Interviewer: Welcome to the 60 Minutes chat room. This live interview is moderated.
Interviewer: Professor Plimer thank you for joining us tonight.
Ian Plimer: Thank you. I'd just like to point out that in history of the planet, we’ve always had earth quakes, always had tsunamis and always volcanoes.
Milo asks: what causes an earthquake?
Ian Plimer: The plates of planet earth are always moving. They are being pulled apart and pushed back together and by breaking the rocks or pushing them back together again we release energy and that gives us an earthquake.
Lilly asks: Professor is there a specific reason why we have had so many major earthquakes in the past few days?
Ian Plimer: Yes, we have cycles of volcanic and earthquake activity. This is quite normal to have periods of stress building up then we start to release it.
Otis asks: Can you predict Earthquakes?
Ian Plimer: No, we’ve been trying for a long while to predict earthquakes and we have failed. However there is a French Geologist Dr Blot who is almost successful at predicting earthquakes 2 years in advanced.
Billabong asks: How many earthquakes worldwide occur each day? Each year?
Ian Plimer: There are about 10,000 each year, about 300 each year are major. Most of these occur in the middle of the ocean.
Quick asks: At what magnitude does damage begin to occur in an earthquake?
Ian Plimer: What we hear in the press is the Richter magnitude of the earthquake. Damage relates to what we are built on, to the Richter magnitude of the earth sand what the building is made out of. The safest buildings are made of wood and most unsafe buildings are made of stone. The safest material beneath you is to build on rock, and the most unsafe material to build on is wet sand.
Paddlepop asks: Where do most of our region's quakes occur?
Ian Plimer: They occur in two major areas. The pacific belt around the edge of the Pacific and the second zone is from the Mediterranean through to Asia.
Riley asks: How far underground is an earthquake formed?
Ian Plimer: We have earthquakes forming from the surface to 700km underground. The most damaging and most intense occur from the surface at 30 km depth.
Pink asks: How fast do tsunami waves travel?
Ian Plimer: They travel at the speed of a jet airplane when they are out in the ocean, when they get closer to the land they slow down. The final speed when they hit the land is about 50km an hour. Jet airplanes travel at 700km an hour.
StormRule asks: Can the ground open up during an earthquake?
Ian Plimer: Yes it does, you’ve seen that in earthquakes in Australia. Tennant creek in NT during 1989 and the Mekering earthquake in 1968, the ground opens up half a metre to a metre. Sometimes out of the crack in the ground water bubbles out of the crack.
Gucci asks: Why does seawater recede a long way out before a tsunami?
Ian Plimer: As the wave energy comes towards the shore, needs more water, and it sucks water from the ocean and it plucks water from the shoreline. And the indicator of a tsunami is that water leaves the shoreline, so if water leaves the shoreline, head of the hills. This can all occur within 30 seconds to 3 minutes.
monkeys asks: Professor. Is it possible that Melbourne could get a earthquake?
Ian Plimer: Melbourne has had many tremblers, and that’s because the Great Diving Range is still moving up wards. Every now and then Eastern Australia gets earthquakes and that includes Melbourne.
sonny asks: Is there any link between the recent seismic activity in south-east Melbourne and that in the pacific?
Ian Plimer: There is no relationship, the seismic activity in Melbourne is due to a great event, pushing New Zealand further out into the ocean. And as a result, the Great Dividing Range rises.
bksmum asks: Why are the earth quakes mostly around the pacific belt?
Ian Plimer: This is because middle of the Pacific is pulling apart and we are pushing for the Pacific behind the edge of the continent.
Wiitard asks: Given the amount of activity that we are seeing in the 'Ring of Fire' Subduction Zone, what would you like to see in the way of protection for the millions of people in the area?
Ian Plimer: It is very hard to protect people against the great forces of nature. We see in history that the great civilizations never appeared around the ocean basins. They appeared in valleys, in mountains, in inland. This is because of great tsunamis and asteroids that drop into the oceans and give us tsunamis. If you want to survive, don’t live on the coast.
