Suchergebnisse

Abstract. Submarine volcanism makes up approximately 85 % of volcanism that occurs on Earth, and its eruptions have the potential to cause several hazards including ash dispersal, pumice rafts, pyroclastic density currents, sector collapses, and tsunamis. Recent examples include the eruptions in Japan and in the Kingdom of Tonga in 2021 and 2022 respectively, but there has been little to no study of submarine volcanism in Southeast Asia and surroundings. Here we provide a compilation of 466 seamounts from the region, from different published sources, through the SEATANI dataset (Southeast Asia, Taiwan, and the Andaman and Nicobar Islands). We use this newly compiled dataset to assess on a regional level the seamount hazard potential and exposure potential as a springboard for future more quantitative hazard studies of the region. The hazard potential was assessed through seamount morphological and structural analyses, to determine the seamount evolution stage and grade of maturity. The exposure potential was evaluated with two different approaches: an areal analysis of the number of assets within a 100 km radius of each seamount and the development of a hazard-weighted seamount density map to highlight potential areas of interest for future more-in-depth studies. Our results show that there are several potentially hazardous seamounts in this region. Taiwan has the highest hazard and exposure potential, for all assets considered, while the Philippines, Indonesia, and Vietnam have relatively high exposure potential for submarine communication cables and ship traffic density. The results from this work serve as a first step towards Southeast Asia and neighbouring countries becoming more resilient against and prepared for submarine volcanic eruptions in the region.

The value of historic observational weather data for reconstructing long-term climate patterns and the detailed analysis of extreme weather events has long been recognized (Le Roy Ladurie, 1972; Lamb, 1977). In some regions however, observational data has not been kept regularly over time, or its preservation and archiving has not been considered a priority by governmental agencies. This has been a particular problem in Southeast Asia where there has been no systematic country-by-country method of keeping or preserving such data, the keeping of data only reaches back a few decades, or where instability has threatened the survival of historic records. As a result, past observational data are fragmentary, scattered, or even absent altogether. The further we go back in time, the more obvious the gaps. Observational data can be complimented however by historical documentary or proxy records of extreme events such as floods, droughts and other climatic anomalies. This review article highlights recent initiatives in sourcing, recovering, and preserving historical weather data and the potential for integrating the same with proxy (and other) records. In so doing, it focuses on regional initiatives for data research and recovery – particularly the work of the international Atmospheric Circulation Reconstructions over the Earth's (ACRE) Southeast Asian regional arm (ACRE SEA) – and the latter's role in bringing together disparate, but interrelated, projects working within this region. The overarching goal of the ACRE SEA initiative is to connect regional efforts and to build capacity within Southeast Asian institutions, agencies and National Meteorological and Hydrological Services (NMHS) to improve and extend historical instrumental, documentary and proxy databases of Southeast Asian hydroclimate, in order to contribute to the generation of high-quality, high-resolution historical hydroclimatic reconstructions (reanalyses) and, to build linkages with humanities researchers working on issues in environmental and climatic history in the region. Thus, this article also highlights the inherent value of multi/cross/inter-disciplinary projects in providing better syntheses and understanding of human and environmental/climatic variability and change.

Abstract. Seismogenic tsunami hazard assessments are highly dependent on the
reliability of earthquake source models. Here in a study of the Manila
subduction zone (MSZ) system, we combine the geological characteristics of
the subducting plate, geometry, and coupling state of the subduction
interface to propose a series of fault rupture scenarios. We divide the
subduction zone into three rupture segments: 14–16, 16–19, and 19–21.7∘ N inferred from geological structures associated with the down-going Sunda plate. Each of these segments is capable of generating earthquakes of a magnitude between Mw=8.5+ and Mw=9+, assuming a 1000-year seismic return period as suggested by previous studies. The most poorly constrained segment of the MSZ lies between 19 and 21.7∘ N, and here we use both local geological structures and characteristics of other subduction zone earthquakes around the world, to investigate the potential rupture characteristics of this segment. We consider multiple rupture modes for tsunamigenic earthquake and megathrust-splay fault earthquakes. These rupture models facilitate an improved understanding of the potential tsunami hazard in the South China Sea (SCS). Hydrodynamic simulations demonstrate that coastlines surrounding the SCS could be devastated by tsunami waves up to 10 m if large megathrust earthquakes occur in these segments. The regions most prone to these hazards include west Luzon of Philippines, southern Taiwan, southeastern China, central Vietnam, and Palawan Island.

