Introduction

• Key volcanic and seismic issues
• Site description
• The McBirney et al 2003 study
• The Sumintadiredja et al 2007 study
• Japanese seismic standards and the proposed Muria nuclear power plant site
• Later volcanic and seismic studies

Analysis

• General sources
• May 26 2006 Jogjakarta earthquake
• Sidoarjo mudflow
• Muria analyses (reverse chronological)

See also

• C.B. Connor, N.A. Chapman, and L.J. Connor (eds.), Volcanic and Tectonic Hazard Assessment for Nuclear Facilities, Cambridge University Press, 2009

Introduction

Volcanic and seismic hazards associated with the proposed Ujung Lemah Abang nuclear power plant site have been repeatedly addressed in official studies over three decades by the Indonesian National Nuclear Agency (BATAN) and the International Atomic Energy Agency (IAEA). Major consultant studies were conducted for BATAN by NIRA (Nucleare Italiana Reattori Avanzati), NewJEC (originally New Japan Engineering Consultants, a subsidiary of Kansai Electric), and the National Technical Team (NTT, Indonesia). However, none of the original reports from these major studies are publicly available. Nevertheless, some summary materials have been published, and some of the scientists and consultants have published parts of their findings in academic and research journals.

Key volcanic and seismic issues

• The Muria volcanic complex is a capable volcano.

• The proposed nuclear power plant site is definitely within screening distance values for fallout of pyroclastic material, pyroclastic flows and surges, debris flows, lahars, floods, and opening of new vents.

• Indonesian researchers have identified two major north-south faults through the Muria volcanic complex.

• While there appear to be no capable faults at or near the site of the proposed nuclear plant the nature of the foundation sediments at the site and the high level of ground water raise serious concerns in the face of wider seismogenic conditions.

• Indonesian government claims that there are no significant volcanic or seismic hazards attached to the proposed Muria nuclear power plant site are not supported by public reports by IAEA and Indonesian government consultants with access to restricted official studies.

• Almost all official Indonesian and IAEA volcanic and seismic studies have been kept from the public domain over more than three decades.

• One report which utilized these numerous studies  draw attention to significant methodological and data limitations in these studies.

• Reliance on earthquake resistance standards derived from earlier Japanese modelling is inappropriate due to great differences between the site’s geological conditions and those in Japan.

• Japanese authorities no longer use the earthquake safety standards that these reports are based upon. In 2007, they substantially rewrote their safety standards based on their experience of the 2007 Chuetsu earthquake which caused serious damage to a reactor in Niigata.

 

 

Desa Balong: 1:25000

Desa Balong, extracted from Keling Lembar 1409 – 621, Skala 1:25,000, Peta Rupabumi Digital Indonesia, , Badan Koordinasi Survei dan Pemataan Nasional (BAKOSURTANAL), Edisi I – 1999.

Source: Desa Balong, extracted from Keling Lembar 1409 – 621, Skala 1:25,000,
Peta Rupabumi Digital Indonesia, Badan Koordinasi Survei dan Pemataan Nasional (BAKOSURTANAL), Edisi I – 1999.

Site description

Very limited technical information is available about the precise geological and hydrological characteristics of the Ujung Lemahabang site itself. An IAEA document (2000) prepared by BATAN contributors provided the following description

One of the best candidate site selected for the medium reactors (MRs), based on the assessment study up to the writing of this document, is on the North coast of the Muria peninsula, tentatively at Ujung Lemahabang. The size of this tentatively preferred site is approximately 3 Km length in East-West direction and 2 Km wide in North-South direction. Elevated land in a height of about 10 m is well developed at the coast continued by gentle hilly slope behind it. The depth of moderately harder layer lies about 12 m below Mean Sea Level.

Ujung Lemahabang site lies on volcanic and sedimentary rocks of Pleistocene. Site geology mainly consists of four zones: soil zone, upper tuff zone, middle sandstone zone and lower tuff zone. The mean value of unconfined compressive strength of each rock type/class of the bedrock varies between 16 kgf/cm² and 62 kgf/cm².

The McBirney et al 2003 study

The most important study publicly available, McBirney et al, Volcanic and seismic hazards at a proposed nuclear power site in central Java, (2003), resulted from an invitation in 1991 by the Indonesian government to the IAEA to evaluate existing safety studies of the proposed Muria site. The investigation of the volcanic and seismic hazards was carried out over a period of eight years “first by the contractor and later by a joint team of Indonesian geologists and consultants to the International Atomic Energy Agency.”

The lack of well-established internationally accepted guidelines for hazard assessment in such cases led to the IAEA forming a panel to prepare a Safety Code between 1993-1997. The result was the IAEA document titled Provisional Safety Standards Series No. 1, Volcanoes and Associated Topics in Relation to Nuclear Power Plant Siting, issued in July 1997. This process and the subsequent guideline framework is set out in McBirney and Godoy, Notes on the IAEA Guidelines for Assessing Volcanic Hazards at Nuclear Facilities, (2003). Examples considered by the IAEA team included the Armenian Nuclear Power Plant, the proposed Muria project, the Yucca Mountain Repository in Nevada, the Mulheim-Karlich Nuclear Power Plant in Germany, and the Petropavlovsk-50 facility in Kamchatka. McBirney and his colleagues carried out their study of Muria volcanic and seismic hazards at the same time as collaborating on the development of the IAEA volcanic hazards guidelines, and published their studies on both matters in the same issue of a leading scientific journal in the field.

The McBirney et al study was also the most procedurally transparent and open about its sources and their limitations. As well as carrying out their own surveys, McBirney et al drew on the findings of earlier studies by BATAN, NIRA and NTT. However they were sharply critical of the limitations of earlier seismic studies and of datasets in particular:

The seismological database for the Muria region was very poor, and no reliable earthquake catalogue was available. There had been very little useful investigation of primary historical or instrumental data for earthquakes occurring in the region.

