Today I learned that the largest and longest ever recorded silent earthquake occurred in none other than Acapulco, and the area around it. Honestly, I also learned about the existence of such an event today as well, a phenomenon that's apparently new to the science world in general as a concept. Moving here, I vaguely knew that I was moving to an earthquake zone, but I really didn't think much into it. I didn't know much about earthquakes at the time, and being on the run I was more focused on getting out than learning a lot about where I was headed. I got the important information, like cost of living and potential for freedom and ran with it. Now that I've been here awhile, I've started to learn a lot about my environment, which is ever changing!
No Quakes for Months, Then BANG
In the first several months I was here, I didn't actually feel any of the earthquakes that my community members were discussing, which was somewhat disappointing. Then one night one so strong and loud woke me up out of a dead sleep, that was my first real earthquake. We noticed a rumbling for half a minute and the neighborhood dogs freaking out. The ground started to shake and we heard a loud crack, ending the quake. We've had several that I've noticed, since that first one, but none of that magnitude. There's generally just a prolonged rumbling sometimes ending with a bang.
Lots of Little Quakes in Acapulco, Recently
In the last week or so, we've noticed an increase in the frequency of our local earthquakes. We've experienced several in a short amount of time, something that's a little out of the ordinary. One of the community members was looking into it (or maybe he just looks into this stuff in general, not sure on that one) and found that Ben Davidson, someone famous for predicting earthquakes and other seismic events, had put out an alert, saying that the Acapulco area had a higher chance of experiencing an earthquake with magnitude up to 7.4 now, than any other time. This alert was put out before our recent string of quakes, which were around a magnitude of 4-5.
Community Raising Awareness, Peaking Interest
This community member made a group and started sharing information about this alert, as well as information on the 2001 giant silent earthquake that occurred in this area. The purpose of the group is to help keep those interested informed of any alerts or other seismic news relating to the area. Upon looking over the information, I realized that I knew very little about earthquakes, especially silent earthquakes so I went and did a little research myself on the topic.
5.7 Magnitude Quake That No One Noticed, For Awhile!
I found that it's actually a fairly new concept to science. There was a pretty large one in November of 2001 in the main island of Hawaii, noted the largest quake in that area in more than a decade. 2000 cubic kilometers of the southern slope of the Kilauea volcano slid 10cm further into the ocean over 36-48 hours, recording a 5.7 magnitude earthquake, spread out over that time. The crazy thing was that no one noticed (not even the seismologists!) until after the fact, it was such a slight and slow change. It was awhile before scientists noticed and investigated what happened.
Four Different Ways for Pieces of the Planet to Collide!
There are four different types of seismic zones. The first follows the line of mid-ocean ridges and has pretty mild activity, as there isn't enough pressure built up for large earthquakes. The second is referred to a shallow focus event (meaning it happens on the surface) without volcanic activity, meaning two mature plates are rubbing together. This is the source of large violent earthquakes.
Swallowing Ocean, Making Mountains
The third kind is related to the collision of continental and oceanic plates, where one gets swallowed by the other, generally the continental plate swallowing the oceanic plate. This is the type that exists off the coast of Guerrero, and in many places where silent earthquakes are common. The fourth occurs between boundaries of continental plates, often resulting in large severe mountain ranges, like the Himalayas.
Largest Silent Earthquake Ever Recorded!
The largest recorded silent earthquake happened along what is referred to as the Guerrero seismic gap, shown in the diagram above. This is essentially the fault line, where the subduction zone (which is the area where tectonic plates meet, and seismic events occur) exists. These zones seem to exist right along the coast line and the Guerrero seismic gap is about 60 km wide and a 200 km long gap, capable of a lot of seismic activity. What happened started in October of 2001 and lasted for 6-7 months before it stopped, reaching a magnitude of 7.5. Because it was a slow, silent earthquake, most people were completely unaware that anything was going on.
Silent Events Could Help Predict Large Sudden Earthquakes
Scientists have been looking to studying the activities of areas, like Acapulco, where silent earthquakes seem to be common. This could be useful in determining when and where more destructive quakes will occur. They use slow events to gauge where stress points are, and where they are developing indicating where quakes might occur next. There's apparently been little means to gauge and predict these things until recently.
Scientists and People Predicting Seismic Events
Ben Davidson is one well known person who has been predicting earthquakes with surprising accuracy. He's pays attention to changes in the subduction zones, allowing him to accurately guess when there's a higher likelihood of these events occurring. There are youtube videos featuring a lot of the events he predicted, that have come true.
Life's Journey is a Learning Experience
Acapulco is the first place I've ever lived that's experienced earthquakes. The ones recently have sparked my interest, and the new information shared by a community member floored me. I had no idea there was a such thing as a silent earthquake. Some of the most intense seismic events aren't even noticed by the anyone (save for scientists who are now looking for this sort of thing), which is amazing.
These slow events have low chance of turning into a catastrophic event, so areas prone to these are likely to experience less of a chance of a devastating quake, which is good news for Acapulco. If there were to be a huge quake, there's potential for a lot of damage to come from it, likely to devastate Acapulco and surrounding areas. Luckily, the chances of that are low, and with the work scientists have been doing recently, we could even be able to see such an event coming so long as we pay attention. This sort of thing has a lot of potential to help the world, we'll just have to watch and see where it goes.