A pause in the disaster

1 March 2021

Early on in the Covid-19 pandemic, it occurred to me that the nationwide disease outbreak was exactly like what most of us call “natural disasters” — floods, droughts, heat waves, wildfires, hurricanes, landslides, earthquakes of course, and the like. And in the literature, and on Twitter, I started to pay more attention to the specialists. Not so much the specialists in the phenomena, although those are crucial people, but the specialists who call themselves part of the disaster community: social scientists rather than natural scientists.

Those are the people who hate the term “natural disaster.” They’ll tell you “there are no natural disasters.” By that they mean an insight that galvanized me when I first read it a generation ago: “Human beings, not nature, are the cause of disaster losses. The choices that are made about where and how human development will proceed actually determine the losses that will be suffered in future disasters.”

It underlies what I do in this blog. It was in this book.

Disasters by Design came out in 1999, the outcome of a conference of disaster-related specialists sponsored by the National Science Foundation and several federal agencies. It laid out an ambitious vision of how society can deal with the disasters that happen when we get in nature’s way.

First, it pointed out that our current practices of mitigation aren’t enough. Our warning systems, building codes, and other measures succeed only in saving lives. Consider the case of hurricanes: they no longer kill many people, but they still cause record-breaking economic losses every year. Even the small ones cost more these days. Hurricanes haven’t changed much at all, but we have. The Northridge earthquake of January 1994, not such a big one, killed only a few dozen people, yet it caused more than $20 billion in insured damages alone.

And our mitigation measures have bad side effects. For example, the hurricane warning system makes people feel safer, but now it’s harder to keep them from building on the beach, from paving the dunes, from moving sand from one coast to another for short-lived patches on degrading shorelines. And in earthquake country, new structures preserve people’s lives, but the growing population is still vulnerable, living too far from jobs and served by elaborate electrical and water systems. People die less and less, but they keep paying more and more. Surely we can do better.

Disasters by Design explores how to go beyond mitigation toward a more resilient way of life, one that rolls with nature’s punches and returns to normalcy quickly. This desirable goal, “sustainable hazard mitigation,” means living politically the way we live personally, in ways our descendants won’t end up paying for. And if it’s done right, the community gains benefits beyond the insurance that the new policies provide — the people and their institutions are stronger, and wealthier too. That great work needs the help of social scientists, whose research on the people side complements the expertise on the engineering and prediction side.

The reason this book was a best-seller for its publisher, used as a textbook for a generation of practitioners and launching a movement in and beyond the disaster community, was its author. Social scientist Dennis Mileti was a gifted communicator who could hold an audience without a PowerPoint deck, a teacher who always had time for a student, and a leader who knew how to energize and drive diverse committees and teams. He went to the same conferences I do, and I sought out his talks.

Mileti died of Covid-19 on 30 January, two days before he was scheduled to get the vaccine. Last year he told a writer for the Washington Post that America’s approach to the pandemic scared him: “We have people saying, ‘It will be over soon!’ and other people saying, ‘It could be months.’ That gives the public the ability to pick the answer they like, which is the No. 1 no-no in public messaging.”

I opened my copy of his book last week — and it’s his despite having dozens of contributors — and it does not read like it’s 21 years old. The vision is still strong and the insights are still valid. You might say that means we haven’t achieved sustainable hazard mitigation, and in truth that’s a very difficult project. It takes everyone’s involvement, under skilled and patient guidance, to change a community.

But for some reason being reminded of the vision is still inspiring. And over the years I’ve seen the vision infiltrating my own piece of the disaster community, the Earth hazards sector. Tsunami specialist Lori Dengler wrote an appreciation of Mileti just last fall, which reminded me that he was involved with the ShakeOut earthquake-drill program, and before that was an advisor for this pamphlet many of you may remember from after the Loma Prieta earthquake. Dennis Mileti worked here too, for us.

And that’s just the earthquake crowd. He was involved with the full range of disasters, bringing insight into how to communicate alarms and alerts, what motivates genuine change, what steps to take beyond reciting facts at people. And yet it was a funny thing: while Mileti died of Covid-19, Disasters by Design doesn’t address disease epidemics. But over the last year I’ve read a lot of pandemic coverage, and awareness is seeping in that disease outbreaks are just part of this planet, and that if we are creating situations where animal viruses can leap to our species — imperiling ourselves by getting in nature’s way — then Covid-19 is just as much a “natural disaster” as a levee break during a flood.

It may be time for a new book that adds pandemics to the rogues gallery of disasters. It would be fitting if we could tie together the lessons learned from the pandemic and the quest to bring about sustainable hazard mitigation. Sustainability is about not just growing wisdom, but also passing wisdom forward, and Dennis Mileti did both. Let us not forget his name.

