Abstract
Earthquake doublets have been described in fault systems around the world but have not yet been confidently resolved in paleoseismic records. Our current knowledge is limited to historical occurrences, preventing researchers from uncovering potential patterns or recognizing common fault behavior. Identification of prehistoric doublets is thus of crucial importance for adequate seismic hazard assessment and risk mitigation. We developed a new methodology to reveal the sedimentary imprint of earthquake doublets in lacustrine paleoseismic records based on flow direction analysis in multipulsed turbidites, because the delayed arrival of turbidity currents originating from the same source location demonstrates the occurrence of individual triggering mechanisms. As grains tend to align in the presence of a flow, we analyzed flow directions by determining the dominant orientation of elongated grains using a combination of grain size, paleomagnetism, and high-resolution X-ray computed tomography. This methodology was applied to a turbidite deposited by the 2007 CE earthquakes in West Sumatra (Mw 6.4 and 6.3, 2 h apart), and it provides the first unmistakable sedimentary evidence for an earthquake doublet. We argue that this methodology has great potential to be applied to multipulsed turbidites in various subaquatic paleoseismic records and can reveal the occurrence of unknown earthquake sequences.
| Original language | English |
|---|---|
| Pages (from-to) | 1301-1306 |
| Number of pages | 6 |
| Journal | Geology |
| Volume | 49 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - 1 Nov 2021 |
Bibliographical note
Funding Information:K. Wils acknowledges the Special Research Fund (BOF) of Ghent University (Belgium). Field work was funded by the Research Foundation Flanders
Funding Information:
K. Wils acknowledges the Special Research Fund (BOF) of Ghent University (Belgium). Field work was funded by the Research Foundation Flanders (FWO, G042812N) and carried out with an Indonesian Foreign Research Permit (7B/TKPIPA/E5/Dit.KI/VII/2017). We thank all field-work participants and S.Y. Cahyarini and the Indonesian Customs for sediment core shipment. We are grateful for the constructive comments provided by M. Strasser, J. Howarth, and an anonymous reviewer on an earlier version of this manuscript.
Publisher Copyright:
© 2021 Geological Society of America. For permission to copy, contact [email protected].
Funding
K. Wils acknowledges the Special Research Fund (BOF) of Ghent University (Belgium). Field work was funded by the Research Foundation Flanders K. Wils acknowledges the Special Research Fund (BOF) of Ghent University (Belgium). Field work was funded by the Research Foundation Flanders (FWO, G042812N) and carried out with an Indonesian Foreign Research Permit (7B/TKPIPA/E5/Dit.KI/VII/2017). We thank all field-work participants and S.Y. Cahyarini and the Indonesian Customs for sediment core shipment. We are grateful for the constructive comments provided by M. Strasser, J. Howarth, and an anonymous reviewer on an earlier version of this manuscript.