# Monthly Archives: March 2014

## LA Earthquake: Don’t panic.

I wrote an anti-hysterical guide to the earthquakes in Los Angeles for io9. Head over for the geology, seismology of recent earthquakes, interpreting risk forecasting, and preparing for the Big One without freaking out.

## Detecting Density Anomalies

Gravity field surveying is a passive technique to detect gravity anomalies. Gravity is a global field that always points vertically down, with anomalies caused by very small variations in density of the underlying materials. A gravity base station measures the … Continue reading

## Hazard, Risk, and the Steelhead Landslide.

The Oso, Washington landslide was predicted and preventable, and that doesn’t matter. Journalists, stop snarking about how they never should have built there — you live somewhere risky and are apparently clueless about it. Geologists, the community listened to their … Continue reading

## Characterizing Density

Measuring density is a simple method of measuring the mass, measuring the volume, then calculating the density as mass divided by volume. Dry density, wet density, and grain density can all have geotechnical utility. All three are calculated by dividing … Continue reading

## Density of Geological Materials

The density of a rock is closely tied to its mineralogy. Sedimentary rocks have a lower density than igneous rocks, with most sandstones having a density close to the density of quartz (ρ = 2.65 g/cm3), suggesting that they are … Continue reading

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## Density

Density (ρ) is the mass (m) of a material divided by its volume (V), given in units of mass per unit volume (kg/m3): ρ = m/V ￼The density of a material is a function of the density of the individual … Continue reading

## Pancake Rocks

In a decidedly inedible celebration of Pancake Day, I’ve written about the Pancake Rock formation over on io9. (If the link isn’t live yet, I’ve mucked up my cross-timezone scheduled posts. It’ll be out at 1pm EST.)