Chlorophyll increases off the coasts of Japan after the 2011 tsunami using NASA/MODIS data

E Sava,B Edwards,G Cervone

doi:10.5194/nhess-14-1999-2014

E Sava, B Edwards + Show 1 more

Open Access

https://doi.org/10.5194/nhess-14-1999-2014

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Abstract

Abstract. Large chlorophyll anomalies are observed after the 2011 Japanese tsunami using the NASA MODIS instrument onboard the TERRA and AQUA satellites. These anomalies are observed both along the eastern coast of Japan, where the tsunami wave hit with maximum force, and in the deep water surrounding the epicentral region. Although both satellites show agreeing spatio-temporal patterns, larger anomalies are detected using the AQUA satellite. A temporal analysis shows increased chlorophyll concentrations immediately after the tsunami, and higher values are observed for nearly one month before reversing to pre-tsunami levels.

Highlights

On 11 March 2011 at 05:46 UTC a massive Mw = 9.0 underwater earthquake occurred 70 km offshore the eastern coast of Japan
The objective of this study is to investigate the effects of the 2011 Japanese tsunami on chlorophyll a concentrations and the distribution before and after the event using data from MODerate Resolution Imaging Spectroradiometer (MODIS)-AQUA and TERRA satellites
Chlorophyll concentration values were downloaded from the NASA Ocean Color website for 2011 for the 3-day and 8-day 4 km gridded products

Summary

Introduction

On 11 March 2011 at 05:46 UTC a massive Mw = 9.0 underwater earthquake occurred 70 km offshore the eastern coast of Japan. The location of the earthquake was triangulated by the United States Geological Survey (USGS) to 38.322◦ N 142.369◦ E and the hypocenter was computed to 32 km beneath the surface. The earthquake generated a tsunami that rapidly hit the eastern coast of Japan, and propagated across the Pacific Ocean to the western coast of the Americas. A tsunami warning was issued by NOAA affecting all countries with coastlines along the Pacific Ocean. Waves up to 40 m high were reported and coastal areas were flooded up to several kilometers inland. National Oceanographic and Atmospheric Agency (NOAA) models predicted waves higher than 30 m along the eastern coast

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