Geobulletin alpha

Concord fault update 2025 

When I wrote about the Concord fault last year, I showed places where the fault is easy to see by the way it pulls apart street curbs and makes cracks in paved areas. I stayed in the northern part of town, mainly for lack of time, but I said, “There are probably other similar features

Earthquakes and engineering 

I live in earthquake country, but I confess I’m no better prepared than most people. I witnessed our 1957 and 1989 quakes, plus dozens of smaller shakers. I learned a bunch of earthquake-related science in geology school, and more since then. The media tells me to be ready for the next big one. I tell

M4-M5 earthquakes in the Awash area of Ethiopia (late 2024) 

There have been numerous M4-M5 earthquakes in the Awash area of Ethiopia over the last few months. This is within the Main Ethiopia Rift at its NE end where it begins to open into the Afar. In the old days, and our support crew still will, we used drive right through there. You may also recall that there is a young volcano Fentale in that area which had an eruption last in 1820. As far as I can see from the USGS, there have been 16 >M4 earthquakes in the area since Sept 2024 (LINK): [...]

Further earthquake reading: Philip Fradkin 

Lately I’ve been going through my bookshelf and revisiting some memorable titles by and about geology, from the 1830s to today. Today I want to share three standout books of particular relevance to Oakland readers, all by the late Philip L. Fradkin (1935-2012). They constitute his “earthquake trilogy,” published between 1998 and 2005. They all

Our ongoing earthquake 

The other day I strolled the length of Center Street, a kilometer of pure classic century-old West Oakland residences. Along the way I passed Cypress Freeway Memorial Park, the park at Mandela and 14th that commemorates the 1989 earthquake. This is the back end―that is, at Center and 13th Streets. I was stopped in my

Heritage versus survival 

The Hayward fault, as many have noted, is the most threatening earthquake source in the Bay area. It won’t necessarily produce the largest possible quake in these parts, but in terms of likely damages — dollars and lives — it’s number one. And it’s ready to let loose, maybe as you’re reading this post. HayWired,

Earth’s inner core has an inner core? 

We all know that the Earth’s mostly iron core is divided into a molten outer core and solid inner core. But that may not be the whole story: some just-published seismic data suggests that the Earth’s inner core is divided … Continue reading →

What name shall we give Earthquake? 

I think about earthquakes nearly every day, in one aspect or another. Every now and then I toy with the pre-scientific ideas about them. Before science, before literacy itself, every culture stored knowledge about the world in the form of images and especially in stories, told and sung, that were passed down the generations. Natural

A deep origin for the Tohoku earthquake? 

So if I’m reading this summary in Eos right, there is a new study suggesting that there was significant deformation of the subducted plate in the lead up to the M9 2011 Tohoku earthquake occurred – enough mass was redistributed to measurably … Continue reading →

Readings: Deep Time Mexico, Neanderthals, Early Mammals 

Relish these articles.1) Mexico City Deep Time Sickness.  Modern day Mexico City is built on the bed of lakes that formed around 2 million years ago. The Mexica people in the 14th century constructed a series of dams and dykes partitioning salt water and fresh water areas. They developed agriculture called as 'chinampas' on islands made up of mud and organic debris. This region became the

The long-term seismic impact of mega thrust earthquakes 

Here’s a very interesting analysis of aftershock patterns in the wake of M9+ megathrust events: the aftershocks in a ‘core’ region closest to the rupture shut off within a few years of the main shock, after which seismicity might remain … Continue reading →

Utah's Pandemic Earthquake of March 2020 

Continuing on through my pile of photos I come across the start of the lockdown in March of 2020 and I am reminded that at the very start of the lockdown, Utah was hit with the largest earthquake it has seen in recent memory and the largest earthquake I personally have ever been a part of.  On the morning of March 18th, 2020 at 7:09 am local (MST) time, western Salt Lake County was hit with a 5.7 magnitude earthquake. At the time we lived in the valley to the west, not 13 miles from the [...]

Stop saying “overdue” 

The last week has had its share of local earthquake news, even though there weren’t any earthquakes nearby. It all centered around the release of volume 3, the last part, of the massive HayWired Scenario report, conveniently timed for 21 October, anniversary of the 1868 Hayward earthquake (not to be confused with the 17 October

Why do we get earthquakes a long way from plate boundaries? 

There’s already a lot of good info out there about this week’s magnitude 5.9 earthquake near Melbourne, Australia. I wanted to dig a little more into the broader reasons you can get earthquakes like this in places you might not … Continue reading →

The HayWired scenario of lost homes 

Soft-story damage in San Francisco’s Marina district, 1989. Retrofit programs in Oakland aim at preventing this kind of destruction. As you all know, the Hayward fault runs through the middle of Oakland and the whole East Bay, and as you all know it will rupture some day in a large, destructive earthquake — a catastrophe

Mountain View Cemetery’s earthquake plot 

The pandemic has eased enough that Mountain View Cemetery, the Bay area’s finest landscape, has opened its gates again to the public, though only on Wednesdays and Saturdays for the moment and with an earnest plea for your good behavior. Thus on Wednesday I was finally able to visit Plot 1, where the first earthquake

Earthquake advice for Oaklanders 4: What to do 

The first thing to do about earthquakes in Oakland is PREPARE! Well OK, but prepare for what? To get our attention, a team of federal and state geologists got together a few years ago and prepared an elaborate forecast of a seriously large earthquake on the Hayward fault, a magnitude 7 rupture from Point Pinole

Earthquake advice for Oaklanders 3: The quakes 

The first two posts in this series were about the Hayward fault itself in Oakland and about the different types of ground in Oakland that earthquakes on the fault will affect. This post goes into some details about the kinds of earthquakes we can expect in Oakland. I’m going to try and ignore all the

Earthquake advice for Oaklanders 2: The ground 

In my last post I talked about the Hayward fault itself, the actual crack in the ground. I argued that the extra hazard of living right on the fault doesn’t add much to the risk, which is already high for other reasons. Those reasons are mainly two: the size of likely earthquakes and the type

Earthquake advice for Oaklanders 1: The fault 

The topic of this set of posts arises from the terrible wildfire season we’re experiencing in 2020, on top of the terrible pandemic, on top of the unemployment crisis, and other more distant events that may be affecting our friends and family. We’re all learning a lot about these topics because directly or indirectly they