Last night we had an earthquake in the Bismarck Sea, a region that is formed by an oceanic spreading ridge and bordered to the north and to the south by subduction zones. This M = 5.3 earthquake is small in…
Amlia fracture zone earthquake: Update #1
While in my slumber, the USGS prepared a moment tensor and another aftershock occurred. Below is an updated map to my initial report here. I plot this moment tensor, which shows a compressional mechanism. I placed a moment tensor /…
Earthquakes along the Amlia fracture zone!
There were just a few earthquakes in the mid 5 magnitude range. The first one was largest, so we would consider the others aftershocks. They appear to align north-south, so may be related to the Amlia fracture zone. The Amlia…
Earthquake in Bayside (northern California)!
We just had a small earthquake in northern California. Here is the USGS website for the M = 3.4 earthquake. If you felt it, please go to the USGS “Did You Feel It?” website to fill out a report! This…
Earthquake in Vanuatu! (western Pacific)
We just had an earthquake in the Vanuatu region, along the New Hebrides subduction zone. This earthquake is at great depth and will most likely not produce a tsunami. The USGS magnitude is currently set at M = 7.3. UPDATE:…
10/23/2015 Inaugural Cascadia GeoSciences Present
You’re invited to come network with old friends and colleagues, meet new ones, enjoy a locally-made beverage, maybe learn something and share your local knowledge with others. Cascadia GeoSciences presents: A Research Presentation by Todd B. Williams and Dr. Jason…
Cascadia subduction zone: Tectonic Earthquakes of the Pacific Northwest
IRIS and the US Geological Survey have recently produced an educational video about tectonic earthquakes in the region of the US Pacific Northwest. The project was funded by the National Science Foundation. The Video YT link for the embedded video…
Plate Tectonics: 200 Ma
Gibbons and others (2015) have put together a suite of geologic data (e.g. ages of geologic units, fossils), plate motion data (geometry of plates and ocean ridge spreading rates), and plate tectonic data (initiation and cessation of subduction or collision,…
Crescent City Tsunami Deposits: Sand Mine Marsh, 1700 A.D. Cascadia subduction zone earthquake generated tsunami
I collected some cores in the Crescent City region. The sedimentary evidence of the 1700 A.D. Cascadia subduction zone earthquake and tsunami is preserved in these cores. Watch the video below. Here is a composite of the two cores that…
2015.09.16 Chile Update #3
The aftershocks continue and will do so for weeks. Aftershocks from the 2011.03.27 Tohoku-Oki M 9.0 earthquake continue today. The decay rate for seismicity relates to characteristics of the fault called the b-value. The b-value can be determined/modeled in several…