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For #SeismogramSaturday #SeismoTwitter I thought it would be interesting to talk about a lesser known seismic phenomenon called “slow-rupture tsunami earthquakes, or simply “tsunami earthquakes”.
There’s been some great info about the M 7.5 Ecuador earthquake a couple days ago, and this topic will discuss frequency content of earthquakes. Notably why earthquakes with the same magnitude may be very different from one another.
Tsunami earthquakes differ from other M 9+ tsunamigenic earthquakes such as the 2004 Indian Ocean earthquake and the 2011 Japanese earthquake. Tsunami earthquakes have more moderate-size magnitudes but produce large tsunami for their size.
Okay, #SeismoTwitter, it's (almost) #SeismogramSaturday! I'll be offline for most of Saturday, so I'm posting a little early. Here's today's seismogram! 
Today, we have show shaking caused by the M9.0 Tohoku earthquake on March 11, 2011. This figure shows shaking at a station in North Dakota (caused by a quake in Japan!).
The three wiggles here show how the ground shook in an east-west manner (top panel), north-south (middle) and vertical (bottom).
Hey #SeismoTwitter! I propose that we do #SeismogramSaturday, to teach about the world of our wiggles. Feel free to pick your favorite (or least favorite) seismogram to tell us about. We'll do it next week too.
I'll start. This is a normal little quake. Info follows:
I'll start. This is a normal little quake. Info follows:
First, a seismogram literally shows us how the ground shook when seismic waves reached the seismometer. The vertical axis is a proxy for this (I'll explain the units later).
This image shows a magnitude 2.0 earthquake that took place near Monroe, WA, a few days ago. No one felt it, since it was tiny and took place about 17 miles underground.
