M 7.1 offshore Honshu Japan

Posted on October 25, 2013 by Jay Patton

Extensional earthquake in Pacific plate “up-dip” of the 11 March 2011 Tohoku-Oki earthquake.
Here is the USGS page.
Here is the moment tensor:

Here is a map of the epicenter and Japan:

Here is a map of the epicenter and Japan with historic seismicity (dominated by 2011):

Here is a zoomed in map of the epicenter and Japan with the “did you feel it” overlay on land:

Here is a zoomed in map of the epicenter and Japan with the Intensity Contours plotted:

Here is the usgs map for the region:

Here is what it looks like on HSU’s Benioff (photo credit to Amanda Admire):

Here is the national tsunami warning center information bulletin:

Here is the Japan Meteorological Society Page
All warnings and advisories have been lifted It appears that small (~30cm) waves were recorded along the coast in Japan.
Here is the moment tensor page:

Here is the PAGER page:

Hookton Slough Coring

Posted on October 20, 2013 by Jay Patton

Tom Leroy and I went to my old coring site 01-BR-05 to make sure it was usable as a field trip stop for my class. We will be going here this coming Wednesday. Thanks Tom for helping me out.
I will write more about these cores and what our interpretations are after the field trip. I want the class to come up with their own interpretations. I have a few photos of the core we collected today.
This is an overall view of the 3rd core section down. This core samples sediment of approximately 1 meter in length. This core sampled sediment from approximately 1.8 to 2.8 meters. Up is to the left. The base of the core includes blue-gray silty-clay, overlain by an organic rich brown muddy peat, overlain by a clean mud and then a series of muddy sand and sandy mud layers, which is finally overlain by some more mud. Some of the mud has darker grey layers.
Here is an overall view of the middle of the core.
Here is a “zoom in” of the middle of the core.
Here is a map of the regional tectonics.

M 6.4 Gulf California

Posted on October 20, 2013 by Jay Patton

Strike Slip in the Gulf. These transform faults connect the Cascadia subduction zone (CSZ) with the Middle America trench (MAT). Transform faults are strike skip fault systems that connect spreading mid oceanic spreading ridges. The northern end of this transform fault system begins at the Gorda rise offshore northern California with the Mendocino fault. Next in line is the San Andreas fault system, which is composed of many many different faults. The SAF system extends into the Gulf of California where it meets a spreading ridge/transform stepped fault system that is causing the Gulf of CA to open up (similar to the Atlantic Ocean opening up ~105 Ma). The gulf of CA is unzipping and this unzipping is heading north. Some day the east side of the Sierra Nevada’s will look across the Gulf.
Here is the USGS page where i got many of these resources.
Here is the moment tensor. This is probably representative of a northwest striking right-lateral slip on a strike-slip fault. This is the orientation of the transform faults in this region.

Here is a map that shows the epicenter as it relates to the general plate tectonics of the region.

Here is a map that shows the epicenter as it relates to the general plate tectonics of the region with historic epicenters.

Here is a map that shows the USGS interpretation of regional faulting, earthquakes, and subduction geometry.

Here is a map that shows the epicenter as it relates to the local faulting.

Here is a map that shows the epicenter as it relates to the local faulting with historic epicenters.

Here is a map that shows the epicenter as it relates to ground shaking models of MMI (Modified Mercalli Intensity).

Here is a map that shows the epicenter as it relates to ground shaking models of MMI (Modified Mercalli Intensity) with historic epicenters.

Here is a map that shows the epicenter as it relates to ground shaking models of PGA.

Alaska Earthquakes

Posted on October 18, 2013 by Jay Patton

The 1964 Great Alaska Earthquake occurred on Good Friday, March 27th. It and rocked the state with strong ground shaking for 4.5 minutes. At magnitude 9.2, it was the second largest quake ever recorded by seismometers.
This animation shows the underlying causes of that earthquake, and tells how research done on the ground deformation contributed to confirmation of early theories of plate tectonics.
Here is a download link for the embedded video below (85 MB mp4).

