The shockwave of the explosion pushed Joseph forward, however he was able to regain his balance using the sudden change in momentum caused by the boat crashing onto shore. The only immedeate danger was the fire, he decided to take a bit to recharge his EP, which had gotten a bit low.

That Sumeragi forces would be arriving soon was both a curse and a blessing. They were his target, so he should get as close as possible, however Joseph had to remain able to get away too. As such, Joseph began looking for a place where he could safely watch the events to be unfold, preferably a high vantage point, such as the roof of a skyscraper, if one was sufficiently close.

In any case, staying on the wreck would not do him any good, so he pulled his luggage towards him with his septima, after he let his EP charge a bit.

While once more focussing on regaining EP, such that he could safely fly onto the roof of the trainstation, above the people trying to evacuate, Joseph noticed someone was taking pictures of the people present. He didn't like being photographed without being asked first, although now his objective also meant he should avoid being photographed, so he used his septima to move his suitcases in the way, such that his picture could not be taken.
Half a second later, he was ready to take off, and thus ascended, softly landing on the rooftop of the trainstation, while his suitcases still covered him from the view of the camera.

Once on the roof, Joseph continued looking for safe lookout points. If he found one, he would move to it; if he found none, he would continue recharging his EP and then fly towards his hotel on the quickest route possible.