Off the coast of Chile a strong shallow earthquake triggered a tsunami. Warnings have been going out to Chile, Peru, Hawaii and New Zealand. The first estimation of the energy of the earthquake was at M7.9 but was then corrected to 8.3. This correction results in an update of the tsunami predictions. I created this […]

# Category Archives: Earth Science

# Exploring Challenger Deep

The Challenger Deep at the Marianna trench is the deepest point on earth measuring 10.91km. People used to think our oceans were pretty flat underneath the water and did measurements with a plumb. So when surveyors came to this particular point at this subduction zone the line proved to be too short. When tectonic plates […]

# Progressing ash plume of Eyjafjallajökull

In May 2010 air transportation in Europe came to a halt, when Eyjafjallajökull on Iceland erupted. Now, two years after that eruption scientist have gathered and evaluated all kinds of data how the ash plume moved through Europe. This data taken from satellites, plane and the earth can help evaluate particle dispersion better and limit […]

# Aran Islands, Ireland

The Aran Islands just off the coast of Ireland left geologists puzzled for a while now. On top of this cliff huge boulders are found. Up to now the only explanation for waves energetic enough to transport these rocks would be a tsunami. Unfortunately, at least for the explanation, no tsunami happened there since 1755. Now […]

# The subjective science of seismic interpretation

The final step in the work with seismic data is seismic interpretation. In a scientific field called geophysics, interpretation sounds highly subjective; Very different from the usual statistics, ray and wave phenomenae. This can’t be right, right? I’d love to say it’s very clear and seismic data reveals a perfect image of the subsurface. But […]

# Moeraki Boulders, New Zealand

There are a couple of places in this world, I really would like to see. A friend just added the Moeraki Boulders to this list, posting it to facebook. These are spherical boulders off the coast of New Zealand of unusual size. My first guess, would be dinosaur eggs (wouldn’t that be cool?). The actual explanation […]

# New on StackExchange: Temporal Resolution of Seismic data

Radius of the Fresnel zone is given by [math]Rf=(v/2)(t_0/f_\mathrm{dom})^{1/2}[/math] where v: velocity of layer [math]t_0[/math]: two way travel time [math]f_\mathrm{dom}[/math] :dominant frequency in the spectrum This shows that high frequencies give better resolution than lower frequencies and resolution deteriorates with depth and increasing velocities. However I found some text in “Seismic Data Analysis- Yilmaz” which […]

# To what accuracy and precision do we know the volume of the Earth?

Satellites such as GOCE and GRACE measure the geoid with unprecedented accuracy. Altimeters can determine local surface elevation with millimetre-precision. This makes me wonder: to what precision and accuracy can we measure (or calculate) the volume of the Earth? I’m a lay when it comes to solid Earth, and I find it surprisingly hard to […]