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Remarkable Regions – The Kenya Rift

Remarkable Regions – The Kenya Rift

Every 8 weeks we turn our attention to a Remarkable Region that deserves a spot in the scientific limelight. After looking at several convergent plate boundaries, this week the focus lies on part of a nascent divergent plate boundary: the Kenya Rift. The post is by postdoctoral researcher Anne Glerum of GFZ Potsdam.

Of course an active continental rift is worthy of the title “Remarkable Region”. And naturally I consider my own research area highly interesting. But after seeing it up-close and personal on a recent 10-day trip organized by the University of Potsdam, Roma Tre and the University of Nairobi (stay tuned for the travel log, or read that of the University of Potsdam), I must say, the Kenya Rift is a truly beautiful and fascinating region.

Figure 1. Topography (Amante and Eakins 2009) and kinematic plate boundaries (Sarah D. Stamps based on Bird 2003) of the East African Rift System (EARS). Plate boundary colors schematically indicate the western and eastern branches of the EARS.

Constituting one segment of the 5000 km long East African Rift System (EARS, Fig. 1), the Kenya Rift is host to an amazing landscape, wildlife and people, all of which somehow tie back to continental rifting processes. Although the youngest rifting phase in Kenya commenced in the Miocene, the east African region as a whole has been shaped by rifting episodes since Permian times (Bosworth and Morley 1994). The present active rift system runs from the Afar region in the north all the way south to Mozambique and is split into a western and an eastern branch that run around the Archean Tanzanian Craton (Chorowitz 2005, see Fig. 1). Generally speaking, the western branch is more seismically active, but deprived of magmatism, compared to the eastern branch, of which the Kenya Rift is part (Chorowitz 2005). Three processes characterize the EARS (Burke 1996) as well as the Kenya Rift specifically: normal faulting, volcanism and uplift.

Uplift

The Tanzanian Craton together with the enveloping western and eastern EARS branches constitutes the broad, uplifted area coined the East African Plateau (~1200 m elevation, Strecker 1991; Simiyu and Keller 1997, Fig. 2). The onset of uplift of this plateau can be constrained to the Early Miocene with the help of one of the longest phonolitic lava flows on Earth (> 300 km, Wichura et al. 2010; 2011) and a whale that stranded inland 17 Ma (and was only recently found again after going missing for 30 years, Wichura et al. 2015). Plume-lithosphere interaction is thought responsible for the uplift (e.g. Wichura et al. 2010), although there is disagreement about the continuity of the low seismic velocity anomalies seen in the east African upper mantle and whether they are connected to the lower mantle. For example Ebinger and Sleep (1998), Hansen et al. (2012), Sun et al. (2017) and Torres Acosta et al. (2015) advocate for one East African superplume, while Pik et al. (2006) distinguish separate lower and upper mantle plumes and Davis and Sack (2002) and Halldórsson et al. (2014) consider a lower mantle plume splitting in the upper mantle.

Figure 2. Topography (Amante and Eakins 2009) and fault traces (GEM) of the central EARS. Triangles indicate off-rift volcanoes, dotted grey lines the three segments of the Kenya Rift.

Magmatism and volcanism

The northward motion of Africa over this hot mantle anomaly has been thought the cause of a north-to-south younging trend in the age of the ensuing EARS volcanism and rifting (e.g. Ebinger and Sleep 1998; George et al. 1998; Nyblade and Brazier 2002), although more recent studies arrive at a more spatially disparate and diachronous rifting evolution (Torres Acosta et al. 2015 and references therein). In general, massive emplacement of flood-phonolites preceded the onset of rifting in Kenya around 15 Ma (Torres Acosta et al. 2015). With ongoing rifting, and localization of faulting towards the rift axis, volcanism also migrated towards the center of the rift. Since the Miocene, massive amounts of volcanics have thus been emplaced (144,000-230,000 km3, MacDonald 1994; Wichura et al. 2011). Moreover, dyking also accommodated a significant part of the extension, with 22 to 26 % of the crust in the rift valley being composed of dykes (MacDonald 2012). Not surprisingly, the highlands directly around the rift valley, the Kenya Dome (Fig. 2) formed through a combination of volcanism and uplift (Davis and Slack 2002) with elevations of up to 1900 m.

