LITTLE PICTURE: Comparing Seismograms From the M6.4 Alaska Earthquake 08/12/2018

A large #earthquake shaked #Kaktovik, #Alaska at 14:58hrs UTC (or 09:58 am CST).  The #focaldepth was 9.9kms and the #epicenter is ~48 polar degrees away from Spring, TX.  The #seismograms below present the #groundmotion recorded in Spring, TX from the M6.1 event.  The #figure shows a #comparison of seismograms recorded on two different #seismicinstruments at the same location – observations of differing #technologies and their associated #instrumentation sensitivities.

Top Image: Recording from the #EQ1 #EducationalSeismograph with a 10Hz filter applied.

Bottom Image: Recording from a #RaspberryShake with a bandwidth filter 0.1 to 1.2 Hz.





Interpreting a Seismogram: Indonesia 09 August 2018

Recording global #teleseismicwaves, particularly large #magnitude earthquakes, is exciting, but the quake itself has the potential for damages and a very dangerous event.  As #geophysicists, we seek to further our understanding of the Earth’s #geology below the #crust.  These large quakes give us this research opportunity,  The #seismogram below presents the #groundmotion recorded in Spring, TX from the 08/09/2018 05:25hrs UTC magnitude M6.9 powerful #Indonesianearthquake.  An interpretation of the #wavephases is also provided.  The seismogram was recorded on an #EQ1 #EducationalSeismograph.





The Generous Blessing Of HOPE: Part 2

** #SCIENCE PHOTOS ADDED ** Thanks to our generous #donors, we raised enough money on our #GoFundMe campaign to build (and donate) the #shakeboards seen below.

TXESP had the honor of hosting the #scienceactivity at the #Willis Community Breakfast on 06/27/2018.  Watching the site of giving and #service reminded us that our mission to share #scientificknowledge with the public is a great gift to give. Photographs demonstrate shake boards which facilitate learning concepts in: #geology, #geophysics, and #geohazard #engineering.


TEACHING MOMENT 2: Wave Propagation

#TeachingMoment 2:  This week, we have observed a very unique #seismic phenomenon through our #TX/#MA research collaboration.  While #Texas is close to #tectonicplatesboundaries, and #Massachusetts is located within a “stable” plate interior, the #teleseismicwaves may arrive at our two stations at different times!  When global earthquakes occur far enough away (>100 pol deg) from TX/MA, we can observe a #timedelay on the #seismographs (see below). 

The three examples shown demonstrate how these specific earthquakes arrived ~12 to 13 minutes earlier in #Boston than in #Texas !!  This is an effect of #wavepropagation, or how a seismic wave travels through the Earth.  Why do you think the seismic waves arrived ~12 to 13 minutes later in Texas?  The time difference is due to the type of geology between our two stations, how fast waves move through different types of #rocks, and overall distance (kms) between monitoring stations.

Shown below: Three #educationalseismograph recordings of #global earthquakes.  Top: Station E1TX (Spring, TX) operated by #TXESP.  Bottom: Heath School, Brookline (#Boston, MA) operated by #BCESP.



The 05 August 2018 Indonesian earthquake.


The 07 August 2018 Greenland Sea earthquake.


The 09 August 2018 Indonesian earthquake.



#TeachingMoment:  On 09 August 2018 at 19:21hrs UTC, a moderately-sized M5.6 #earthquake occurred.  If we compare two #seismographs, one located in Spring, TX and the other located in Brookline, MA, we observe a very common phenomenon – the #seismicevent is detected in #Texas, close to #tectonicplatesboundaries; but, the same event is not detected in #Massachusetts, located within a “stable” plate interior.

Shown below: Comparison of two #educationalseismograph recordings of an earthquake in #CentralAmerica.  Top: Spring, TX.  Bottom: Brookline (#Boston), MA



Twice the Dice – Greenland Sea and Columbia

On 07 August 2018, two #earthquakes were recorded by Station #E1TX.  The #epicenters of both quakes are shown in the #maps below.  The first event, in the #GreenlandSea was at 13:57hrs UTC, a strong M5.8 and a shallow #focaldepth of 10 kms.  The second event, 2 hours later, occurred in #Columbia at 15:53hrs UTC, M5.4 and a deep focal depth of 148 kms.  It is always fascinating that we can detect #teleseismicwaves traveling across the globe!  The Columbian #seismogram is a nice recording of several seismic #wavephases.

Shown below: A map of the epicenters (highlighted in blue) of the two earthquakes on 08/07/2018.



Screenshot of the two moderate earthquakes recorded at Station E1TX


Epicenter of the 08/07/2018 M5.8 Greenland Sea earthquake.


Seismogram of the 08/07/2018 Greenland Sea event.


Epicenter of the 08/07/2018 M5.4 Columbian earthquake.


Seismogram of the 08/07/2018 Columbian event.

Trio Shake Guatemala

On 04 August 2018, two similar #earthquakes shook #Guatemala.  The #epicenters of both quakes were proximal to each other (see in map below).  The first event was at 05:46hrs UTC, M4.9 and a depth of 37.7 kms.  The second event, 5 hours later, occurred at 10:27hrs UTC, M5.1 and a depth of 35 kms.  

Today, 09 August 2018, the largest of three recent Guatemalan earthquakes occurred at 19:21hrs UTC with a magnitude M5.6 and a focal depth of 30.2kms. If you look closely, the three #seismograms look very similar suggesting the #seismicwaves traveled similar paths towards Station #E1TX, operated by #TXESP.

Shown below: A map of the epicenters (highlighted in blue) of the Guatemalan earthquakes on 08/04/2018 and 08/09/2018.



Screenshot on 08/04/2018 of two Guatemalan earthquakes.


Epicenter of the 08/04/2018 at 05:46hrs UTC, M4.9 earthquake.


Seismogram of the 08/04/2018 at 05:46hrs UTC event.


Seismogram of the 08/04/2018 at 10:27hrs UTC event.


Epicenter of the 08/04/2018 at 10:27hrs UTC, M5.1 earthquake.


Screenshot of the 08/09/2018 at 19:21hrs UTC M5.6 Guatemalan earthquake.


Epicenter of the 08/09/2018 M5.6 Guatemalan earthquake.


Seismogram of the 08/09/2018 M5.6 event.

Missouri, DYFI?

#Missouri residents, were you awoken this morning by a light #shake or rattling noise?  Today at 09:56hrs UTC (04:56 CST) a small #magnitude M2.6 #earthquake occurred near #WestPlains.  We wouldn’t expect you to feel this earthquake, but it’s possible it may have made your knees wobble – let us know!

Shown below: A map of the #epicenter (highlighted in blue) of the West Plains, Missouri earthquake on 08/03/2018.




A closer look at the El Salvador seismogram recorded on the EQ1 Seismograph.


Epicenter of the July 27th, 2018 Offshore, Northern Atlantic Ocean M5.1 earthquake.


Comparing the N. Atlantic seismograms recorded on the EQ1 and Raspberry Shake Seismographs.