Abstract. The tsunami hazard posed by the Flores back-arc thrust, which runs
along the northern coast of the islands of Bali and Lombok, Indonesia, is
poorly studied compared to the Sunda Megathrust, situated ∼250 km to the south of the islands. However, the 2018 Lombok earthquake
sequence demonstrated the seismic potential of the western Flores Thrust
when a fault ramp beneath the island of Lombok ruptured in two Mw 6.9
earthquakes. Although the uplift in these events mostly occurred below land,
the sequence still generated local tsunamis along the northern coast of
Lombok. Historical records show that the Flores fault system in the Lombok
and Bali region has generated at least six ≥Ms 6.5 tsunamigenic
earthquakes since 1800 CE. Hence, it is important to assess the possible
tsunami hazard represented by this fault system. Here, we focus on the
submarine fault segment located between the islands of Lombok and Bali
(below the Lombok Strait). We assess modeled tsunami patterns generated by
fault slip in six earthquake scenarios (slip of 1–5 m, representing Mw 7.2–7.9+) using deterministic modeling, with a focus on impacts on the
capital cities of Mataram, Lombok, and Denpasar, Bali, which lie on the
coasts facing the strait. We use a geologically constrained earthquake model
informed by the Lombok earthquake sequence, together with a high-resolution
bathymetry dataset developed by combining direct measurements from the General Bathymetric Chart of the
Oceans (GEBCO)
with sounding measurements from the official nautical charts for Indonesia.
Our results show that fault rupture in this region could trigger a tsunami
reaching Mataram in <9 min and Denpasar in ∼ 23–27 min, with multiple waves. For an earthquake with 3–5 m of
coseismic slip, Mataram and Denpasar experience maximum wave heights of
∼ 1.6–2.7 and ∼ 0.6–1.4 m, respectively.
Furthermore, our earthquake models indicate that both cities would
experience coseismic subsidence of 20–40 cm, exacerbating their exposure to
both the tsunami and other coastal hazards. Overall, Mataram is more
exposed than Denpasar to high tsunami waves arriving quickly from the fault
source. To understand how a tsunami would affect Mataram, we model the
associated inundation using the 5 m slip model and show that Mataram is
inundated ∼ 55–140 m inland along the northern coast and
∼230 m along the southern coast, with maximum flow depths of
∼ 2–3 m. Our study highlights that the early tsunami arrival
in Mataram, Lombok, gives little time for residents to evacuate. Raising
their awareness about the potential for locally generated tsunamis and the
need for evacuation plans is important to help them respond immediately
after experiencing strong ground shaking.

Abstract The value of historic observational weather data for reconstructing long-term climate patterns and the detailed analysis of extreme weather events has long been recognized (Le Roy Ladurie, 1972; Lamb, 1977). In some regions however, observational data has not been kept regularly over time, or its preservation and archiving has not been considered a priority by governmental agencies. This has been a particular problem in Southeast Asia where there has been no systematic country-by-country method of keeping or preserving such data, the keeping of data only reaches back a few decades, or where instability has threatened the survival of historic records. As a result, past observational data are fragmentary, scattered, or even absent altogether. The further we go back in time, the more obvious the gaps. Observational data can be complimented however by historical documentary or proxy records of extreme events such as floods, droughts and other climatic anomalies. This review article highlights recent initiatives in sourcing, recovering, and preserving historical weather data and the potential for integrating the same with proxy (and other) records. In so doing, it focuses on regional initiatives for data research and recovery – particularly the work of the international Atmospheric Circulation Reconstructions over the Earth's (ACRE) Southeast Asian regional arm (ACRE SEA) – and the latter's role in bringing together disparate, but interrelated, projects working within this region. The overarching goal of the ACRE SEA initiative is to connect regional efforts and to build capacity within Southeast Asian institutions, agencies and National Meteorological and Hydrological Services (NMHS) to improve and extend historical instrumental, documentary and proxy databases of Southeast Asian hydroclimate, in order to contribute to the generation of high-quality, high-resolution historical hydroclimatic reconstructions (reanalyses) and, to build linkages with humanities researchers working on issues in environmental and climatic history in the region. Thus, this article also highlights the inherent value of multi/cross/inter-disciplinary projects in providing better syntheses and understanding of human and environmental/climatic variability and change.

The value of historic observational weather data for reconstructing long-term climate patterns and the detailed analysis of extreme weather events has long been recognized (Le Roy Ladurie, 1972; Lamb, 1977). In some regions however, observational data has not been kept regularly over time, or its preservation and archiving has not been considered a priority by governmental agencies. This has been a particular problem in Southeast Asia where there has been no systematic country-by-country method of keeping or preserving such data, the keeping of data only reaches back a few decades, or where instability has threatened the survival of historic records. As a result, past observational data are fragmentary, scattered, or even absent altogether. The further we go back in time, the more obvious the gaps. Observational data can be complimented however by historical documentary or proxy records of extreme events such as floods, droughts and other climatic anomalies. This review article highlights recent initiatives in sourcing, recovering, and preserving historical weather data and the potential for integrating the same with proxy (and other) records. In so doing, it focuses on regional initiatives for data research and recovery – particularly the work of the international Atmospheric Circulation Reconstructions over the Earth's (ACRE) Southeast Asian regional arm (ACRE SEA) – and the latter's role in bringing together disparate, but interrelated, projects working within this region. The overarching goal of the ACRE SEA initiative is to connect regional efforts and to build capacity within Southeast Asian institutions, agencies and National Meteorological and Hydrological Services (NMHS) to improve and extend historical instrumental, documentary and proxy databases of Southeast Asian hydroclimate, in order to contribute to the generation of high-quality, high-resolution historical hydroclimatic reconstructions (reanalyses) and, to build linkages with humanities researchers working on issues in environmental and climatic history in the region. Thus, this article also highlights the inherent value of multi/cross/inter-disciplinary projects in providing better syntheses and understanding of human and environmental/climatic variability and change.