The composition of rift magmatism is bimodal, showing phonolites and trachytes on the one side and nephelinites and basalt on the other, predominantly resulting from fractional crystallization of a basaltic source. The low viscosity of these magmas allows the young volcanoes in the volcano-tectonic axis to reach significant heights (see Fig. 3; MacDonald 2012). The most impressive volcanoes are to be found outside of the rift however (Fig. 2), with Mnt. Elgon reaching 4321 m and Africa’s highest mountains Mnt. Kenya and Mnt. Kilimanjaro reaching up to 5200 m and 5964 m, respectively (Chorowitz 2005).

Figure 3. View on the crater rim of the 400 ky old Mnt. Longonot volcano in the tectono-magmatic rift axis, at 2560 m asl. Courtesy of Corinna Kallich, GFZ Potsdam.

Normal faulting

The Kenya rift itself is composed of 3 asymmetric segments, distinguished by sharp changes in their orientation (Chorowitz 2005, Fig. 2). The 2300-3000 m high Elgeyo, Mau and Nguruman escarpments result from the steep Miocene east-dipping border faults in the west, while the antithetic border faults on the eastern side formed later during the Pliocene (Strecker et al. 1990). The older border faults formed along preexisting foliation generated by the Mozambique Belt orogeny in the late Proterozoic (Shackleton 1993; Hetzel and Strecker 1994). A change in strike of this foliation from NNE in the northern and southern Kenya rifts to NW determined the change in orientation in the central Kenya rift (Strecker et al. 1990). Consequently, different generations of faults in the northern and southern rift segments run parallel, while in the central segment, the Pleistocene change in extension direction from ENE-WSW/E-W to the present-day WNW-ESE/NW-SE directed extension results in obliquely reactivated border faults and younger, en echelon arranged left-stepping NNE-striking fault zones along the rift axis (Strecker et al. 1990). Extension is transferred between the different zones by coeval normal and strike-slip faulting or dense sets of normal faults.

Figure 4. View of lake Magadi and the Nguruman escarpment. Lake Magadi is a saline, alkaline lake, commercially mined for trona. Courtesy of Corinna Kallich, GFZ Potsdam.

Human evolution

The uplift, volcanism and normal faulting together have set the stage for human and animal evolution. For example, the shift in hoofed mammals from eating predominantly woods to grazing species evidences that the large-scale uplift modified air circulation patterns resulting in aridification and savannah-expansion at the expense of forested areas (Sepulchre et al. 2006; Wichura et al. 2015). The rift basins enabled the formation of large lakes, which were subsequently compartmentalized by tectonic and volcanic morphological barriers (Fig. 4). On the short-term, lake coverage varied due to tectonically induced changes in catchment areas, drainage networks and outlets. Maslin et al. (2014) actually found a correlation between this ephemeral lake coverage and hominin diversity and dispersal. Lake highstands link with the emergence of new species and allowed the spread of hominins north and southward out of east Africa. Remarkable, or what!

