Is there a Nascent Plate Boundary in the Northern Indian Ocean?

Aurélie Coudurier-Curveur (1, 2) , Çağil Karakaş (1, 3) , Satish C. Singh (2, 1) , Paul Tapponnier (1, 4) , Hélène Carton (2) , Nugroho Hananto (5)

1 EOS - Earth Observatory of Singapore
2 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
3 Schlumberger Research Center, Risabergvegen 3, 4068 Stavanger, Norway
4 Institute of Crustal Dynamics, China Earthquake Administration, Haidian, Beijing, 100085, China
5 RCO - Research Center for Oceanography

The northern Indian Ocean has been widely recognized as an area of broadly distributed deformation within the composite India-Australia-Capricorn plate, hosting several diffuse boundary zones and a diffuse triple junction. The occurrence, along reactivated fracture zones, of the exceptionally large (M w =8.6 and M w =8.2) 2012 Wharton Basin strike-slip earthquakes, however, questions whether this composite plate is breaking apart along a discrete boundary. Using recent bathymetric and seismic data, we analyze the most prominent fracture zone (F6a), whose structural trace is particularly well-expressed. We identify sixty kilometric-scale pull-apart basins with geometric properties (length/width ratios) similar to those observed along continental strike-slip plate boundaries. Four of the pull-aparts formed above narrow, sub-vertical faults extending into the oceanic crust. Within the broad Wharton deformation zone, the significant slip rates (0.8 to 2.5 mm/yr) and unusually large co-seismic displacements recorded along F6a suggest that it may be a nascent plate boundary

Mots clés: Sixty kilometric-scale

Domaines: Planète et Univers [physics]; Océan, Atmosphère

Aurélie Coudurier-Curveur, Çağil Karakaş, Satish C. Singh, Paul Tapponnier, Hélène Carton, et al.. Is there a Nascent Plate Boundary in the Northern Indian Ocean?. Geophysical Research Letters, 2020, 47, ⟨10.1029/2020GL087362⟩. ⟨insu-02520618⟩