Hasbi Ash Shiddiqi

King Abdullah University of Science and Technology | KAUST · Division of Physical Sciences and Engineering (PSE)

The Zabargad Fracture Zone (ZFZ), located between 23.5o N-26o N is the largest rift-axis offset in the Red Sea. The ZFZ is a fundamental tectonic element of~100 km rift-axis offset that marks the transition between the northern and central Red Sea. Due to data scarcity, our understanding of the seismic activity and the potential presence of transfo...

On 21 November 2022, a destructive earthquake (Mw 5.6) struck Cianjur, West Java, Indonesia, resulting in at least 321 deaths, damage to 47,000 buildings, and economic losses of up to 7.7 trillion Indonesian Rupiahs (∼US $546 million). Prior to this earthquake, the fault on which slip occurred had not been mapped, thus making further analysis cruci...

On September 26, 2019, an Mw 6.5 earthquake occurred 23 km northeast of Ambon City, Indonesia, followed by numerous aftershock series related to a complex fault network reactivation in the Ambon and Seram region. Using moment tensor inversion, we identify the kinematics of fault reactivation based on the focal mechanism solution of 20 aftershocks w...

The Horda platform on the eastern margin of the North Sea Rift is a designated area for future CO2 storage, currently hosting three CO2 storage licenses at Aurora, Smeaheia and Luna. To successfully conduct CO2 sequestration, an understanding of the background seismicity in the broader area around an injection site is essential. Based on a seismici...

Seismic swarms have been observed for more than 40 years along the coast of Nordland, Northern Norway. However, the detailed spatio-temporal evolution and mechanisms of these swarms have not yet been resolved due to the historically sparse seismic station coverage. An increased number of seismic stations now allows us to study a nearly decade-long...

Nordland, Northern Norway, is a seismically active stable continental region. Along its coast, clusters of small earthquakes controlled by local extensional stresses are observed. In this study, we present a comparison between two adjacent seismically active areas along the Nordland coast: Jektvik and Rana, which have distinct spatiotemporal patter...

Nordland, situated along the rifted mid-Norwegian margin, has one of the highest seismicity rates in continental Northern Europe. The 1819 M 5.9 event, which occurred in Lurøy, Nordland, is the largest documented earthquake in Norway. Recent earthquakes have small to moderate magnitudes, with frequent seismic swarm activity in several areas. Seismo...

Spectral analysis method is commonly used in estimating moment magnitude for small to medium size earthquake. Most moment magnitude studies have been focused on the consistency of the average values with other methods. However, little attention is put into the study of moment magnitude sensitivity to its input parameter. In this study we attempted...

On the 15th of January 2021 (local date), an MW 6.2 earthquake struck the Mamuju and Majene regions of West Sulawesi, Indonesia. This event killed more than one hundred inhabitants, leaving at least thirty thousand people displaced from their homes, and damaged almost eight thousand buildings within a radius of ∼30 km from the mainshock's epicentre...

A destructive earthquake (Mw 6.1) struck Pasaman, West Sumatra, Indonesia, on 25 February 2022, resulting in at least 18 deaths and damage to 1765 buildings. Our relocated foreshock, mainshock, and aftershocks and their source mechanisms reveal a previously unknown ~20 km long segment of the Sumatran Fault as a result of dextral strike-slip motion...

Seismic swarms have been observed for more than 40 years along the coast of Nordland, Northern Norway. However, the detailed spatio-temporal evolution and mechanisms of these swarms have not yet been resolved due to the historically sparse seismic station coverage. An increased number of seismic stations now allows us to study a nearly decade-long...

High seismicity rates in and around West Java and Sumatra occur as a result of the Indo-Australian plate converging with and subducting beneath the Sunda plate. Large megathrust events associated with this process likely pose a major earthquake and tsunami hazard to the surrounding community, but further effort is required to help understand both t...

The island of Sulawesi, Indonesia, is located in a complex and tectonically active region, and has experienced tsunamis in the past. One of the major earthquake and tsunami events was the 23 February 1969 event that struck the Majene region in western Sulawesi Island. Interpretation of the historical accounts revealed that the Mw 7.0 earthquake gen...

