Towards the Atera Fault, compared to the background density, the
fracture density increases drastically within a distance of ca. 200 m
from the main fault plane (see Figure 4a–d). This observation is consistent
with the occurrence within this zone of fractures formed by fault
movement, which are additional to the background fractures.
It was also observed that fractures of relatively short length have
been additionally formed in the vicinity of the fault plane (Figure 5).
The data shown in Fig. 5 are the fracture frequencies in different outcrops
at different distances from the fault plane. Within approximately
40 m of the fault plane, the rock is intensely crushed and it is therefore
difficult to count the number of fractures. However, it can still be seen
that the lengths of fractures less than a few metres clearly increase towards
the fault plane. These short features form a network-type structure
(Oshima and Yoshida, 2004; Yoshida et al., 2009). Furthermore,
the dense accumulation of these features is associated with crushing
of the host rocks' matrices (Figure 4c and d).
However, fractures that have a relatively long length (traceable for
more than several metres) tend to not vary much in density, either in
the damage zone along the fault plane or in the host rock distributed
far from the fault plane (Figure 5). In outcrops, such single, traceable,
straight fracture planes are readily distinguishable from the short,
network-forming fractures. The frequencies of the traceable fractures
within the vicinity of the fault plane are only slightly increased from
that observed among the ‘background’ fractures further from the fault
plane
Towards the Atera Fault, compared to the background density, thefracture density increases drastically within a distance of ca. 200 mfrom the main fault plane (see Figure 4a–d). This observation is consistentwith the occurrence within this zone of fractures formed by faultmovement, which are additional to the background fractures.It was also observed that fractures of relatively short length havebeen additionally formed in the vicinity of the fault plane (Figure 5).The data shown in Fig. 5 are the fracture frequencies in different outcropsat different distances from the fault plane. Within approximately40 m of the fault plane, the rock is intensely crushed and it is thereforedifficult to count the number of fractures. However, it can still be seenthat the lengths of fractures less than a few metres clearly increase towardsthe fault plane. These short features form a network-type structure(Oshima and Yoshida, 2004; Yoshida et al., 2009). Furthermore,the dense accumulation of these features is associated with crushingof the host rocks' matrices (Figure 4c and d).However, fractures that have a relatively long length (traceable formore than several metres) tend to not vary much in density, either inthe damage zone along the fault plane or in the host rock distributedfar from the fault plane (Figure 5). In outcrops, such single, traceable,straight fracture planes are readily distinguishable from the short,network-forming fractures. The frequencies of the traceable fractureswithin the vicinity of the fault plane are only slightly increased fromthat observed among the ‘background’ fractures further from the faultplane
การแปล กรุณารอสักครู่..
