New model reveals previously unrecognized complexity of oceanic earthquake zones

December 21, 2020

Tsukuba, Japan - Researchers from the University of Tsukuba applied seismic data from around the world to build a model of the 2020 Caribbean earthquake. Oceanic transform faults are generally considered to be linear and simple and have been widely used in studies of earthquake dynamics. However, the research team found that high complexity in rupture speed and direction can occur even in a supposedly simple linear fault system.

On 28 January 2020, a large oceanic earthquake with magnitude 7.7 occurred at the Oriente transform fault in the Caribbean Sea, between Jamaica and Cuba. It caused a minor tsunami of 0.11 m height and was felt as far afield as Florida.

A research team at the University of Tsukuba have developed a new finite-fault inversion method for building models based on teleseismic waveform data from earthquake monitoring stations. This new approach to using the data takes a more flexible approach to resolving the fault geometry. Rather than relying on prior assumptions, the faulting components are separately evaluated in a wider model in both time and space, allowing all possible rupture evolutions to be considered. The team were keen to use the Caribbean earthquake to help to understand the faulting processes that occur during these shallow oceanic quakes.

"Some cases of complex rupture dynamics have recently been reported in previous earthquake studies, raising the question of whether or not we are correctly modeling these even in supposedly simple fault systems," says study author Professor Yuji Yagi. "The initial monitoring of this January 2020 event suggested variations in the waveform shape between two stations at similar distances from the epicenter, suggesting that there remains complexity to be explored at this fault."

This was an excellent opportunity to test the new method developed by the team, which used data from 52 seismic stations to construct a detailed model of the geophysical processes within the fault that gave rise to the earthquake.

"The results revealed complex rupture during the earthquake, caused by a bend in the fault that led to the changes in rupture speed and direction detected in the monitoring data," explains author Professor Ryo Okuwaki. "These variations triggered several successive rupture episodes that occurred along the 300-km-long fault." The modeling approach also allows some suggestions to be made about the possible occurrence of subsidence and the shape of the surrounding seabed following the earthquake event.

These findings reveal that oceanic transform faults, considered to be simple and linear, may be much more complicated than previously accepted, and therefore require a more comprehensive approach to earthquake modeling. This work will shed light on a possible interaction between the earthquake-fault motion and the evolution of the ocean floor around the transform boundary.
The article, "Rupture Process of the 2020 Caribbean Earthquake along the Oriente Transform Fault, Involving Supershear Rupture and Geometric Complexity of Fault" was published in Geophysical Research Letters at DOI: 10.1029/2020GL090899.

University of Tsukuba

Related Science Articles from Brightsurf:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.

Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.

Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.

Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.

World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.

PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.

Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.

Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.

Read More: Science News and Science Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to