Thursday, October 10, 2019

Sitting atop a subduction zone talking about modeling subduction zones: The MCS RCN Megathrust Modeling Workshop

This past Sunday through Wednesday I attended the Modeling Collaboratory for Subduction (MCS) Research Coordination Network (RCN) ( Megathrust Modeling Workshop held at the University of Oregon in Eugene. A megathrust is a very large thrust faults, such as those found along subduction zones, and they are capable of producing very large, devastating earthquakes and tsunamis, such as the 2011 Tohoku-oki earthquake and tsunami in Japan.

The first thing that struck me upon landing in Portland, and then again in Eugene, is how green and lush everything is. You can smell it in the air. I think I’ve acclimated to California, which is brown a good portion of the year, and I’d sadly forgotten how lush other places can be. Flying into Portland I could sand waves in the Columbia River and Mt Hood off in the distance. 


While at the workshop, they mentioned a few times how we were discussing subduction zone modeling while sitting atop the Cascadia subduction zone, arguably the greatest geologic threat to the northwestern US. 

image credit: FEMA
Much of the first day was talking about different types of slip along the megathrust, from various types of aseismic slip to devastating earthquakes. Aseismic slip is slip that doesn’t register on seismometers. Examples include earthquakes that are too small and don’t radiant enough energy, low-frequency tremor, and my current favorite: slow slip events, or silent earthquakes. Slow slip events can last hours to months (the longest ones observed have lasted ~1.5 years). The rupture is very slow, but above the normal plate motion rate. The amount of slip accommodated over the duration of these events can be quite large, equivalent to a magnitude 7 earthquake. 

The workshop then got into dynamic slip and tsunami modeling. Dynamic slip modeling involves modeling co-seismic slip (slip along the plate boundary during an earthquake) to learn more about the rupture process, earthquake source parameters, and fault properties. Tsunami modeling uses outputs from dynamic rupture models (the amount of slip and surface deformation) to determine the size, energy, and inundation that might occur during an earthquake-triggered tsunami. There is currently a big effort to couple these models together, so that the tsunami models are informed as the modeled slip during the earthquake is occurring, rather than waiting for the net result. It is not just the total amount of slip and deformation that matters for a tsunami, a lot can depend on where and how the slip develops.

Finally, we got into geodynamic and surface process modeling. This is the type of modeling I’m most interested in at the moment. How does the geometry of the megathrust affect fault behavior and earthquake slip? We know the dip of the subducting plate is very important to the amount of friction along the plate boundary interface and the size of the locked portion of the fault. The locked portion is the part of the fault that is assumed to slip in large, devastating earthquakes. How does the topography and surface roughness of the plate boundary interface affect the structural development of the fault? While dynamic slip modeling is interested in the few second to minutes of fault slip and deformation that occurs during the earthquakes, or just after and before the earthquakes (pre- and post-slip), geodynamical modeling is typically interested in plate boundary slip and deformation that happens over geological time scales of thousands to millions of years. However, these models can be used to inform each other, and the work should not be done in isolation. This was one of the motivating factors of the workshop. To better understand subduction zone processes, we need to facilitate collaboration between all the different groups doing subduction zone research.

There was a previous workshop earlier this year that focused on fluid transport through subduction zones, and there will be a final workshop next year on modeling volcanic systems. The presentations and breakout session notes (where key questions related to fluid transport were posed to the attendees) for the fluid transport workshop are already online, and the white paper summary of the meeting is coming soon. The same materials will also be available for the megathrust modeling workshop, and eventually for the future volcanic systems modeling workshop. The idea of the MCS RCN to be as open and transparent as possible so that these discussions benefit the community at large. These workshops are meant to generate a consensus in the subduction zone science community as to what some of the primary areas of focus should be and to guide future NSF proposals to allow the develop of a community model.

I found the workshop to be very informative, and I met some great people that I look forward to being able to collaborate with in the future. The presentations and breakout discussions were fantastic, and I certainly feel motivated to pursue this field of science.

