Release: Aspermigas: Yogyakarta earthquake triggered Sidoarjo mud volcano
Expert Panel Calls on Government to Declare Natural Disaster
Friday, December 15 2006 - 03:29 AM WIB
The expert panel concluded that there is a correlation between the May 27, 2006 Yogyakarta earthquake and the start of the Sidoarjo mudflow on May 29. The earthquake created new fractures in the ground, or reactivated a pre-existing fault zone. It triggered the movement of the mud from the underground, and the faults and fractures became the conduit through which the mud reaches the surface.
The Sidoarjo mudflow is therefore a natural phenomenon, originating from an underground layer of overpressured shale which has become plastic and mobile due to its low density and undercompacted nature in geological terms this is called a mud volcano.
Mud volcanoes are common in the East Java Basin, and this is the seventh time mud volcanoes have erupted in East Java The first six erupted thousands of years ago and were obviously not related to drilling activity, and there is no indication that this seventh mud volcano eruption is different.
It was also concluded that the effort to stop the mudflow through pne or two relief-wells will most likely be unsuccessful. Around the Banjarpanji-1 well there are 31 other smaller broaches where the mud and gases are currently flowing, and they can become new main outlets for the mud lithe current main broach is stopped. This is based on the fact that while a mud volcano usually has many cracks, the flow will be centered through one or a couple of vents.
A mud volcano can only be stopped if the pressure at the source of the mud is reduced to an equilibrium with the overburden pressure. This depends heavily on the underground conditions and can be reached in months, years and even hundreds of years. Based on the understanding of the geology in the area, the Sidoarjo mudflow is a mud volcano. Therefore all current efforts to block or stop the mudflow through the drilling of relief wells should be stopped.
The expert panel recommends the government to declare the Sidoarjo mudflow a natural disaster and a disaster-prone area that immediately should be cleared of houses and other buildings. The natural disaster status is needed to quickly take comprehensive operational steps and give certainty to the people about their safety and future.
The seven speakers at Aspermigas? December 7, 2006 seminar were:
1. Dr, Ir. Pruhadi Sumintadireja, Lecturer in Geology Department of Bandung Institute of Technology (ITB)
2. Dr Ir Suyoto, Lecturer of Geological Technology Faculty. Veteran National Development University (UPN), Yogyakarta
3. Dr. Ir. Agus Guntoro, Msi, Lecturer of Geological Technology, Trisakti University, Jakarta
4. Dr. Ir, Syamsu Alam. a member of Indonesian Geologists Association (IAGI)
5. Ir. M. Husen, MSc, Assistant Oil Deputy at Coordinating Ministry for the Economy
6. Ir. Kersam Sumanta, a member of National Team for the Mitigation of Sidoarjo?s Mud
7. Ir. Effendy Siradjudin, alumni of Oil Technology Department of ITB, Chairman of Aspermigas anti Chairman of National Oil and Gas Caucus
Moderators were:
1. Dr. Ir Agus Handoyo at Center of Geological Studies ITB
2. Ir. Bambang Purwohadi, Msi of Oil and Gas Drilling Association. (end of release)