SM
Seismology

Seismology

Molding seismic surface waves

Following each major earthquake that occurs close to nearby cities many people wonder what scientist and engineers can do to minimise the seismic hazard on society. Whilst scientist try to understand the mechanism of each fault system on the globe, engineers try to find solutions for buildings to be more safe.

One interesting experiment I came across lately is published in last month’s Physical Review Letters by Brûlé et al.,: Experiments on Seismic Metamaterials: Molding Surface Waves.

The authors show an experiment of a seismic test carried out using seismic waves generated by a monochromatic source. Measurements of the particles’ velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. This large-scale experiment was needed to show the practical feasibility of seismic metamaterials for complex natural materials such as soils and to stress their importance for applications in civil engineering.

medium

Top: The seismic testing device cross section in the x-z plane Middle: Photograph of the seismic metamaterial experiment. The 3 dashed perimeters account for the location of sensors, seismic metamaterial, and rotating source (a vibrating probe set on a crane). Bottom: Measurements for a monochromatic source. Experimental results map after interpolation between sensors: (a) the difference and (b) ratio of the measured energy field.

You can download the article here.

Earthquake shakes Twitter users and geeks do some science (oh, and celebrities said they felt it too)

The ever increasing use of mobile phones constantly connected to the internet is bring on a new era in scientific research called crowdsourcing. On Wikipedia crowdsourcing is the defined as the practice of obtaining needed services, ideas, or content by soliciting contributions from a large group of people, and especially from an online community.

In recent years social media is being used as a real-time earthquake alert mechanism and disaster response. A case in point is the use of Twitter. People are increasingly becoming more expressive about their daily activities and tend to post immediately any ‘extra ordinary’ life experiences such as an earthquake. Along with these textual or photographic posts comes through hidden, important information such as the time and geographic location of when the post was sent. Several scientific researches have used Twitter for the purpose of real-time earthquake detection, for example: Sakaki et al., 2010, Earle et al., 2010Crooks et al., 2013.

Earthquake in LA

Last month California was under (or on top) of a series of earthquakes. Shaking was captured live on TV during a news broadcast.

Many have used the internet to search for scientific information about the earthquakes either by visiting the USGS website or other websites such as the EMSC:

Internet quake detections at EMSC. Internet activity at EMSC following earthquake in Los Angeles.

Internet quake detections at EMSC. Internet activity at EMSC following earthquakes in Los Angeles.

…while others took on to Twitter to report their experience, including celebrities. The USA media went into a frenzy with reporting about the tweeted reaction of worldwide famous movie stars and artists. So what did the celebrities say after all?

Paris Hilton: OMG! Did anyone just feel that Earthquake? So scary, woke me up out of an already scary nightmare. I hate earthquakes. 🙁
Kim Kardashian: Earthquake was scary? Were all ok though! Anyone else feel it?
Hilary Duff: Good morning guys! We are all safe! Hope everyone else is too❤️not the most pleasant way to wake up with everything shaking

Job opportunity with EGU

The EGU is seeking to appoint a Communications Officer to work with the EGU Media and Communications Manager in maintaining and further developing media- and science-related communications between the EGU and its membership, the working media, and the public at large. The Communications Officer will also work under the direction of the EGU Executive Secretary on activities related to the promotion of the organisation. The position will be based at the EGU Executive Office in Munich, Germany.

Salary and starting date

The position, to start in July 2014, will be for two years initially, with the possibility of further renewal, and will be subject to one year of probation. Remuneration is according to the German public service pay scale and can be up to E13 TV-L, depending on expertise and experience.

Informal enquiries about this position can be made to the Media and Communications Manager, Bárbara Ferreira (media@egu.eu, +49-89-2180-6703). Applications should be addressed to Bárbara Ferreira and Philippe Courtial and be submitted by e-mail in a single file to vacancy@egu.eu by 8 May.

More information about this vacancy, including main tasks, requirements, application materials, and salary and starting date, is available at
http://www.egu.eu/news/105/job-opportunity-at-the-egu-executive-office-communications-officer/

PDF: http://static2.egu.eu/media/filer_public/2014/03/18/comms_officer_advert.pdf

Have you been drinking Guinness for St Patrick’s?

bubbles

Numerical simulations of bubbly flows for the pint and anti-pint.. The curves show the streamlines for the bubbles, the colour shows the void fraction f. The snapshots displayed correspond to t = 4 s.

Yesterday was St Patrick’s day, celebrated world wide, probably with a pint of Guinness. Perhaps while sipping down a pint you may have wondered why do bubbles in Guinness sink? Here is one-of-a kind paper that discusses just this! They concluded that the flow in a glass of stout depends on the shape of the glass. If it narrows downwards (as the traditional stout glass, the pint, does), the flow is directed downwards near the wall and upwards in the interior and sinking bubbles will be observed. If the container widens downwards, the flow is opposite to that described above and only rising bubbles will be seen (
http://arxiv.org/abs/1205.5233).

Read it all here:
http://arxiv.org/pdf/1205.5233v1