SBA Seismology Lab (SBCA)

Welcome to the Sitting Bull Academy Seismology Lab. We are an educational resource for the school and community. The lab began gathering data in 2006 and is now in full-time operation (except during power interruptions, computer crashes, and system maintenance). Our official network designation is SBCA (Sitting Bull - CAlifornia).

We are part of a larger network of school-based seismographs funded and coordinated by IRIS (Incorporated Research Institutions for Seismology) and their Seismographs in Schools (SIS) program. We are proud to be one of the more active stations in the program, and we are currently assisting with beta testing of new display and analysis software. To learn more about the Seismographs in Schools program, visit the Seismographs in Schools program web site.
 
Current Seismogram
The seismogram below is updated every 10 minutes. Click it to open a larger version in a new window. (This page automatically updates every 2 minutes, or you can click here to refresh your browser window.) To view records of recent seismic events, see the Recent Events section at the bottom of this page.

The seismogram displays the data collected over the previous 24 hours. The vertical (Y) axis of the seismogram shows the date and hour in Coordinated Universal Time (UTC). To convert to Pacific Standard time, subtract 8 hours; to convert to Pacific Daylight Time, subtract 7 hours. Minutes past the hour are displayed on the horizontal (X) axis. (Click the image to enlarge.)

September 3 Update
As of about 00:50 UT September 4, we have installed a new version of the jAmaSeis software that corrects the problems we were having with negative readings. Everything seems to be working nicely now! Our thanks to the jAmaSeis programming team for their dedication in hunting down and fixing the error.
 
 
 

Equipment

Our equipment consists of an AS-1 vertical seismograph and jAmaSeis software. This equipment was provided through the Seismographs in Schools program.

The AS-1 seismograph measures the vertical (up and down) motion of the ground, and archives the data on computer for study and analysis by Sitting Bull Academy staff and students. The AS-1 is sensitive enough to detect nearby weak earthquakes (Magnitude 2-3) as well as major quakes (Magnitude 7 and higher) worldwide. Since we live in a geologically active region, we detect many earthquakes and aftershocks every month. We have recorded as many as dozens of quakes within a single 24-hour time span.


What can we measure?

By carefully measuring the difference in the arrival times of the earthquake waves, we can estimate the distance to the earthquake's epicenter. Locating the epicenter requires the triangulation of distances using data from three or more seismograph recordings. Knowing the distance to the event, we can also estimate the quake's intensity, or magnitude.

Where is the SBCA Seismology Station?

We are located in the Sitting Bull Academy Upper Campus Library - specifically, in the Technology Office, Room 204. The seismograph itself sits on the hard floor in the far corner of the room, away from footsteps and other disturbances.

Sitting Bull Academy Seismology Lab


USGS Recent Earthquakes

QuakeMonitor(USGS)



Recent Events
 
Click the thumbnail images below to view seismograms of recent events:

5 September 2012 14:42:10 UTC, 60 km (38 mi) SSE of Liberia, Costa Rica (M 7.6)

Apple Valley is about 4200 km (2600 mi) away from the epicenter of this quake.


This earthquake "rang" Earth like a bell for over 2 hours! Here's what the whole event looks like on a single time line.



23 January 2011 05:30:01 UTC, Lázaro Cárdenas, Baja California, Mexico (M 4.3)

This seismogram shows four quakes, but only three are known. The three quakes shown here are:
 


18 January 2011 20:23:17 UTC, Southwestern Pakistan (7.4 Mw)

This image shows the normal seismograph display. The time of the event is marked on the image, as well as the time the first waves were detected by the SBCA Seismograph. The total travel time was about 20 minutes through Earth's interior. The quake was strong but very far away (over 6700 miles or nearly 11,000 km). These distant quakes are called teleseisms. Click to enlarge.

Filtered for high frequency (short period) waves

The data recorded by the seismograph can be mathematically filtered to enhance the detection of different types of seismic waves. In teleseisms, the short period waves die out pretty quickly. Longer period waves (from 10 - 1000 seconds) travel greater distances, and may continue for hours after the event. In a sense, the quake "rings" earth like a bell, causing the whole planet to vibrate. This image shows the data enhanced to show these lower frequencies. Click to enlarge.

Filtered for low frequency (long period) waves

15 December 2010
This seismogram shows 5 events in less than 5 hours, all near Brawley, CA: (plus a few smaller ones - can you find them? Also, notice that numbers 4 and 5 overlap. Cool, huh?) This set of events provides a good comparison of different magnitude events at the same distance from the seismograph. Compare the record of the M3.3 with the M4.3 event. A magnitude increase of 1 represents an increase of energy by a factor of 32; a magnitude difference of 2 represents 1000 times as much energy released!
  1. 15:27:47 M3.3
  2. 18:59:15 M3.7
  3. 19:16:47 M4.3
  4. 19:33:41 M3.4
  5. 19:35:03 M3.8
  6. 19:44:33 M3.1

More to come!
 
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