Brunahraun is lava from the northern Laki crater row that flew down to the coast following the the valley of Hverfisfljót river.
The larger lava field Eldhraun www.ipernity.com/doc/523247/44215764 was created by flows from the southern crater row down Skaftá river valley.

In the backgound are the cliffs of the former coastline. The lava itself is very difficult to cross because of the many cracks and sharp edges and anyway you shouldn't because the vegetation is easily damaged and takes decades to grow back.

The lava is colonized by Racomitrium moss and wild thyme.