References:
Amante, C. and Eakins B. W., 2009. NOAA Technical Memorandum NESDIS NGDC-24. National Geophysical Data Center, NOAA.
Bosworth, W. and Morley, C.K., 1994.  Tectonophysics 236, 93–115.
Burke, K., 1996. S. Afr. J. Geol. 99 (4), 339–409.
Chorowitz, J., 2005. J. Afr. Earth Sci. 43, 379-410.
Davis, P. M. and Slack, P. D. 2002. Geophys. Res. Lett. 29 (7), 1117.
Ebinger, C.J. and Sleep, N.H., 1998. Nature 395, 788-791.
George, R. et al., 1998.  Geology 26, 923–926.
Halldórsson, S. A. et al., 2014. Geophys. Res. Lett. 41, 2304–2311,
Hansen, S. E. et al., 2012.  Earth Planet. Sc. Lett. 319-320, 23-34.
Hetzel, R., Strecker, M.R., 1994. J. Struct. Geol. 16, 189–201.
Macdonald, R. et al., 1994a. J. Volcanol. Geoth. Res. 60, 301–325.
Macdonald, R., et al., 1994b. J. Geol. Soc. London 151, 879–888.
MacDonald, R., 2012. Lithos 152, 11-22.
Maslin, M. A. et al., 2014. Quaternary Sci. Rev. 101, 1-17.
Nyblade, A. A. and Brazier, R. A., 2002. Geology 30 (8), 755-758.
Pik, R. et al., 2006. Chem. Geol. 266, 100-114.
Sepulchre, P. et al., 2006. Science, 1419-1423.
Shackleton, R.M., 1993. Geological Society, London, Special Publications 76, 345–362.
Simiyu, S.M., Keller, G.R., 1997. Tectonophysics 278, 291–313.
Strecker, M., 1991. Das zentrale und südliche Kenia-rift unter besonderer berücksichtigung der neotektonischen entwicklung, habilitation, Universität Fridericiana.
Sun, M. et al., 2017.  Geophys. Res. Lett. 44, 12,116–12,124.
Torres Acosta, V. et al., 2015. Tectonics 34, 2367–2386.
Wichura, H. et al., 2010. Geology 38 (6), 543–546.
Wichura, H. et al , 2011. The Formation and Evolution of Africa: A Synopsis of 3.8 Ga of Earth History, eds. D. J. J. Van Hinsbergen, S. J. H. Buiter, T. H. Torsvik, C. and Gaina, S. J.
Wichura, H. et al., 2015. P. Natl. Acad. Sci. USA 112 (13), 3910-3915.

EGU 2018: Experience of a first time attendee

EGU 2018: Experience of a first time attendee

Your first time at the General Assembly can be a daunting experience. It’s not easy to navigate the scientific programme and let’s not even mention navigating the building! It becomes even more difficult if you do not know many people in your scientific community yet. Luckily, one of the easiest things to do at EGU is meeting new people. Jyotirmoy Paul, PhD student at the Indian Institute of Science in Bangalore, India, shares his experience of attending the EGU GA for the first time this year.

I am a geologist, but I am (slowly) turning into a geodynamicist. My research area is numerical modelling of geodynamical problems. I simulate 3-dimensional models of the spherical earth by solving thermo-chemical convection equations. My present work aims to understand the long-term stability of cratons. The stability of cratons since the Archaean is a hot topic in the geosciences community as it can potentially throw light on some of the key features of Archaean geodynamics. Several studies have already addressed this problem. I had the great opportunity of presenting parts of my work and discussing science with the international community at a large gathering such as the EGU GA. With a lot of different opinions on craton stability, I was able to add some more confusion into the mix! It was nice that I got helpful suggestions and constructive criticism about my research, which was much needed. Apart from discussing with the established scientists, it was really great to talk to my fellow student researchers and have dinner with them. Unfortunately, I was not aware of this ECS GD community before attending EGU, so I missed some of the important courses. I hope to meet the community again during another conference, maybe at AGU 2018!

Apart from helpful scientific discussions, the whole atmosphere at EGU was new to me. This was my first large-scale international conference, so – naturally – I was overwhelmed to meet the pioneers of geosciences. I interacted with those very people whose ideas had influenced my thought processes throughout my student life. Talking and listening to them was intriguing and I developed many new ideas that I will be able to use throughout my career. Besides that – in the multi-cultural environment of the General Assembly – I was representing a minority community from the largest democracy in the world (as it is called): the community of geodynamics researchers in India! The number of geodynamics researchers in India is tiny and may not even reach two digits. The sudden change from a pond to the ocean was overwhelming, intriguing, and terrifying. Phew!

