Monday, April 22, 2013

The Iran and China earthquakes as captured by the UNH seismometer

This past week has been has been a tense one for sure. Not only was there the Boston Marathon bombings and the fertilizer plant explosion in Texas, but there were also major earthquakes in both Iran and China.

The 7.8 magnitude event in Iran occurred on April 16th, near the Iran/Pakistan border. Pakistan bore the brunt of the quake, with at least 35 dead and an entire town essentially destroyed. You can view all the scientific/technical details of the event on its USGS page. We can see the earthquake quite clearly on the UNH seismometer. The event hits our station at 10:56 UTC (06:56 am EST). The shaking intensity when the surface wave hits is strong enough that the seismic wave looks clipped in the display (in green).

The magnitude 6.6 earthquake in China struck on April 20th. Although smaller than the Iran earthquake, this earthquake was very shallow and hit a more densely populated area. The latest estimates put the death toll at 188, with over 11,000 people injured and many are still missing. The USGS page for the event can be seen here.

It takes about 13 minutes for the initial P-wave from the earthquake to reach our station, and you can see when it hits if you look at the top black line. Just after the 30-minute mark on the same line, you can see the S-wave hit. The much larger amplitude surface waves can be seen in red, starting about 21:03 EST.

These earthquakes have devastated the villages they have hit, particularly the one in China. Construction in these small towns is often very old and not up to code. Landslides bury entire structures and block roadways, making it hard for aid to get to those who need it the most. 

My thoughts go out to everyone affected by this past's weeks events, both here in the US and abroad.

The UNH seismometer is part of the larger New England Seismic Network. You can visit their page here.

Saturday, April 20, 2013

Proposing a session on oceanic transform fault and intraplate environments at AGU!

Last year, while I was presenting my poster at the AGU Fall meeting, I realized that there is a small, but dedicated community of folks that study fault zone structure and processes related to oceanic transform faults. I had only met a few of them, but I wanted to do something to facilitate bringing everyone together for discussion and possible collaboration. I decided that I was going to propose an AGU session that specifically focused on oceanic transform fault research. I started off by talking to some other folks at the conference about it to gauge interest, and everyone I mentioned it to seemed pretty keen about the idea. Encouraged by the level of interest, I decided to move forward.

A friend of mine, Kasey Aderhold, is a PhD student at Boston University. Her research looks at strike-slip earthquakes in the ocean, both in the intraplate regions and along fracture zones. We decided to team up and propose a joint session, along with our respective advisors. We are pretty stoked about it, and hope that this session is successful in bringing everyone together. It will also be an invaluable experience for us, as students, to be able to convene an AGU session. Our advisors are both influential women in the field, and while I have nothing against all the male geophysicists out there, I am proud that our session is all woman-powered. 

We won't know until June if our session has been approved, but our fingers are crossed. If you know anyone who studies fault structure and/or seismicity in the ocean, feel free to share this with them. The more the merrier. It would be very exciting if we had enough abstract submissions to our session that we can have both a poster and oral session.

Saturday, April 13, 2013

Detecting Earthquakes at UNH

I've decided a great way to get back into blogging would be to show some of the great seismograms the UNH seismometer has been recording since we set it up in 2011.

While most of the signals we record on the station are from passing trains, we have also recorded some pretty impressive earthquakes.

Check out this seismogram from an earthquake swarm near the Solomon Islands on Feb. 8, 2013. In a little over 40 minutes, there were 3 large earthquakes. A magnitude 8.0 struck at 1:12 (UTC), followed by a 7.1 event 11 minutes later, and a 7.0 event 30 minutes after that. In addition, there were smaller magnitude 5's and 6's both preceding and succeeding these larger events. When the surface waves from the 7.0 event hit our station, surface waves from the preceding 7.1 and 8.0 event were already shaking it. In the image below, the signal is so strong that it actually goes off the page!

Remember the Colorado and Virginia earthquakes that occurred back in August of 2011? The UNH
seismometer captured those earthquakes as well:

While we are looking at more local events, let's not forget the small Maine event (magnitude 4.0) that occurred on Oct. 16 of last year. See that impuse response in green at the bottom of the chart in the image below? Well, that's it. The earthquake occurred very close to our station, so the P, S, and surface waves hit at nearly the same time. The response that we see in the long-period signal, therefore, is very sharp. I have to admit, I was quite excited when this earthquake occurred. This was the first earthquake that I really felt and realized what it was while it was occurring -- well, truth be told I first thought my furnace was about to explode, but only for the first second or two. In fact, I not only felt the earthquake, but I heard it. I actually heard the earth rumble.

Finally, let's look at a seismogram from a magnitude 6.9 earthquake that occurred on Feb. 02, 2013 in Japan. This is a great seismogram because we can clearly see when the P, S, and surface waves arrive at the station.

Pretty cool, eh? If you want to check out some seismograms for yourself, you can do so at the New England Seismic Network webpage. To view the UNH stations, click on current seismograms and select DUNH as the station.

Saturday, April 6, 2013

Still Alive!

So I know it has been a while since I have posted anything to my blog, but I was a bit shocked to learn that "a while" is actually almost 2 years.

In the past 2 years a lot has happened:

  • I passed my departmental exams and advanced to candidacy
  • I sailed as member of the scientific party on IODP Expedition 343: Japan Trench Fast Drilling Project (JFAST).
  • I was selected to participate in a NASA Social, during which I was able to go to the Jet Propulsion Laboratory in Pasadena for the landing of Curiosity, the Mars Science Lab rover
  • I got married to Kurt Schwehr, who is much better about updating his blog than I am mine
In the next year, I'll be wrapping up my research and getting ready to defend. As I do so, I am going to make an effort to keep my blog updated. 

I realize that not only has my blog been helpful to me, as I have often referred back to it to remember how I did something, but that it has also been helpful to others as well. Having something that I posted save someone else a lot of grief and head-banging is pretty sweet, and I hope that some of my future posts will continue to be beneficial to people.
So buckle up and hang on to your hats folks, here we go....