The Nordland region, Northern Norway, situated in an intraplate continental setting, has the highest seismicity rate in mainland Norway. However, the exact cause of seismicity in this region is still debated. Better understanding of factors that influence the seismicity in Nordland can help increase knowledge of intraplate seismicity in general. He...

The geological setting of Jakarta and its immediate surroundings are poorly understood, yet it is one of the few places in Indonesia that is impacted by earthquakes from both the Java subduction zone and active faults on land. In this study, a borehole seismic experiment with low noise characteristics was deployed to record seismic activity on the...

We studied the February 23rd, 1969 M7.0 Majene, Sulawesi earthquake and tsunami. It was followed by tsunami reported at five locations. At least 64 people were killed and severe damage on infrastructures were reported in Majene region. Based on damage data, we estimated that the maximum intensity of the earthquake was MMI VIII. Focal mechanisms, de...

This article presents earthquake catalogs of the 2019 Ambon aftershocks compiled from regional the Agency for Meteorology, Climatology, and Geophysics of Indonesia (BMKG) and local seismic networks deployed in [1]. The final earthquake catalogs are comprised of 1,009 and 1,764 aftershocks compiled from regional [2] and local network [1], respective...

On September 26, 2019, a significant, Mw 6.5, earthquake shook Ambon region, Indonesia, causing severe damage on the Island(s) of Ambon. Due to the complexity of the fault network and in-situ stress field it was, up to now, not possible to define the fault plane using data from the BMKG regional seismic network. In this study, we analyze the fault...

Relocation of earthquakes recorded by the agency for meteorology, climatology and geophysics (BMKG) in Indonesia and inversions of global positioning system (GPS) data reveal clear seismic gaps to the south of the island of Java. These gaps may be related to potential sources of future megathrust earthquakes in the region. To assess the expected in...

High seismicity rates in eastern Indonesia occur due to the complex interaction of several tectonic plates which resulted in two deadly, destructive earthquake sequences that occurred in Lombok Island and the city of Palu, Sulawesi in 2018. The first sequence began in July with an Mw 6.4 event near Lombok, culminating in an Mw 7.0 event eight days...

The Mw 4.5 southern Viking graben earthquake on 30 June 2017 was one of the largest seismic events in the Norwegian part of the North Sea during the last century. It was well recorded on surrounding broadband seismic stations at regional distances, and it generated high signal‐to‐noise ratio teleseismic P arrivals at up to 90° with good azimuthal c...

The purpose of this study is to investigate apparent first‐motion polarities mismatch at teleseismic distances in the determination of focal mechanism. We implement and compare four seismic raytracing algorithms to compute ray paths and travel times in 1D and 3D velocity models. We use the raytracing algorithms to calculate the takeoff angles from...

Earthquake monitoring in Myanmar has improved in recent years because of an increased number of seismic stations. This provides a good quality dataset to derive a minimum 1D velocity model and local magnitude (⁠ML⁠) scale for the Myanmar region, which will improve the earthquake location and magnitude estimates in this region. We combined and repro...

The source process of an intraslab intermediate‐depth earthquake (h=90 km) that occurred near Chauk, central Myanmar, on 24 August 2016 was investigated using teleseismic body‐wave inversion. The focal mechanism solution showed a thrust mechanism with nearly vertical or subhorizontal fault planes. The slip‐inversion results for both fault planes gi...

The tectonics of the Sunda arc region is characterized by the junction of the Eurasian and Indo‐Australian tectonic plates, causing complex dynamics to take place. High‐seismicity rates in the Indonesian region occur due to the interaction between these tectonic plates. The availability of a denser network of seismometers after the earthquakes of M...

A reverse fault earthquake (Mw 7.1) occurred in the Northern Molucca Sea, Indonesia, on 15 November 2014 at 2:31:40 UTC. The earthquake produced small tsunami waves that are recorded at Jailolo (9 cm), Tobelo (1 cm), and Menado (3 cm) tide gauges. The Indonesian Agency for Climatology, Meteorology, and Geophysics (BMKG) issued a timely (5 minutes a...

An intermediate-depth Mw 6.8 earthquake struck Myanmar on 24 August 2016. This earthquake was felt throughout the country and caused some damage in the Chauk and Bagan areas. USGS reported the earthquake mechanism as a thrust fault (Strike1: 166, Dip1: 83, Rake1: 89 and Strike2: 356, Dip2: 7, Rake2: 100), which would be cutting the subducting slab...