A record of instrumental seismicity was compiled using data from eight stations in three different networks that were operating on Muria Peninsula for different periods during the project…The exact number of recorded events is not known but is of the order of several hundred and maximum magnitude is in the range of 3-4. Unfortunately, the records from these sources were never combined into a single data set for all of Muria Peninsula. The epicenter determinations are not very reliable and hypocenters, focal mechanisms, and stress drop data are missing. Because of these deficiencies, the macro- and microseismicity data were of little use for defining seismogenic structures.

Structures related to potential faulting have been mapped at a scale of l:50 000 by different consulting companies, but the documentation and evaluation of the data are incomplete and appear to contain errors. In any case, the accuracy of these maps was questionable and the detection, characterization, and dating of the faulting are unclear.

While McBirney and his colleagues were then able to use geologic, geomorphological and geophysical data to reach their conclusions on the seismic and tectonic characteristics of the site, it is important to note that neither previous nor subsequent reports of these earlier studies made any mention of these limitations.

McBirney and his colleagues were clear that the proposed site faces serious volcanic and seismic hazards from the Muria volcanic complex, which they regarded as “capable of future volcanic and seismic activity” within the expected lifetime of the plant. Two key characteristics of the site pose serious hazards:

Firstly, in terms of volcanic hazards, the site lies

within the screening distances for at least four possible types of events: (1) fallout of pyroclastic material, (2) pyroclastic flows and surges, (3) debris flows, lahars, and floods, and (4) opening of new vents. Adequate safeguards for pyroclastic fallout can be incorporated into the design of the plant, but the other possible hazards are more serious.

The research group specified a very low level of acceptable risk from volcanic hazards for sensitive facilities such as a nuclear power plant: from 10^-8  to 10^-6 per year, “depending on the longevity of the facility”. With substantial provisos concerning the limitations of the original geological datasets, McBirney and his colleagues attempted to calculate probabilities of either a large eruption that would impact on the site, or the formation of new vents in the region of the site. As a result, McBirney et al suggested

probabilities of major eruptive episodes impacting the site of 5 x 10^-4 to 4 x 10^-5 during the next 100 years.

Secondly, in terms of seismic hazards, while “there appear to be no capable faults at or near the site of the proposed nuclear plant”,  “the assessed seismogenic potential could prejudice the feasibility of the plant”. This serious concern arises from

the bearing capacity of foundation sediments and the feasibility of a dewatering system during construction and operation of the plant under static and dynamic (earthquake) conditions. In this regard, it is important to recall that: (1) the geotechnical properties of the sediments at the site are very poor because they are very weathered to depths well below the proposed excavation, and (2) the permeability of these volcanic terrains is very high, and the groundwater level is at sea level near the coastline.

The IAEA Indonesian team (IAEA, 2000) provided the design basis parameters for the proposed Muria plant as follows:

Bearing capacity	kg/cm2	? 7.5
Shear wave velocity	m/sec	? 300
Flood level	m	? 0.3
		below finish grade
Peak ground acceleration	gal	? 400
Volcanic ash	cm	? 20
Max. ambient temperature	oC	36

As far as can be determined, these are the only publicly available indication of intended site design parameters. McBirney et al did not provide any statement of their understanding of expected bearing capacities of foundation rock.

The Sumintadiredja et al 2007 study

The McBirney study was followed several years later by a report from a team of Indonesian scientists from the Bandung Institute of Technology and BATAN (Sumintadiredja et al, 2007). The text suggested (somewhat ambiguously) that the authors had access to unspecified, geo-datasets that were not available to McBirney et al. The core of the report is a probability analysis of volcanic hazard at the site, in particular, the probabilities of  a large eruption from Mount Muria and of a new vent being formed within the wider Muria volcanic complex. Sumintadiredja et al addressed this problem by incorporating further data sets, though precisely which datasets were incorporated, distinct from those available to McBirney et al, is not completely clear.

Sumintadiredja et al rejected McBirney et al’s range of acceptable volcanic hazard probability for such a facility (10^-8 – 10^-6 per year) in favour of a 10^-4 level:

Evaluation of the effects of these particular phenomena at the site [tephra fallout, lahars, and pyroclastic flows] is necessary and since none of these phenomena at the Muria Volcanic Complex are likely to be Holocene, the hazard assessment of the volcanic hazard introduced by these phenomena should use a spatial temporal probabilistic approach with acceptability factor 10^-4 per hundred years.

The key conclusion of the study by Sumintadiredja and his colleagues was that

Spatio-temporal probabilistic analysis of volcanic hazards for nuclear power plant Ujung Lemah Abang results in a range of value of 2.463×10^-7 to 7.825×10^-6 every 100 years.

Japanese seismic standards and the planned Muria site

Of the publicly available significant studies, only McBirney et al addressed the issue of seismic hazard criteria. They noted that

The original plan was to construct a nuclear plant using safety standards developed for Japan. The criteria included a back-ground earthquake of magnitude 6.5 located 10 km from the site. This criterion has been used for nuclear power plant sites in Japan where the foundation rocks are no younger than Tertiary.

The authors had previously drawn attention to

two important issues [which] are still open: the bearing capacity of foundation sediments and the feasibility of a dewatering system during construction and operation of the plant under static and dynamic (earthquake) conditions. In this regard, it is important to recall that: (1) the geotechnical properties of the sediments at the site are very poor because they are very weathered to depths well below the proposed excavation, and (2) the permeability of these volcanic terrains is very high, and the groundwater level is at sea level near the coastline.

Consequently, they argued

The use of Japanese criteria at the Muria Peninsula site could be inappropriate, and application would make the stability of the foundation questionable. Similarly, the effectiveness of the dewatering system would be uncertain.

While they noted that, on the other hand, there appears to be a lower seismic hazard at this site than in Japanese cases, and that consequently “the seismic criteria for defining the feasibility of the site may be less severe”, they were writing in 2003.

