All posts by Lucy

COMET Central Asia Fault Database

COMET researcher Tamarah King, based at the University of Oxford, has recently written a blog providing a research update on the COMET Central Asia Fault Database; progress report.

The COMET Central Asia Fault Database integrates decades of fault mapping and field-studies by researchers from the UK NERC Centre for Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET), and global collaborators.

Central Asia is home to one of the world’s great mountain ranges–the Tien Shan–which is formed by vigorous crustal convergence across a multitude of tectonic faults. Here we describe the motivation to assemble the database and the choices that we have made in its structure, which are based on utility, necessity, and limitations in available information. We are working towards a full public release of the dataset, so keep an eye out!

Key points:

  • COMET researchers have assembled a comprehensive database of active faults and associated attributes within Central Asia.
  • The database is comprised of structures identified by COMET researchers from both remote and field mapping (rather than a digitization of all published maps).
  • Faults are represented at three scales to suit various applications, e.g., geotechnical site exposure, geomorphic and neotectonic science, structural continuity for regional deformation models, and an inventory of seismogenic sources.
Image from field-work along the Dzhungarian Fault, Tien Shan, Kazakhstan (Credit: Austin Elliot)

Background Motivation

COMET researchers have been investigating active tectonic structures across the Central Asia region since the early 2000s through programs such as Earthquakes without Frontiers and Looking Inside the Continents from Space, along with local partner institutions in the region such as the Kyrgyz Institute of Seismology. Alongside remote mapping, field campaigns with collaborators have produced a large amount of tectonic and earthquake related information. The COMET Central Asia Fault Database assembles these data to produce a cohesive fault database of use to a wide range of geoscientists, as has been done recently across other regions of the planet.

Figure 2. Trenching with collaborators along the Dzhungarian Fault, Tien Shan, Kazakhstan (Credit: Austin Elliot)

Individual contributors had mapped faults at variable times (~2000 to present), variable resolutions (field-mapping to coarse satellite imagery), and for variable purposes (field site to continental-tectonic scale studies). Rather than reduce this variability to a single representation of the fault network, we produce a database that contains three resolution levels, to increase suitability for various applications.

The blog continues at Blog – Earthquakes in Central Asia.

In the meantime, if you’d like to be involved or would like more information, please get in touch with Tamarah King via tamarah.king@earth.ox.ac.uk

 

The Global Waveform Catalogue

The Global Waveform Catalogue hosted by COMET is now fully interactive.

The Global Waveform Catalogue was published by COMET Associate Dr Sam Wimpenny (University of Cambridge) at the links below.

Paper: https://pubs.geoscienceworld.org/ssa/srl/article-abstract/92/1/212/593118/gWFM-A-Global-Catalog-of-Moderate-Magnitude

Dataset: https://github.com/samwimpenny/Global-Waveform-Catalogue

Description

This is the central repository for the Global Waveform Catalogue (gWFM) v1.0, which is a database of point-source fault-plane solutions and focal depths for moderate-magnitude earthquakes that have been modelled by an analyst using synthetic seismograms. Most earthquakes have been modelled using the program MT5 [see McCaffrey et al., 1991, McCaffrey and Abers 1988], which is described in detail by Molnar and Lyon-Caen 1989 and Taymaz et al., 1990. A number of smaller earthquakes (Mw < 5.3) have also been studied by modelling the P, pP and sP phases on vertical-component short-period or broadband seismograms [e.g. Maggi et al., 2000].

Most of the earthquakes in this database come from the literature, with some solutions from theses that are available online.

The database is complimentary to other global catalogues of earthquakes, such as the global centroid moment tensor (gCMT) catalogue and the ISC-EHB bulletin. What this catalogue brings to the table are the well-constrained focal depths of moderate-magnitude earthquakes. A short manuscript describing origins of the gWFM and how it compares to the gCMT and ISC-EHB is currently in preparation.

