30 May 2008 -- The great Sichuan earthquake caused the ground in Colorado to shake up and down by 1mm!
Eight gPhone Gravity Meters Simultaneously Capture Sichuan, China Earthquake
2008 Sichuan earthquake
 |
| Date |
May 12, 2008 |
| Magnitude |
8.0 Ms / 7.9 Mw |
| Depth: |
19 kilometres (12 mi) |
| Epicenter location: |
31°01′16″N 103°22′01″E (Sichuan earthquake)
(Wenchuan County in Sichuan province) |
The 2008 Sichuan earthquake (Chinese: 四川大地震), or Great Sichuan Earthquake which measured at 8.0 Ms and 8.3 Mw according to the China Seismological Bureau, and 7.9 Mw according to USGS, occurred at 14:28:01.42 CST (06:28:01.42 UTC) on 12 May 2008 in Sichuan province of China. It was also known as the Wenchuan earthquake (Chinese: 汶川大地震), after the earthquake's epicenter in Wenchuan County in Sichuan province. The epicenter was 80 kilometres (50 mi) west-northwest of Chengdu, the capital of Sichuan, with a depth of 19 kilometres (12 mi). The earthquake was felt as far away as Beijing (1,500 km away) and Shanghai (1,700 km away), where office buildings swayed with the tremor. The earthquake was also felt in nearby countries.
The earthquake signal was detected on six different gPhone gravity meters that were under test at Micro-g LaCoste, Inc. (Lafayette, CO). Each gPhone recorded gravity data at 1 second intervals. The first graph shows 14 hours of data plotted at 1 second intervals starting at 00:00:00 GMT on 12 May 2008. There are actually 8 different lines plotted using different colors in the graph but the agreement between meters is so good that only one line is visible.
Gravity from Six gPhones
The next graph shows 5 minute time slices of the gravity data. There are actually 8 different lines plotted using different colors in each graph but in most cases the agreement is so good that only one line is visible. You may select different time slices by clicking on the right/left arrows. You can also enter the starting time of the time slice into the textbox.
The velocity was calcuated for each instrument by integrating the position. This signal is similar to what would be measured by a seismometer. Notice that the velocity more clearly shows another signal at around 750 minutes due to the surface waves traveling around the globe. There are actually 8 different lines plotted using different colors in the graph but the agreement between meters is so good that only one line is visible.
Velocity from 6 gPhones
The next graph shows 5 minute time slices of the gravity data. There are actually 8 different lines plotted using different colors in each graph but in most cases the agreement is so good that only one line is visible. You may select different time slices by clicking on the right/left arrows. You can also enter the starting time of the time slice into the textbox.
|
