Premium
Tomographic evidence for a subducted seamount beneath the Gulf of Nicoya, Costa Rica: The cause of the 1990 Mw = 7.0 Gulf of Nicoya earthquake
Author(s) -
Husen S.,
Kissling E.,
Quintero R.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl014045
Subject(s) - geology , seamount , subduction , seismology , aftershock , thrust fault , asperity (geotechnical engineering) , fault (geology) , tectonics , paleontology , geotechnical engineering
Tomographic images constrain the existence of a subducted seamount beneath the Gulf of Nicoya, Costa Rica. The subducted seamount is found at a depth of 30 km within the rupture area of the March 25, 1990, Mw = 7.0 Gulf of Nicoya earthquake. The Gulf of Nicoya earthquake was a typical thrust‐type subduction earthquake and occurred on a shallow dipping thrust fault parallel or along the boundary between the subducting Cocos plate and the overriding plate. Precise relocation of the mainshock and its aftershocks in a 3‐D P‐wave velocity model shows that the area of the mainshock rupture is coincident with the imaged subducted seamount. Most of the aftershocks are relocated within or close to the inferred subducted seamount above the subducting oceanic plate. We interpret the subducted seamount as an asperity whose rupture caused the 1990 Gulf of Nicoya earthquake.