Since the 2004 Sumatra-Andaman earthquake and Indian Ocean Tsunami, there has been an increase both in the frequency of large earthquakes, and in the data for monitoring the seismic and sea level disturbances associated with them, especially in the Australasian region. The increased number of high-quality recordings available for these large earthquakes provides an important opportunity to assess methods for rapid determination of their source properties, which potentially could be used to support tsunami warning systems. In this presentation we will consider how well the available data allow us to characterise the rupture of a earthquake, consider how rapidly this could be done, and assess how well the resulting models can be used to predict far-field tsunami waveforms.

A probabilistic tsunami hazard assessement (PTHA) was developed for the island of Tongatapu, All modelled tsunamis were initiated by hypothetical thrust earthquakes on the nearby Kermadec-Tonga subduction zone. We provide raster outputs containing the inundation depth with an estimated 10% and 2% chance of being exceeded in 50 years, as well as the code used to perform the analysis [both available here: https://github.com/GeoscienceAustralia/ptha/tree/master/misc/probabilistic_inundation_tonga2020].

We have run several thousand tsunami propagation models in order to determine the effect of uncertainty in an earthquake's rupture parameters (specifically strike, dip, rake, depth and magnitude) on the maximum wave height of the tsunami that it creates. We have shown that even for the simple case of a tsunami propagating over flat bathymetry, the Coefficient of Variation (CoV) of the maximum wave height was a complex function of the choice of rupture parameter, distance and azimuth. For example, if the strike of the fault was varied, the CoV was at maximum on either side of the tsunami beam, but if the dip was varied the CoV was at a maximum along the strike of the rupture. We then created maps of the skewness of the distribution of the maximum wave height. They also showed a complex dependence on the choice of the rupture parameter, azimuth and distance. Finally, we have examined the effect of a realistic bathymetry on CoV and skewness by mapping them for three hypothetical earthquakes on different types of subduction zones (Kermadec, Java and the Solomon Islands). These examples showed that the areas of shallow bathymetry in either the local or far field can also make a significant difference to both the CoV and skewness of the distribution of maximum tsunami wave heights at a point.

As part of its response to the Indian Ocean tsunami of 26 December 2004, the Australian Government funded the establishment of the Australian Tsunami Warning System (ATWS). The ATWS has three objectives: (i) provide a comprehensive warning system for Australia, (ii) contribute to international efforts to establish an Indian Ocean Tsunami Warning System, and (iii) facilitate tsunami warnings in the Pacific Ocean. The ATWS has been issuing warnings for Australia since July 2006, and in 2007 started sharing advisories with other warning centres. It expects to begin issuing advisories directly to other countries during 2009. To be successful, an end-to-end warning system must develop mitigation strategies to prepare communities for tsunami. Mitigation strategies include taking steps to minimise the impact of a tsunami, eg., avoiding building in the likely inundation zone and building sea walls when this can't be avoided, and response procedures, such as evacuations, when an event occurs. The warning system must monitor for tsunami and issue warnings; and it must implement response strategies when a tsunami approaches the coastline and a recovery phase afterwards (Figure 1). In Australia, responsibility for these phases is shared by Commonwealth, State/Territory and Local Governments. Etc ...

Real-time Earthquake Monitoring at the Joint Australian Tsunami Warning Centre From November 2006, Geoscience Australia began to monitor, analyse and alert for potentially tsunamigenic earthquakes that could threaten Australia's coastline, on a 24/7 basis. This ongoing role forms part of the Australian Tsunami Warning System (ATWS) that was announced in the Australian Government's May 2005 budget to complement the Indian Ocean Tsunami Warningand Mitigation System that was being implemented by the International Oceanographic Commission. The Joint Australian Tsunami Warning Centre (JATWC), as the operational arm of the ATWS, became fully operational in October 2008. It combines the efforts of Geoscience Australia's seismic measurement and analysis and the Australian Bureau of Meteorology's coastal and deep ocean sea level monitoring and modelling to produce timely tsunami warnings for Australia and the Indian Ocean region. A beneficiary of the setup of the JATWC was Geoscience Australia's ongoing role of reporting local Australian earthquakes, as it is now also able to function on a 24/7 basis; an upgrade to its earlier on-call arrangement. This paper describes the setup of Australia's tsunami warning capability and the methodology, systems and processes used to publish potentially tsunamigenic, local Australian and large international earthquake information. The paper will also highlight some of the future development activities to improve the accuracy and timeliness of Geoscience Australia's earthquake information.