On July 16, 2007, a 6.8 Richter scale earthquake on the seabed 16 km offshore from the Kashiwazaki-Kariwa nuclear power plant complex in Niigata, Japan. Four of the seven power generators shut down automatically when the seismic acceleration exceeded the design values. The earthquake damage resulted in radioactive water leakage in to the sea from two reactors, a transformer fire that took two hours to put out, and other substantial damage. As a result, according to a report by the Japanese Nuclear and Industrial Safety Agency, the Seismic Guide for Japanese reactors, already revised less than a year before to incorporate more severe levels, more careful investigation, and more sophisticated methodology of assessment, were to be revised even further in as still more stringent manner. The necessity for even more comprehensive revaluation of procedures for specifying appropriate seismic standards for nuclear power plant sites was underlined by the subsequent revelation by the Tokyo Electric Company less than a week later that

A study that it [TEPCO] conducted from October last year to April this year, for the purpose of complying with new quake-resistance guidelines set out by the government last year, had neglected to check for undersea faults.

In the light of McBirney et al’s analysis of the problematic foundation rock and ground-water issues, the implications for the proposed Muria site can only be considered serious. In particular, the claim by Romantika and Jidin (2008) that the long history of volcanic and seismic disasters in Java “would not deter planting of NPPs in Java if the long experience of Japan in erecting nuclear plants can be adopted” is not based on any detailed assessment of the evidence publicly available about the Muria site or the Japanese current debate following the Kashiwazaki-Kariwa complex shutdown after the 2007 Chuetsu earthquake.

Later volcanic and seismic studies

In addition to ongoing debate in the Indonesian media about the Muria proposal, there have been media reports of subsequent seismic and volcanic studies relevant to the Muria proposal, with vigorous debate spurred on by three catastrophic events: the magnitude 6.3 May 26, 2006 Jogjakarta earthquake, which killed 5,749 people in and around the city; the magnitude 7.5 earthquake 110 km offshore from Jakarta on August 9 the following year; and the Sidoarjo mudflow that began near Surabaya in East Java on May 28, 2006, two days after the Jogjakarta earthquake.

Two reported studies are important here. The Central Java newspaper Suara Merdeka reported 18 April 2007 that researchers from the Research and Development Centre for Marine Geology Research in the Department of Energy and Mineral Resources had identified two large faults and numerous smaller faults in the Muria area: two large parallel faults known as the Tempur Fault and the Rahtawu Fault run north-south through the volcanic complex. On March 26, 2006, two people died in land movements in the village of Rahtawu on southern slope of Mount Muria.

In August 2007, researchers reported to the Indonesian Geophysical Experts Association (HAGI) [PDF, 2.3 Mb] that they concluded from US Geological Survey data that as a result of the meeting south of Jogjakarta of two major faults running northwest – southeast (the Pamanukan-Cilcap Fault) and southwest – northeast (the Kebumen-Muria Fault) through Central Java, a large block in the region north of Jogja, including the Muria peninsula, was locked in an uplifted position, and as a consequence, is relatively free of earthquakes. However, according to a Kompas report on the meeting, the researchers treated the claim with some scepticism, as have other industry observers.

Analysis

General sources

Gempa Bumi [Earthquakes], Badan Meteorologi dan Geofisika [Meteorological and Geophysical Agency], Indonesia.

Earthquake information  for Indonesia, U.S. Geological Survey.

Muria, Global Volcanism Program.

Includes geological and eruption data, and satellite photographs.

May 26 2006 Jogjakarta earthquake

M6.3 Java Earthquake of 26 May 2006, U.S. Geological Survey.

Detailed volcanic, seismic and tectonic information in poster form (html and pdf).

M 6.3 Java, Indonesia, May 27, 2006, Earthquake Engineering Research Institute.

Earthquake on the island of Java, Indonesia, International Charter – Space and Major Disasters.

Yogyakarta, Indonesia earthquake – May 26, 2006, ReliefWeb.

Magnitude 7.5 – Java, Indonesia, 2007 August 08, U.S. Geological Survey.

Sidoarjo mudflow

Learning from the East Java Mudflow: Disaster Politics in Indonesia, Jim Schiller, Anton Lucas, Priyambudi Sulistiyanto, Indonesia, Volume 85 (April 2008), 51–78.

A study of the grim results of the erupting mud volcano in East Java that was apparently triggered in May 2006 by the company, Lapindo Brantas, which was digging an exploratory well in search of natural gas near Sidoarjo. The toxic mud now covers over 2,000 acres in East Java, and all efforts to plug the mudflow have failed. The authors discuss the scale of the disaster; theories concerning its cause (due to natural factors or negligence?); the tangled politics complicating the relief and mitigation efforts, which have involved many uncoordinated governmental and non-governmental agencies, as well as Lapindo Brantas (which seeks to limit its liability); and the enormous human, social, and economic costs.

Un-natural disaster, Jim Schiller, Inside Indonesia 91, January-March 2008.

Sidoarjo mud flow, Wikipedia.

Indonesia mud volcano may last 30 years: expert, AFP, 2009-06-18

Curtin University of Technology’s doctor Mark Tingay, who has just returned from the disaster site in East Java, said about 100,000 people remained under threat from subsidence three years after the volcano first erupted. He said the volcano could produce enough scalding mud to fill Sydney Harbour twice over in the next 30 years but admitted the time-scale was only an estimate. Australian oil and gas giant Santos, which was drilling in the area when the volcano erupted, by September had declared previsions of just 88.5 million dollars to cover the clean-up cost.

Hot mud flow in East Java, Indonesia.

Geo-scientist’s technical blog.