Abstract. Vietnam is a major rice producer, and much of the rice grown is concentrated in the Red River Delta (RRD) and the Mekong River Delta (MRD). While the two deltas are highly productive regions, they are vulnerable to natural hazards and the effects of human-induced environmental change. To show that the processes and issues affecting food security are reinforcing, interdependent and operating at multiple scales, we used a systems-thinking approach to represent the major linkages between anthropogenic land-use and natural hazards and elaborate on how the drivers and environmental processes interact and influence rice growing area, rice yield and rice quality in the two deltas. On a local scale, demand for aquaculture and alternative crops, urban expansion, dike development, sand mining and groundwater extraction decrease rice production in the two deltas. Regionally, upstream dam construction impacts rice production in the two deltas despite being distally situated. Separately, the localized natural hazards that have adversely affected rice production include droughts, floods and typhoons. Outbreaks of pests and diseases are also common. Climate-change-induced sea level rise is a global phenomenon that will affect agricultural productivity. Notably, anthropogenic developments meant to improve agricultural productivity or increase economic growth can create many unwanted environmental consequences such as an increase in flooding, saltwater intrusion and land subsidence, which in turn decreases rice production and quality. In addition, natural hazards may amplify the problems created by human activities. Our meta-analysis highlights the ways in which a systems-thinking approach can yield more nuanced perspectives to tackle "wicked" and interrelated environmental challenges. Given that deltas worldwide are globally significant for food production and are highly stressed and degraded, a systems-thinking approach can be applied to provide a holistic and contextualized overview of the threats faced in each location.

Abstract. Tropical cyclones have devastating impacts on the environment, economies,
and societies and may intensify in the coming decades due to climate
change. Stable water isotopes serve as tracers of the hydrological cycle, as
isotope fractionation processes leave distinct precipitation isotopic
signatures. Here we present a record of daily precipitation isotope
measurements from March 2014 to October 2015 for Metropolitan Manila, a
first-of-a-kind dataset for the Philippines and Southeast Asia. We show that
precipitation isotopic variation at our study site is closely related to
tropical cyclones. The most negative shift in δ18O values
(−13.84 ‰) leading to a clear isotopic signal was
caused by Typhoon Rammasun, which directly hit Metropolitan Manila. The
average δ18O value of precipitation associated with tropical
cyclones is −10.24 ‰, whereas the mean isotopic value
for rainfall associated with non-cyclone events is −5.29 ‰. Further, the closer the storm track is to the sampling
site, the more negative the isotopic values are, indicating that in situ isotope
measurements can provide a direct linkage between isotopes and typhoon
activities in the Philippines.

Abstract. Modern tsunami events have highlighted the vulnerability of port structures to these high-impact but infrequent occurrences. However, port planning rarely includes adaptation measures to address tsunami hazards. The 2011 Tohoku tsunami presented us with an opportunity to characterise the
vulnerability of port industries to tsunami impacts. Here, we provide a
spatial assessment and photographic interpretation of freely available data
sources. Approximately 5000 port structures were assessed for damage and
stored in a database. Using the newly developed damage database, tsunami
damage is quantified statistically for the first time, through the development of damage fragility functions for eight common port industries.
In contrast to tsunami damage fragility functions produced for buildings
from an existing damage database, our fragility functions showed higher
prediction accuracies (up to 75 % accuracy). Pre-tsunami earthquake damage was also assessed in this study and was found to influence overall damage assessment. The damage database and fragility functions for port industries can inform structural improvements and mitigation plans for ports against future events.

Abstract. On 23 August 2017 a Category 3 hurricane, Typhoon Hato, struck southern China.
Among the hardest hit cities, Macau experienced the worst flooding since
1925. In this paper, we present a high-resolution survey map recording
inundation depths and distances at 278 sites in Macau. We show that one-half
of the Macau Peninsula was inundated, with the extent largely confined by the
hilly topography. The Inner Harbor area suffered the most, with a maximum
inundation depth of 3.1 m at the coast. Using a combination of numerical
models, we simulate and reproduce this typhoon and storm surge event. We
further investigate the effects of tidal level and sea level rise on coastal
inundations in Macau during the landfall of a "Hato-like" event.