Abstract:The locations and details of 145 Antarctic subglacial lakes are presented. The inventory is based on a former catalogue of lake-type features, which has been subsequently reanalysed, and on the results from three additional datasets. The first is from Italian radio-echo sounding (RES) of the Dome C region of East Antarctica, from which 14 new lakes are identified. These data also show that, in a number of occasions, multiple lake-type reflectors thought previously to be individual lakes are in fact reflections from the same relatively large lake. This reduces the former total of lake-type reflectors by six, but also adds a significant level of information to these particular lakes. The second dataset is from a Russian survey of the Dome A and Dome F regions of East Antarctica, which provides evidence of 18 new lakes and extends the coverage of the inventory considerably. The third dataset comprises three airborne RES surveys undertaken by the US in East Antarctica over the last five years, from which forty three new lakes have been identified. Reference to information on Lake Vostok, from Italian and US surveys taken in the last few years, is now included.

We present an analysis of the active hydrologic system of MacAyeal Ice Stream (MacIS), West Antarctica, from a synthesis of multiple remote-sensing techniques: satellite laser altimetry; satellite image differencing; and hydrologic potential mapping (using a satellite-derived DEM and a bedrock DEM from airborne radio-echo sounding). Combining these techniques augments the information provided by each one individually, and allows us to develop a protocol for studying subglacial hydrologic systems in a holistic manner. Our study reveals five large active subglacial lakes under MacIS, the largest of which undergoes volume changes of at least 1.0 km3. We discuss the hydrologic properties of this system and present evidence for links between the lakes. At least three of the lakes are co-located with sticky spots, i.e. regions of high local basal shear stress. We also find evidence for surface elevation changes due to ice-dynamic effects (not just water movement) caused by changes in basal resistance. Lastly, we show that satellite radar altimetry is of limited use for monitoring lake activity on fast-flowing ice streams with surfaces that undulate on ∼10 km length scales.

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There is a little seismologist in everyone. One secret to unlocking a student’s science potential at the undergraduate level is to offer laboratory exercises that leverage the inspiration, team spirit, and creativity already present in the current generation of incoming college students. In this lab exercise we do that by using smartphones to cause a bit of scientific mischief. In the Flash Mob Science seismology experiments described here, several groups of 5–15 students download a mobile app that can record time-series data from their phones using the phone’s vibrational sensors. This allows each device to record acceleration in the X, Y, and Z directions. We conduct quantitative experiments using student-created linear seismic arrays and deploy these arrays at prominent San Diego, California, landmarks that are known to vibrate in response to relatively small forces. These include the Spruce Street suspension footbridge in Hillcrest and the top floor of a parking garage at Southwestern College’s Higher Education Center. Our research team of students tested how these landmarks responded to different energy sources (people jumping, rocks dropping, and rubber mallet impacts). To model strike-slip fault motion, we also used a washing machine drip pan loaded with 150 pounds of sand that we attached to a car bumper using 4 × 48 inch bungee cords. For the experiment, the instructor drove forward at speeds of ∼5 mph, and the students recorded the “strike-slip” motions. Students studied individual event recordings and the collective suite of data presented as record sections. Concepts such as wavespeeds, wave types, noise, moveout, and reverberations were all discussed. These data exhibit several distinct sets of waves with different frequency characteristics that the students analyze. We found that when students record the data they study, they become more engaged in analyzing the results and postulating what the data impart.