Thursday, September 26, 2019

New Website

I now have a new website. While has been a good site and the domain is great (one I share with my husband, Kurt Schwehr) it has gotten burdensome to update, and as you can tell hasn't been updated in nearly as long as this blog :)

iWeb made creating a website so easy, why oh why did Apple abandon it. I still managed to use it for years after it was abandoned, and was able to export the CSS into a project which I could then upload to

So in an effort to create an updated website that has current content and research, I've created a site:

(The "schwehrwolf" is a nod to a joke between me, Kurt, and several of our friends and family that we should have combined last names into the epic Schwehrwolf. Kurt was pretty established at the time, so it wasn't really realistic, but man oh man, would that be a great last name.)

I may end up paying eventually to remove the ad banner at the top and have a personal domain, but for now the free version gives me all that I need. Like iWeb, creating the website is drag-and-drop and it is infinitely more customizable than WordPress, at least in my own comparison of the free version of each. One downside of Wix is that you cannot download the CSS, so moving your website to another domain or web-hosting service isn't really possible.

So here's to hoping I can stick to keeping my website up-to-date, and even get back into blogging. Between work and kids, by the time I have any down time, I just want to veg out and do nothing.

Sunday, February 21, 2016

February's Baking Challenge: Molten Chocolate Cake

This year I decided to take on Cake Baking Bucket List challenge. Each month I am baking a different cake, learning some new tricks, and honing my skills.

February's cake is a molten chocolate cake. One of the things I love about the recipe is that it make 4 individual cakes, perfect for having a couple friends over for dinner. It's also extremely simple and fast. The cakes bake in 12 minutes, and since you want to serve them warm, there is hardly any wait time. I made them after dinner on Friday night, and the whole process took about 30 minutes from initial prep to first bite.

Once I had the cakes placed on dessert plates, I sprinkled them with powdered sugar and topped them with a small scoop of vanilla bean ice cream. Delicious!

Edit: we just ate the remaining two cakes last night (they'll keep 5 days in a airtight Tupperware in the fridge), and I drizzled some caramel sauce over the top once I added the scoop of ice cream. Amazing! Caramel sauce and vanilla bean ice cream: that is definitely my recommended way to serve these.

Friday, February 12, 2016

Dissertation is available online

Hi Guys,
  A couple weeks ago ProQuest published my dissertation online.  Most institutional libraries will have access to it through a subscription to ProQuest's Thesis and Dissertations Database. 

  I also want to make it available to those that don't have access to a university library, so I am hosting it on Google Drive.

  If you would like to view/download a copy of "The relationship between oceanic transform fault segmentation, seismicity, and thermal structure," you can find a link to it here.

Sunday, February 7, 2016

The Ultimate Cake Baking Bucket List: A Monthly Cake Challenge

As one of my goals for 2016, I decided I want to expand my skills in the kitchen. I love baking, so why not find a way to challenge myself and make some tasty treats at the same time?

Enter the
Ultimate Cake Baking Bucket List. The list, which assigns a cake to bake for each month of the year, is designed to introduce the baker to multiple techniques while also, making them more confident and comfortable behind the stove. 

January's cake was a citrus angel food cake. I postponed making it until this weekend, as I thought it would be a fun activity to do while hiding out from the Super Bowl madness occurring just down the road from us (we're only 10 minutes from the stadium, and live right along the public rail line). 

One thing I noticed about some of the recipes on Food & Wine is that they don't list out all the steps, which can be a bit confusing. For example, the recipe for the angel food cake lists heavy cream and powdered sugar in the ingredients list. The directions never mention these ingredients though. From the picture and the ingredients themselves, it's obvious they want to make a simple icing to drizzle on the cake, but it would be nice if they mentioned that.

I followed the recipe almost exactly as it appears on the webpage, with a couple exceptions:
  1. My egg whites would not whip up into stiff peaks no matter how much I beat them in the KitchenAid until I added more cream of tartar. I believe this possibly due to the grated lemon zest preventing the egg whites from forming good structure.

    To over come this, I gradually added additional cream of tartar, approximately 1/4 teaspoon at a time. The recipe calls for 1 teaspoon, and it total I think I used about 2.5. One nice thing I learned, adding additional cream of tartar does not seem to affect the recipe at all. Yeah!
  2. The icing: the recipe mentions 2 tablespoons heavy cream and 1 cup confectioner's sugar. I used 1.5 tablespoons whole milk (I didn't have heavy cream), and 1/2 tablespoons homemade vanilla extract (I'll make a post later on how to make the extract). Once the cake was cooled and out of the pan, I just mixed up the icing with a metal whisk and drizzled it over the cake.

