This is from the Manila Times. It seems likely that the blast was accidental. It always did to me but it certainly is taking a long time to be certain. At least this article explains why the police found traces of a military type explosive. However, there is also a sceptical account of the accident explanation. One wonders about the skills of investigators.
Police: Glorietta 2 mall
explosion ‘likely accidental’
MALACAÑANG officials said there is a “high” probability that last Friday’s blast at the Glorietta 2 mall in Makati City was an accident.
The Philippine National Police (PNP) on Tuesday presented to the National Security Council the results of its investigations at a meeting convened by President Gloria Arroyo, four days after the explosion.
Despite the Glorietta incident, the country’s economic growth is expected to remain strong, driven mainly by consumption growth this year. The peso also strengthened further while the stock market index climbed, apparently shaking off the initial woes caused by the bombing.
Mrs. Arroyo also ordered the strengthening of antiterror and security measures to ensure the public’s safety.
The Interior and Local Government Secretary Ronaldo Puno, concurrently presidential political adviser, said police report showed a “high certainty” that the blast was not planned. Investigators, however, have not dismissed the bombing angle, although their findings showed otherwise.
The investigators said they are waiting for the result of a separate probe by forensic experts before they can conclude that a bomb did not cause the explosion.
Police bomb experts over the weekend detected from the blast site the presence of RDX, a component used to produce C-4, or military plastic explosives.
Puno, however, said it is too early to conclude that the RDX came from a bomb, since that chemical is also an ingredient in items such as aerosol and cosmetics. Police are yet to recover other bomb components from the site.
Puno said a hole found in the mall’s diesel storage tank reinforces the theory that the explosion was not a deliberate act. Also, an explosion caused by a bomb should have left a large crater at the site.
Earlier, a police official said they had received information, which they are still verifying, that the air vent at the basement could have been accidentally closed, which caused the trapping of a volatile gas, such as methane, emanating from the septic tank or pipes.
Accident angle doubted
A chemical engineering professor from the University of the Philippines-Diliman said it is impossible that the explosion that rocked Glorietta 2 was caused by methane and diesel.
During an interview with the TV network ABS-CBN, Dr. Wilfredo Jose of the Chemical Engineering Department said diesel doesn’t explode easily, and will ignite only if it is subjected to heat measuring 200 degrees Celsius.
Jose also doubted that methane that leaked from the septic tank and pipes caused the “blast wave.”