 

Harmony: Mission Candidate for the Earth Explorer 10

COMET scientists Professor Juliet Biggs (University of Bristol) and Professor Andy Hooper (University of Leeds) both serve on the Harmony Mission Advisory Group and are delighted to have been chosen to develop the concept further.

On February 18-19, ESA’s Programme Board for Earth Observation (PB-EO) decided on the continuation of the three Earth Explorer (EE) mission candidates towards the next phase in the path to their implementation. The three missions, namely, Daedalus, Hydroterra and Harmony, were selected in 2018 for a Phase-0 feasibility study out of 21 submitted proposals. The PB-EO has made now the unprecedented decision of selecting only one mission for Phase A, namely Harmony, instead of more than one as done in previous EE calls.

The Harmony mission is dedicated to the observation and quantification of small-scale motion and deformation fields at the air-sea interface (winds, waves, surface currents), of solid Earth (tectonic strain and height changes at volcanoes), and in the cryosphere (glacier flows and height changes). In order to achieve the different mission goals, the Harmony mission shall deploy two companion satellites following one of ESA’s Copernicus Sentinel-1 satellites. The companions will be flying in two different formations (see Figure 1): the stereo formation, with one Harmony satellite placed in front and one behind Sentinel-1, in both cases at a distance of about 350 km from it; and the cross-track formation, with both Harmony units flying close to each other (~200-500 m) also at 350 km from Sentinel-1. Each Harmony satellite carries as main payload a receive-only synthetic aperture radar (SAR), which shall acquire the reflected signals transmitted by Sentinel-1 towards the Earth. A multi-view thermal infra-red payload is also included to measure cloud height and cloud motion vectors. The angular diversity provided by the Harmonies in combination with Sentinel-1 will allow the retrieval of deformation measurements of the sea and earth surface with unprecedented accuracy (see Figure 2), while the cross-track configuration will allow the accurate measurement of elevation changes for land-ice and volcanic applications.

 

 

 

 

 

Figure 1: Representation of the (left) stereo and (right) cross-track flying formations for Harmony. The Sentinel-1 satellite is depicted in black color. Sentinel-1 transmits a signal and acquires the backscattered echoes (represented with magenta arrows), while the Harmony satellites receive part of the energy that bounces towards them (represented with the green arrows). Copyright: Harmony Mission Advisory Group.

Dr. Paco López-Dekker from the Delft University of Technology and principal investigator of the Harmony mission, comments “It is very exciting that our multi static-SAR concept, which combines many ideas that were matured during my years at HR, has made it to this final stage. During Phase-0 we have drafted a beautiful and elegant mission concept promising an unprecedented view at Earth System processes. Now we have the responsibility to look at it from all sides and be sure that it will work. Challenging and fun.”

Professor Juliet Biggs from the University of Bristol and member of Harmony’s Mission Advisory Group at ESA adds “The Harmony mission is remarkable in that it promises new scientific discoveries across an astonishing breadth of topics: from the gradual motion of tectonic plates to small-scale processes on the ocean surface. I’m delighted that we have been selected to develop the concept further and that Harmony is one step closer to becoming a reality”

Dr. Pau Prats, from the German Aerospace Centre, DLR and member of Harmony’s Mission Advisory Group at ESA, is convinced of the benefits a mission like Harmony will bring to the community: “The unique configuration of the Harmony satellites in combination with Sentinel-1 will allow us to literally add a new dimension to SAR observations, a fact that will foster SAR technology and its applications during the next two decades.”

Figure 2: Coloured areas show regions straining at greater than 10 nanostrain per year (the threshold above which 95% of earthquake fatalities occur). Blue regions are those that have a small component of north-south strain and can be imaged by Sentinel-1 alone. Red regions indicate the extra area that will be constrained by Harmony. From Harmony Report for Assessment. 2020.  

So, what’s next? Even though Harmony is currently the only EE-10 mission candidate it does not mean it will be implemented. The industry and science teams have one and a half years of hard work ahead to demonstrate the mission has reached the technological and scientific level of maturity required to enter into the next phase, that will ultimately result in the launch of the Harmony satellites by the end of this decade.

