Calendar

February 2020

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Seminar
“Is it harmful to breathe this ash?” Public health hazard assessment and protection in communities impacted by eruptions

“Is it harmful to breathe this ash?” Public health hazard assessment and protection in communities impacted by eruptions

Seminar
Speaker: Claire Horwell
Date: Mon, 2020-02-10 16:00 to 17:00
Venue: ASE 3D Visualisation Laboratory (N2-B1c-16c)

About the Event

During volcanic eruptions, and their aftermaths, communities may be very concerned about inhaling fine-grained ash, which can be rich in the deleterious mineral crystalline silica. Prof Claire Horwell, Director of the International Volcanic Health Hazard Network (www.ivhhn.org), will lead us through her interdisciplinary career journey, from trying, for a decade, to answer the question “Is it harmful to breathe this ash?”, by mineralogical, geochemical and toxicological analyses of ash samples from around the world, to her realisation that this question cannot easily be answered in the timeframe of acute community exposures. In 2015 she embarked on the Wellcome Trust/DfID-funded project Health Interventions in Volcanic Eruptions (HIVE; http://community.dur.ac.uk/hive.consortium/) which aimed to answer a more pertinent question: “How can I protect myself from breathing this ash?”. The HIVE project has built the first evidence base on the effectiveness of common materials used to protect communities in volcanic crises including cloth, surgical and industry-certified masks. The key finding is that industry-certified facemasks are more effective than any other type of protection, even with no fit training.  Incorporating laboratory analyses, on the filtration efficiency and fit of 17 forms of respiratory protection, with psychological (questionnaire-based) and anthropological (interview-based) social surveys in Mexico, Japan and Indonesia, and a review of ethical considerations for agencies, the project has culminated in the development of a variety of audio-visual and printable public informational products for IVHHN which are already being widely used in Indonesia.



Claire Horwell

Professor Claire Horwell is Director of the International Volcanic Health Hazard Network and Professor of GeoHealth at Durham University.


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Claire Horwell
16:00 to 17:00
 
 
 
 
 
Seminar
Great earthquakes and tsunamis: Insight from marine geophysical studies offshore Sumatra, Indonesia

Great earthquakes and tsunamis: Insight from marine geophysical studies offshore Sumatra, Indonesia

Seminar
Speaker: Satish Singh
Date: Fri, 2020-02-14 16:00 to 17:00
Venue: ASE 3D Visualisation Laboratory (N2-B1c-16c)

About the Event

The Andaman Sumatra subduction system extends over 4000 km starting from the Andaman Island in the north up to Java in the south, where the Indo-Australian plate subducts beneath the Sunda plate. In the last 16 years, the Sumatra section offshore has hosted three great earthquakes with Mw>8.4, one tsunami earthquakes with Mw~7.8, and has induced two other great earthquakes (Mw>8.2) on the subducting Indo-Australian plate in the Wharton Basin. In order to understand the nature of these earthquakes and their links with tsunami generation, we have carried out 8 marine experiments, of which three were in collaboration with EOS (MegaTera, MIRAGE I and II). These results show faulting, bending and un-bending of the plate as it subducts, subducted seamounts and plateaus down to 30-60 km depth beneath the forearc. Our results also show that there is a causal link between frontal rupturing and tsunami generation. We find that the morphology of the subducting lower plate controls the position of the décollement, and influences the earthquake segmentation both along strike and along dip direction.

In the intra-plate deforming Wharton Basin, we have discovered the presence of conjugate shear zones, thick sedimentary basins along re-activated fracture zones, and propose that these re-activated fracture zones might be the sight of a nascent plate boundary between India and Australia; the occurrence of the 2012 twin earthquakes, Mw=8.6 and 8.2, supports this hypothesis. In this talk I will highlight some of these results, specifically focusing on the three joint IPGP-EOS experiments.



Satish Singh

Singh was born and raised in Varanasi, also known as Banaras, India and did PhD in theoretical seismology at the University of Toronto, Canada, and spent a year at the University of Cambridge, England. He joined the Institut de Physique du Globe de Paris as a post-doc in 1988 and then moved to the University of Cambridge as a Researcher in 1990 where he developed a group in theoretical seismology. In 1998, he led the establishment of LITHOS Group to develop methods to jointly analyse seismic and marine EM data, but soon after that he moved to the Institut de Physique du Globe de Paris to lead the creation of the Marine Geoscience Department that he ran until 2008, while keeping his part time position at the University of Cambridge, maintaining the LITHOS Group between the two institutions. After the 2004 great Andaman Sumatra Earthquake and Tsunami, he persuaded Schlumberger to fund the acquisition and processing of long offset seismic data offshore Sumatra in 2006 and later persuaded CGG to fund a similar experiment in 2009, deploying 15 km long streamer, the longest streamer ever deployed. In 2015, he partnered again with Schlumberger to acquire ultra-deep seismic reflection data across the Atlantic Ocean to image the base the lithosphere down to 100 km depth.  In 2012, he created the Paris Exploration Geophysics (GPX) Group, in collaboration with Mines ParisTech and other industry partners and started an international Master of Research in Exploration Geophysics, which has now become the International Master in Solid Earth Sciences at IPG Paris. Singh has a very broad research interests, from earthquake and tsunami to the inner core.