This cake is light, airy, and very delicious. The zest and fresh lemon juice really give the cake a nice pop of citrus flavor without making it tart. I was honestly surprised just how flavorful this cake was, as plain angel cake is so mild and generally a bit boring on it's own.

I did have some trouble getting the cake off the bottom of the pan, until I started cutting it. I used a non-stick angel food pan, but since angel food batter climbs the walls of your pan as it bakes, I am not sure how much the non-stick coating actually helps. I need to get a nice rubber or silicon icing spreader that I can also use to separate the cake from the pan for easy removal. You'll notice in my pics that the cake was still on the bottom part of the pan when I iced it. 

(sorry for the dirty pan in the pic, my husband had just sauteed some veggies)

Sunday, January 17, 2016

Learning QGIS - a simple tutorial

One of my goals for early 2016 is to learn how to use QGIS, a freely available open source Geographic Information System.

I have been an ArcGIS user for years, and consider myself fairly proficient. If you're a student and your university has a site license for ArcGIS, you can actually get a free personal license, good for one year from the date of install. The ability to have ArcGIS installed on my personal machine, and not having to rely on remote desktop connections, really helped facilitate my research during the last couple years. I have an Apple laptop, but I found that if I allocate sufficient memory (4 GB) and hard disk space to my Windows virtual machine, I can run ArcGIS quite happily. ArcGIS is extremely powerful, but it is also prohibitively expensive for many individuals and for small organizations, and is also Windows-only at this time. I am not sure where I will end up working at this time, and I certainly cannot assume I will have access to ArcGIS when I get there. As such, I feel that it behooves me to learn alternative solutions for any GIS needs I have.

QGIS provides many of the same powerful analysis tools as ArcGIS, thanks to its integration with other open source GIS tools, such GDALGRASS GISPostGIS, and MapServer.

GDAL is a translator library for raster and vector data, allowing you to transform your data into a number of different projections (coordinate reference frames) and data formats. It can generate hillshade, compute statistics on a grid file, etc.

GRASS GIS provides a lot of the analytical, modeling, and image processing tools found in QGIS. The difference between GRASS GIS and QGIS can be confusing as GRASS GIS can be also used as a standalone GIS. Earlier versions of GRASS did not include a GUI; commands were run via a command shell and results were displayed using the X11 windowing system. QGIS interfaces directly with GRASS to provide a nice user-interface, that folks already familiar with ArcGIS might be more comfortable with. Also, to my knowledge GRASS does not integrate directly with MapServer. Early versions of QGIS did not integrate with GRASS. Those early versions of QGIS could still handle a lot of GIS needs, but it did not have a lot of the analytical tools that GRASS did.

PostGIS brings geospatial capabilities to PostgreSQL databases, allowing you to run queries and perform database operations based off geometries, locations, etc. This tool is what provides QGIS with its database capabilities.

MapServer allows for the publishing of geospatial data on the web, and provides a suite of interactive mapping tools. QGIS uses MapServer to allow you to publish your maps to web.

The most recent version of QGIS (v. 2.12) brings together these individual tools, along with a number of others, in a nicely packaged open source software that is a serious competitor to ArcGIS.

My first project:

For my first project, I decided to create a map of the Discovery Transform Fault.

To create this image:
  1. I brought in an ASCII Grid file (.asc) of the bathymetry data, using Layer --> Add Layer --> Add Raster Layer. This brings the grid file in as a grayscale image.

  2. To change the color, double-click on the layer, then go Style --> Render Type --> singleband pseudocolor. Now you can select your colormap, choose between continuous and discrete modes, create classes, and adjust your bounds just as you can in ArcGIS.

  3. You can create the hillshade effect by going to Raster --> Analysis --> DEM. Under mode you will find options for computing slope, aspect, hillshade, etc. 

  4. Once your hillshade layer is created, move it down below your grid layer in the layers panel. Then, go to Layer Properties for your grid, and set a transparency so you can see the hillshade through the data. 

  5. The plate boundary line that you see on the map was brought in as a geotiff. To make the white background transparent, you go to Layer Properties --> Transparency and set the RGB values to 255.

  6. Next I added the earthquake data, the purple circles that are sized by magnitude. The earthquake data was in a comma-separated file (.csv) so I went to Layers -->Add Layer --> Add Delimited Text Layer.

