Jawaban:

1. The purpose of the text is to report on a tragic incident that occurred at the Pasar Rumput Rusunawa construction site in South Jakarta, where an iron block fell from the construction site and hit a woman named Tarminah, who unfortunately passed away at the scene. The text provides details about the incident, including eyewitness accounts, statements from local authorities, and the response from the project developer, PT Waskita Karya. The text also expresses condolences for Tarminah's family and loved ones.

2. Based on the information provided in the text, it is not clear why the iron block fell from the Pasar Rumput Rusunawa construction site in South Jakarta. However, the incident is under investigation, and authorities are likely looking into the cause of the accident. It is possible that the accident was caused by human error, equipment malfunction, or other factors, but further details would need to be confirmed through the investigation.