Current research recommends that earthquakes in subduction zones take place across a complicated network of fault airplanes, rather than a single airplane. This finding, obtained from in-depth seismic data gathered in Ecuador and examined with AI, obstacles traditional views of how seismic tension is launched. The research study, which also offers brand-new insights into the behavior of aftershocks, might significantly impact future earthquake modeling and threat evaluations in subduction zones.The initially high-precision image of a seismic fault zone changes our understanding of earthquakes.The idea that earthquakes launch stress by a single strong quake along a single fault plane might require to be fixed. Recent research carried out by the Karlsruhe Institute of Technology (KIT), in collaboration with the GFZ German Research Centre for Geosciences and other global institutions, suggests that earthquakes happen within a zone including multiple fault planes, some of which are parallel.According to the authors, the results of the study can help to create more realistic models for earthquakes and earthquake hazards in subduction zones. The research study has been published in the journal Nature.The worldwide group led by very first author Caroline Chalumeau from KIT investigated a series of earthquakes in Ecuador on the west coast of South America. There, the Pacific Plate is subducted beneath the continental South American Plate. Subduction repeatedly results in extremely serious earthquakes. The most recent series of earthquakes in Taiwan, the primary quake of which killed 9 individuals and caused comprehensive damage on Taiwans east coast at the start of April, can also be associated to subduction.The sketch reveals the 100 to 600 meters thick seismogenic zone in which the fault aircrafts (5 to 20 meters thick) and thus the ruptures lie. Credit: Dr. Caroline Chalumeau, Dr. Hans Argurto-Detzel, Prof. Andreas Rietbrock, Dr. Michael Frietsch. Prof. Onno Oncken, Dr. Monica Segovia, Dr. Audrey Galve: Seismological proof for a multifault network at the subduction user interface. Nature, 2024. DOI: 10.1038/ s41586-024-07245-yThe series of earthquakes in Ecuador examined by the group started on 12 March 2022 and ended on 26 May 2022. The most serious quake (magnitude 5.8) occurred on March 27 and activated numerous smaller aftershocks over a brief time period. A dense network of 100 seismometers was found in the region at this time. It had actually been established for the offshore experiment “High-resolution imaging of the subduction fault in the Pedernales Earthquake Rupture zone” (HIPER for short). In-depth Seismic Data AnalysisWith the extraordinarily detailed data from the HIPER experiment and utilizing artificial intelligence, the scientists had the ability to map more than 1,500 earthquakes and their particular fault planes at a depth of 15 to 20 kilometers in extremely high resolution. “We observed that the seismicity of earthquakes occurred in a primary region– the main earthquake, so to speak– and in a secondary area, i.e. the aftershocks,” states initially author Dr. Caroline Chalumeau from the Geophysical Institute (GPI) at KIT. “Within the primary region, we observed that the seismicity took place on several different fault aircrafts, often on top of each other. In some locations, parallel seismically active planes took place, in other places just single ones.” The parallelism of the quakes was not connected to a specific depth. “We have discovered signs that the previous idea that the stress is released by a single strong quake along a single fault aircraft might be a distant memory,” says Professor Andreas Rietbrock from the GPI. “Instead, we must rather speak of a fault network in which a series of ruptures discharges within a single earthquake.” The analysis of the Ecuadorian quake series likewise provides brand-new insights into aftershocks. These very first happened near the epicenter of the main quake and after that gradually spread in other instructions, states Chalumeau. She concludes from this that the propagation of aftershocks in the area is primarily managed by afterslip. Prof. Onno Oncken from the GFZ says: “With this work, Caroline Chalumeaus team has presented the very first sharp seismological image of a seismogenic plate boundary. On the one hand, it verifies existing geological observations and, on the other hand, successfully explains the proliferation of aftershocks with a new method. Previous assumptions that, for example, fluid diffusion causes aftershocks have actually hence been refuted.” The results are also essential for evaluating the earthquake risk in subduction zones. “The research study will influence the future modeling of earthquakes, however likewise of aseismic slips, i.e. plate motions without earthquakes,” states Andreas Rietbrock.Reference: “Seismological evidence for a multifault network at the subduction interface” by Caroline Chalumeau, Hans Agurto-Detzel, Andreas Rietbrock, Michael Frietsch, Onno Oncken, Monica Segovia and Audrey Galve, 17 April 2024, Nature.DOI: 10.1038/ s41586-024-07245-y.
Current research recommends that earthquakes in subduction zones occur throughout a complex network of fault aircrafts, rather than a single airplane. The study, which also provides new insights into the habits of aftershocks, could substantially impact future earthquake modeling and risk assessments in subduction zones.The initially high-precision image of a seismic fault zone transforms our understanding of earthquakes.The concept that earthquakes launch stress by a single strong quake along a single fault aircraft may require to be remedied. Current research study conducted by the Karlsruhe Institute of Technology (KIT), in collaboration with the GFZ German Research Centre for Geosciences and other international institutions, suggests that earthquakes occur within a zone including several fault airplanes, some of which are parallel.According to the authors, the outcomes of the research study can help to produce more reasonable designs for earthquakes and earthquake risks in subduction zones. “We observed that the seismicity of earthquakes happened in a main region– the primary earthquake, so to speak– and in a secondary area, i.e. the aftershocks,” states initially author Dr. Caroline Chalumeau from the Geophysical Institute (GPI) at KIT. “The study will affect the future modeling of earthquakes, however also of aseismic slips, i.e. plate motions without earthquakes,” says Andreas Rietbrock.Reference: “Seismological evidence for a multifault network at the subduction user interface” by Caroline Chalumeau, Hans Agurto-Detzel, Andreas Rietbrock, Michael Frietsch, Onno Oncken, Monica Segovia and Audrey Galve, 17 April 2024, Nature.DOI: 10.1038/ s41586-024-07245-y.