Abstract:
The purpose of this study is the seismic hazard assessment of Sulaiman lobe,
Central Indus Basin, Pakistan. The curve-shaped Chaman transform fault, ~1000km
long, the major active fault between Pakistan and Afghanistan demarks the western
boundary of the Indian plate. Many catastrophic earthquakes have been occurred in this
region. Until now, very few studies have been conducted to ascertain the earthquakes/
fault interaction and hazard assessment for this region. By employing the stress
triggering theory, an earthquake sequence, comprising of fifteen earthquakes occurred
in the study region since 1888 is studied. Our findings reveal that eight out of fifteen
earthquakes are triggered by the preceding earthquakes. The 1908, 1910, 1935, 1966,
1997 of magnitudes Mw 6.3, 6.2, 7,4, 6.2, 7.1 respectively are somewhat independent
earthquakes in this sequence. The 1935 earthquake significantly increased the positive
stress at both ends of its rupture. Later, the 1975 earthquake with ΔCFS above the
triggering threshold value, and the 1990 earthquake occurred on the Ghazaband fault in
the southern positive lobe. Since 1935 earthquake significantly increased the ΔCFS at
both ends of the rupture, the 2008 Ziarat doublet earthquakes with magnitude Mw 2008
occurred on the Urghargai fault in the northern positive stress lobe where ΔCFS is
positive. Furthermore, the northern segment of Chaman fault, southern segment of the
Ghazaband fault and the northwestern segment of the Urghargai fault demonstrates a
high value ΔCFS. It has the potential to cause seismicity in these areas necessitating
plans to prevent any future seismic hazards. The seismic hazard maps indicated that
some areas needed to be studied more thoroughly due to the hazard levels expected
there. This research work aims to improve our understanding of earthquake triggering
and fault interaction in the area of interest. For future work, an improved CFS maps
related to earthquake triggering may be produced by incorporating definite lithospheric
dynamics which requires instrumental data investigations for the area being studied.