The Paleocene blob revisited

15 February 2021

It may seem to readers like I’ve been out in the field during the past year, but in fact I’ve been holding back since the lockdown last March, taking my own advice. Last week, on the verge of receiving the Covid vaccine, I decided to formally resume geologizing, and start by giving a small patch of rocks a new, more thorough inspection.

It was thirteen years ago when I first reconnoitered this odd little area of rocks, shown on the geologic map as unit Ta, “unnamed glauconitic sandstone (Paleocene).” It’s described as “coarse-grained, green, glauconite-rich, lithic sandstone with well-preserved coral fossils. Locally interbedded with gray mudstone and hard, fine-grained, mica-bearing quartz sandstone.”

Here’s a closeup in Google Maps with the outline of the “Ta” unit. It manifests as a ridge-forming substrate that is undermined by an active landslide scar (part of which is the notorious Snake Road/Armour Drive landslide) on its northwest end.

In a systematic approach, I sought out the three places marked on the map with strike-and-dip symbols. (I used this same strategy a couple years ago with the overlying Eocene mudstone unit.)

The northernmost site, at the stub end of Armour Drive, is hopeless; it’s been thoroughly disrupted by the Snake Road landslide, and the fortress houses being built on the scar will disturb it more as the owners landscape their grounds. There were no good exposures at all, let alone one showing beds dipping 80 degrees south. But this is what some of the rock looks like: a dark siltstone with a greenish tinge and a bit of clay in it.

The middle locality was where my hopes were highest — an aborted foundation pit on Saroni Drive where the “well-preserved coral fossils” had been documented. In fact, I had asked Russ Graymer, compiler of the geologic map, about this pit. That was in 2009, which by his account was 14 years after he’d visited it (or a good 25 years ago today). He replied that his notes from the site were as follows: “The rock here is massive, black, coarse-grained, glauconitic sandstone and pebbly sandstone. There are many fossils here, including pecten, coral (Paleocene?), shark teeth, and snail. There is also pink-brown siltstone and brown mudstone.”

All I can say is I wish I’d been here 25 years ago.

I gave the site a thorough look, without hammering anything as is my practice. I saw no pebbly mudstone, not even any coarse-grained sand. I noted clayey siltstone and silty shale, hard here and soft there, with fine to massive bedding. On the lefthand side the shale beds were vertical, with the upper side to the east. Nothing that I could possibly interpret as overturned beds with a 60-degree dip.

Elsewhere the rocks had no reliable bedding. Down in front were some crumbling mudstone boulders. One of them had some vague fossil-like shapes that fizzed in acid, but the eyes can be fooled and our rocks commonly have some lime in them. It’s not always meaningful, though I always check for it.

You may wonder how this rock unit was determined to be of Paleocene age, unique in Oakland. As I recall our conversation, Graymer was accompanied that day by Earl Brabb, who said the corals reminded him of Paleocene corals he knew from the Santa Cruz Mountains. In fact I wrote Brabb for more detail and he replied with the location of the roadcut he had in mind. But I never got over there, the email was lost, and Earl Brabb died a few years later. Now I would never gainsay Brabb’s judgment — he was a top-tier field geologist — but that’s the main line of evidence behind this age assignment.

I wish he had been with me at the third site. It’s under a power-line tower north of a bend in Balboa Drive and consists of thin-bedded siltstone, nicely tilted. This spot, at least, is still good.

The roadcut on Balboa Drive was where I hit paydirt. Bedding surfaces were exposed that included sole marks. These occur on the underside of beds, and they indicate that here the rocks are overturned, contrary to what the map shows.

And in the gutter of the curve, buffed by errant car tires, were a couple of these round, laminated objects nestled in situ among the siltstone beds. They responded to acid, indicating that the laminations included calcite. And the rocks nearby displayed a fine vein of solid calcite about 4 millimeters thick.

I would peg these as some sort of fossil, but Earl Brabb might well have said they were just like the Paleocene corals he knew from the Santa Cruz Mountains. The setting could have been a cold seep, such as are known elsewhere in the Great Valley Sequence.

The rocks of the Oakland Hills are poorly organized and poorly exposed, and hence not really well mapped. They’ve been overturned and broken and shuffled around. Whenever I try to make sense of them I doubt my senses; that’s the way the Earth just is here. A geologic map is as much an exercise in imagination as in observation. The pros are certainly better mappers than I am, but they aren’t superhuman and their work can be interrogated; the rocks can speak differently with each visit. The outline on the map, as far as I can tell by checking around its edges, is fairly correct — you’ll notice that every line is dashed, meaning it’s inferred, not firmly nailed down.

