Earth Planets Space, Vol. 57 (No. 4), pp. 303-308, 2005LETTER
Makoto Okubo, Yasuhiro Asai, Harumi Aoki, and Hiroshi Ishii
Tono Research Institute of Earthquake Science, Association for the development of Earthquake Prediction, 1-63 Yamanouchi, Akeyo-cho, Mizunami, Gifu 509-6132, Japan
(Received November 30, 2004; Revised March 25, 2005; Accepted April 8, 2005)
Dynamic strain seismograms obtained by high-speed sampling include not only long-period changes, such as 'strain-step', step change in strain, but also short period variations, such as body waves. We studied dynamic strain variations caused by the 2004 off the Kii peninsula earthquakes. Using such strain seismograms, we clarified the relation between dynamic strain and velocity. Our results will contribute greatly to seismology. We also clarified the strain-step formation process. This result and the concept of dynamic strain will bring more information to geodetics.
Key words: Dynamic strain seismogram, broadband velocity seismogram, global/local structure, strain-ramp function, geodetical strain-step.