Thanks for your very interesting--if difficult--question, Ryan.

Earthquakes remain extremely difficult to predict. A lot comes down to the question of what one means by "near future." To a High School sophomore, that might mean tomorrow, but to a geologist that might mean 10,000 years. "Strong," also has to be defined.

As you know, California is extremely active seismically--for one thing, the North American and Pacific plates grind past one another along the San Andreas fault. Segments of that fault let loose on average every couple of hundred years, causing large earthquakes. Some sections of this fault (and others related to it) are "overdue" for an earthquake, meaning we have reasons to believe these sections haven't moved for longer than their historical average repeat times.

Check out the nice map in this article. It gives the seismic risk almost like a weather forecast. Instead of saying, "tomorrow there's a 20% chance of rain," this map shows what the chances of an earthquake greater than magnitude 6.7 occurring over the next 30 years are. As you'll learn, California will see plenty of strong shaking in its future.

We know California can experience frequent - and sometimes very destructive earthquakes (EQs). Identifying the locations where we expect frequent large EQs can help us prepare for these inevitable events, but scientists cannot yet make accurate predictions of the date, time, and place. Instead, we use probabilities to inform how hazardous an area is. Our best guess is that there is a ~98% chance that one of the many faults in California will experience an EQ with a magnitude of ~6.5 or higher (quite destructive) within the next 30 years. The fault with the highest probability of a large magnitude EQ is the southern section of the San Andreas. We predict that there is a 60% chance that the San Andreas will experience a destructive EQ in the next 30 years.

To understand how and why we use probabilities... First, it is important to know that EQs occur along faults. Faults are breaks in the Earth's crust and are most often found all around the boundaries of tectonic plates. The largest fault in California is the San Andreas Fault, which is the boundary between the North American and Pacific Plate. As the plates try to slide past each other they get stuck, and stress (force per unit area) builds up between them. When enough stress accumulates, the Earth's crust can break along this boundary and release all the energy that has built up (think of trying to push a refrigerator and it doesn't move until you push it really hard and then it suddenly breaks loose and slides very rapidly). This release of energy causes shaking, which is very destructive. Sometimes, it doesn't actually break along the plate boundary and another piece of the crust will break. Over the last 20 million years, many pieces have broken, and California is full of faults. It is like a broken windshield. There are some larger faults and some smaller ones. Some are inactive and some are very active. The general concept is that the biggest EQs occur on the biggest and most active faults. We can map some of the faults at the surface and dig trenches across them to look at the history of EQ's along them. Here we can determine the size and how often past EQs occurred.

When we can't see the fault at the surface we use methods from seismology to "see" the faults that are releasing energy (shaking) in the subsurface below and investigate their size and location. Lastly, we have GPS stations all around California to look at how the surface is moving (or not moving, like that refrigerator you were trying to push). Here we can see where the land is slowly moving (releasing stress along faults) and where it is not (building up stress along faults). If one area of a fault is moving slowly and one area is not, this means that stress is building up and it will inevitably break free and release a lot of energy. Sometimes small movements happen and we get magnitude 1's, 2's and 3's ....etc. The cool thing about this is that the size of the EQ's follow the Gutenburg-Richter Law. This law says that for every single magnitude 10 you have, you will have 100 magnitude 9's, and 1000 magnitude 8's, and 10,0000 magnitude 7's....you see where I'm going with this. There is a nice scaling relationship between the size and the frequency of EQs that occur. So, all of these things (mapping, digging trenches, seismology, GPS positions, and scaling relationships) help us assign a probability to which faults are most active and when and where we think they might occur. It's a very tough and interesting problem!!

Here is a map of the most hazardous faults in CA. They are outlined in red. The shaking can affect larger areas though. It's good to be prepared and know what to do in an EQ. So, check out these websites to calculate the hazard where you live and to brush up on what to do before, during, and after an EQ 1. temblor.
2. earthquakecountry.

Scientists can not predict an earthquake, but they can forecast them! There's a BIG difference - a prediction means that you are giving an EXACT time, place, and how strong - and that's impossible to do. We can forecast earthquakes by looking at how often they occur along certain faults, how large they tend to be, and how long it's been since an earthquake occurred on a certain portion of a fault.

So, because every bit of fault in CA is different, there's a different probability for an EQ to occur depending on where you are! And, there's always a greater probability of a smaller earthquake occurring (see here screenshot ).

Lucky for you, the State of CA made an Earthquake Rupture Forecast back that answers your EXACT question (and it's attached! )

Seismologists make EQ forecasts for 30-year periods because that's the length of the average home mortgage, and that's what people care about. You can see the difference in EQ forecasts between San Francisco and Los Angeles here.

That depends on how long is the "near future". Powerful earthquakes are inevitable. They will happen. I don't believe that we can predict them with certainty.

The most powerful earthquakes that the types of faults along most of the coast of California produce are magnitude 8 earthquakes. You need subduction trenches, which only the northernmost part of California has, to produce magnitude 9 earthquakes.

Los Angeles area: Within the next 30 years the probability is: 60% that an earthquake measuring magnitude 6.7. 46% that an earthquake measuring magnitude 7. 31% that an earthquake measuring magnitude 7.5.

Neither the USGS nor any other scientists have ever predicted a major earthquake. We do not know how, and we do not expect to know how any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur in a specific area within a certain number of years. Predict earthquakes

No, California is not going to fall into the ocean. California is firmly planted on the top of the earth's crust in a location where it spans two tectonic plates. ... There is nowhere for California to fall, however, Los Angeles and San Francisco will one day be adjacent to one another! Read here.

There was a popular song about San Francisco falling into the ocean when my family and I were living near there. Then there were some little earthquakes, and we moved back home to Santa Barbara 1 day earlier than we were planning to. That was in 1980.