Abstract
At 5:33 a.m. on April 13, 2013(JST), an earthquake of magnitude 6.3 occurred beneath Awaji Island in western Japan. This paper summerizes the results of damage investigation conducted in Sumoto plain of Sumoto City immediately after the earthquake, focusing characteristics of damage to Japanese traditional wooden houses. The major type of the damage was partial collapse of roofs and slide down of roof tiles on one- or two- story wooden houses. Housing damage was concentrated at Takenokuchi town and at reclaimed areas. For clarifying such concentration, microtremor measurements were followingly performed across the plain. Their results showed that predominant periods were relatively longer around the reclaimed areas. In Takenokuchi town, predominant periods of ground varying from 0.2 to 0.3 seconds were close to the range of predominant period of typical wooden houses, which suggests the possibility of soil-structure resonance phenomenon during the earthquake shaking.