Singh has supervised over 85 PhD students and post-docs, published more than 180 papers in peer reviewed journals, including 14 in high impact journals such as Nature and Science. He was elected the American Geophysical Union Fellow in 2010, awarded the Grand Prix of the French Academy of Sciences in 2011, the European Research Council Advance Grantin 2013, and the Society of Exploration Geophysicists Distinguish Lecturer in 2018. He was a frequent visitor to the Scripps Oceanographic Institution, University of California, San Diego until 2012, and presently shares his time between Paris and Singapore since 2013, specially in winter.


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Satish Singh
16:00 to 17:00
 
 
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Seminar
The Seismic Structure of the Central Indo-Burman Subduction Zone

The Seismic Structure of the Central Indo-Burman Subduction Zone

Seminar
Speaker: Eric Sandvol
Date: Tue, 2020-02-18 16:00 to 17:00
Venue: ASE 3D Visualisation Laboratory (N2-B1c-16c)

About the Event

Studies of the evolution of the India-Eurasia collision have shown that the geodynamic processes associated with trench/slab rollback along the Indo Burma ranges have played a significant role in the large scale rotational deformational patterns and influenced the building of the Eastern Himalayan Syntaxis portion of the Tibetan Plateau. Furthermore, this complex tectonic system provides an excellent opportunity to study the nature of mantle deformation in response to the dynamic interaction of a possible clockwise rotation around the Eastern Himalayan Syntaxis and its relation to the subduction of the Indian plate. The crustal clockwise rotational deformation continues into northern Myanmar, accommodated by a series of East Northeast-West Southwest left-lateral strike-slip faults bounded between the Sagaing Fault and the Red River Fault. The relative contribution of crustal and mantle processes to surface clockwise rotational deformation remains debatable. GPS and fault slip data indicate that this rotational deformation extends to the Sagaing Fault, the western boundary of the Burma platelet, mantle deformation measured from shear wave splitting data deviates greatly from crustal deformation in regions south of 27°N. Characterizing the mantle flow field can lead to understand the deformation and regional tectonics of this part of plate boundary.  In order to estimate the three dimensional anisotropic seismic structure as well as the geometry of the subducting Indian lithosphere, and seismic structure of the Indian-Burma plate boundary we have deployed a swath of seismic stations across central Myanmar extending from the Myanmar-India border regions to the Shan plateau.

Firstly, we have begun using both deep local and teleseismic shear waves to create a detailed map of variations in upper mantle anisotropy.  This map shows dominant trench-parallel North-South fast direction.  We suggest that this is due to the trench-parallel flow possibly induced by trench migration. We also observe splitting lag times gradually decrease towards the back-arc with increasing complexity in the fast directions.   Local splitting from deep events show over 1s lag time suggesting a highly anisotropic mantle wedge compared to anisotropy above the slab in other subduction zones. Additionally, the relatively small difference in lag times between local and tele-seismic S wave splitting indicates that the mantle wedge above the slab is the main source of anisotropy, especially towards the back arc. Furthermore, a linear east-west fast directions trend emerges from the local splitting that is consistent with a slab tear or termination of subducting slab around 24°N. Our results also indicate a complex splitting pattern in northeast and southeast directions that may be attributed to the toroidal flow around the slab and poloidal flow below the slab respectively.

 



Eric Sandvol

Eric Sandvol has worked on characterizing crustal and upper mantle seismic velocity structure beneath continental plateaus and mountain belts in South America, Eurasia, the Middle East and North Africa.  This research has been focused at utilizing seismic waveforms to measure Moho thicknesses, crustal and upper mantle shear-wave velocities, as well as propagation efficiencies. He has more recently worked on applying surface wave tomography to broadband data sets in South America, Tibet, and eastern Turkey.


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Eric Sandvol
16:00 to 17:00
 
 
 
 
 
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Seminar
Climate change, permafrost and fluvial dynamics in the Arctic

Climate change, permafrost and fluvial dynamics in the Arctic

Seminar
Speaker: Emmanuèle Gautier
Date: Tue, 2020-02-25 16:00 to 17:00
Venue: ASE 3D Visualisation Laboratory (N2-B1c-16c)

About the Event

Permafrost strongly influences hydrology and fluvial dynamics in high latitude regions. Periglacial hydrosystems show a very specific behavior: the reduced underground water supply determines very low water level in winter and the flood outburst mainly depends on the elevation of temperature in spring.

The first part of the presentation will concern interactions between permafrost, hillslope and river hydrology in order to understand the effect of the current climate change. The increasing water transfer between hillslope and river can be considered as the mean result of the global warming. The second part will focus on the Lena River in Eastern Siberia. Draining the coldest region of the Northern Hemisphere, the Lena River is deeply impacted by the climate change, which is particularly pronounced in periglacial areas characterized by deep and continuous permafrost. A hydrologic change is clearly identified, with an increase in water discharge and a change of flood in terms of season, intensity and duration. The changing water discharge induces a destabilization of the fluvial bed. A 50-year study of the fluvial forms reveals important changes, mainly expressed by the forested islands evolution. 



Emmanuèle Gautier

Details to follow.


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Emmanuèle Gautier
16:00 to 17:00