A blog post about my experience at EGU would be incomplete if I didn’t mention Vienna. The beautiful city has witnessed several turning points in world history. As an art history lover, roaming around the city was bliss. The mosaics of Stephansplatz, the medieval baroque architecture of the Habsburg dynasty and the modern city on the left bank of Danube transported me back in time through Europe’s history. Gustav Klimt, the famous Austrian painter, lived in Vienna exactly 100 years ago. His major works are showcased in the Belvedere museum. Despite the tight schedule of EGU from morning to evening, I managed to find one free slot to visit his gallery at Belvedere. I could not leave Vienna without seeing “The Kiss”!

The Kiss, Gustav Klimt
Credit: Jyotirmoy Paul

To serve Geoscientists

To serve Geoscientists

The Geodynamics 101 series serves to showcase the diversity of research topics and methods in the geodynamics community in an understandable manner. We welcome all researchers – PhD students to professors – to introduce their area of expertise in a lighthearted, entertaining manner and touch upon some of the outstanding questions and problems related to their fields. For our latest ‘Geodynamics 101’ post, Fabio Crameri, postdoctoral researcher at the Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Norway, joins us again. Continuing from his earlier post on the harmful use of the rainbow colour map, Fabio shares his thoughts on some of the expressions and phrases used in the community that propagate confusion, and how the new “Ocean-Plate Tectonics” concept offers relief for at least some on them. 

Blog author Fabio Crameri – in a shirt that translates from Tamasheq as “deserts” or “empty spaces.” You can expect no empty spaces in your lunchtime conversations after reading this post.

Do you, after reading the title, still wonder what this blog post is all about?
I’ll give you a hint, it’s about the Earth. No, wait, it’s about Earth, or perhaps earth, or isn’t it? And maybe it is a little bit about Moon, I mean the Moon. But also, it is about the Venus, I mean Venus.

It is not confusing, it is just well mixing.

You’ve got it; it is about confusion in the Geosciences. Confusion caused by symbols, letters, words and phrases through misuse, ambiguity or over-interpretation. So, after all, this is a blog post about geo-semantics rather than about culinary excursions.

The Geodynamics community is a diverse group of people with different backgrounds, native languages and customs. This is an attractive breeding ground for semantic related problems, particularly when you throw in some inherent peculiarities of the English language in which we largely operate.

Some use the symbol “a” for years, for years and years.

In line with a widely used standard definition (Holden et al., 2011) – but against the common convention of the Geosciences – the author of this blog post was using the unit of time “a”, or arguably just its symbol, for “years” (and I mean calendar years, neither financial years nor dog years), for years and years. A distinction between discrete points in time and the duration of time is at the heart of this confusion, and indeed has plagued a sub-selection of discussions, working groups and interpretations of the International System of Units (SI; e.g., Christie-Blick, 2012).

Figure 1. An ambiguously phrased situation near the recent end of the Cretaceous.

The symbol “a” for “annus” [year] (“Ma” being the symbol for 106 years, or “mega-annus”) in the Geosciences is most commonly used for a specific time or date in the past as measured from now. For example, “At 65 Ma (which is 65 Myr ago), the dinosaur looked up the sky.” (see Figure 1). On the other hand, “yr” for “year(s)” is commonly used for a duration of time, as in “The Cretaceous period ran for 79 Myr (from approximately 145-66 Ma).”. Other mutations within the convention of time in the Geosciences include “My”, “Myrs”, “Mya” or “m.y.” for “Millions of years”. Thus, the time unit and symbols for multiples of a “year” are likely amongst the most ambiguous expressions in the Earth Sciences, likely because, in contrast to the “second”, a universally applied scientific definition for the “annus” still remains elusive (Thompson and Taylor, 2008).

Such quibbling over semantics may seem petty.

Amongst other examples to cause geodynamic misunderstandings (e.g., Figure 2) might be the misuse of the phrase “stagnant slabs”? Are slabs ever really stagnant? Or are they just being deflected, slowing down, interrupting their downward motion, not directly entering the lower mantle at the same speed and trajectory as before?

Figure 2. One ambiguously phrased geodynamic explanation.