Animation & graphics by Jenda Johnson, geologist
Directed by Robert F. Butler, University of Portland
U.S. Geological Survey consultants: Robert C. Witter, Alaska Science Center Peter J. Haeussler, Alaska Science Center
Narrated by Roger Groom, Mount Tabor Middle School
Maps from Google Earth. Video from US Army Corps of Engineers. Tsunami animation from National Oceanic & Atmospheric Administration (NOAA). Photographs from US Geological Survey.
Errata: 1) Fourth Ave., not Fourth St. 2) After 2min48sec the epicenter was shifted N. Should be ESE of that, closer to Prince William Sound. Apologies from animator.
Youtube Source IRIS
WMV file for downloading.

M 7.1 Panguna, Papua New Guinea

Posted on October 16, 2013 by Jay Patton

Here is a deep one (currently) and a big one. There may be a local tsunami, but there are no focal mechanisms yet. Ill add those when they become available.
Here is a screenshot from the
Here is a map that shows the epicenter as it relates to the general plate tectonics of the region.

Here is a map that shows the epicenter as it relates to the general plate tectonics of the region with historic epicenters.

Here is a regional map that shows the epicenter as it relates to the region.

Here is a regional map that shows the epicenter as it relates to the region with historic epicenters.

Here is the map of the local tectonic setting from the USGS.

Mw 7.1 Phillipines 2013.10.15

Posted on October 14, 2013 by Jay Patton

Fairly big earthquake. Sounds like it has caused some damage. Farly big earthquake. Sounds like it has caused some damage. Looks like a thrust or reverse earthquake, USGS poses the fault is in the Sunda crust. Fairly deep earthquake, but this is continental crust i believe, so might not be too deep after all.
Here are some news web sites reporting of damage:
FOX news
CNN news
Al Jazeera news
CBC news
WSJ news
Here is the USGS moment tensor page

Here is a map that shows the epicenter as it relates to the general plate tectonics of the region. the Philippine plate is subducting westward beneath the Sunda plate, part of the Eurasia plate. The island of Sumatra is on the western side of this plate, where the India-Australia plate subducts northeasterly to form the Java, Sumatra, and Andaman subduction zones.

Here is the same map with historic earthquakes plotted. Note how they outline the plate boundaries.

Here is a map zoomed into the region.

Here is the same map with shaking intensity plotted.

Here are the PAGER data (estimates for the amount of people or fiscal damage).

Here is the PAGER map (estimates for the amount of people or fiscal damage).

Here is the map of the local tectonic setting from the USGS.

Ken Aalto Talk on the Franciscan Today 10/14/13

Posted on October 14, 2013 by Jay Patton

Today at HSU Founders Hall Room 25 at 5PM

Mw 4.9 Trinidad 2013.10.11

Posted on October 11, 2013 by Jay Patton

All right! That was exciting and a little bit scary. Most all earthquakes scare me because I recognize they might get bigger or trigger a bigger one.
This earthquake is most likely on a northeast striking strike-slip fault in the downgoing Gorda plate. The GP is caught in a vice between the older and stronger North America and Pacific plates.
Here is the moment tensor

Here is the seismogrpaph at HSU (photo credit Lori Dengler)

Here is a map I made in google earth showing historic earthquakes. Note the larger gray circle to the northeast of today’s earthquake. That is the 1980 Mw = 7.2 earthquake that caused extensive damage in Humboldt County (knocking the bridge partly down on hwy 101 near CR). Today’s earthquake appears to be along the same fault system that ruptured in 1980:

Here is the seismogrpaph at Jacoby Creek (data credit Lori Dengler). The vertical lines are six seconds apart.

Here is a map that Chris Rollins used in his 2010 paper. It shows historic seismicity in this region, including the 1980 swarm.

Here is a map that I made in google earth that shows the shaking intensity (Modified Mercalli Intensity Scale).

Here is a map that I made in google earth that shows the % Peak Ground Acceleration (% of g, where g is defined as 9.8 m/s^2).

These are the models for tectonic deformation within the Gorda plate as presented by Jason Chaytor in 2004.

Here is the SCEC page: http://www.data.scec.org/recenteqs/Quakes/nc72086051.html
Here are the seismologic information:

Here is the SCEC map I went to before it showed up on the USGS page. Note that no magnitude had been assigned yet: