Opak Fault Research Articles

Analysis of subsurface Resistivity Structures in Relation to the Level of Damage Caused by Earthquakes Using the Audio-Magnetotelluric (AMT) Method (Case study: the 2006 Yogyakarta Earthquake)

Abstract The 2006 Yogyakarta Earthquake had caused a disaster in Bantul area. Although the magnitude reached only Mw = 6.4, it left more than 6,000 fatalities and up to 1,000,000 homeless. The earthquakes that occur in this area is shallow earthquakes that originate on land (Opak fault) and triggers quite high surface damage. This damage includes damage to buildings and infrastructure that support community activities. The main objective of this research is to determine the subsurface structure and be able to identify soft layers based on the distribution of resistivity values that can be correlated to the value of the amplification factor. The Audio-Magnetotelluric (AMT) method was conducted in this area using five components of electric and magnetic fields. The Audio-Magnetotelluric (AMT) method utilizes electromagnetic waves with a frequency of 1 Hz to 100KHz. Based on the one-dimensional (1-D) inversion result calculated from 3 sites show that there is a low resistivity value (10 - 70 Ωm) from the surface to the depth of 1000 m. This ticked conductive zone interpreted as a sediment layer that can triggers the high amplification factor values.

Analysis and Evaluation of Earthquake Hazard Zones Based on Spatial Models for Regency Regional Development Bantul

Abstract Earthquakes are a natural disaster that occur frequently in Indonesia. A region susceptible to earthquakes is the Bantul district. Buildings and infrastructure could be damaged by this disaster, especially in highly populated metropolitan areas where the Bantul Regency earthquake (Mw 6.4) on May 27, 2006, resulted in significant damage.The purpose of this research is to identify the distribution of the region’s level of stability against the possibility of an earthquake occurring, as well as the degree of compatibility between the vulnerability zone and the Development Territory Unit (SWP) of Bantul district. This research uses data collection techniques by direct observation with microtremors to calculate surface peak ground acceleration (PGA) with a value of Vs.30. The regional stability weighting matrix approach is used in this study, which is governed by Minister of Public Works Regulation Number 21 of 2007 covering Guidelines for Spatial Planning in Volcanic Eruptions and Earthquake-Prone Areas. The research results for Bantul Regency have a distribution of Vs.30 values between 175 - 350 m/s which is included in the Soft Rock (SC) category with surface peak ground acceleration (PGA) values between 0.112 g - 0.418 g. The final score for Bantul Regency is 20 - 43 which falls into the stable and less stable categories. The Development Area Unit (SWP) of Bantul Regency SWP, which is in the unstable zone, is dominantly distributed around the Opak Fault. SWP II, III, IV, and V require mitigation measures when used for residential areas. Spatial planning that is in accordance with built-up and non-built zones will be able to reduce risk factors.

Preliminary study of liquefaction potential on the NYIA-Kulon Progo Toll Road Construction Project (Klaten Interchange STA 21+800 – 22+300)

Abstract The Solo-Jogja NYIA Kulon Progo toll road construction project section 1 package 1.1, which connects Kartasura to Klaten Regency. Based on the regional geological conditions, the Klaten interchange at STA 21+800-22+300 is situated in the Opak Merapi-Merbabu fault area predominantly composed of sandy lithology. Consequently, there is a potential for liquefaction when an earthquake occurs. This research analysis of liquefaction potential using a field test data approach, namely the SPT (Standard Penetration Test) was conducted to assess the seismic and subsurface conditions at Klaten Interchange STA 21+800 - 22+300. The seismic conditions at the Klaten interchange, located 6-7 km from the Opak fault, result in a Peak Ground Acceleration (PGA) value of 0.78 g, corresponding to class 5 on the BMKG MMI scale, potentially causing serious damage to buildings. The VS30 value in the research area ranges from 278.9 - 654.3 m/s, indicating a medium soil type. Subsurface conditions at STA 21+800-21+300 are divided into three zones based on the distance of each borehole. The SPT result shows that zone 1 is dominated by Silty Sand with Loose to Medium Dense consistency, zone 2 is dominated by Silty Sand to Sand with Medium Dense to Very Dense consistency, zone 3 is dominated by Silty Sand with a Medium Dense to Very Dense consistency. The results of the liquefaction potential calculation study indicate that several borehole points have the potential for liquefaction because the safety factor (FS) value is less than 1. Zone 1 has three points that have the potential for liquefaction: DBs-01, DBs-05, and DBs-07. Zone 2 includes two points with potential liquefaction: DBs-08 and DBs-09. Zone 3 has one point with potential for liquefaction: DBs-10.

OPTIMALISASI PENILAIAN MANDIRI SATUAN PENDIDIKAN AMAN BENCANA (SPAB) DALAM MENDORONG KESIAPAN MENGHADAPI BENCANA GEMPA BUMI DI KAWASAN SESAR OPAK KABUPATEN BANTUL

The implementations of self-assessment using Inarisk SPAB's (Disaster Safe School) e-monev tools in Bantul Regency are currently not optimal. According to SPAB e-monev study and analysis by BNPB in 2023 stated that 11% of the 8,268 schools only in DI. Yogyakarta did it. The capacity and preparedness for schools in Bantul, especially those on the Opak Fault, to face the threat of earthquakes is absolutely necessary through reinforcement of SPAB. To ensure the schools in the Opak Fault area consistently implement Disaster Safe School (SPAB) standards in increasing preparedness to face earthquakes, periodic self-assessments should be carried out. However, self-assessment using Inarisk SPAB's (Disaster Safe School) e-monev tools in the Opak Fault has not been optimal, which means that schools have not attempted to provide guarantees of optimal preparedness to face the risk of earthquake disasters for its members. This research is qualitative research with a descriptive approach involving 32 key informan and triangulation. The results are stated that four of six schools in Opak Fault, Bantul Regency are less prepared to face earthquakes, while the others are almost ready and ready category.

Detailed seismic structure beneath the earthquake zone of Yogyakarta 2006 (Mw ∼6.4), Indonesia, from local earthquake tomography

The earthquake, which occurred in Yogyakarta, Indonesia, on May 26, 2006, at 22:53:58 UTC with Mw ∼6.4, was one of the most destructive earthquakes in Indonesia. The earthquake caused thousands of fatalities, tens of thousands of injuries, and hundreds of thousands of house damages in the Yogyakarta area and its surroundings at a loss of billions of dollars. Previous studies from seismic tomography and satellite radar imaging hypothesized that the earthquake was caused by activating a so far unknown fault east of the Opak Fault. Although, in the beginning, the Opak fault was suspected to be the source of the Yogyakarta earthquake in 2006. This assumption was made because the damage was maximum in the Bantul area west of the Opak Fault. This study demonstrates that our seismic tomography achieved a higher resolution than the previous study and could resolve a failed complex fault system. We utilized more aftershocks (2170 events) and smaller grid sizes for seismic tomography inversion. Four focal mechanisms from aftershocks for Mw ≥ 4.5 were also conducted to support structure interpretation in the study area. Our results successfully delineate the Opak Fault and the second fault, namely the Ngalang Fault, parallel to the eastern part of the fault at a depth of 9 km. Two faults could be indicated by the velocity contrast of Vp, Vp/Vs ratio, and Vs from a horizontal section tomogram. Our focal mechanisms also support seismic tomography, revealing two fault planes in our study area. The results show that the two faults are connected by the Oyo Fault, which is ruptured in the opposite direction compared to the two faults.

Hazard analysis of earthquake in Pleret, Bantul Regency, Yogyakarta Special Region based on microtremor data

Pleret, one of the sub-districts in Bantul Regency, Yogyakarta, is prone to earthquakes. This area is traversed by an active fault system known as the Opak fault, with a maximum magnitude of 6.6 Mw. The local geological conditions can be determined based on microtremor data from 43 measurement points. The purpose of this research is to understand the dynamic characteristics of the local geological conditions, including the dominant frequency (f0), shear wave velocity (Vs30), peak ground acceleration (PGA), and to map the earthquake impacts on the population and structures. Microtremor measurements were conducted for approximately 20 minutes, revealing a dominant frequency range of 0.61-10.85 Hz. The HVSR curve inversion revealed the Vs30 range 213 to 826 m/s distribution. Peak Ground Acceleration (PGA) values varied from 0.16 to 0.26 g. Using InaSAFE software, the estimated affected population reached 49,052 people, with over 23,176 structures affected. The results of this mapping are expected to be utilized as a step towards enhancing disaster preparedness.

Liquefaction potential hazard assessment and its effect on toll road construction in Seyegan Subdistrict, Yogyakarta

Toll road construction is a vital infrastructure connecting the two economic centers on Java Island. However, given the potential disaster risks in the region, it is essential to assess the geological and geotechnical conditions to determine the potential for liquefaction in the area. The special region of Yogyakarta is susceptible to earthquakes and associated disasters. One of the most significant earthquakes occurred on May 27, 2006 with a magnitude of 6.3 Mw resulting from the Opak Fault. Furthermore, the toll road is constructed above the Mataram Irrigation Canal, characterized by a shallow groundwater level and young volcanic deposits that are vulnerable to liquified. The study aimed to determine the potential for liquefaction in the area and predicted the vertical settlement caused by liquified soil. The analysis of liquefaction potential utilized the simplified procedure to obtain factor of safety and Liquefaction Severity Index (LSI) to assess the vulnerability index of liquefaction. Results indicated the research area had a very low to medium liquefaction susceptibility index. In addition, the calculation of vertical settlement using Idriss and Boulanger (2008) equation showed a predicted vertical settlement range of 0.4 cm – 44.64 cm. The predicted vertical settlement range underscores the importance of considering the potential for liquefaction to mitigate any adverse effects on the toll road’s construction and operation.

Study of responsive tourism destination areas to reduce disaster risk: Canden Village, Bantul

Canden Village currently has a vision of a Wellness Tourism Destination. Kiringan Hamlet, located in Kalurahan Canden, was designated a Tourism Village of Jamu Gendong (Herbal Medicine) in 2016. Canden has several natural, cultural, artistic, and culinary tourism potentials spread across Canden Hamlet, Ngibikan Hamlet, Suren Kulon Hamlet, Suren Wetan, and Banyudono. Several problems related to access, namely, the primary entrance to Kalurahan Canden is not feasible, the physical condition of the road could be more suitable for motorized vehicles, and there needs to be an area marker as a wayfinding facility. In addition to accessibility conditions, disaster response in the area is critical. Canden’s location around the Opak Fault and the Opak River causes this area to have several potential natural disasters. This study of disaster response needs to be conducted to enhance a tourism village as a tourist destination that is safe, comfortable, and sustainable. The object of this study is Canden Village in Bantul, which has several disaster risks. The research aims to determine the level of disaster response in Canden as a Tourism Village. The research method is a qualitative research method using grounded theory and space syntax connectivity-visibility analysis. The concept of disaster response consists of evacuation routes, protective areas, safe zones, open spaces, and public facilities. The results of the study show that the aspect of disaster response in the region is essential to support regional security factors. This research can be a study for disaster response tourist spots and support the sustainability of an area as a tourist destination.

