Global variation of seismic energy release with oceanic lithosphere age

Nicolás Pinzón,Carlos A Vargas

doi:10.1038/s41598-020-80475-y

Abstract

Variations in Mid Ocean Ridge seismicity with age provide a new tool to understand the thermal evolution of the oceanic lithosphere. The sum of seismic energy released by earthquakes during a time, and for an area, is proportional to its lithospheric age. Asthenospheric temperatures emerge on ridge centers with new crust resulting in high seismic activity; thus, the energy released sum is highest on the young lithosphere and decreases with age. We propose a general model that relates the systematic variation of seismic energy released with the lithospheric age. Our analysis evaluates the main physical factors involved in the changes of energy released sum with the oceanic lithosphere age in MOR systems of different spreading rates. These observations are substantiated based on three cross-sections of the East Pacific Rise, six sections in the Mid Atlantic Ridge, and three profiles in the Central Indian Ridge. Our global model provides an additional tool for understanding tectonic processes, including the effects of seismicity and mid-plate volcanism, and a better understanding of the thermal evolution for the young oceanic lithosphere.

Highlights

Corner magnitude of spreading earthquakes is about 5.8, independent of the spreading rate
We propose a general model, with a broader scope for the variation of the sum of seismic energy released with age and cooling of young oceanic lithosphere
Our results show that changes in spreading rates lead to changes in the seismic regime on mid-ocean ridges (MOR)’s and, calculating the sum of energy released for individual transects, we find that it is a little higher in fastspreading MOR’s systems than for slow-spreading rates regimes (Fig. 3)

Summary

Introduction

Corner magnitude of spreading earthquakes is about 5.8, independent of the spreading rate. The number of earthquake events decreases gradually, where rates are close to 40 mm/year. Decrease considerably at spreading rates larger than 80 mm/year[22]. We demonstrate the variations and contrasts in the sum of seismic energy as a function of lithospheric age between different spreading centers and the main implications on the thermal structure beneath each ridge system. Based on these observations, we propose a general model, with a broader scope for the variation of the sum of seismic energy released with age and cooling of young oceanic lithosphere

Methods

Results

Conclusion