Intraplate earthquakes induced by reactivation of buried ancient rift system along the eastern margin of the Japan Sea - Intraplate Earthquakes - page 237

Coast SKTL

b

W35N E35S

0 0 0 0 0

Y = +10 km

5 5 5 5 5

DCT

10 10 10 10 10

15 15 15 15 15

-40 -40 -40 -40 -40 -35 -35 -35 -35 -35 -30 -30 -30 -30 -30 -25 -25 -25 -25 -25 -20 -20 -20 -20 -20 -15 -15 -15 -15 -15 -10 -10 -10 -10 -10 -5 -5 -5 -5 -5 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 15 15 15 15 20 20 20 20 20 25 25 25 25 25

0 0 0 0 0

Y = +5 km

5 5 5 5 5

DCT

10 10 10 10 10

15 15 15 15 15

2007

-40 -40 -40 -40 -40 -35 -35 -35 -35 -35 -30 -30 -30 -30 -30 -25 -25 -25 -25 -25 -20 -20 -20 -20 -20 -15 -15 -15 -15 -15 -10 -10 -10 -10 -10 -5 -5 -5 -5 -5 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 15 15 15 15 20 20 20 20 20 25 25 25 25 25

0 0 0 0 0

Y = 0 km

5 5 5 5 5

DCT

A2

10 10 10 10 10

A1

15 15 15 15 15

-40 -40 -40 -40 -40 -35 -35 -35 -35 -35 -30 -30 -30 -30 -30 -25 -25 -25 -25 -25 -20 -20 -20 -20 -20 -15 -15 -15 -15 -15 -10 -10 -10 -10 -10 -5 -5 -5 -5 -5 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 15 15 15 15 20 20 20 20 20 25 25 25 25 25

0 0 0 0 0

Y = -5 km

5 5 5 5 5

DCT

10 10 10 10 10

2004

15 15 15 15 15

-40 -40 -40 -40 -40 -35 -35 -35 -35 -35 -30 -30 -30 -30 -30 -25 -25 -25 -25 -25 -20 -20 -20 -20 -20 -15 -15 -15 -15 -15 -10 -10 -10 -10 -10 -5 -5 -5 -5 -5 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 15 15 15 15 20 20 20 20 20 25 25 25 25 25

0 0 0 0 0

Y = -10 km

5 5 5 5 5

DCT

10 10 10 10 10

15 15 15 15 15

-40 -40 -40 -40 -40 -35 -35 -35 -35 -35 -30 -30 -30 -30 -30 -25 -25 -25 -25 -25 -20 -20 -20 -20 -20 -15 -15 -15 -15 -15 -10 -10 -10 -10 -10 -5 -5 -5 -5 -5 0 0 0 0 0 5 5 5 5 5 10 10 10 10 10 15 15 15 15 15 20 20 20 20 20 25 25 25 25 25

Cross-section X (km)

2 3 4 5 6 7

Vp (km/s)

Figure 9.2 (b) Depth sections of the V p model along W35N-E35S lines in Figure 9.2a. Relocated
aftershocks (gray circles) distributed within ± 2.5 km of each line are superimposed. Masked areas
correspond to low model resolution. White curves denote iso-velocity contours of V p = 5.7 km/s,
and white broken lines show faults suggested from aftershock streaks, top surface geometries of the
basement, or velocity changes within the basement. DCT, deep central trough. Blue and red arrows at
the top of each section correspond to surface locations of the SKTL and the coastline. Moment tensor
solutions for the 2004 and 2007 Niigata earthquakes (NIED) are shown using a lower hemisphere
projection rotated into the plane of the section. For color version, see Plates section.