BasaltPlains asks: Hello Ian, Thanks for the opportunity to talk with you. A couple of questions. I am wondering what are the chances that the western basalt plains of Victoria (Melton) could become active? Also in terms of earth slides as a result of earthquakes, what factors determine these?
Ian Plimer: In Western Victoria the first sign of an eruption was about 70 million years ago and the last eruption was about 500 years ago. The reason why Western Victoria has such good agriculture is because of these volcanoes. Western Victoria is still active and it will still have volcanoes, it will be a great tourism place for visitors will the next volcanic eruption in the area. Earth slides are determined why how wet the soil is. If we have wet soil on steep slopes, it will fail. If we shake the land, it will fail even quicker; this is the most common process of erosion.
bundygirl_79 asks: so from those predictions, are there any large events in the near future that may affect Australia?
Ian Plimer: Australia has many catastrophes, we have cyclones, bush fires, drought, floods, we have had volcanoes, we’ve had a fatal earthquake in 1989. We have had tsunamis in South Eastern Australia, we have had more than 20 asteroids hit Australia. Every catastrophe that could happen, has happened in Australia.
dogyman11 asks: hi, how likely is it that we will have a super volcano erupt in the next century?
Ian Plimer: We have super volcanoes on the land, and 85% of the world’s volcanoes we do not see, and they are under the ocean. It is quite common to have submarine super volcanoes, the last big super volcano was Toba 74,000 years ago and in New Zealand we have had many super volcanoes and we pray for another because that is the only way we will beat New Zealand rugby.
massy-e asks: Professor Plimer my husband was saying to me that with everything we do to the earth, like take oil out the ground, mining, could effect the earth?
Ian Plimer: The forces of nature are far far greater than anything we humans do. It is only those who have a supreme ego that could argue that humans could change the planet from oil or from mining.
Paul asks: Are there any links between the Samoan earthquake and the Sumatran earthquake?
Ian Plimer: There are no links, it is a coincidence, but the Australian plate moves northwards about 7 cms each year which gave the Sumatran earthquake. The pacific plate is being pushed underneath the Australian plate, which gave us the Samoan earthquake. And this is a coincidence.
BasaltPlains asks: Is the speed of the earthquakes tremors altered as it passes through different substrates in the earths crust i.e. granite, sands, etc?
Ian Plimer: Yes, the speed of the earthquake changes, depending upon the rock type and depending upon whether material is solid or liquid. One earthquake shockwave is like a sound wave, and this goes through solid and liquid. Another type of earthquake shockwave is rather like the wave you see in the oceans, and this only goes through solid material. There is some really bizarre research on earthquake waves. Some years ago a scientist in the United States received research money to look at the speed of earthquake waves in different sorts of cheese. And he found that the earthquake did indeed in a Norwegian Green Cheese as the same as a rock from the moon. This is coincidence, but if you were of a different mind, you might say that the moon is made of Norwegian Green Cheese.
happycamper7 asks: Hi Professor, are we seeing more tsunamis in the last few years? Are there different types of earthquakes happening?
Ian Plimer: We are not seeing more tsunamis and there are no different types of earthquakes. What we are seeing is 24 news. 100 years ago if there was an earthquake or a tsunami, we would have read about it in the newspapers a month or so later. But today with instance communication, we are hearing every earthquake and tsunami reported in real time.
benjimin asks: You mentioned wood buildings as the safest, is this even in comparison to modern buildings (say, concrete and steel hotels)?
Ian Plimer: Wood is very flexible and will move and bend. Concrete does the same and steel does the same. But wood is much more flexible, then concrete and steel and so is better in an earthquake.
Renhen asks: Professor, do you think these earthquakes are a result of climate change?
