The bulletins were terrifying: a powerful earthquake had struck off the coast of this Central American country, spawning a tsunami warning and bringing fears of widespread catastrophe. But Costa Rica suffered remarkably little damage from Wednesday’s magnitude-7.6 quake — a few blocked highways, some collapsed houses and one death, of a heart attack caused by fright. Officials credited the relatively deep location of the quake and building codes that Costa Rican officials call as strict as those in California and Japan.