In 2011, a massive earthquake struck off the eastern coast of Japan. The destructive power of the earthquake was amplified by a giant tsunami that swept ashore, killing over 15,000 people. A major cause of the tsunami was the 50-m slip along the plate boundary fault between the subducting Pacific plate and the overriding North American plate. Patrick Fulton and his team set out to find out why there was so much movement along the fault by installing a temperature observatory in a borehole drilled right through the fault zone. Patrick Fulton uses observation, quantitative analysis, and numerical modeling to study heat and fluid in fault zones. He applies his research to the physics of earthquakes, tectonic processes, and the transport of subsurface heat and fluids. In the podcast, he describes how he and his team installed a borehole temperature observatory below 7 km of ocean. The observatory detected the remnants of frictional heating generated by the slip that caused the 2011 Tōhoku Earthquake and the devastating tsunami that led to the Fukushima nuclear disaster. Patrick Fulton is an Assistant Professor in the Department of Earth and Atmospheric Sciences at Cornell University. For more about Geology Bites and illustrations that support the podcast, go to geologybites.com.