Muria analyses (reverse chronological)

• A Feasibility Study of Planting Nuclear Power Plants in Java-Bali-Madura, Indonesia
• Kondisi Jateng Berbeda [Conditions in Central Java are different]
• Central Java seismic schematic
• Volcanic Hazard Analysis for Proposed Nuclear Power Plant Siting in Central Java
• Pembangunan PLTN, Aman atau Membahayakan (1): Peringatan Dini dari Patahan Muria [Nuclear power plant development, safe or dangerous (1):…
• Gunung api maar di Semenanjung Muria [Volcanic maars on the Muria Peninsula]
• Offshore fault assessment: Implication to predict earthquake and tsunamigenic potential along the coastal area of Muria peninsula, Central…
• Gerakan Tanah [Land movement], Statistik Bencana Alam Geologi Tahun 2006
• Volcanic and seismic hazards at a proposed nuclear power site in central Java
• Notes on the IAEA Guidelines for Assessing Volcanic Hazards at Nuclear Facilities
• Annex: Small and Medium Reactor User Requirements Document: Indonesia, Guidance for preparing user requirements documents for small and…
• Site Safety Review Mission: Final Review of the Siting Studies at Muria Peninsula, Indonesia (External Events Topics)
• Profil / Karakteristik Tapak, (Hasil Studi Newjec 1991-1996), Studi Tapak dan Lingkungan, [Site Profile/Characteristics, (Results of the…
• Prospect and potential of nuclear power plants in Indonesia
• Pemetaan Geologi Dan Radioaktivitas Alami Semenanjung Muria, Jawa Tengah [Geology And Natural Radioactivity Mapping Of Muria Peninsula,…
• The problems of groundwater assessment in the volcanic-sedimentary environment of Central Java

General Geological Setting Related To Seismic Sources – Indonesian Archipelago: Java – Muria Peninsula, A.S. Sastratenaya and Nanang T. Puspito, Center for Development of Nuclear Energy (PPEN), National Nuclear Energy Agency (BATAN), and Department of Geophysics, Institute of Technology Bandung, presented to at the International Workshop on Lessons Learned from Strong Earthquakes, June 2008

Muria Peninsula in which the first NPP candidate site is located, situated in the north coast of central Java. Referirng to the seismic zoning (Figure 4) the Muria Peninsula is located in zone 2 with the estimated PGA = 0.05 – 0.15 g. While based on the historical earthquake data the largest earthquake occurred near Muria Peninsula was the 1890 Pati earthquake. This earthquake was assumed to have magnitude M=6.8 and the estimated maximum intensity in Muria Peninsula was about MMI=VIII. The calculated maximum acceleration at the NPP candidate site was resulted by several previous studies. By using the formulas of relationship between intensity and acceleration, the estimated maximum acceleration of the historical earthquake was about 50—143 gal. Figure 9 shows earthquake distribution in the radius of 500 km from the Muria Peninsula. Red circle denotes shallow earthquake, yellow circle is intermediate earthquake, and blue circle shows deep earthquake. The data was taken from BMG (2007) for earthquakes with magnitude M>4.0 for a period from 1976 to 2000.

Previous studies have identified several supposed capable faults in the Muria Peninsula and its surrounding. At least there are 10 supposed capable faults located in the Muria Peninsula and its surrounding. The studies have calculated that the maximum acceleration in the NPP candidate due to those faults could be from 102 to 290 gal. Figure 10 shows the supposed capable faults in the Muria Peninsula and its surrounding. The estimated maximum acceleration is also shown in the figure 10. Among several formulas, that of McGuire resulted the most conservative one.

 

Source: General Geological Setting Related To Seismic Sources – Indonesian Archipelago: Java – Muria Peninsula, A.S. Sastratenaya and Nanang T. Puspito, Center for Development of Nuclear Energy (PPEN), National Nuclear Energy Agency (BATAN), and Department of Geophysics, Institute of Technology Bandung, presented to at the International Workshop on Lessons Learned from Strong Earthquakes, June 2008

A Feasibility Study of Planting Nuclear Power Plants in Java-Bali-Madura, Indonesia, J. Romantika and R. Jidin, International Association of Science and technology for Development (IASTED), AsiaPES 2008, April 2008.

The frequency of earthquakes and distribution of active volcanoes in Java are quite high and the country is subjected to the frequent major disasters. However, those disasters would not deter planting of NPPs in Java if the long experience of Japan in erecting nuclear plants can be adopted.  Though Japan receives about 21 % of earthquakes in the world (NSC, 2006),  Japan has 56 units of NPP with a total capacity of around 48.7 GW NPPs. Japan has been taken all precautions especially her NPPs are designed to withstand major earthquakes in accordance to stringent installation practices. Similarly, Taiwan which lies on the seismic active region as well has NPPs that can withstand earthquake measuring up to four Gs. The design of NPP must consider the maximum scale of earthquakes based on the historical statistics of earthquakes, effects of highly active faults, near field shallow earthquake and seismic-tectonic structure. BATAN as the National Nuclear Energy Agency in Indonesia so far has investigated fourteen potential sites for NPP in Java Island according to the atomic agency (IAEA) safety standard. The five sites, which are found safe and most suitable for NPP include Pujul Cape and Parigi  in West Java, Muria Peninsula and Lasem in Cental Java,  and  Situbondo in East Java.  Further studies on those sites between BATAN & NEWJEC have shown that Muria Peninsula gives the highest rank site to be developed for NPP (BATAN, 2005).

Kondisi Jateng Berbeda [Conditions in Central Java are different], Kompas, 31 August 2007

[Partial translation] The 7.5 Richter scale earthquake that took place on 9 August has raised questions about the seismic and tectonic conditions on the island of Java. Geological, seismic and gravitational data approaches suggest the region of Central Java possesses different characteristics from those of East and West Java.  This was the conclusion of views expressed at a luncheon meeting of the Indonesian Geophysical Experts Association (HAGI) in Jakarta on Tuesday (30/8) titled “Unexpected Recent Earthquake in North Java Region : Implication on Tectonics and Mantle Structures”. There were three speakers – professor of seismology at Bandung Institute of Technology, Prof Sri Widiyanto PhD; organiser of HAGI, Dr M.Untung; geological expert from BP Migas in the Department of Energy and Mineral resources, Awang Harun Satyana, with Dr Djedi S Widarto as moderator. 

Based on data from the United States Geological Survey and tomographical and relocation data, Ilik, as Sri Widiyantoro is known, concluded that in central Java there is a seismic gap [English original], without earthquakes. According to Ilik, digital data starts from 1964. He used data from 1964-2005. In his paper with Sri Widiyantoro, Untung concluded that that there are fewer gravitational anomalies in Central Java than in West Java and East Java. This is an indication that there are no active faults in the region.

Meanwhile in Awang’s presentation on strain ellipsoid kinematics [English original], he said there are two chief faults delimiting the Central Java region, namely the Pamanukan-Cilcap Fault and the Kebumen-Muria Fault. The two meet in the south of Central Java “because the region is locked up, then its strata are uplifted”, he said.

Questions about the possibility of large quakes in the region emerged from these facts. In his reply, Ilik had a sceptical attitude. “I have a conservative attitude. … The quake data only cover 40 years. If the period was more than 200 years, it means we have no records. We shouldn’t be too optimistic.”

Unexpected Recent Earthquake in North Java Region : Implication on Tectonics and Mantle Structures [PDF, 2.26 Mb], Muharram J. Panguriseng, Resonansi, Edisi-5, 2007, p. 16-17.
 

 Central Java seismic schematic (Satyana, 2007)

Source: &quot;Java: Slab Earthquakes and Reactivation to faults and volcanoes at the overriding Plate,&quot; Harun Satyana, reproduced in Special event – Luncheon Talk HAGI : Unexpected Recent Earthquake in North Java Region : Implication on Tectonics and Mantle Structures, Muharram J. Panguriseng, Resonansi, Edisi-5, 2007, p. 16-17.<br />

 

Volcanic Hazard Analysis for Proposed Nuclear Power Plant Siting in Central Java, Indonesia, P. Sumintadiredja, M.L. Tobing, B. Wibowo, I G.B.E.Sucipta, M. Nurhasanudin, H.Wibowo, Geomathematics and GIS Analysis of Resources, Environment and Hazards, IAMG 2007 Annual Conference, Beijing, China, August 26-31, 2007.

Conclusion

Volcanic hazard studies in Muria Peninsula conducted before 2005 used deterministic analysis with focused that Mt. Muria is a non-capable volcano. In 2005, with more additional geology and geophysics data and temporal probabilistic approach, volcanic hazard analyses concluded that Mt. Muria is a capable volcano. The proposed NPP site lies within the screening distance values (SDV) for several volcanic phenomena such as fallout of pyroclastic material, pyroclastic flows and surges, lava flows, debris flows, lahars, and opening of new vents. Evaluation of the effects of these particular phenomena at the site is necessary and since none of these phenomena at the Muria Volcanic Complex are likely to be Holocene, the hazard assessment of the volcanic hazard introduced by these phenomena should use a spatial temporal probabilistic approach with acceptability factor 10^-4 per hundred years.

Spatial temporal probabilistic analysis is a part of geology risk analysis of Muria Peninsula to the proposed nuclear power plant site. Spatio-temporal probabilistic analysis of volcanic hazards for nuclear power plant Ujung Lemah Abang results in a range of value of 2.463×10^-7 to 7.825×10^-6 every 100 years. Gravity data incorporation to improve the volcanic hazard model was not performed in Muria study, due to present lack of clear understanding of the relationship between vent locations and gravity information. A further research regarding this matter might be required in the future study.

Pembangunan PLTN, Aman atau Membahayakan (1): Peringatan Dini dari Patahan Muria [Nuclear power plant development, safe or dangerous (1): Muria Fault early warning], Muhammadun Sanomae dan Sukardi, Suara Merdeka, 18 April 2007.

[Partial translation] Researchers from the Research and Development Centre for Marine Geology Research in the Department of Energy and Mineral Resources have discovered two large faults in the Muria area. “…There are two large faults in the Mount Muria region, in Rahtawu and Tempur”, said Priyantono, a researcher at the Centre, working in Jepara since 2 April.

Natural features supporting the existence of faults includes, amongst other things, the discovery of a number of waterfalls, and the fact that there are fault planes [?]. He said that the position of the large Rahtawu Fault (in Kecamatan Gebog, Kudus) is parallel to and not connected with the Tempur Fault (in Keling, Jepara). “The Tempur Fault reaches to Mount Genuk near Benteng Portugis. We discovered  many small faults near Mount Genuk.”

Gunung api maar di Semenanjung Muria [Volcanic maars on the Muria Peninsula], Sutikno Bronto dan Sri Mulyaningsih, Jurnal Geologi Indonesia, Vol. 2 No. 1 Maret 2007: 43-54.

Three maars are well identified in the Muria Peninsula, i.e. Bambang Maar, Gunungrowo Maar, and Gembong Maar. The maars were formed by monogenetic volcanic eruptions due to the interaction between heat source (magma), groundwater and calcareous basement rocks. This interaction is able to produce very high pressure of gas and steam causing phreatic explosions, followed by phreatomagmatic- or even magmatic explosions and ended by a lava extrusion. Satellite image analyses have recognized twelve circular features, comprising Bambang Maar, Gunungrowo Maar, and Gembaong Maar. Physiographically, these maars are characterized by circular depressions which are surrounded by hills that are gently sloping down away from the crater or having a radier pattern morphology. Outcrops and drilling core in the circular areas that are considered as volcanic maars are lava flows, pyroclastic breccias, lapillistones, and tuffs, located far away from the eruption centres of Muria and Genuk Volcanoes. One of the circular features, i.e. Jepara Circular Feature, is also supported by negative anomaly (<30 mgal) showing a circular pattern. In the future, a maar volcano could possibly erupt depending on the tectonic reactivity in the region. 

Volcanic maars in the Gunung Muria region

Source: Gunung api maar di Semenanjung Muria [Volcanic maars on the Muria Peninsula], Sutikno Bronto dan Sri Mulyaningsih, Jurnal Geologi Indonesia, Vol. 2 No. 1 Maret 2007: 43-54.

Note: Bambang, Gunungrowo and Gembang maars, and other maars circled. (Landsat data.) NPP-ULA represents proposed the Ujung Lemah Abang nuclear power plant site.

Offshore fault assessment: Implication to predict earthquake and tsunamigenic potential along the coastal area of Muria peninsula, Central Java, Ediar Usman, I Wayan Lugra, and Subatian Lubis, APRU/AEARU Research Symposium 2007. 

The seismic data were obtained from the existing data of NIRA (1982), Pertamina-Bicep (1985), Conoco (1983), Sceptre (1984), Newjec (1993) and MGI (1991,1992, 2006, 2007). Interpretation results of the records found indication of some typical faults such as normal faults, strike-slip fault and thrust fault. An unusual long fault was found in this region. The total length of the fault is approximately 160 km oriented northeast-southwest direction and it comprises at least seven fault segments.

The new data records from MGI (2006, 2007) provide information on faults north and east of the Muria peninsula. Faults within 5 km of the coastal area is interpreted as post Tertiary activity, although some faults within 25 km of the coastline may stil be active growth-type faults. In the eastern part of Muria waters area exhibits two prominent fault sets, a normal fault as indicated by a half graben fault or growth fault set, and strike-slip fault set. Previous reports suggested that the former was Quaternary in age. New interpretation suggests that both fault sets have been active through the Quaternary.

Gerakan Tanah [Land movement], Statistik Bencana Alam Geologi Tahun 2006, [Google cache, accessed 18 June 2008].

Land movement occurred in Rahtawu, Kecamatan Gebog, Kabupaten Kudus, Jawa Tengah on 20 March 2006. Two people died, six injured, six houses destroyed, two houses damaged, four buffalo and 15 goats died.

Volcanic and seismic hazards at a proposed nuclear power site in central Java, Alexander R. McBirney, Leonello Serva, M. Guerra, Charles B. Connor, Journal of Volcanology and Geothermal Research 126 (2003) 11-30.

Abstract

In order to assess the risk posed by a large volcano for which there is no record of historical eruptions, it was necessary to determine the age of the last activity by geological and geochronological means and to deduce from this whether the volcano posed a credible risk. Similarly, because there was no adequate record of seismic activity, the seismic hazards were investigated mainly by geological, geomorphological, and geophysical methods that identified and characterized potential seismogenic sources related to the volcano or tectonic movements (i.e. active/capable faults). Muria Volcano has not erupted since about two thousand years ago, but the last activity was sufficiently recent to rule out any assumption that the volcano is extinct. Detailed studies indicated that the proposed site may be vulnerable to the effects of air-borne tephra, pyroclastic flows and surges, debris flows, lahars, and opening of new vents. A more serious factor, however, was the poor geotechnical properties of the foundation material that required a careful analysis of the seismic hazards.

Summary and conclusions

The geological investigation has shown that the volcanic complex on Muria Peninsula must be considered capable of future volcanic and seismic activity. Evidence of recent volcanic eruptions is manifested in explosion craters on the flanks of Muria Volcano. Judging from the records of other volcanoes of this type, the period that has elapsed since these craters were formed 2000-5000 years ago is less than the intervals between eruptions of many long-dormant volcanoes of similar form and composition. Further evidence that an active magmatic body still resides beneath the area is found in the composition of gases emitted near the base of the volcano and in boreholes near the site of the proposed plant.

The site lies within the screening distances for at least four possible types of events: (1) fallout of pyroclastic material, (2) pyroclastic flows and surges, (3) debris flows, lahars, and floods, and (4) opening of new vents. Adequate safeguards for pyroclastic fallout can be incorporated into the design of the plant, but the other possible hazards are more serious.

The studies also showed that although additional confirmatory data are needed, there appear to be no capable faults at or near the site of the proposed nuclear plant. Our seismotectonic model for assessing the seismic hazards of the area indicates that the hazards are less than the criteria used for construction of nuclear power plants in Japan. On the other hand, taking into account the poor geotechnical properties of the foundation materials and the high groundwater level, the assessed seismogenic potential could prejudice the feasibility of the plant.

Satellite image showing the location of the proposed nuclear power plant with respect to Muria volcano, (McBirney et al, 2003)

Volcanic and seismic hazards at a proposed nuclear power site in central Java, Alexander R. McBirney , Leonello Serva, M. Guerra, Charles B. Connor, Journal of Volcanology and Geothermal Research 126 (2003), Figure 1

 

Volcanoes within a distance of 150 km of the proposed site, (McBirney et al, 2003)

Source: Volcanic and seismic hazards at a proposed nuclear power site in central Java, Alexander R. McBirney , Leonello Serva, M. Guerra, Charles B. Connor, Journal of Volcanology and Geothermal Research 126 (2003) , Fig. 4.

 

Volcanic and tectonic features in the vicinity of the proposed nuclear power plant (McBirney et al, 2003)

Source: Volcanic and seismic hazards at a proposed nuclear power site in central Java, Alexander R. McBirney , Leonello Serva, M. Guerra, Charles B. Connor, Journal of Volcanology and Geothermal Research 126 (2003), Fig. 5.

Notes on the IAEA Guidelines for Assessing Volcanic Hazards at Nuclear Facilities, Alexander McBirney and Antonio Godoy, Journal of Volcanology and Geothermal Research, Volume 126, Issues 1-2, 10 August 2003, Pages 1-9.

