This Special Event web page is intended to provide direct links to and images of data and materials available from IRIS programs and preliminary research results from the seismology community. We welcome any additional contributions containing original content that might be of interest to the research community. Please send them to the email address listed below.
IRIS does not necessarily endorse the views or scientific validity of the posted items.
January 23, 2018 M7.9 Gulf of Alaska earthquake
Email contributions to:
All scientific contributions addressed to the community will be forwarded to the special-events mailing list. If you DO NOT want your email being forwarded, please address it to IRIS or explicitly write do not forward.
Email contributions to: ¶
Event parameters (from USGS) ¶
These are preliminary results and are subject to change without notice. Please check the USGS page for the latest official information.
|UTC Time||Tuesday January 23, 2018 at 09:31:42 UTC|
|Region||Gulf of Alaska|
|Distance||280km SE of Kodiak, Alaska|
|Details||USGS Executive summary page|
- IRIS Earthquake Sci, @IRIS_EPO
- Alaska Earthquake Center, @AKEarthquake
- Stephen Hicks, @seismo_steve
- Anthony Lomax, @ALomaxNet
- patton_cascadia, @patton_cascadia
- Jascha Polet, @CPPGeophysics
Videos & Animations ¶
[IRIS DMC GMV Product] Alaska view of the Ground Motion Visualization (LHZ,LHN,LHE)
M7.9 earthquake, GULF OF ALASKA
Miscellaneous Contributions ¶
M7.9 Alaskan Earthquake recorded in Nevada using the Raspberry Shake (4.5 Hz) and a 1 Hz geophone
[Jim O'Donnell, HHseismic] The M7.9 event was recorded on two sites recording with Raspberry Shake (RS) seismometers (Z component); One at Nevada State College (Henderson) and one in Boulder City, 11 Kms separation, see Figures 1and 1aa. The Boulder City site also had 4.5, 2.5 and 1.0 Hz geophones recording on a Sigma 4 recorder for comparison. The comparison is quite good as can be seen in the Time Series and the Amplitude Spectra below for the RS and 1 Hz geophone. The RS uses a standard 4.5 Hz geophone (29V/m/s) while the 1 Hz geophone has an output of 200V/m/s. For many years prior to the development of Broad Band seismometers, like the Guralp CMG-3T in ~1980, the 1 Hz geophone was a very popular sensor in recording earthquakes in the western US.
The RS uses an inverse filter, in real time, to extend the frequency response from 4.5 Hz (~0.2s) to 0.2 Hz (5s). The 5s (0.2 Hz) response was modified to a 20s (0.05 Hz) response with a digital inverse filter. Consequently all the sensors (geophones) had the same response which was extended to f=0.05 (20s). This works quite nicely if you can stay above the noise of the recorder/sensor. Both the programs used to process the data and apply the Inverse filters were: WinQuake (Larry Cochrane-Public Seismic Network) and Sigma 4 (John Giles- Seismic Source Company). The RS also comes with adequate software to enable you to output rough plots and mini-seed format for further analysis (http://www.raspberryshake.org).
IRIS DMC Event Page
The IRIS DMC event page for this event contains links to additional tools and data.
These other pages were tagged similarly:
- Hawaii [Special Event: 2018-05-04]
- North of Anchorage, Alaska [Special Event: 2018-11-30]
- Central California [Special Event: 2019-07-04]
- Northern Peru [Special Event: 2019-05-26]
- 2017 North Korean nuclear test [Special Event: 2017-09-03]
- Are You Ready? Introducing Research Ready Data Sets (RRDS) [Newsletter Article: 2018-03-26 Vol. 20, Num. 1]
- GMV2 [Product]
- Generalized GMVs: post-TA ground motion visualizations [Newsletter Article: 2025-12-28 Vol. 22, Num. 2]
- How do I interpret magnitudes and magnitude types? [FAQ]
- South Island, New Zealand [Special Event: 2016-11-13]