On 17 July 1998, a magnitude 7.0 earthquake rocked the north coast region of Papua New Guinea (PNG). The Aitape tsunami took over 2000 lives, caused extensive damage to houses and public infrastructure, and altered the environment around the village.

The development of the Indian Ocean Tsunami Warning and mitigation System (IOTWS) has occurred rapidly over the past 5 or so years. One of the major elements of the IOTWS is the concept of a Regional Tsunami Watch Provider (RTWP). An RTWP is a centre that provides an advisory tsunami forecast service to one or more National Tsunami Warning Centres (NTWC). One requirement of an RTWP is that they must have access to numerical model-based tsunami forecasts. Products provided to the NTWCs are also exchanged with other RTWPs. An important part of the RTWP concept is that the services provided by the RTWPs are inter-operable. In this context, 'inter-operable' means that the products exchanged are in the same format and relate to the same physical parameters. The aim of the present work is to determine to what extent event-specific tsunami amplitude forecasts from different numerical forecast systems might differ, and therefore, how the related products from RTWPs might differ.

The historical record reveals that at least five tsunamis generated by earthquakes and volcanic eruptions along the Sunda Arc have impacted the West Australian coast (1883, 1977, 1994, 2004 and 2006). We have documented the geomorphic effects of these tsunamis through collation of historical reports, collection of eyewitness accounts, analysis of pre- and post-tsunami satellite imagery and field investigations. These tsunamis had flow depths of less than 3 m, inundation distances of up to several hundred metres and a maximum recorded run-up height of 8 m. Geomorphic effects include off-shore and near-shore erosion and extensive vegetation damage. In some cases, vegetated foredunes were severely depleted or completely removed. Gullies and scour pockets up to 1.5 m deep were eroded into topographic highs during tsunami outflow. Eroded sediments were redeposited as sand sheets several centimetres thick. Isolated coral blocks and rocks with oysters attached (~50 cm A-axis) were deposited over coastal dunes however, boulder ridges were often unaffected by tsunami flow. The extent of inundation from the most recent tsunamis can be distinguished as strandlines of coral rubble and rafted vegetation. It is likely that these features are ephemeral and seasonal coastal processes will obscure all traces of these signatures within years to decades. Recently reported evidence for Holocene palaeotsunamis on the West Australian coast suggests significantly larger run-up and inundation than observed from the historical record. The evidence includes signatures such as chevron dunes that have not been observed from historical events. We have compared the geomorphic effects of historical tsunami with reported palaeotsunami evidence from Coral Bay, the Cape Range Peninsula and Port Samson. We conclude that much of the palaeotsunami evidence can be accounted for via more traditional geomorphic processes such as reef evolution, aeolian dune formation and archaeological site formation.

This cross agency report, highlights the areas of the central NSW continental slope prone to sediment mass wasting over time. It includes the critical factors which contribute to slope failure including basement geometry, angle of slope and thickness of overlying sediments. Evidence of slope failure are observed through: surficial tension cracks; creep features; faulting; redistribution of sediments, multiple relict slides on the sea floor and erosional surface scars.

The study of palaeotsunamis preserved in the sedimentary record has developed over the past three decades to a point where the criteria used to identify these events range from well-tested and accepted to new methods yet to receive wide application. In this paper we review progress with the development of these criteria and identify opportunities for refinements and for extending their application to new settings. The emphasis here is on promoting the use of multiple proxies, selected to best match the context of the site or region of interest. Ultimately, this requires that palaeotsunami research must be a multidisciplinary endeavour and indeed, extend beyond the geological sciences of sedimentology and stratigraphy to include knowledge and approaches from field such as archaeology, anthropology and sociology. We also argue that in some instances, despite the use of multiple proxies, the ev