Assessment of liquefaction potential and damage on the toll road construction in earthquake-prone area, Sleman Regency, Yogyakarta

The construction of toll roads in earthquake-prone areas presents significant challenges due to the potential occurrence of liquefaction, a seismic phenomenon in fine-grained soils losing strength during earthquakes. The research was conducted at a toll road construction site in Sleman Regency, Yogyakarta, an area near the active Opak fault which increases its vulnerability to liquefaction. The objective of this study is to analyse the liquefaction potential and damage on the surface in research area. The method used is simplified procedure by Idriss and Boulanger which assessing the cyclic stress ratio and cyclic resistance ratio based on standard penetration test and laboratory data. Then, Liquefaction Potential Index (LPI) and Liquefaction Severity Index (LSI) are calculated. Finally, vertical displacement caused by liquefied soil is estimated using the post-cyclic reconsolidation model to understand its impact on the surface. The study shows low to very high liquefaction potential at the toll road construction site in Sleman Regency. With a vertical displacement of 4.69 cm to 38.83 cm, surface damage can range from low to extensive, emphasizing the need for liquefaction mitigation in earthquake-prone areas like Yogyakarta during toll road infrastructure planning.

A study of earthquake potential analysis in central java and Yogyakarta provinces, Indonesia based on the calculation of a and B-Values with the maximum likelihood method

There are several active faults in Central Java and Yogyakarta (Indonesia), such as the Opak Fault, Baribis- Kendeng Fault, Merapi-Merbabu Fault, and others. In addition, Central Java and Yogyakarta are located near the subduction zone in the south of Java Island due to the collision of the Eurasian Plate and the Indo-Australian Plate. This has contributed to the fact that earthquakes can occur in Central Java and Yogyakarta. The purpose of this research is analyze the earthquake potential in Central Java, which includes an analysis of the a-value (seismicity level) and b-value (regional stress level) as an earthquake hazard mitigation effort. The Gutenberg-Richter equation expresses the relationship between earthquake frequency and magnitude as a straight-line equation containing the a-value and b-value parameters. The calculation of the b-value of the Gutenberg-Richter equation can be conducted with a modification of the maximum likelihood method. From 122 main earthquake events in the IRIS catalog, the values for depth (0-33) km are b = 1.01 ± 0.01 and a = 6.31, for depth (0-10) km, b = 1.44 ± 0.2 and a = 7.58; while for depth (10-33) km, b = 0.91 ± 0.1 and a = 5.73. The depth of (0-33) km and the depth of (0-10) km shows high a-value and b-value, while the depth of (10-33) km shows low a-value and b-value.

Analysis of Liquefaction Potential in Solo-Yogyakarta-NYIA Kulon Progo Sta. 16+700 – 22+500

The Solo-Yogyakarta-NYIA Kulon Progo is a National Strategic Project to accelerate the accessibility to New Yogyakarta International Airport (NYIA). This toll road will pass through Central Java Province and the Special Region of Yogyakarta Province. Previous studies have investigated that during the 2006 Yogyakarta Earthquake with a moment magnitude, Mw of 6.3, liquefaction was found in some areas in Klaten Regency of Central Java Province. This study aims to determine liquefaction potential in the Solo-Yogyakarta-NYIA Kulon Progo Toll Road Section 1, focusing on stations 16+700 to 22+500, which were located in Klaten Regency. This study first analyzes soil conditions and groundwater depth based on soil investigation data. Analysis of liquefaction potential was found out using Idriss-Boulanger based on Standard Penetration. Parameter of peak ground acceleration using two approaches; probabilistic and deterministic. For probabilistic, the peak ground acceleration using probability of 7% in 75 years and 2% in 50 years. For deterministic using the attenuation function of Campbell and Bozorgnia (2014). Then, the Liquefaction Potential Index was also used to determine the level of liquefaction vulnerability in the study area. The results of liquefaction potential analysis using each approach of peak ground acceleration show the differences in safety factor of liquefaction values. It can be concluded that several sites along the study area have the potential to liquefy at a very low to a very high level, with PGA value at least 0,43 for probability of 2% in 50 years, 0,32 for probability of 7% in 75 years, and 0,36 for deterministic approaches sourced by Opak Fault. Then, the location with the highest liquefaction potential is at stationing 20+550, with LPI values of each approach of 42.91, 33.36, and 34.70.