From the literature, you might be forgiven for having the false impression that slabs either fully stagnate around the upper-mantle transition zone or directly and effortlessly penetrate it; they likely do neither of the two (as explained in e.g., in an earlier Geodynamics101 post here).

When these slabs sink, and not temporally stagnate, they induce flow in the surrounding mantle. “Slab suction” is the downward suction induced by the nearby mantle that is set in motion through its dynamic coupling with the slab [e.g., Conrad and Lithgow-Bertelloni 2002]. Or isn’t it? “Slab suction” is also contrarily used as an upward directed force on the slab itself that is induced by the upper plate and might foster low-dipping shallow-depth slab portions in the uppermost upper mantle (unambiguously speaking of which: see again Figure 2).

The downward directed version of “slab suction” can induce “dynamic topography”. Estimates of the maximum amplitude of “dynamic topography” on Earth range from only a few hundred meters up to a few kilometres (see e.g., Molnar et al., 2015 and references therein). Such unusually large ranges of estimates are, as a general rule, a quite solid indicator for an underlying ambiguous definition, or in this case, rather a mix-up of multiple different definitions for the term “dynamic topography”. 

If you’re not confused, you did not pay attention.

As I keep talking about geodynamics, I hope we are all on the same page about subduction, one of the key players: Let’s assume planet XY has one single active subduction zone. Another subduction zone initiates on the opposite side of the same planet. Did “subduction” start once or twice on that planet?

It started once on that planet. Because “subduction” describes a process and not a physical feature; it is nonetheless easily mistaken for a physical feature.

And what about “plate tectonics”, the 50 yr old overarching concept that fascinates us, and for so many of us has become the foundation of our professional lives. Let’s approach this by considering the big question: When did “plate tectonics” start? Serious opinions in the plate tectonics community range from around 850 Ma (Hamilton 2011) all the way back to 4.3 Ga (Hopkins et al., 2008). – Remember what unusually large estimate ranges often indicate? – It is not surprising that the only commonly accepted specific answer everyone seems to agree on currently is that it depends on the very definition of plate tectonics.

So, what is the definition of “plate tectonics”? According to its original formulation, “plate tectonics” is the horizontal relative movement of several discrete and mostly-rigid surface-plate segments (Hess, 1962; see the corresponding visual representation in Figure 3). A generous interpretation of the original formulation might additionally define the plate-interface nature, but that is all.

Figure 3. As long as it is not overinterpreted, there is nothing wrong with the original definition of plate tectonics that solely describes the horizontal motion of several discrete surface plates: It does not discriminate the oceanic from the continental plate, does not consider the important framework of mantle convection, and does not specify the underlying key driver of the surface motion.

Considering the knowledge we have gained about the moving surface plates and their underlying causes and consequences during the past 50 yr, this is an extremely broad definition: As of today, we know that (A) the surface plates with their relative motion are an integral part of whole mantle convection (Turcotte and Oxburgh, 1972), that (B) Earth’s surface has a characteristic bimodal nature due to the partitioning into long-lived continental plates and short-lived oceanic plates (e.g., Wilson, 1966), and that (C) the latter are mainly driven by their very own subducted portions (i.e., all or parts of their slabs; Forsyth and Uyeda, 1975; Conrad and Lithgow-Bertelloni, 2002).

A clear, unambiguous and up-to-date definition for such a crucially important, wide-reaching concept is imperative. It is therefore not surprising that less ambiguous re-definitions have been suggested recently. To avoid propagating confusion, the introduction of alternative phases of plate tectonics that describe the various different possible modes of mantle convection during Earth’s evolution have been cast into the arena (e.g., Sobolev 2016). These include “plate-tectonics phase 1”, in short “PT1”, describing regional, plume-induced plate tectonics (e.g., until 3.0 Ga), “PT2” describing episodic, global plate tectonics (e.g., between 2.5-1.0 Ga), and finally “PT3” describing stable, global plate tectonics (e.g., 1.0-0.0 Ga). Other efforts result in different naming conventions, such as “modern plate tectonics”. However, apart from the fact that “modern” is a time dependent term, “modern plate tectonics” might be a somewhat unfortunate expression, as other planets like Venus might have undergone different, modern styles of plate tectonics than present-day Earth.

