Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

We present a probabilistic tectonic hazard analysis of a site in the Otway Basin,Victoria, Australia, as part of the CO2CRC Otway Project for CO2 storage risk. The study involves estimating the likelihood of future strong earthquake shaking and associated fault displacements from natural tectonic processes that could adversely impact the storage process at the site. Three datasets are used to quantify the tectonic hazards at the site: (1) active faults; (2) historical seismicity, and; (3) GPS surface velocities. Our analysis of GPS data reveals strain rates at the limit of detectability and not significantly different from zero. Consequently, we do not develop a GPS-based source model for this Otway Basin model. We construct logic trees to capture epistemic uncertainty in both the fault and seismicity source parameters, and in the ground motion prediction. A new feature for seismic hazard modelling in Australia, and rarely dealt with in low-seismicity regions elsewhere, is the treatment of fault episodicity (long-term activity versus inactivity) in the Otway model. Seismic hazard curves for the combined (fault and distributed seismicity) source model show that hazard is generally low, with peak ground acceleration estimates of less than 0.1g at annual probabilities of 10-3-10-4/yr. The annual probability for tectonic displacements of greater than or equal to 1m at the site is even lower, in the vicinity of 10-8-10-9/yr. The low hazard is consistent with the intraplate tectonic setting of the region, and unlikely to pose a significant hazard for CO2 containment and infrastructure.

Legacy product - no abstract available

An assumption of probabilistic seismic hazard assessment is that within each source zone the random earthquakes of the past are considered a good predictor of future seismicity. Random earthquakes suggest a Poisson process. If the source zone does not follow a Poisson process then the resulting PSHA might not be valid. The tectonics of a region will effect its spatial distributions. Earthquakes occurring on a single fault, or uniformly distributed, or clustered or random will each have a distinctive spatial distribution. Here we describe a method for both identifying and delineating earthquake clusters and then characterising them. We divide the region into N cells and by counting the number of earthquakes in each cell we obtain a distribution of the number of cells versus the number of earthquakes per cell. This can then be compared to the theoretical Poisson distribution. Areas which deviate from the theoretical Poisson distribution, can then be delineated. This suggests a statistically robust method for determining source zones. Preliminary results suggest that areas of clustering (eg. SWSZ) can also be modelled as a Poisson process which differs from the larger regional Poisson process. The effect of aftershocks and swarms are also investigated.

Legacy product - no abstract available

A comprehensive earthquake impact assessment requires an exposure database with attributes that describe the distribution and vulnerability of buildings in the region of interest. The compilation of such a detailed database will require years to develop for a moderate-sized city, let alone on a national scale. To hasten this database development in the Philippines, a strategy has been employed to involve as many stakeholders/organizations as possible and equip them with a standardized tool for data collection and management. The best organizations to tap are the local government units (LGUs) since they have better knowledge of their respective area of responsibilities and have a greater interest in the use of the database. Such a tool is being developed by PHIVOLCS-DOST and Geoscience Australia. Since there are about 1,495 towns and cities in the country with varying financial capacities, this tool should involve the use of affordable hardware and software. It should work on ordinary hardware, such as an ordinary light laptop or a netbook that can easily be acquired by these LGUs. The hardware can be connected to a GPS and a digital camera to simultaneously capture images of structures and their location. The system uses an open source database system for encoding the building attributes and parameters. A user-friendly GUI with a simplified drop-down menu, containing building classification schema, developed in consultation with local engineers, is utilised in this system. The resulting national database is integrated by PHIVOLCS-DOST and forms part of the Rapid Earthquake Damage Assessment System (REDAS), a hazard simulation tool that is also made available freely to partner local government units.

Legacy product - no abstract available

Legacy product - no abstract available