Ian Plimer: No, there is absolutely no relationship between earthquakes and climate. In the history of planet Earth, climate has always changed for 80% of time our planet has been warmer and wetter then now. We are living in an ice age which started 37 million years ago. We are actually in cold times.
ella345 asks: can a tsunami wave be slowed down with anything?
Ian Plimer: No, the only thing that will slow a tsunami will be deep water. When it comes to the shore in the shallow water, it slows down but gets bigger.
sonny asks: Professor, what are your views on the 'expanding earth theory' whereby there is only outward movement of tectonic plates and no actual submersion of one beneath another at the other side?
Ian Plimer: The theory of an expanding earth is not a popular theory, however there is evidence that the earth is expanding and there is also evidence of the popular theory called plate tectonics. It appears that the popular theory of plate tectonics cannot explain everything we observe, that is why I’m a little bit sympathetic to the ideas of an expanding earth that were promoted by Sam Carey.
Alex asks: How are tsunamis predicted and monitored
Ian Plimer: It is very hard to predict a tsunami because some large earthquakes in the ocean do not produce tsunamis. To monitor tsunamis can be done with ocean sea level hearing stations, but the problem is that if the earthquake produces the tsunami occurs very close to the land then the time between the tsunami monitoring and when the tsunami hits the land is so short that there are seconds or minutes warning before a tsunami.
Rockhound asks: with the earthquakes happening around the indo aus plate recently do you think the pressure is building or being released
Ian Plimer: Every time there is an earthquake, the pressure is released and then it started to build up again, then it is released with the next earthquakes, and then it builds up against and released again.
123456 asks: How far can a tsunami travel in on land beyond the shoreline?
Ian Plimer: This depends upon how big the wave is and how steep the land is, we do know that past tsunamis from massive volcanic eruptions or from asteroids dropping into the ocean, we do know tsunamis can be 100 of metres high, which means they go 10s of kms inland.
NILES asks: Hello Ian, can tremors lead to earthquakes?
Ian Plimer: Tremors normally lead to earthquakes because we are releasing energy, many times and slowly. Tremors are the regular release of energy, when we have energy building up and it is not released as a tremor, it can be suddenly released as a large earthquake. Tremors indicate of that we are always releasing energy and the chances of a big earthquake are unlikely.
vicman asks: How advanced is our science in terms of being able to predict earthquakes? Investment in the tsunami warning system has probably made a difference, is there something else we can do for earthquakes?
Ian Plimer: We have not been very successful at predicting earthquakes. The tragedy is that there have been two scientists who have saved 10s of thousands of lives from their earthquake predictions in Melanesia. These scientists are ignored by the bulk of the scientific community.
Geoff asks: On a recent visit to the Atherton Tablelands, it was obvious that there area contained several extinct volcano's. In the past were the Atherton Tablelands Australia's most active volcanic area !
Ian Plimer: The Atherton Tablelands has some build volcanic craters and volcanic crater lakes. This is one of the areas in Australia where we have had recent volcanic activity, on mainland Australia the most recent volcanic activity has been in Western Victoria. Oh Heard Island Australia has an active volcano called Big Ben and Big Ben is higher than Mt Kosiosco, it’s not only Australia’s highest mountain, it’s Australia’s only active volcano.
Leisa asks: Is there somewhere online where we can see where earthquakes have occurred?
Ian Plimer: The United States geological survey has an online map of the world’s showing earthquakes that have occurred. This is an international corporative scheme starting from people measuring nuclear explosions and then looking at where natural earthquakes occur. Search, “United States geological survey” for this website.
Interviewer: Unfortunately we are out of time Professor, do you have any final comments for us tonight?
Ian Plimer: The websites to look at are United States geological survey (centre of all information coming in about earthquakes) and the US Volcanically Institute.
Interviewer: Thank you Professor for a most interesting discussion, and goodnight.
Interviewer: This concludes our chat with Ian Plimer, Sunday October 4, 2009.
