Travel: Santa Fe and UNM

I was in Santa Fe last week for a conference, it is really beautiful there, even on the train from Albuquerque (highly recommend to take the train, cheap, relax and beautiful). I also visited University of New Mexico, thanks to Brandon and Chengxin, who hosted me there, I had a great time at UNM. Here are some pictures I took, and enjoy it!

On the train's 2nd deck

View from the train

Santa Fe

Albuquerque

University of New Mexico

Nice sayings I like

This weekend is the Chinese new year, happy new year everyone! I don't know what to write, therefore, I will turn this week's post into a page to keep the nice sayings I really like:

• To begin, begin. - William Wordsworth
• Sooner or later, those who win are those who think they can. - Paul Tournier
• The finest steel has to go through the hottest fire. - Richard M. Nixon
• It’s always too early to quit. - Norman Vincent Peale
• There are many ways of going forward, but only one way of standing still. - Franklin D. Roosevelt 
• Love the giver more than the gift. - Brigham Young
• The only way to discover the limits of the possible is to go beyond them into the impossible. - Arthur C. Clarke
• Man is so made that when anything fires his soul, impossibilities vanish. - Jean de La Fontaine
• Be faithful to that which exists within yourself. - Andre Gide
• Curiosity will conquer fear even more than bravery will. - James Stephens
• Dreams are necessary to life. - Anais Nin
• When your work speaks for itself, don't interrupt. - Henry J. Kaiser
• Every failure is a step to success. - William Whewell
• We must make the best of those ills which cannot be avoided. - Clarence Day
• Our entire life - consists ultimately in accepting ourselves as we are. - Jean Anouilh
• It is not how old you are, but how you are old. - Jules Renard
• Don't think, just do. - Horace
• It's better to be a lion for a day than a sheep all your life. - Elizabeth Kenny
• Failure is success if we learn from it. - Malcolm Forbes
• Millions saw the apple fall, but Newton was the one who asked why. - Bernard Baruch
• Believe and act as if it were impossible to fail. - Charles Kettering
• The art of being happy lies in the power of extracting happiness from common things. - Henry Ward Beecher
• The less you talk, the more you're listened to. - Pauline Phillips
• One faces the future with one's past. - Pearl S. Buck
• Cherish your human connections: your relationships with friends and family. - Joseph Brodsky

Paper: Structural Health Monitoring of Buildings Using Smartphone Sensors

Recently, our new paper - Structural Health Monitoring of Buildings Using Smartphone Sensors is out, which is part of our exploration of what MyShake data could be used.

Think about this: most of the smartphones will be used inside a building, for example, at night, your phone is in your building, and during the day, it is likely to be in your office building. If we could utilize the phones in the building to record the movement of the building during the earthquake, could we monitor the health state of the buildings? This is what we want to show in the paper by doing a shaker test, which you can find the description from my previous blog.

In the paper, we propose to use the smartphones to potentially extract the fundamental frequency of the building before and after the earthquake as a way to monitor the health state of the building. Why the fundamental frequency change can work as an indicator of the health state of the building? Let’s have a look below.

If we think we use a tractor pull the house with a rope, and what will happen if we cut the rope suddenly?

The building will start to move back and forth for a while as shown in the above picture. It is basically can be seen as an inverted pendulum that could oscillate at a certain frequency (or period if you are more familiar with this, the period is just 1/frequency). The building will move back and forth at certain period T, but with a decaying amplitude of the shaking.

Bud different buildings have different characters in terms of oscillation, some oscillate with high frequency (fast) and some oscillate with low frequency (slow) as shown in the above figure. A rule of thumb is the taller the buildings are, the lower frequency they are. The fundamental frequency reflects the nature of the building, with softer building have lower frequency.

Different earthquakes may cause various damages to the same building, with larger earthquakes causing more damage. These damages to the building will cause the building become softer, thus change the fundamental frequency of the building decrease.

Therefore, if we know the fundamental frequency of the building before an earthquake, and we could measure the fundamental frequency of the building during the earthquake, we may get a sense of how much the building damaged during the earthquake. This is our idea of using smartphone sensors to extract the fundamental frequency of the building during the earthquake, you could see the details in the paper.

Of course, there are still a lot of things need to be done to prove it, for one example, how do we find out which floor the phones are. But we do think that the smartphones to monitor the buildings is promising.

Acknowledgement:
The first figure I found online, but I couldn’t remember from where, but I thank the authors for making this image. For the rest of the images, it is all from NICEE - Earthquake Tips, which is a very nice series about the basics of earthquake engineering.

Using ArcGIS Online to create interactive map and share it easily

We talked how to use QGIS to generate a map with population and seismicity. This week, we will talk generate a similar map using ArcGIS online, but much easier steps and an easy sharing option. I think for creating a simple map, it is free, but if you want more advanced features, then it does cost to use it. I will show the free part of it, creating a simple map and share it. I will first show the results from it, you can get access to the map via this link. I can also embed this map here to show you how easy we can share an interactive map with the world using this method (try to move to different regions, or click the earthquake on the map):

How to make it

Now, I will show you how did I make it.

Step 1 Create a map

This step is relatively easy, you go the ‘Content’ tab after you signed in, and click the ‘Create’ button, and choose ‘Map’ as shown in the following figure:

Then you fill in all the informaiton about this map:

Step 2 Add the population data

After you filling in all the information to create a map, you will see something similar to the map below, and choose ‘Search for layers’ from the ‘Add’:

There are many layers online already, especially on the ArcGIS Online, therefore, let’s just search gpwv4 on the ArcGIS Online.

After I select the ‘GPWV4 Population Density, 2010’ layer, you can see the population data will show directly on the map. So simple!

Step 3 Add the earthquake data

Now, let’s add the earthquake data (I’ve already downloaded the worldwide earthquakes larger than M6 from 2006 to 2018, you can find it here). This time, we can directly add data from our local file, you can see the following two figures.

After you import the layer, you can see the earthquake data on the map (I was lazy to change the zoom in level on the map, therefore, you see them all squeeze into the center, you can just change it)

Step 4 Change the style

As we showed before, we want to show the earthquakes in different colors to represent depths and different sizes as magnitudes. We can do this by choose the magnitude as the attribute to show (there are many attributein the earthquake csv file)

We can add ‘depth’ as the other attribute we want to display:

Now we can see in the above figure that the system automatically shows different colors as magnitudes and sizes as the depth, let’s swap them:

We can change the fill color for the depth, and move the breaks on the left panel to set which color corresponding to the different depths, here I choose 100, which results in a legend 0 to 50, and 50 to 100, and 100 above. But I didn’t figure it out how to add more breaks, let me know if you know how to do it.

Do similar thing for the depth:

After you finish changing the depth and magnitude, now you can see we have a very nice map:

Select the Legend to see the legend for different data:

Step 4 Share the map

After you finish the map, you can easily share the map by just click the share button, if you choose everyone, anyone with the link showing there can get access to your map. Also, you can embed the map to your website as well:

More features

When you play with the map, you will soon find some more useful features, for example, if you click the one earthquake, you will find that all the information in the csv file for this earthquake will be shown in the popup window:

Also, if you don’t like the background map, you can easily change it by choosing different ones from the Basemap:

I hope you find this is useful.