November 10, 2016
Earthquake Research Committee,
Headquarters for Earthquake Research Promotion

Evaluation of Earthquake in the Central Tottori Prefecture on October 21, 2016

* On October 21 at 14:07 (JST), there was a Magnitude (M) 6.6 earthquake at a depth of approximately 10 km in the central Tottori prefecture. Maximum seismic intensity 6 Lower was observed in Tottori prefecture with some damage. The maximum earthquake afterwards as of November 10 at 16 o�fclock was a M5.0 that occurred on the same day at 14:53 with maximum seismic intensity 4. Although slightly decaying, the seismic activity around the M6.6 event still continues, and earthquakes are distributed in the region extending about 10 km in an NNW-SSE direction. After October 21 at 12:00 (JST), a slightly concentrated seismic activity had been observed in close vicinity of the event.

* The focal mechanism showed a strike-slip fault type with a compression axis in a WNW-ESE direction. This event occurred within a shallow crust.

* According to the GNSS data, the crustal deformation associated with the recent event was observed: about 7 cm (provisional value) north-north-eastward movement at Hawai observatory (Tottori prefecture). Results from Synthetic Aperture Radar Interferometry Analysis of observation data by the Advanced Land Observing Satellite-2 "DAICHI-2" shows a crustal deformation spreading in a surface near the M6.6 event.

* The seismic fault estimated from the focal mechanism, the distribution of seismic activities, the GNSS and Synthetic Aperture Radar Interferometry Analysis data, is the left-lateral strike-slip fault of 10 km length, extending in an NNW-SSE direction.

* Around Tottori prefecture, there are several examples of consecutive occurrences of similar ones, and also some examples of similar or larger ones after a few months, after the occurrence of a large magnitude earthquake.

* The Earthquake Research Committee evaluated that in the northern Chugoku region including the recent seismic activity area, the seismic activity is comparatively active despite of the small number of active faults, and the possibility of occurrence of M6.8 or over earthquake within 30 years as 40 %.

• Earthquake in the Central Tottori Prefecture on October 21 (1)
• Earthquake in the Central Tottori Prefecture on October 21 (2)
• Earthquake in the Central Tottori Prefecture on October 21 (3)
• Earthquake in the Central Tottori Prefecture on October 21 (4)
• Earthquake in the Central Tottori Prefecture on October 21 (5)
• Earthquake in the Central Tottori Prefecture on October 21 – Focal Process Analysis Using Near Field Strong Motion Waveforms –
• Observed Data Before and After the Earthquake in the Central Tottori Prefecture (October 21, M6.6) (1)
• Observed Data Before and After the Earthquake in the Central Tottori Prefecture (October 21, M6.6) (2)
• Earthquake in the Central Tottori Prefecture – Result of "Daichi-2" SAR (Synthetic Aperture Radar) Interferometry Analysis (1) –
• Distribution of Crustal Deformation of the Earthquake in the Central Tottori Prefecture derived from 3 Dimensional Interfering SAR Analysis
• Seismic Fault Model of Earthquake in the Central Tottori Prefecture (uniform slip on a rectangular fault model)
• Earthquake in the Central Tottori Prefecture on October 21, 2016
• Seismic Activity since October 2015 (1)
• Seismic Activity since October 2015 (2)
• Examples of Consecutive Occurrences of Earthquakes within the Inland Crust in Tottori Prefecture