4 Earthquakes Hit Off Oregon Coast – Is Cascadia Heating Up?

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Within the last 12 hours, 4 earthquakes hit off Oregon’s Coast – 2 along the Blanco fracture zone and 2 on the Gorda Plate.

Cascadia is heating up!

4 earthquakes hit off Oregon Coast on December 28 2019
4 earthquakes hit off Oregon Coast on December 28, 2019. Map via USGS

The Cascadia subduction Zone is currently releasing lots of pressure on its upper end. And now, quakes start quicking off near the lower end of the same Cascadia along the Blanco Fracture Zone and on the Gorda Plate.

The Gorda Plate and the Juan de Fuca Plate are two oceanic plates, subducting underneath the North American Plate in what is known as the Cascadia Subduction Zone.

The Blanco Fracture Zone is a nice transform fault zone that’s a bit like the San Andreas, only underwater. It forms the boundary between the Juan de Fuca and Pacific plates, and is around 200 kilometers west of the Cascadia subduction zone… Not so far…

As shown on the map above, within the last 12 hours, the Blanco Fracture Zone and the Gorda Plate were hit by 2 very shallow earthquakes, respectively:

Animation of Cascadia Earthquakes from 1979 to 2019

The widely-felt M6.3 earthquake of August 29, 2019 on the Blanco Fracture Zone was only the most recent of many moderate-size earthquakes to strike this region off of the Oregon coast.

As this animation shows, such earthquakes are common along the boundaries of the Juan de Fuca plate with the Pacific Plate, which also includes the Juan de Fuca Ridge, the Gorda Ridge, and the Mendocino Fracture Zone.

Fortunately these events rarely pose a tsunami hazard since the largest of these earthquakes tend to have strike-slip mechanisms that move the seafloor mostly sideways with little disruption to the ocean above.

The Juan de Fuca Plate meets the North American Plate, however, with a very different sort of plate boundary: a subduction zone.

This plate boundary can produce megathrust earthquakes with large vertical motions that cause devastating tsunamis.

It has been more than 300 years since the last time the Cascadia Subduction Zone generated such destruction, on January 26, 1700.

This subduction zone also created the volcanoes of the High Cascades, stretching from northern California into southern British Columbia.

To put the recent earthquake in context this animation begins 40 years earlier, in 1979. In that time frame 10 earthquake of M6.0 or larger occurred on the Blanco FZ and more than a dozen along the Mendocino FZ, some with M7.0 or larger.

The fracture zones off of Vancouver Island have also produced numerous earthquakes larger the M6.0, with one as large at M6.8.

The largest earthquake on the Cascadia Subduction Zone in the last 40 years was the M6.8 Nisqually Earthquake in southern Puget Sound on February 28, 2001.

The volcanic activity of Mt. St. Helens is also visible in 1980-1982 and 2004-2008.

As the area covered by the animation extends over North America, it also includes activity unrelated to Cascadia, such as the October 28, 1983, M6.9 southern Idaho earthquake and numerous small events associated with the Yellowstone Caldera.

This animation shows every earthquake in the USGS/NEIC catalog for the Cascadia region. As the animation approaches the present day, seismometer networks are able to detect smaller and smaller earthquakes, creating the illusion of increasing activity. In reality these smaller earthquakes have always been there, but the technology has only recently been able to detect them. [Youtube]

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2 COMMENTS

  1. Since full moon 2019 quakes ,fires, ice age , global hit waves and also since last 2019 of sun eclipse with all quakes waiting to happen. After aero planes crashed in world wide now this emergency news, Fifteen people reported stabbed in rabbi’s home by man who burst in and pulled out a machete at a Hanukkah party before going on the run in upstate New York

    By Ariel Zilber For Dailymail.com
    22:35 EST 28 Dec 2019 , updated 23:59 EST 28 Dec 2019
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    Latest From MailOnline

    Fifteen people reported stabbed in rabbi’s home by man who burst in and pulled out a machete at a Hanukkah party before going on…
    Pictured: Pilot, Wisconsin mom and her 13-year-old daughter killed in Hawaii helicopter crash that left seven dead – as rescue…
    Horrific incident took place in the small, predominantly Jewish hamlet of Monsey in Rockland County, New York
    Reports circulating on social media indicate African American male with machete stabbed 15 people
    Local Hassidic community officials say that two of the victims are listed in critical condition
    They say the suspect was wearing a scarf that was partially covering his face but could see part of his skin
    The suspect is said to have fled the scene in a gray Nissan Sentra with license plate HPT5757
    An assailant stabbed multiple victims in a rabbi’s home during a Hanukkah party in the small upstate New York town of Monsey late on Saturday night, according to several social media reports.

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    Video circulating on Twitter shows emergency vehicles and ambulances hurriedly evacuating victims from a home on Forshay Road in Monsey.

    That home is believed to be next to a house of worship. It belongs to Rabbi Chaim Leibush Rottenberg.

    Rottenberg is the leader of Congregation Netzach Yisrael-Kosson. Locals say that about 300 people pray every Saturday at his congregation.

    One local report is claiming that an African American man armed with a machete stabbed at least 15 people after entering the home.

    Reports indicate that Rottenberg was leading a candlelighting ceremony for the seventh night of Hanukkah when the assailant barged into the house.

    Two of the victims are said to be in critical condition. I predict till January 3 2020 we will have more of the same indeed . Iran, China, Russia mother of all exercises and attack on our troops in Iraq orchestrated by terrorist ayatollahs, world is brink of world war 3 indeed.

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