Abstract:
ABSTRACT
A meridional to NE – SW trending zone of fracturing is believed to represent surface expression
of movement related to the recent central Sudan earthquakes. On Landsat imagery, the zone appears
collinear with Qoz (sand dune) Abu Dulu`, a large, fixed sand dune, 150 Km to the north. The dune was
the epicentre of Khartoum 1996 earthquake. The zone also runs > 100 km southards to as far as Khor
Abu Habil immediately north of Jebel Dumbeir, the epicentre of 1966 erthquake.
This lineament is believed to be Quaternary in age, because a young, narrow seasonal stream
running within the zone truncates the dry streams that once flowed eastwards to join the White Nile as
part of the late Tertiary – Quaternary Nile Valley drainage system. A detailed gravity survey along four
E-W profiles within the postulated fracture zone revealed the presence of a low gravity zone compared
with the surrounding. Very Low Frequency (VLF) electromagnetic measurements along the same gravity
profiles gave high values reinforcing the gravity data. Geophysical models revealed a depth of about 500m
for the fractures, and a geological explanation is provided. Four seismic events have been recorded later
in 2004 by the Sudan Seismic Network along the northerly extension of the postulated fracture zone, with
magnitudes ranging between 2.8-3.8 on Richter Scale.
This recent fracture zone is believed to represent rejuvenation of three meridional to submeridional
earlier movements in the same area. It is noteworthy that the African continent has been
affected by major episodes of rifting since the Proterozoic, through the Mesozoic to the Tertiary-
Quaternary times.