Response Spectrum Design Based on Site Class and Site-Specific Analysis in the Transition Zone

The building structure design needs to pay attention to the seismic code and all its consequences. Building A which will be built in Sleman, Special Region of Yogyakarta is 12.20 km from the Opak Fault causing the Bantul Earthquake of Mw 6.3 in 2006, needs seismic analysis properly using SNI 1726:2019. Based on the site near fault criteria on seismic code, Building A does not belong to the site near fault category, so it used the Probabilistic Seismic Hazard Analysis method. However, considering its distance and magnitude, the value is in the range of the requirements limit. Hence, it is still relevant when compared to the Deterministic Seismic Hazard Analysis method for designing the response spectrum. Based on the site classification in the seismic code, a site that is vulnerable to liquefaction belongs to the site class F and therefore requires site-specific analysis. The site-specific surface response spectrum is taken from the equivalent-linear and non-linear site response analysis using Deepsoil v7.0 software. The response spectrum is also calculated based on site class according to the shear wave velocity (v s) and N-SPT criteria. The site-specific spectral acceleration results are compared to 80% of the site class E spectral acceleration, as required. The site belongs to site class D using v s criteria and belongs to site class E using the N-SPT criteria. Only the equivalent-linear site response spectrum in the modified maximum horizontal direction spectrum is eligible when compared to requirements. Most of the non-linear site response spectrum results or the geometric mean response spectrum of the equivalent-linear site response results can satisfy the requirements compared to 80% of the site class D spectral acceleration because the site response analysis uses the v s parameter. The non-linear site response spectral acceleration is smaller than the equivalent-linear site response spectral acceleration.

Mataram Fault – New Active Fault Crosses East-West in the Centre of Yogyakarta City

Yogyakarta has experienced two devastating earthquake disasters: May 26, 2006, Mw6.4, and the penultimate event, June 10, 1867 Mw7.7. The active fault that is thought to be responsible for the two earthquake events is the Opak Fault. However, the Opak Fault has still not been thoroughly well mapped yet. The lack of a high-resolution image, dense vegetation cover, high sediment flux from the Merapi volcano, and human activities eroding the original landscape challenge studying the on-land fault in this area. Our recent study, however, indicates that the Opak Fault is not the only active fault that can cause a major disaster, but another fault strand exists in the area. We mapped the fault using the best available data of DEMNAS assisted by more detailed DEM and Orthophoto, developed from drone survey, and we also conducted Earth Resistivity Tomography (ERT) survey. We found that inferred new active fault is oriented East-West across the center of the high-populated city. The fault runs parallel and close to the famous Mataram channel (Selokan Mataram). The fault is likely continue the previously recognized Dengkeng Fault, east of the Opak fault. The fault strand is indicated by morphological lineaments and a few steam offsets. Our ERT 2D sections have revealed the fault zone in several locations along the inferred fault line. The fault line cut the Young Quaternary rocks; hence, it is an active fault. Further studies are needed to get further details of this newly recognized active fault, such as conducting paleoseismological studies, detailed seismological survey, geodetic GPS measurement, and acquiring a high-resolution image acquisition survey (LiDAR – Light Detection and Ranging Survey).

Early Result of Imaging 3D Seismic Velocity Structure In Central Java Using Double-Difference Tomography

Central Java is a part of the Sunda Arc and has relatively high seismicity due to the subduction zone between the Indo-Australian Plate and the Eurasian Plate. This study uses double-difference tomography to image the P and S wave 3D seismic velocity structures associated with tectonic patterns due to subduction zones. The data used comes from the earthquake catalogs of BMKG, BPPTKG, DOMERAPI, and MERAMEX, with a recording period from May 2004 to December 2020. The number of earthquakes that successfully relocated was 1930 from 1937 earthquakes recorded by 285 recording stations. The results of hypocentre relocation show that seismic activity in Central Java is relatively high and originates from geological structures, including subduction zones, back-thrust, and the Opak Fault. The tomogram results of the P and S wave velocity models support each other. The high seismic velocity anomaly is associated with the subduction zone of the Indo-Australian Plate to the Eurasian Plate with a maximum resolution of up to 100 km depth. Low seismic velocity anomalies are found at the Merapi-Lawu Anomaly (MLA), the Modern Volcanic Arc (MVA), the Sumbing-Sundoro-Dieng volcanic complex, the Banyumas-Cilacap sedimentary basin, and the Kendeng Basin. A low-velocity anomaly is found at a depth of about 40-50 km and a depth of 100 km, which is associated with the process of slab dehydration and partial melting. The inversion results show the impact of the Indo-Australian Plate subduction and the Eurasian Plate on volcanic activity, seismicity, and the geological structures developed in Central Java.