    QGIS does a great job of reading the file and determining that the first row of data is actually the header row. I simply selected which columns represented the X field and Y field and clicked OK. It then asks you to choose a Coordinate Reference System (CRS) for the data. Select the appropriate projection, hit OK, and the data should show up on your map.

    To size the points by magnitude (you can also color by attribute as well), double-click the layer to bring up Layer Properties --> Style and change Single Symbol to Graduated. Under Method, select size, and for Column, select the attribute (in my case "Mw") that you want to size by. Now you can choose what mode to break by (equal interval, natural breaks, pretty breaks, etc.).

    As with any context menu, you can hit "apply" before you hit "OK" to see how the data will look before you completely exit the menu. 

  7. Now that we have all the data in QGIS, it's time to make the actual map. First, hit the New Print Composer icon (white rectangle w/ yellow asterisk) or go to Project --> New Print Composer.

  8. Select Layout --> Add Map, and then drag using your mouse or trackpad to draw a box where you want the map to appear. Once you let go on the mouse or trackpad, your data will pop into view. You can adjust the visible bounds of your data under Item Properties.

  9. Under Item Properties for the Map object, you will also find options for adding a geographic grid, or graticule, as I did above.

  10. The Add Scalebar and Add Legend options are tucked away under Layout. Each time you choose to add an item under Layout, you'll need to draw a box on your map so the composer knows where to place it. You can always move these items after the fact.

  11. If you do not want all your layers to show up in the legend, simply uncheck Auto Update under Item Properties and the select the layer you wish to remove and hit the minus icon. The icon of the pencil on the paper allows you to edit the names of the visible layers.  The legend item has a "columns" option under Item Properties. This will enable you to have your layers added side-by-side, versus stacked vertically. The icon that looks like a funnel with filter the legend by map content. For my map, this meant that for certain sized earthquakes not visible in my map extents, the corresponding legend entry was removed.

  12. before filtering legend for map content

    after filtering legend for map content

  13. Once you have your map the way you want it, you can easily export it as an image, PDF, or SVG file.

One thing I noticed was that even though I used a continuous colormap for the bathymetry data, the legend shows the colorbar as discrete color blocks. It would be better show a gradual change in color from blue to red. When you first set the colorbar for the layer, the icon for the spectral colormap does show this gradation of colors, so this should be something QGIS can do. I haven't looked into this too much yet, but if I find a solution, I'll post about it.

For a lot of helpful QGIS tutorials, complete with downloadable datasets so you can easily follow along, check out They start out with tutorials on basic map-making and go all the way through advanced statistical analyses of your data. It's a tremendously useful site if you really want to learn QGIS.

Thursday, January 7, 2016

AGU and Post Docs

Well, my re-dedication to my blog hit a brief snafu as AGU ended up being crazy as usual and last minute postdoc applications (*fingers crossed*) took up the rest of my time.

AGU was fun, as always, and completely crazy due to the sheer number of talks and posters, as usual. It was great to meet up with friends, catch up with colleagues, and, of course, catch some great talks and posters.

I presented a poster on my global characterization of mid-ocean ridge transform fault structure and the relationship between fault segmentation and the underlying fault thermal structure, which controls the width of the seismogenic zone. You can view and download a high-res PNG version of my poster here: AGU poster.

Below is a low-res screen grab:

It is stuff I have presented before as preliminary results, but the work is now finalized. I have been working on my global characterization of fault structure for a few years now, updating it as new versions of global bathymetric grids become available. My committee and I decided to hold off on publishing it until we finalize the scaling relation work, as combining the two makes for a much stronger paper. Of course, all of this is now published in my dissertation. Writing this all up for publication in a journal will be one of my top goals over the next couple of months.

Speaking of my dissertation, a link to the PDF document be found here: Dissertation. ProQuest has the final version, and once it is officially published online, I'll write a new post and include the direct link.

Oh, due to said postdoc applications, my AGU poster ended up being put together much later than anticipated. I ended up using AGU's own poster printing services provided by Copy Central. For $119, I received a high-res full color 3' x 5' poster printed on heavyweight paper. It looked amazing, and for the convenience of picking it up at the conference the morning of my presentation, it was worth every penny. I highly recommend their services.