The earthquake swarm events sequence occurred in west Halmahera, north Molucca, Indonesia for the period of October 2015 to February 2016 as reported by Meteorological, Climatological, and Geophysical Agency (BMKG) of Indonesia. There were tenths swarm events with Magnitude larger than four in the region during the period. In this study, we used th...

West Java, part of the Sunda Arc, has relatively high seismicity due to subduction activity and faulting. The first step of tomography study in order to infer the geometry of the structure beneath West Java is to conduct precise earthquake hypocenter determination. In this study, we used earthquake waveform data taken from the regional Meteorologic...

An earthquake with magnitude 4.2 struck Madiun and its vicinity on June 25, 2015. According to Indonesian Meteorology, Climatology, and Geophysics Agency (BMKG), the earthquake occurred at 10:35:29 GMT+7 and was located in 7.73° S, 111.69 ° E, with a depth of 10 km. At least 57 houses suffered from light to medium damages. We reprocessed earthquake...

A Mw 7.2 earthquake struck an area in the Molucca Sea region on November 15, 2014, and was followed by more than 300 aftershocks until the end of December 2014. This earthquake was the second largest event in the Molucca Sea during the last decade and was well recorded by local networks. Although the seismicity rate of the aftershocks was declining...

The Sunda arc is one of the most active tectonic regions, which has a complex tectonic setting due to different tectonic regimes and subduction geometry along this arc. We analyzed variation in b-value for this region in order to obtain better information regarding the state of stress in this region. For the first step, we relocated earthquake hypo...

We compiled and relocated about 32,000 earthquakes events around Indonesia region that reported by Indonesian Meteorology, Climatology, and Geophysics Agency (MCGA) from April 2009 to January 2015. We performed relocation inversion utilizing local, regional and teleseismic arrival time data. Our previous study of 3D seismic velocity model beneath t...

On November 15, 2014, an earthquake Mw 7.2 struck the central part of the Molucca Sea, where the last major earthquake occurred in 2009 at 200 km north of the 2014 earthquake. We investigated the distribution of the mainshock and its aftershocks in order to reveal the earthquake process. We applied teleseismic double-difference hypocenter relocatio...

High seismicity in the Molucca Collision Zone (MCZ) is a result of complex tectonic setting in and around this region. We have relocated more than 7500 earthquakes from the Indonesian Meteorology, Climatology, and Geophysical Agency (BMKG) catalog from April 2009 to January 2015. Relocation process was conducted using teleseismic double-difference...

A two month microearthquake (MEQ) monitoring was conducted in the "WY" geothermal field during fluid injection in 2005. MEQ data provided information related to processes developed in geothermal reservoirs. In total, 198 MEQ data were analyzed, starting from phase identification to location determination using Geiger's method and ending in joint hy...

As a complex tectonic region, Indonesia has a high seismicity rate which is related to subduction and collision as well as strike-slip fault. High-precision earthquake locations with adequate relocation method and proper velocity model are necessary for seismicity analysis. We used nearly 25,000 earthquakes that were relocated using double-differen...

Accuracy of hypocenter location is a crucial obstacle for seismicity study. Therefore, it is important to obtain accurate earthquake location using an adequate relocation method. We have relocated nearly 30,000 earthquakes (with magnitude greater than 2.0) compiled by BMKG from April 2009 to June 2014 around the Indonesian region using teleseismic...

Indonesian archipelago region is located in active tectonic setting and high seismicity zone. During the last decade, Indonesian was experienced with destructive major earthquakes causing damage and victims. The information of precise earthquake location parameters are very important in partular for earthquake early warning to the society and for a...

We have relocated hypocenters of earthquakes occurring in the Molucca collision zone and surrounding region taken from the BMKG catalog using teleseismic double-difference relocation algorithm (teletomoDD). We used P-wave arrival times of local, regional, and teleseismic events recorded at 304 recording stations. Over 7,000 earthquakes were recorde...

During the fluid injection in the "XYZ" geothermal field from February 1998 until March 1998, 37 microearthquakes were recorded around this field. We have determined the locations of those microearthquakes using highly precision hypocenter double difference (HypoDD) earthquake location algorithm. We found that microearthquake hypocenters distribut...