 Within three weeks of the event, scientists from five different countries were on the ground in Java performing a survey of the affected areas, including gathering runup (height above normal sea level) and inundation (distance the surge moved inland from the shore) measurements.The island of Nusa Kambangan () sits on the south coast of Java and is separated from the main island by a narrow strait.It is a large and mostly uninhabited nature reserve, and is referred to as the Alcatraz of Indonesia, due to the three high security prisons that are located at the town of Permisan.