Stern and Gerya (2017) then actually suggests an entire update to the definition of “plate tectonics”:

“A theory of global tectonics powered by subduction in which the lithosphere is divided into a mosaic of strong lithospheric plates, which move on and sink into weaker ductile asthenosphere. Three types of localised plate boundaries form the interconnected global network: new oceanic plate material is created by seafloor spreading at mid-ocean ridges, old oceanic lithosphere sinks at subduction zones, and two plates slide past each other along transform faults. The negative buoyancy of old dense oceanic lithosphere, which sinks in subduction zones, mostly powers plate movements.”

Unfortunately, such a re-definition of the same old phrase makes it impossible to know which version of the definition (i.e., the original or the updated one) an author of a subsequent study should be applying and referring to.

In an effort to prevent all of the above problems, we recently introduced an entirely new concept; one that can coexist in harmony with the original definition; one that fully captures the dynamics of the oceanic plate according to our current knowledge. The concept is called “Ocean-Plate Tectonics” or, if you really like the term, “OPT”.

“Ocean-Plate Tectonics is a mode of mantle convection characterised by the autonomous relative movement of multiple discrete, mostly rigid, portions of oceanic plates at the surface, driven and maintained principally by subducted parts of these same plates that are sinking gravitationally back into Earth’s interior and deforming the mantle interior in the process.” – Crameri et al. (2018).

“Ocean-Plate Tectonics” captures not only the relative horizontal surface motion of plates, but crucially also accounts for (A) the importance of the whole mantle framework, (B) the bimodal nature of Earth’s surface plates, and (C) the underlying engine of the surface-plate motion (see Figure 4).

Figure 4. “Ocean-Plate Tectonics”, the unambiguous up-to-date definition describing the dynamics of the oceanic plate that crucially incorporates the bimodal nature of Earth’s surface, the convecting-mantle framework, and the key driver of surface-plate motion (after Crameri et al., 2018).

“Ocean-Plate Tectonics” is here to serve Geoscientists.

The concept of “Ocean-Plate Tectonics” is intended to bring together the extremely diverse research communities, but also the general public, to meet on common, fruitful ground in order to discuss and further develop our understanding of the fascinating dynamics involved in Earth’s plate-mantle system; the unambiguous “Ocean-Plate Tectonics” is here to serve us.

 

Christie-Blick, N., (2011), Geological Time Conventions and Symbols, GSA Today, 22(2), 28-29, doi: 10.1130/G132GW.1

Conrad, C. P., and C. Lithgow-Bertelloni (2002), How mantle slabs drive plate tectonics, Science, 298 (5591), 207–209, doi:10.1126/science.1074161.

Crameri, F., C.P. Conrad, L. Montési, and C.R. Lithgow-Bertelloni (2018), The life of an oceanic plate, Tectonophysics, (in press), doi:10.1016/j.tecto.2018.03.016 .

Forsyth, D., and S. Uyeda (1975), On the relative importance of the driving forces of plate motion*, Geophysical Journal of the Royal Astronomical Society, 43(1), 163–200, doi:10.1111/j.1365-246X.1975.tb00631.x.

Hamilton, W.B. (2011), Plate tectonics began in Neoproterozoic time, and plumes from deep mantle have never operated, Lithos, 123, 1–20, doi:10.1016/j.lithos.2010.12.007.

Hess, H.H. (1962), History of ocean basins, Petrologic studies, 4, 599–620.

Holden N.E., M.L. Bonardi, P. De Bièvre, P.R. Renne and I.M. Villa (2011), IUPAC-IUGS common definition and convention on the use of the year as a derived unit of time (IUPAC Recommendations 2011, Pure Appl. Chem., Vol. 83, No. 5, pp. 1159–1162, 2011. doi:10.1351/PAC-REC-09-01-22

Hopkins M., T.M. Harrison, C.E. Manning (2008), Low heat flow inferred from >4 Gyr zircons suggests Hadean plate boundary interactions, Nature, 456, 493–96, doi:10.1038/nature07465.

