Frequency dependent Lg attenuation in Northeast China and Korean Peninsula

Nishath R Ranasinghe1, Andrea C Conley nee Gallegos2, Andrea R Trujillo1, Alexander Robert Blanchette3, Thomas M Hearn1, Eric A Sandvol4, James Ni5, Stephen P Grand6, Fenglin Niu7, Yongshun John Chen8, Jieyuan Ning9, Hitoshi Kawakatsu10, Satoru Tanaka11 and Masayuki Obayashi12, (1)New Mexico State University, Las Cruces, NM, United States, (2)New Mexico State University, Las Cruces, United States, (3)Stanford Earth Sciences, Stanford, CA, United States, (4)University of Missouri, Department of Geological Sciences, Columbia, United States, (5)New Mexico State University Main Campus, Las Cruces, NM, United States, (6)University of Texas, Austin, United States, (7)University of Science and Technology of China, School of Earth & Space Sciences, Anhui, China, (8)Southern University of Science and Technology, Department of Ocean Science and Engineering, Shenzhen, China, (9)Peking University, Beijing, China, (10)Earthquake Research Institute, The University of Tokyo, Tokyo, Japan, (11)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, (12)JAMSTEC Japan Agency for Marine-Earth Science and Technology, Research Institute for Marine Geodynamics, Kanagawa, Japan
Abstract:
Lg spectra are collected from 452 crustal events spanning from 1995 to 2014 in Northeast (NE) China and surrounding areas using 202 seismic stations from Northeast China extended seismic Array (NECESSArray), GSN stations in NE Asia, China national seismic network, IRIS PASSCAL experiments in NE China, Korean and Japanese permanent seismic networks to study Lg attenuation in NE Asia. Using reverse two-station and two-station methods we obtained frequency dependent Lg attenuation models for a frequency range between 0.5 Hz to 5 Hz with a resolution of about 2°. We solved for the geometric spreading term by fitting the amplitude to the two-station distance ratios and the absolute distances. The best fit yields a spreading coefficient of 0.36 instead of the traditional cylindrical spreading term of 0.50. Lg Q values in NE China and the Korean Peninsula vary from 50 to 1600. Q values increase rapidly in the Songliao Basin (SNB) for higher frequencies (≥ 2Hz), while they stay relatively constant in the Great Xing’an Range (GXR). Low attenuation regions are found in the Great Xing’an, Lesser Xing’an (LXR) and Songen-Zhangguangcai Ranges (SZR). Overall, attenuation is high in the Songliao, Sanjiang (SNB), Bohai (BHB), Erlian (EB) and Hailar (HB) basins. The highest attenuation is found in the vicinity of Wudalicanchi (WVF), Changbaishan (CBV), and Quaternary volcanic regions, the southern Songliao Basin, west of Erlian Basin, Bohai Basin and the Sanjiang Basin. In general regions with low attenuation (Q > 800) have a low heat flow value (<70 mW/m2) and very thin (< 1 km) or no sediments.
Back to: Imaging the Earth IX Imaging Seismic Anisotropy and Attenuation + Theoretical Developments Posters