Tectonics and Structural Geology

Faults vs. Fractures — How to Tell Them Apart ?

Nkodia Hardy October 16, 2025

$A futuristic Black geologist wearing AR glasses stands in a glowing cave surrounded by four holographic screens labeled Geological Aspect, Geometry, Topology, and Kinematics & Mechanism, each displaying geological diagrams and fracture models, symbolizing modern geoscience visualization.$

Observation. Measurement. Connection. Motion — the four pillars of the Holo-Geologist. Credit: Gemini 2.5.

Faults and fractures can sometimes be confusing, especially for students taking their first geology courses. When they go hiking in the mountains and see a crack in the rock, they often wonder — is this a fracture or a fault? Even scientists sometimes mix the two terms, so it’s good to understand the difference. Since faults and fractures are important in many fields such as tunnel engineering, hy ...[Read More]

Where earthquake faults reach the ground surface: insight from 2016 Kumamoto event

Yuto Sasaki October 2, 2025

Futagawa fault cutting across a road. Picture taken shortly after the earthquake in 2016 (Kumamoto Earthquake Memorial Museum KIOKU, 2025)

What does a seismogenic fault look like? We can sometimes observe surface earthquake faults, which propagate ruptures from the hypocenter to the ground surface. In 2016, intense seismicity was observed during the Kumamoto earthquake sequence in Japan. This sequence consisted of many shallow earthquakes, including a strong foreshock and the subsequent mainshock with numerous aftershocks. The earthq ...[Read More]

Throwback Summer – retracing student steps at the Pic Saint-Loup, France

Lauretta Kaerger September 18, 2025

The Pic Saint-Loup, Occitania, France (Credit: Lauretta Kaerger)

The region around the Pic Saint-Loup is a popular destination for many European universities to teach mapping field courses – and there is a reason for it, even besides the great landscape, good food and nice weather. Let’s take a tour to discover why! The Pic Saint-Loup itself is indeed so impressive that some former students return at later stages in life “dragging” along other geologists ...[Read More]

TS Must-Read – Rowe and Griffith (2015) Do faults preserve a record of seismic slip: A second opinion

The Must-read team April 1, 2025

Earthquakes shake the Earth almost every day, but what exactly happens within rocks during these seismic events is a matter of debate in the scientific community. The article “Do faults preserve a record of seismic slip: A second opinion,” published in 2015, offers a thoughtful review of the sure and potential records of seismic slip in rocks. The paper examines the notion that rocks i ...[Read More]

TS Must-Read – Cowie (1998) A healing-reloading feedback control on the growth rate of seismogenic faults

The Must-read team April 4, 2022

This study provides a simple numerical model of fault rupture that describes the development of fault systems from the initial nucleation of numerous small faults to the localisation of deformation into few major faults. The model presented is based on two main considerations: first, earthquakes cause stress changes that can either advance or delay failure on neighbouring faults. Second, for failu ...[Read More]

TS Must-Read – Caine et al., 1996 Fault zone architecture and permeability structure

The Must-read team February 21, 2022

Caine et. al. (1996) is a cornerstone paper which describes, compares and quantifies brittle fault zones and their permeability (fluid flow) properties from observations. Doing so, the paper initiates the accumulation of information on the permeability of brittle fault zones described previously (Randolph and Johnson 1989; Scholz 2019; Byerlee 1993). The study begins by defining fault zones as com ...[Read More]

Features from the Field: Shear Zones and Mylonites

Samuele Papeschi, Sandra McLaren and Hannah Davies January 25, 2021

Dextral, ductile shear zones crosscut foliated schist at Cap de Creus (Catalona, Spain). Photo © Jordi Carreras

The San Andreas Fault in California, the Alpine Fault in New Zealand, or the Main Frontal Thrust in the Himalayas are some of the most famous and largest fault zones that accommodate the relative displacement between two adjacent crustal blocks. Such faults, however, represent only the shallower expression of something much bigger: a crustal shear zone. In the first 10 kilometers or so of the crus ...[Read More]

TS Must-Read – Mckenzie and Parker (1967) The North Pacific: an example of tectonics on a sphere

The Must-read team September 30, 2020

The paper describes how large, rigid, aseismic regions can be defined with Euler’s theorem, which describes the geometry of motion on a sphere, i.e. the Earth’s surface. Points on these large and rigid blocks move in relation to other blocks describing small circles set by their rotation pole. The paper describes this as “paving stone theory”, where tectonic plates are “paving stones”, and success ...[Read More]

Patience Anne Cowie (1964 – 2020): A Geology Superhero

Anouk Beniest June 23, 2020

An artists illustration of Patience Cowie (credit: Annique van der Boon)

Welcome to the first post in a new series being hosted on the TS blog! This series “Influential women of Tectonics and Structural Geology” is aimed at highlighting women who have had a key contribution to the field of tectonics and/or structural geology. Patience’s contribution to the field of faults changed the way geologists looked at faults. Her work continues to be used to an ...[Read More]

Minds over Methods: Dating deformation with U-Pb carbonate geochronology

EGU Guest blogger August 16, 2019

Cathodoluminescence image of calcite vein in background, with 100 micron laser ablation spots overlain top right and U-Pb isochron overlain left. Image credit: Nick Roberts

For this edition of Minds over Methods, we have invited Nick Roberts, a research scientist at the British Geological Survey, working within the Geochronology and Tracers Facility (GTF) running a LA-ICP-MS laboratory. Nick has a background in ‘hard-rock’ geology, incorporating geochemistry, geochronology, and magmatic and metamorphic petrology across a wide range of tectonic settings, and is now in ...[Read More]