Molnar, P., P. C. England, and C. H. Jones (2015), Mantle dynamics, isostasy, and the support of high terrain. J. Geophys. Res. Solid Earth, 120, 1932–1957. doi: 10.1002/2014JB011724.

Sobolev, S.V. (2016), Plate Tectonics Initiation as Running Hurdles, Workshop on the Origin and Evolution of Plate Tectonics abstract, Ascona, Switzerland, http://jupiter.ethz.ch/~plates/.

Stern, R.J. and T.V. Gerya (2017), Subduction initiation in nature and models: A review, Tectonophysics, doi:10.1016/j.tecto.2017.10.014

Thompson, A., and B.N. Taylor (2008), Guide for the Use of the International System of Units (SI) NIST Special Publication 811, 2008 Edition (version 3.2). [Online] Available: http://physics.nist.gov/SP811 [2018, 05 02]. National Institute of Standards and Technology, Gaithersburg, MD.

Turcotte, D. L., and E. Oxburgh (1972), Mantle convection and the new global tectonics, Annual Review of Fluid Mechanics, 4 (1), 33–66.

Wilson, T. (1966), Did the Atlantic close and then re-open?, Nature, 211(5050), 676–681, doi:http://dx.doi.org/10.1038/211676a0

EGU GD Whirlwind Wednesday: Geodynamics 101 & other events

EGU GD Whirlwind Wednesday: Geodynamics 101 & other events

Yesterday (Wednesday, April 12, 2018), the first ever Geodynamics 101 short course at EGU was held. It was inspired by our regular blog series of the same name. I can happily report that it was a success! With at least 60 people attending (admittedly, we didn’t count as we were trying to focus on explaining geodynamics) we had a nicely filled room. Surprisingly, quite some geodynamicists were in the audience. Hopefully, we inspired them with new, fun ways to communicate geodynamics to people from other disciplines.

The short course was organised by me (Iris van Zelst, ETH Zürich), Adina Pusok (ECS GD Representative; UCSD, Scripps Institution of Oceanography, IGPP), Antoine Rozel (ETH Zürich), Fabio Crameri (CEED, Oslo), Juliane Dannberg (UC Davis), and Anne Glerum (GFZ Potsdam). Unfortunately, Anne and Juliane were unable to attend EGU, so the presentation was given by Antoine, Adina, Fabio and me in the end.

The main goal of this short course was to provide an introduction into the basic concepts of numerical modelling of solid Earth processes in the Earth’s crust and mantle in a non-technical, fun manner. It was dedicated to everyone who is interested in, but not necessarily experienced with, understanding numerical models; in particular early career scientists (BSc, MSc, PhD students and postdocs) and people who are new to the field of geodynamic modelling. Emphasis was put on what numerical models are and how scientists can interpret, use, and work with them while taking into account the advantages and limitations of the different methods. We went through setting up a numerical model in a step-by-step process, with specific examples from key papers and problems in solid Earth geodynamics to showcase:

(1) The motivation behind using numerical methods,
(2) The basic equations used in geodynamic modelling studies, what they mean, and their assumptions,
(3) How to choose appropriate numerical methods,
(4) How to benchmark the resulting code,
(5) How to go from the geological problem to the model setup,
(6) How to set initial and boundary conditions,
(7) How to interpret the model results.

Armed with the knowledge of a typical modelling workflow, we hope that our participants will now be able to better assess geodynamical papers and maybe even start working with numerical methods themselves in the future.

Apart from the Geodynamics 101 course, the evening was packed with ECS events for geodynamicists. About 40 people attended the ECS GD dinner at Wieden Bräu that was organised by Adina and Nico (the ECS Co-representative for geodynamics; full introduction will follow soon). After the dinner, most people went onwards to Bermuda Bräu for drinks with the geodynamics, tectonics & structural geology, and seismology division. It featured lots of dancing and networking and should thus be also considered a great success. On to the last couple of days packed with science!