A number of nuclear power plant sites around the world are located in areas of signi¢cant volcanic risk. In the past, the safety of these facilities has been evaluated without the beneft of well established, internationally accepted guidelines that set criteria and procedures that should be followed in assessing potential hazards. Instead, the investigations have been carried out according to local practices that prevailed at the time the sites were selected.

In order to ensure the safety of nuclear facilities, the International Atomic Energy Agency
(IAEA, an agency of the United Nations) has prepared a Safety Code that establishes strict requirements for the siting and design of these facilities. The aim of the Code is to provide protection from external hazards (i.e. events coming from sources outside the plant fence, e.g. earthquakes, floods, extreme meteorological phenomena, and man-induced events). In addition, because of local conditions, it may be necessary to re-examine certain facilities that are in operation or advanced stages of planning and/or construction, because volcanism poses significant potential hazards. Examples of this kind include the Armenian Nuclear Power Plant (currently in operation), the proposed Nuclear Project in central Java, Indonesia, the Yucca Mountain Repository in Nevada, USA, the existing Mulheim-Karlich Nuclear Power Plant in Germany, and the Petropavlovsk-50 facility in Kamchatka, Russia.

Annex: Small and Medium Reactor User Requirements Document: Indonesia, Guidance for preparing user requirements documents for small and medium reactors and their application, [PDF, 7.01Mb], International Atomic Energy Agency, IAEA-TECDOC-1167, August 2000.

This annex reproduces an interim formulation of the User Requirements Document on Small andMedium Power Reactors (SMRs) for Indonesia, which was prepared collectively by a specially assigned group of scientists and engineers of the National Atomic Energy Agency, while its format and skeleton conform as closely as possible to the ones recommended in Chapter II of the main report. The SMRs cover a broad range of reactor power, up to the equivalent of 300 MW(e) which are called small and very small power reactors (SVSRs) and from 300 to 700 MW(e) which are called medium power reactors (MRs).

In its current form, this report contains the Indonesian requirements on MRs and SVSRs. Whereas sentences typed in italic font are meant additionally for SVSRs.

3.1. Site condition

The SMR plant shall be designed and optimised taking into account the main site and environment data. The plant shall be constructed at a selected site having technical characteristics fall within the requirements stipulated, at a minimum, in IAEA technical documents for NPP siting. Hazards from any single external event or combination of selected external events which might occur in the region should not go beyond the manageable level, threaten the structural integrity, and hamper the normal operation of the plant.

One of the best candidate site selected for the medium reactors (MRs), based on the assessment study up to the writing of this document, is on the North coast of the Muria peninsula, tentatively at Ujung Lemahabang. The size of this tentatively preferred site is approximately 3 Km length in East-West direction and 2 Km wide in North-South direction. Elevated land in a height of about 10 m is well developed at the coast continued by gentle hilly slope behind it. The depth of moderately harder layer lies about 12 m below Mean Sea Level. Ultimately the site is intended to host eight to twelve units with total capacity of 7000 MW(e).

The design basis parameters of the plant shall fall within the parameter envelope listed in the table below.

Bearing capacity	kg/cm2	? 7.5
Shear wave velocity	m/sec	? 300
Flood level	m	? 0.3
		below finish grade
Peak ground acceleration	gal	? 400
Volcanic ash	cm	? 20
Max. ambient temperature	oC	36

3.1.1. Seismic/hydrology/meteorology

Ujung Lemahabang site lies on volcanic and sedimentary rocks of Pleistocene. Site geology mainly consists of four zones: soil zone, upper tuff zone, middle sandstone zone and lower tuff zone. The mean value of unconfined compressive strength of each rock type/class of the bedrock varies between 16 kgf/cm² and 62 kgf/cm². There exist some possible faults around the site including offshore area. Among the historical earthquakes, Pati earthquake, which occurred in 1890 and with estimated magnitude of 6.8, had the most severe effect to the site.

Remote areas in the Eastern part of Indonesia are located in the potentially high levels of seismic intensities since this part of Indonesia represents the junctions of the Indian-Australian, Eurasian, Philippine Sea and Caroline plates. Troughs and trenches as well as series of volcanoes are located. Therefore specific seismic occurrences (tectonic, volcanic and tsunami) out of these areas shall be thoroughly investigated and requirements specifically determined.

Seismological Study of Ujung Lemahabang. (a project report summitted to BATAN), Rekin, 1998.

Site Safety Review Mission: Final Review of the Siting Studies at Muria Peninsula, Indonesia (External Events Topics), IAEA, TC project INS/9/021, IAEA-RU-6847, 1997.

Topical Report on Seismology STEP-3. (a project report summitted to BATAN), Newjec, 1996

Profil / Karakteristik Tapak, (Hasil Studi Newjec 1991-1996), Studi Tapak dan Lingkungan, [Site Profile/Characteristics, (Results of the NewJEC Study 1991-1996), Environment and Site Study], Pusat Pengembangan Energi Nuklir (PPEN), Batan. [accessed 12 June 2008].

1. Surface faulting: expected ground motion (max acceleration) falls into class of 80-250 gal.

2. Seismicity: same as no.1

3. Foundation characteristics: rock class foundation is Cm class

4. Ground characteristics: possibility of liquefaction: not possible

5. Volcanic characteristics: possibility of volcanic activities: not possible

6. Coastal flooding: flood level falls into class of 2 meters.

7. River flooding: possibility of affecting the site: not possible

8. Groundwater movement: favorable

9. Man induced events: ranked I

10. Population distribution: ranked I

11. Resettlement of residents: ranked I

12. Cooling water system: deviation in the length of steel pipes from the best site falls into class of 100% (best site)

13. Harbor facility: deviation in the length of the bridge of pier from the best site falls into class of 100%

14. Depth to foundation level: deviation from excavation volume from the best site falls inclo class of 100%

15. Foundation level below groundwater level: depth between groundwater level and foundation level falls into class of 20 m.