The Effect of Opak Fault on Liquefaction Potential at Toll Road Construction in Klaten Regency, Central Java

The activity of the Opak Fault on May 27th, 2006, caused a strong earthquake of Mw 6.3, then known as the Yogyakarta Earthquake. Previous studies have shown that several damages during the earthquake were caused by liquefaction. This paper aims to determine potential liquefaction hazards at toll road construction in Klaten Regency, within less than 10 km of the Opak Fault. The liquefaction potential was analyzed from Standard Penetration data using the simplified procedure to determine the safety factor and Liquefaction Potential Index by Iwasaki et al. (1981). In addition, vertical displacement caused by liquefied soil was calculated using the equation developed by Yoshimine et al. (2006). Based on the analysis of the liquefaction potential of 10 boreholes, the results showed that liquefaction occurs at 6 boreholes, with a high to a very high level of liquefaction potential index with a maximum horizontal acceleration of at least 0.46g. The extensive ground surface damage potentially occurs at 2 boreholes, with the vertical settlement of 32.55 cm and 47.02 cm, which occur at the nearest site distance to Opak Fault.

The Study of Seismic Hazard in Near-Fault Areas Using Probabilistic and Deterministic Approach

Earthquake is one of the most common natural disasters in Indonesia and usually destroys both high and low-rise buildings as well as triggers liquefaction and Tsunami. This means it is important to provide a robust building design with the ability to resist earthquake load and other induced phenomena. One of the methods commonly used to determine the relevant response spectrum of the bedrock is seismic hazard analysis which can be either Probabilistic Seismic Hazard Analysis (PSHA) or Deterministic Seismic Hazard Analysis (DSHA). The application of PSHA allows the representation of the response spectrum of an earthquake using the return period, thereby providing the engineers with the flexibility of selecting the appropriate natural period. Meanwhile, DSHA is based on geological observations and empirical data that can be easily understood. This research discussed the greater influence of seismic hazard analysis on the bedrock response spectrum of near-fault areas including Bandung situated at a distance of 12.9 km from Lembang Fault, Palu at 3 km from Palu Fault, and Yogyakarta at 8.5 km from Opak Fault. Moreover, EZFRISK Program was used to generate a response spectrum at bedrock and the results showed that PSHA is consistently more conservative than DSHA. It was also noted that there are significant differences at shorter periods for Palu site but these differences were observed at the natural period between 1s and 2s for Bandung and Yogyakarta sites.

Land suitability study for sweet sorghum (Sorghum bicolor (L.) Moench) farming in Pleret Yogyakarta

Marginal land and geological disaster-prone in the Opak Fault zone area need to be studied for the basic potential for the development of multi-purpose crops for food, feed, and renewable energy. The study was aimed to determine the potential of the soil and evaluate the suitability of the land for sweet sorghum (Shorgum bicolor) crop in Gunung Kelir, Pleret District, Bantul, Yogyakarta as part of the Opak Fault line. A total of 20 sample points were collected based on geological data, land use, slope, and administrative maps. Analysis of soil physical and chemical properties was carried out to classify soil types and land suitability for sweet sorghum plants. The developing soils in the study area were originated from volcanic breccias, Young Merapi Volcano, and the alluvial of the Opak River, with included in orders of Entisols and Inceptisols. The cation exchange capacity of soils that develop from volcanic breccias is higher than those that develop from Merapi volcanic soils. Suitability of land for sweet sorghum plants includes S2 class with limiting factors for nutrient retention, temperature, and erosion hazard area of ± 24,011 Ha (76.23%), S3 class with limiting factors for erosion hazard and surface stonies of ± 3.85 Ha (12.22%), and N class with a root zone constraint of ± 0.139 Ha (0.44%), and others are not agriculture. Based on the results of this study it is expected that sweet sorghum is able to be developed in the Opak Fault zone to enhance the use of marginal land.