Announcement can be found on ESA website: https://www.esa.int/Applications/Observing_the_Earth/ESA_moves_forward_with_Harmony

Title figure for the Harmony mission. Copyright: ESA.

 

Marie Edmonds receives the 2020 AGU Joanne Simpson Medal for Mid-Career Scientists

COMET scientist Prof Marie Edmonds based at the University of Cambridge has received the AGU 2020 Joanne Simpson Medal, one of the highest honours bestowed by AGU for her excellence in scientific research, education, communication, and outreach.  In this unprecedented year the award recognises those who have pushed the frontiers of science forward despite our professional and personal lives being turned upside down.

AGU will host an online celebration to formally recognise Marie’s achievement during #AGU20 Fall meeting on Wednesday 9 December 2020 at 15:00 PT/ 18:00 ET/ 22:00 UTC.

Congratulations Marie from all of your COMET colleagues.

 

 

John Elliott receives 2020 AGU John Wahr Early Career award

COMET scientist Dr John Elliott based at the University of Leeds is the latest winner of the John Wahr Early Career award from the AGU Geodesy section.

The John Wahr Early Career Award, formerly the Geodesy Section Award, is presented annually and recognizes significant advances in geodetic science, technology, applications, observations, or theory. The award is given to early or mid-career scientists who demonstrate the potential to be elected AGU Fellows in the future through outstanding contributions to geodesy.

The award will be presented to John at this year’s virtual AGU Fall Meeting in December 2020.  Congratulations John from all of your COMET colleagues.

Satellite images reveal interconnected plumbing system that caused Bali volcano to erupt

A team of scientists, led by the University of Bristol, has used satellite technology provided by the European Space Agency (ESA) to uncover why the Agung volcano in Bali erupted in November 2017 after 50 years of dormancy. Their findings, published in February 2019 in the journal Nature Communications, could have important implications for forecasting future eruptions in the area.

Two months prior to the eruption, there was a sudden increase in the number of small earthquakes occurring around the volcano, triggering the evacuation of 100,000 people. The previous eruption of Agung in 1963 killed nearly 2,000 people and was followed by a small eruption at its neighboring volcano, Batur. Because this past event was among the deadliest volcanic eruptions of the 20th Century, a great effort was deployed by the scientific community to monitor and understand the re-awakening of Agung.

During this time, a team of scientists from the University of Bristol’s School of Earth Sciences, led by Dr Juliet Biggs used Sentinel-1 satellite imagery provided by the ESA to monitor the ground deformation at Agung. Dr Biggs said: “From remote sensing, we are able to map out any ground motion, which may be an indicator that fresh magma is moving beneath the volcano.”

In the new study, carried out in collaboration with the Center for Volcanology and Geological Hazard Mitigation in Indonesia (CVGHM), the team detected uplift of about 8-10 cm on the northern flank of the volcano during the period of intense earthquake activity.

Dr Fabien Albino, also from Bristol’s School of Earth Sciences, added: “Surprisingly, we noticed that both the earthquake activity and the ground deformation signal were located five kilometres away from the summit, which means that magma must be moving sideways as well as vertically upwards”.

Our study provides the first geophysical evidence that Agung and Batur volcanoes may have a connected plumbing system. This has important implications for eruption forecasting and could explain the occurrence of simultaneous eruptions such as in 1963.

The study is funded by the Centre for Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET), a world-leading research centre focusing on tectonic and volcanic processes using earth observation techniques.

Paper: ‘Dyke intrusion between neighbouring arc volcanoes responsible for 2017 pre-eruptive seismic swarm at Agung’ by F. Albino, J. Biggs and D. Syahbana in Nature Communications https://rdcu.be/bmImV

Sentinel-1 InSAR data showing ground uplift on the flank of Agung volcano. Picture by Fabien Albino, COMET, University of Bristol.