The GEM Global Active Faults Database (and Webmap)

Over the past two years, I have been working for the Global Earthquake Model Foundation (GEM). My main task has been building the Global Active Faults Database (GEM GAF-DB), which is just what it sounds like—a database that contains all of the world's active faults. This work is nearing …

Making polygons from lines in Python

This post covers an algorithm to make polygons from connected lines, in the context of making geologic rock unit polygons from contacts mapped in a GIS program.

Mapping active faults for fault databases and seismic hazard analysis

cross-posted from the GEM Hazard Blog

I've had several conversations with geologists recently who are considering creating new active fault databases (or datasets). These geologists are all government scientists who are interested in both tectonics research and seismic hazard, and would like to make maintainable databases that suit both purposes …

A statistical picture of strain partitioning

Strain partitioning has interested me since I first heard about it. The basic idea is that in some regions, the strain field is not aligned exactly with the dominant fault system, so that fault system can't act as a 'pure' strike-slip or dip-slip fault system and relieve all of the …

The exponential decay of information

One of the major challenges of geology is the increasing sparsity of information about increasingly older times in Earth's history. This presents difficulties both when one is investigating a particular era, and when one is interested in looking at the frequency of events through time, or the frequency of rare …

New paper in review on earthquake cycle and slip rate variability

Around the new year, I wrote a quick blog post to answer for myself a question about how the natural variability in earthquake timing can effect slip rate measurements over different timescales. The results from the blog post demonstrated that there is a lot of slip rate variability over timescales …

Science writing: What we know vs. what we don't know

Academic science writing (primarily journal articles) uses a rhetorical framework that lays out a portion of some scientific discipline or natural process, locates and describes the 'knowledge frontier' that bounds what is known and what is unknown, and zooms into that frontier to answer a tidy question and install a …

Very short earthquake recurrence times

The belief that earthquakes release most or all of the accumulated shear stress on a fault is widespread among both scientists and the general public. It is closely related to, and may stem directly from, Henry Reid's idea of elastic rebound theory: The crust slowly accumulates elastic strain until the …

Side projects and sabbatical projects

In my work as a scientist, I work on projects of a range of scales. While my major projects, which I do for work, are generally multi-year and often team-based, I also frequently start smaller projects. These are generally done to scratch an intellectual itch: quantifying a certain effect that …