Ocean Seismic Thermometry

Session: Environmental and Near Surface Seismology: From Glaciers and Rivers to Engineered Structures and Beyond [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

As a key component of the Earth’s climate system, the ocean absorbs more than ninety percent of excess heat by human-induced global warming and thus plays a key role in pacing climate change. Although the ocean observing system has been drastically improved over the past two decades, accurate estimation of global ocean heat content change is still challenging due to the inadequate sampling. We develop a novel and low-cost method of using seismic waves from small-magnitude (i.e. M3-6) repeating natural earthquakes to measure large-scale average ocean temperature changes, that complements the existing observations. Similar to active ocean acoustics, we take advantage of the high sensitivity of sound speeds to ocean temperatures but use natural earthquakes. In this study, we search for repeating earthquakes in 2005-2016 around the Nias Island of Sumatra and measure travel time changes of T waves from the seismic station DGAR in the central Indian Ocean. Numerical simulations of wave propagation are conducted to infer the ocean temperature anomalies averaged over a 3000 km long section in the equatorial East Indian Ocean with an accuracy of 0.006 K. Our inverted results show prominent temperature change at various time scales, such as 10 days, 6 months and 12 months. The decadal warming trend from T waves indicates a significant underestimation of warming in previous models. Our seismic ocean thermometry method uses natural sources to avoid interference with marine animals and provides new opportunities for monitoring ocean warming globally.

Presenting Author: Wenbo Wu

Authors