16. Access road: Deviation in the length of access road from the best site falls into class of 100%.

17. Site land arrangement: deviation in the surplus or lacking volume of soil/rock from the best site is same as no 12.

18. Land and water use: order of ranking is rank I

19. Endangered species and historical monuments: order of ranking is rank I

20. Ecology: order of ranking is rank I

Review of the Preliminary Site Data Report for the Muria NPP (a project report summitted to BATAN), S&L and Rekin, 1995.

Prospect and potential of nuclear power plants in Indonesia, [PDF, 738 Kb], I.R.Subki, Adiwardojo, M.S.Kasim, A. Iskandar, Mulyanto, (BATAN), IAEA.

[Ed: Summary report of the NewJEC Feasibility Study completed December 1993.]

Networks of Microearthquake Telemetring System (MTS) consists of 5 and 3 seismometers are installed in the area. This system records every single earthquake with the magnitude < 3 Richter. To record earthquake having M > 3-5, a Strong Motion Accelerometer (SMA) system is installed at the Ujung Lemahabang site. So far, no single earthquake that could trigger this SMA system is ever recorded. (sic)

There are two volcano systems in the area, they are, the Genuk and Muria volcanoes. Mount Genuk (719 m) had activities in the age between 3.29 to 1.65 ma, and had lasted till about 0.49 ma. Mount Muria (1602 m) that is situated in the center of peninsula had activities between 2.1 to 0.8 ma. The last volcanic eruption is judged to have occurred about 0.32 ma ago. The candidate site, Ujung Lemahabang, has never been affected by lava or pyroclastic flows from either volcano. Careful assessment of the phreatic and gas emission at flank of Muria is underway. (sic) (pp. 24-5).

Pemetaan Geologi Dan Radioaktivitas Alami Semenanjung Muria, Jawa Tengah [Geology And Natural Radioactivity Mapping Of Muria Peninsula, Central Java], Soeprapto Tjokrokardono, Djoko Soetamo, Mudiar Masdja, Sutomo Budihardjo, Sutarman, Sucipta, dan Nasrun Syamsul, PPGN, BATAN.

This paper describes geology and natural radioactivity of Muria Peninsula, which is covered by intended four-years mapping periode starting 1995/1996 until 1998/1999. The activities were conducted in the area covering 3550 km²  or 75 km radii from Ujung Lemah Abang, the selected NPP site. The objective is to collect baseline data for environmental monitoring of Muria Peninsula. Mapping activity are conducted at three selected areas included candidate site of NPP site of Tanjung Jelamun, their site vicinity of Ujung Lemah Abang and almost the area of Muria Peninsula. Observation parameters include geology, natural radioactivity, radiation exposure, and radioelement content in soil, stream sediment and water. Geological data indicate that Muria Peninsula is by stratovolcanoes of Muria and Genuk Complexes. Geologically, it consists of Patiayam Formation, Genuk volcanic products, Muria volcanic products and Alluvial. Soil radioactivity ranged from 20-300 cps. Geochemically, Muria’s soil contains 3.59-135.65 ppm eU, 2.73-108.30 ppm eTh and 0.27-31.23 % K. Uranium content of river water taken from the area are about 0.01 -2.98 ppb U, however Potassium content is abaut 1.10 -164.80 ppm ppm K. Uranium content within stream sediment taken from the river is about 0.51-3.72 ppm U. At the candidate site and site vicinity of Ujung Lemah Abang, the soil’s radioactivity, radioelement contents, and exposure rate are relatively slightly higher than those of mean of Muria Peninsula. Radioactivity and Exposure rate patterns of Muria are related to genetic and distribution of litology than those of landuse and morphology of the area.

Environmental changes on the coasts of Indonesia,  Eric C. F. Bird and Otto S. R. Ongkosongo, United Nations University, 1980.

Chapter 2. The changing coastlines of indonesia

East of Semarang large-scale progradation is thought to have taken place in recent centuries. Demak, a sixteenth-century coastal port, is now about 12.5 kilometres inland behind a prograded deltaic shoreline. Continuing progradation is indicated by the small delta growing at the mouth of a canal cut from the River Anyar to the sea, but otherwise the coastline north to Jepara is almost straight at the fringe of a broad depositional plain. According to Niermeyer (1913: quoted by Van Bemmelen 1949) the Muria volcano north-east of Demak was still an island in the eighteenth century, when seagoing vessels sailed through the strait that separated it from the Remang Hills, a strait now occupied by marshy alluvium. This inference, however, needs to be checked by geomorphological and stratigraphical investigations.

Beyond Jepara the coast steepens on the flanks of Muria, but the shores are beach-fringed rather than cliffed. To the east the Juwana River opens on to the widening deltaic plain behind Rembang Bay, but at Awarawar the coast consists of bluffs cut in Pliocene limestone. Tuban has beaches and low dunes of quartzose sand, supplied by rivers draining sandstones in the hinterland, but otherwise the beaches on northern Java are mainly of sediments derived from volcanic or marine sources. Hilly country continues eastwards until the protrusion of the Solo River delta.

[Citing R.W.Van Bemmelen, The Geology of Indonesia, The Hague, 1949.]

The problems of groundwater assessment in the volcanic-sedimentary environment of Central Java, J.W.Lloyd, R.H.Pin, M.D.Watkins, and A.Suwara, Quarterly Journal of Engineering Geology and Hydrogeology, 1985, Vol. 18, pp. 47-61.

While much of the geological setting [of Central Java] is relatively old, very recent events have had significant impact; for example, in the 12th century the Gunung Muria volcano was separated from the main island by shallow seas, while in 1006 AD Gunung Merapi erupted and devastated the local civilization.  

  Project coordinator: Richard Tanter
Additional research: Arabella Imhoff
Updated: 24 March 2010