Sub surface Fault

Sub surface fault is a fault located beneath a surface, invisible to people above. While conventional fault is easily detectable by seeing difference in rock type, or displacement over placemarks like fence, road, or cracks at wall, sub surface fault is hard to detect. A subsurface fault might be a fault which is active, but its presence is covered by a layer of sediments / rock of same type - so any displacement made by the fault is 'seems to be invisible'. One way to detect a subsurface fault is by doing a research over seismic data; I mean, firstly we should have a data of earthquake occurence around our area of interest. Then we do a more comprehensive geophysical survey like raw seismic data processing with computer programs. Then we can correllate the result of data processing to the shape of fault and even how it's moving. Another try to know how is the subsurface fault looks like is by doing geoelectrical survey or seismic survey, but it's unlikely to be success if it done in / near a densely populated area.

Conventional fault, Bordeaux, France (wikipedia)

Subsurface fault in Iraq, near Tigris river. This fault is invisible to people above because it is covered with Tigris river's deposits. The corresponding geoelectrical pseudo-resistivity is shown below. These data are obtained after Nabeel Hameed Al Saigh in this paper. We could see that the densest contour is corresponding to change in rock type and thus it may be concluded that there is faulting activity there.

In the case of Haryana earthquake, I really have no idea how the fault is moving. But by seeing the geological map of India, the case seems like that of Tigris River: A subsurface fault covered by Yamuna river deposits has triggered 5.5 M earthquake. Video here, in NDTV (the earthquake movement is not obviously seen but people runs out). Unfortunately, there is no fault plane solution so I can't infer the fault movement. But from seismograph record here I might say that this sub surface fault would be a normal one. For reader, correct me if I'm wrong haha :-).