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February Meeting: Massive Earthquakes and Tsunamis: Contributing factors revealed by IODP Exp 362 – Dr. Peter Vrolijk

Come join the FCGS for our February meeting!

Tickets/RSVP links found below description. If those links are not working, you can RSVP with this link:

Location: Fort Lewis College campus, Student Union Building, Vallecito Room.


5:30 to 6:30 pm: Happy Hour with Appetizers, Salads, Cookies, and Pizza

6:30 to 8:00: Business, Talk, and Raffle

Talk Abstract: 

On the day after Christmas, 2004, the world awoke to an immense tragedy – one of the largest earthquakes ever recorded (Mw 9.2) struck Sumatra in Indonesia.  In the following hours and days, the tragedy grew as a massive tsunami swept around the Indian Ocean and world, inundating coastal communities with tremendous loss of life.

Our appreciation of the variability of subduction zone earthquakes has grown in the past decades and encompasses non-destructive, slow-slip earthquakes, like those along the Hikurangi margin of New Zealand, and massive, destructive tremors, like the Sumatra earthquake (and everything in between).  IODP Expedition 362 sailed in summer of 2016 to evaluate whether the thick sedimentary section subducted at the Sumatra margin consists of materials that through burial and diagenetic processes could contribute to one of the largest earthquakes recorded and rupture the seafloor and trigger a devastating tsunami.  We discovered a ca. 1300 m turbidite fan section (Nicobar Fan) dominated by detritus eroded from the Himalayas and deposited within 7 m.y.  Early, low-temperature diagenetic reactions (opal transformations) were detected, and burial, thermal, and diagenetic modeling suggest that many diagenetic processes, like smectite-illite transformation, may be advanced by the time the sediments start subduction and may no longer contribute to overpressures created under the rapid loading of subduction.  Cementation processes, like quartz cement formation, may also have begun in the section prior to subduction initiation, further contributing to an overall stronger section than found at most subduction margins.  These results offer one more constraint on the myriad expressions of subduction zone seismicity.