The “Ta” rock unit hasn’t revealed itself to me as a coarse-grained green lithic sandstone, more like a fine-grained sorta greenish lithic siltstone. Geologists train themselves and have tools to specify rock colors, but to me green is always suspect; our woods favor mosses and algae, and our weathering environment favors rusty colors.

The rock here is definitely something other than the Redwood Canyon Formation to the south and the Eocene mudstone to the north. It’s a little piece of somewhere different.

Mapping rocks never ends

1 February 2021

A few days ago I took part in the latest monthly meeting of my local geological society — we do it via Zoom these days — and our speaker, Christie Rowe of McGill University, reported on three research projects her grad students are doing in the Bay area, specifically the Franciscan Complex. The Franciscan is a scramble of different rocks that has challenged geologists since they first came to California.

Fifty years ago Stanford’s Gary Ernst recognized that the Franciscan represents the mess of material that gathers around a subduction zone, where oceanic crust (a now-extinct neighbor of the Pacific plate, in our case) slides beneath continental crust (the North America plate). So now we know what it is — the tectonic equivalent of the dirt in a bulldozer’s blade — and prompted by that knowledge we can try to unscramble the mixed-up pieces and learn what they might tell us about California’s geologic history or what happens in subduction zones.

Rowe is a Marin County native who’s been working since her PhD days on the latter problem, in the Franciscan rocks of her home ground. Specifically, she’s been looking for preserved bits of ancient earthquake faults. Normally these are buried deep underground, but they’re important because subduction-related earthquakes, so-called megathrust events, are the largest on the planet. Think of the 2011 Tohoku earthquake in Japan, the magnitude-9 monster whose tenth anniversary is coming up on 11 March. The Marin Headlands are full of them, broken in pieces.

Rare bits of the Franciscan have survived being subducted deeper than 25 kilometers and then returned to the surface, without totally wiping out what happened to them down there. The work requires dogged persistence. You have to look hard to find these “high-grade blocks” in the first place, then put your face close to them, magnifiers out, detect signs of slippage, then bring samples to the lab and determine what that slippage means — whether it happened on the way down, on the way up or afterward as the San Andreas fault system wrenched it all sideways.

Heart Rock, at Jenner Beach up the Sonoma coast, is small enough to fit inside a living room. One of Rowe’s grad students is mapping it at centimeter scale, spending a master’s thesis worth of effort on this one outcrop looking at rocks like this.

Seeing all this during Rowe’s talk took my mind, among other places, out to the rocks of Shepherd Canyon and Redwood Peak. The last person to give those strata a PhD-level scrutiny, using all available tools of the time, was a Berkeley grad student named Jim Case around 1960. Yes, 1960, a time when researchers were stuck in a mental framework of now-forgotten concepts and plate tectonics was still years in the future, when optical microscopes, brass seives, fossil correlations and test-tube chemistry were the best tools we had.

Case got his PhD, demonstrating that he’d mastered these tools as well as the literature, but he didn’t accomplish much more than correct a couple of ideas from earlier studies, establish a few new rock units on the map and tentatively correlate them with other units scattered around the East Bay. He put his little brick into the Wall of Science, then went on to a long research and teaching career doing other things.

Since then, other distinguished geologists have been over this territory. Case collaborated with Dorothy Radbruch of the USGS, a sharp and able field geologist. And in the late 1990s when Russ Graymer was putting together the East Bay geologic map that I rely on, he tramped the area with the late Earl Brabb and was ably advised by the late David Jones. Each of these workers found new things and revised their predecessors’ achievements. It always paid to reinspect the rocks. Nevertheless, none of them pulled out all the stops and pioneered a new in-depth reassessment of this interesting area.

We could do much better today. Every tool has advanced. The jigsaw puzzle of ancient California is far enough finished that any piece, if studied closely enough, can be placed on the table near — or even exactly on — its correct position and joined to other pieces. This would be more satisfying than what Case could accomplish in his time. We just need another grad student to take it on, another local who has imprinted on his or her home ground.

Mapping never ends, and geologic mapping always improves. New bits of rock are being exposed all the time. Fresh eyes see new things, and persistence furthers.

Anza and the Fan

18 January 2021

After Pedro Fages came through the East Bay in 1770 and 1772, no one from New Spain appears to have visited the land on which Oakland sits until Juan Bautista de Anza led an exploring expedition here in the spring of 1776. Scholars seem to be quite sure of where the group went, but when I examine the record I find more and more room for interpretation and inference.

I’m not going to pretend I’ve examined the manuscripts or know 18th-century Spanish. I’ve accessed translations of those manuscripts and, well, here’s some of the questionable things and wiggle room I see in the record.