Analysis of liquefaction potential in Opak Fault nearby area (case study: Solo-Yogyakarta-NYIA Kulon Progo Toll Road construction section I.2)

Construction of the Solo – Yogyakarta – NYIA Kulon Progo Toll Road Section I.2 is a part of Java's toll road network system that connects Solo and Yogyakarta. The presence of this opak fault allegedly cut the toll road alignment. Based on Indonesia's Liquefaction Vulnerability Zone Map, the alignment location is in a medium liquefaction vulnerability zone. This study aims to determine the potential of liquefaction in the construction of Solo – Yogyakarta – NYIA Kulon Progo Toll Road Section I.2 (stationing 29+000 - 36+000). The maximum peak ground acceleration on the surface was calculated using the Deterministic Seismic Hazard Analysis calculation. Calculating liquefaction potential analysis uses the simplified procedure method developed by Idriss and Boulanger. The research shows that ten borehole points with sandy soil types 2 m – 18 m below the surface have liquefaction potential. The depth of the groundwater table is between 0.2 m – 10 m below the ground surface. Based on the Liquefaction Potential Index analysis, the research location is in a low - high level of liquefaction vulnerability.

Earthquake statistical performance due to increasing of the seismic network around Opak Fault, Yogyakarta

The seismic event in May 2006 underscored the critical necessity of continuous earthquake monitoring. Observational enhancement through adding more stations is very crucial to obtain a more refined data quality. From January 2009 to September 2019, BMKG PGR (Pusat Gempa Regional/Regional Earthquake Centre) VII documented approximately 1847 seismic events with magnitudes from 0.9 to 4.9. With the integration of additional seismic station into the array by December 2022, there was a notable increase of 1418 recorded events in the same magnitude interval. The earthquake observation average is increasing as well, from 15.4 events in a month to 20.5 events in a month. This study leverages this data to assess the impact of augmenting seismic stations proximal to the Opak Fault on seismicity parameters within that region. Employing ZMAP 6.0, a comparative analysis of seismicity parameters was conducted between the earthquake catalog from January 2009 to September 2019 and the expanded catalog from January 2009 to December 2022. Declustering process result 1790 and 3141 main earthquake events in each catalog. This research indicate that the inclusion of more stations significantly influences the Mc value and earthquake density, however, it does not have a significant effect on the b and a-value.

Integrating gender mainstreaming in disaster risk reduction through providing geospatial information to create community resilience in Muntuk Village, Bantul Regency

Muntuk Village, Bantul Regency has a high multi-risk disaster potential, in the form of earthquakes and landslides. This is due to the location of Muntuk Village which is in the Bukit Batur Agung formation and is directly connected to the Opak Fault. The implications of these threats result in high disaster vulnerability. The focus of this research is to examine aspects of social vulnerability with the main subject being women, especially since the number of victims of the 2006 Bantul earthquake was dominated by women. This research seeks to integrate the development of Prima Village to increase the resilience of women's communities. The method used is a concurrent mixed method using questionnaires, interviews, and observations, as well as mapping data processing. The results of the analysis produced several outputs, including Sex Ratio Map, Economic Resilience Index Map, Prima Village Feasibility Standard Map, Landslide Prone Area Map, Logistics Warehouse Coverage Effectiveness Map, Logistics Warehouse Development Plan Map, and policy recommendations. It is hoped that this output can be used as input in designing regional disaster planning policies, both pre-disaster, during a disaster, and post-disaster, especially for women to improve community empowerment programs to achieve the goals of Prima Village.