismicity, and possible lava flows. In other words, it’s doing what volcanoes do, regularly and without comment.
On the other side of the world, in Iceland, another very big beast may be stirring. The ice-covered Öraefajökull is a contrast to Krakatau’s recent incarnation. Rather than building slowly and erupting regularly, it has only two recorded eruptions in historical time, in 1362 and 1727, and both were very large (VEI 5 and VEI 4 respectively) though neither approached Krakatau in scale.
This week, the Iceland Meteorological Office issued a statement regarding the volcano which indicated that: “Öræfajökull volcano is showing clear signs of unrest with an inflation phase for at least a year and a half. The inflation is ongoing and it is reflected by increased seismic activity and characteristic deformation pattern.”
They went on to note that: “Öræfajökull is in a typical preparation stage before an eruption but the temporal evolution and the outcome is unknown.” In other words, there is no certainty about when, or indeed whether, the volcano will actually erupt.
If it does, and if it erupts with anything like the violence previously shown, I’ll lay a small bet that we’ll all learn the name (and the spelling and the pronunciation) of this particular volcano very quickly indeed. It may be isolated, but the impacts of an eruption in terms of volcanic gases, ash fall and an ash cloud could well be significant on a regional scale.
How Cold Does It Get?
We don’t know for certain how cold it gets (or, indeed, how hot) because we rely for our data on there being instrumentation to measure it, and that instrumentation isn’t always accurate. It isn’t as easy as you might think to come up with a definitive answer for highest and lowest temperatures but, for the record, the World Meteorological Office database lists the maximum recorded temperature as 56.7º C/134.06º F (at the aptly-named Furnace Creek in California in 1913) and the lowest as -89.2º C/-128.56º F in Vostok, Antarctica, in 1983.
These days, temperature measurements in the world’s harshest environments are improving in accuracy through the use of satellite technology, and new research suggests that the WMO’s database may need to be updated, for the lowest temperature at least. The previous lowest temperature came from a weather station, but satellites allow meteorologists effectively to search for the lowest temperature rather than record the temperature at a fixed point.
Recent research has indicated that the lowest temperature on the planet has reached -98º C/-144º F, a reanalysis of past satellite data in the light of new technology — a temperature which, the researchers have concluded, is as cold as it’s possible to get on Earth.
The United States Geological Survey’s Kilauea updates keep pinging into my inbox, indicating ongoing activity but little variation. In other words, the lava is still pouring out, volcanic emissions continue and there are regular explosions at the summit.
There have been a couple of newsworthy changes, though. One is the appearance of an island off the coast — very small, and a natural part of the land-building process on which volcanoes are key.
The other is rather more salutary. It’s easy to forget just how dangerous volcanoes can be, especially when the eruption is effusive rather than explosive. So far Kilauea has been a pussy cat rather than a tiger, causing damage to property but allowing residents plenty of time to get clear.
This week news media have reported 23 injuries when a lava bomb struck a boat carrying tourists who wanted to get a good look at the spectacular sight of lava entering the ocean. Fortunately no-one was killed — but it’s yet another reminder of just how dangerous natural forces can be.