  • Apparently no one in the group, neither Anza nor the group’s diarist, Father Pedro Font, had been with Fages in the earlier visits, so they had only a slim written record to compare against the countryside they saw. We can’t rely on their interpretation, especially as it appears they took a different route than Fages.
  • We can’t rely on their directions. The East Bay from Berkeley south is persistently slanted 33 degrees west of north (thanks to the Hayward fault and the plate boundary of which it’s part) making it hard to eyeball true directions; magnetic north was apparently 12 degrees east of true north at the time (thanks, NOAA); and Font complained about the poor quality of his compass, so the explorers’ impressions are suspect. The men were not experienced sailors either, people I might trust, but army soldiers. Moreover, I wonder about the transcriptions. There seem to be too many instances of “northwest” (noroeste) and not enough of “northeast” (noreste) to fit the written route on modern maps. And the scholars, whom I trust on this topic, point out that very discrepancy between different copies of these documents, all of which were made by hand.
  • We can’t rely on their distances. No one had odometers. Font did his best, prefacing his notes with a discussion of the length of the Spanish league (approximately 2.6 miles, apparently), but even so the men were on horseback whereas Fages had been on foot. On the day they came through Oakland, Anza wrote down that they went “about ten leagues” while Font put it at “some fourteen leagues.” The day’s ride was long, from Hayward to Pinole, and the group was in a hurry, with their goal still ahead of them. (And just as Fages had complained in 1772, the Anza party was beset with mosquitoes all that day.)

Long story short, I think that whereas Fages mostly skirted the Fan as he sought (and failed to find) an easy level route through Oakland, Anza rode pretty straight through it.

Anza’s group set out from their camp on San Lorenzo Creek, in present-day Hayward, that morning at 7 and rode along the foot of the hills, with a jog upstream to get across the deep arroyo of San Leandro Creek, and then on to the edge of the Fan, the hill of Pleistocene gravel occupied by Evergreen Cemetery, in the lower right corner of this digital elevation model.

Where Fages turned left to stay on the flats, Anza headed the horses straight, toward a promising gap in the hills,

and into the Allendale flat. Almost fifty years later, Luís Maria Peralta’s family would put the first hacienda on their huge East Bay land grant there, just across Peralta Creek. “About two leagues” after crossing San Leandro Creek into Oakland territory, Font wrote that they “crossed a small arroyo without water and almost without trees,” which I think was Peralta Creek. “Then a little further on we ascended a hill which is on a straight line with the mainland and the plain which runs toward a very thick grove of oaks and live oaks on the banks of the estuary,” where he sketched the view toward the Golden Gate. That is this drawing, showing the Alameda peninsula flanked by San Leandro Bay on the left and the Estuary on the right:

In my interpretation, he would have been sitting on the ridge where Patten University sits today but higher up, maybe where Lincoln Avenue starts today. It also could have been down on Carrington hill; both ridges line up with the Alameda peninsula, which was a large encinal (live-oak grove) at the time.

“Then, descending the hill, we crossed another arroyo almost without trees and with some little pools of water which did not run. This appears to be the arroyo which Father Crespi called the Arroyo del Bosque and which empties into the extremity of one arm of the estuary.” He refers to Sausal Creek as described by the Fages party in 1772.

“We continued the journey over hills and plains, crossing two more arroyos with little water, deep beds, and a heavy growth of trees, the second one having more than the other, and both of them flowing into a bay which the arm of the estuary forms on this side.” These I interpret as Indian Gulch and Pleasant Valley Creeks, which clearly both drain into Lake Merritt, which was then a narrow inlet with wide mudflats. I don’t think the group went near the Lake but instead were higher up the valleys — they were on horseback, after all.

“Afterward we entered a plain in which we crossed two small arroyos without water.” Finally they had left the hills of the Fan and were back on the East Bay plain. That would make these two streams Temescal and Strawberry Creeks. “From this plain we clearly descried the mouth of the port, and when the point of the red cliff on the inside was in line with the outer point of the mouth, I observed the direction in which they ran, and saw that it was to the west with some declination to the south.” That matches the view of the Golden Gate as seen from Berkeley.

Oakland remained something of a distant place until the San Francisco and San Jose missions had captured or driven off the native people and established their own purposes on the territory: food and fodder cultivation in the Richmond area and cattle range in the flats from Fremont to East Oakland.

I want to note that Fages and Anza did not come as conquerors. Their assignment, at the dawn of Alta California, was to establish friendly relations with the natives. They exchanged gifts with every group they met: glass beads, generally; and a surprising number of native groups gave them duck decoys in addition to food. The situation did not last. The priests could not even perceive the fine-tuned ecosystem in which the Ohlone were the keystone species, only naked children of nature who must be trained in their own god’s image.