Acknowledgments
We thank Eileen Martin, Zi Xian Leong and Sam Hone for proofreading the article. We thank Chris Marone for his warm support to convince the Penn State Institute of Natural Gas Research to provide seed money to the DAS fiber array. We thank Todd Myers, Ken Miller at Penn State University, Thomas Coleman from Silixa Inc. who help setup the fiber-optic DAS array. The DAS array was supported by Penn State Institute of Environment and Energy seed grant and Institute of Natural Gas Research.