Intraplate earthquakes in North China - Intraplate Earthquakes - page 108

also found that the recurrence intervals of major earthquakes differ for individual fault
segments, individual faults, and composite fault zones. One of the major faults is the 220 km
long Daqingshan normal fault zone, which was initiated in the Eocene, with a total slip of
more than 2.4 km since the Quaternary. Seven major paleoseismic events have occurred
since 19 kaBP (thousands of years before present), with an average recurrence interval of

432 years (Ran et al ., 2003b ) .
Along the Yinchuan rift valley on the northwestern edge of the Ordos Plateau, Deng
and Liao (1996) identified four large earthquakes (M 8.0) at around 8,400, 5,700, 2,600,
and 256 years before present, with a recurrence interval of 2,300-3,000 years. Within the
Weihe rift valley, where the Huaxian earthquake (M 8.0) occurred in 1556 (see below),
trenching unveiled two more events around 2,715 and 5,610 years before present (Xu et al .,
1988 b ).
The Shanxi rift zone on the eastern side of Ordos has produced many large earthquakes
( Figure 5.2 ) . In its southern part where an M 8 event occurred in 1303 (see below), two
more events occurred around 3,336-2,269 and 5,618-4,504 years before present (Bi et al .,
2011 ) . On one of the faults in the central segment of the Shanxi rift, trenching shows three
events around 3.06-3.53,

2,000 ±

8.36 kaBP; the coseismic vertical slips of these
events were 1.5-4.7 m, indicating magnitudes to be M 7.0 or above (Guo et al ., 2012 ) . On
the western branch of the northern segment of the Shanxi rift, four events occurred around
2.52, 5.68, 6.76-10.82, and 12.34 kaPB (Xie et al ., 2003 ) . Trenching of various fault strands
of the Shanxi rift system has revealed many other events, with recurrence times typically
of a few thousand years.
Paleoseismic studies in the North China Plain, which is covered by thick Quaternary
sediments, are less extensive and have been focused on where large historic earthquakes
occurred. On the Tanlu fault, where the Ms 8.5 Tancheng earthquake occurred in 1668 (see
below), trenching uncovered at least three more events around 3,500, 5,000-7,000, and

5.32, and

10,000 years before present (Lin and Gao, 1987 ) . The fault system bounding the northern
side of the North China Block hosted the 1679 Sanhe earthquake (M 8.0; trenching studies
there suggested three previous events around 10.85-9.71 kaBP, 7.390-6.68 kaBP, and
5.416-2.233 kaBP (Xu and Deng, 1996 ) .

5.5.2 Large historic events

The Chinese catalog of historic earthquakes shows 49 large (M 6.5) events in North

China since 1303 (Min et al ., 1995 ) , including five catastrophic (M 8.0) events, which

are described here.

1303 Hongdong earthquake (M 8.0)
The Great Hongdong earthquake occurred on September 17, 1303, near the Hongdong
County within the Shanxi rift zone. The epicenter is estimated to be around 111.7

° E,

36.3 ° N. The damaged area was about 500 km long and 250 km wide; the intensity reached