Continental transform faults evolve when two plates slide along each other. The most prominent examples are the San Andreas Fault in California and the North Anatolian Fault in Turkey.
Earthquakes along those faults typically do not exceed earthquake magnitudes around M8 but occur at shallow depth thus posing a major threat to nearby metropolitan regions such as San Francisco or Istanbul.
To estimate the seismic hazard and resulting risk it is essential to know the maximum earthquake magnitude to be expected along particular faults. This, however, is not trivial since instrumental recordings date back only 150 years while the recurrence period for the largest earthquakes can be much longer.
A team of scientists from the GFZ German Centre for Geosciences in collaboration with the University of Southern California has now presented a global evaluation of observed maximum earthquakes along all major transform faults allowing to better estimate the maximum earthquake strengths.
The major findings of the study are that for 75% of the data the observed maximum magnitude generally scales with the offset across the faults if exceeding 10 km. The offset across a fault results from the continuous slip of several mm to a few cm per year leading to offsets of kilometers after millions of years. Furthermore, it was found that the length of the rupture of individual earthquakes scales with mapped fault length.
For the remaining 25% of the earthquakes a larger coseismic stress drop was found to occur. ‘This means that those earthquakes release more seismic energy during the rupture process and they all occur along faults with low slip rates allowing to distinguish them from the majority of events that show a direct relation to cumulative offset’ says GFZ-scientist Patricia Martínez-Garzón, lead author of the study.
The results contribute towards developing refined building codes, risk mitigation concepts and early-warning systems and are, thus, of great relevance for millions of people living in population centers near transform faults.
Patricia Martínez-Garzón, Marco Bohnhoff, Yehuda Ben-Zion, Georg Dresen: “Scaling of maximum observed magnitudes with geometrical and stress properties of strike-slip faults”, Geophysical Research Letters, DOI: 10.1002/2015GL066478
Franz Ossing | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen
The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Physics and Astronomy
16.11.2018 | Life Sciences
15.11.2018 | Earth Sciences