Every week this summer, we'll be taking an historical tour of the Hollywood blockbuster by examining an older film that is in some way a spiritual precursor to one of the weekend's wide releases. This week: we all know that San Andreas brings back the noble and intensely clichรฉ-happy formula of the all-American disaster picture. What is perhaps a bit surprising is just how far back in history this particular lineage can be traced.

The greatest of all city theme songs, "San Francisco" ("...open your golden gate / You let nobody wait outside your door") feels like something that should have simply come into being spontaneously, not turned out as the result of something so crude as songwriters writing it. But that's exactly what happened: before it became one of the official songs of one of the world's great cities, it was written by Bronislaw Kaper, Walter Jurmann, and Gus Kahn as the theme for 1936's San Francisco, one of MGM's biggest productions that year, headlined by its A-listers Clark Gable and Jeanette MacDonald. It's common for even non-musical Hollywood production of that era to sport a big song (and with MacDonald in one of the lead roles, San Francisco can't help but start to drift into the world of the musical), but rare indeed for that song to be used in such a structural way as we see here: over the course of the movie, "San Francisco" starts out off as a brash declaration from the rough-and-tumble underclass of the Barbary Coast, the most long-lived outpost of the city's birth in Old West lawlessness, it gradually shifts into an audible signifier of the characters' humble, honorable pasts as they attempt to disguise and redefine themselves, and it finally ends the film in the same way it's been used for eight decades since: as an anthem for the pride and resourcefulness of the people of a city that survived and rebuilt in the face of one of the most destructive natural disasters in North American history, the earthquake of April, 1906.

For that is exactly the subject San Francisco takes for itself. Not the earthquake itself, precisely, though the very first thing Anita Loos's screenplay does it to remind us via a title card that at 5:12 in the morning on 18 April, the city was devastated by a major quake, and the second thing it does is to portentously roll back the clock to the stroke of midnight on New Year's Day, 1906. Thus the first three-quarters of the movie (which comes in just shy of two hours) take on a grim cast, as the reasonably conventional romantic drama that makes up the bulk of the drama clicks by without ever quite letting us forget that we're only months - weeks - days - from the onset of horror. But the movie is only about the earthquake symptomatically; its deeper concern is with the rugged survival instinct of its characters, the kind of people who'd set up shop in what was, in 1906, just s 57-year-old city and still very aware of its rough, brutal roots. The film is enormously guilty of making Sweeping Proclamations about the kind of people who live in a given place, but it's still one of the best combined tributes to and criticisms of the character of a community. You needn't go any further into the future than 10 months later to find Fox's In Old Chicago, a movie that's almost a carbon copy of San Francisco in its plot structure and characterisations, to see what this looks like when it's not going right. This picture might be corny as all hell and its depiction San Francisco might be clichรฉd, essentialist, and reductive, but it has the goods.

As is already clear, I suspect, the film's basic shape is identical to disaster movies for decades to come: we get to know the characters, we get (hopefully) invested in their hopes and dreams, and we are as wrenched as they are by the slashing interruption of death and destruction across the smooth development of a conventional series of dramatic and melodramatic plot beats. And for as much as the movie hangs a sign reading "mind the earthquake" around the movie right at the start, it's genuinely startling and confusing when the world finally starts to move - having seen the film twice, I managed to be caught completely off-guard even the second time. Before that all happens, though, we get a loving recreation of the Barbary Coast of decades ago, in which "Blackie" Norton (Gable) is the owner of the Paradise, one of the Coast's most beloved and glamorously tacky clubs. The film kicks off when he hires Mary Blake (MacDonald), a classically trained singer from Colorado who has been in San Francisco for several fruitless weeks, trying to make her fortune in California like so many hopefuls before and after. Mary's exquisite voice is too rich and big for the Paradise, and she's aggressively courted for a job by Jack Burley (Jack Holt), a member of San Francisco high society and manager of the Tivoli opera house. Complicating things, while Blackie and Burley feud over Mary's career, they're both falling deeply in love with her, and her attraction to Blackie gets in the way of her own best judgment for her career and her dignity. Complicating things even more, Blackie has been tapped by the rest of the Barbary Coast business owners to run for the city's board of supervisors, a position he takes not to help secure their crooked interests, but to help reform and rebuild the coast. And he thus makes a major political enemy in the form of none other than Jack Burley. While all of this swirls around, Blackie's childhood best friend, Father Tim Mullin (Spencer Tracy) tries to act as his conscience, but at least tries to make sure that Blackie can't drag Mary down into the mud with him.

The film benefits from a director with as tight a control of characterisation as Loos, and from director W.S. Van Dyke, one of those studio workhorses who has been almost entirely lost to history, but who could always be counted on for a drum-tight treatment of whatever story or genre was handed to him (his film with the longest shelf-life is undoubtedly The Thin Man, a crackerjack sophisticated comedy that resembles San Francisco only in that it is fearlessly well-paced and has a great central pair of performances). Having been gifted with a handsome reconstruction of 1906 San Francisco thanks to all of MGM's considerable resources, the filmmakers smartly fail to linger on it for the sake of sheer period spectacle, one of the most common mistakes of that studio's most prestigious film in that decade. Instead, the focus in on character and performance, with the result that the central trio of Gable, MacDonald, and Tracy are in great form: even stalled in the "beaming, moralistic Catholic" mode that he dealt with somewhat often at this point of his career, Tracy is up to some of his best work of the decade, while MacDonald is as good here as any anything she ever made outside of her defining collaborations with Ernst Lubitsch.

But Gable is the stand-out, given a tole that plays to every single one of his strengths, minimises his weaknesses, and guided by direction that encourages him to own the nastiness of his character rather than use his huge charisma to paper over it. Temperamentally and functionally, Blackie is a pure stock character, and there's nothing Gable can to do to fully eradicate that fact, but he does deepen it considerably. The actor and character mix sharp business acumen, borderline thuggish emotional bullying of Mary and Father Tim, and a goofy, sweet little boy attitude to love and the possibility of making the world a better place. He is a deeply enthusiastic figure, above all things, which makes his passions all the more moving (the way he cheerily snaps off the phrase "art-tistic achievement" is as good a line reading as any in Gable's career), and his blindly self-serving cruelty all the more horrifying, since we can so easily understand why his victims can be carried along with his pettiness.

Gable's performance is the thematic spine of San Francisco: the combination of can-do will and unsophisticated roughness that the film posits as the defining characteristics of the city's people. He makes such a life force on screen, in fact, that the movie can't quite cope with it: Loos's script, perhaps owing to jitters about glamorising bad boy behavior in the early Production Code era, obsessively ventriloquises Christian morality that it doesn't fully believe in, harping on Blackie's sinfulness and the danger he poses to Mary's very soul. But it feels very much not of a piece with the rest of the film, and the harder it tries to veer towards religion (which it does most strenuously in the final scene), the more inauthentic it feels. Doing good and being good isn't the film's true purpose: moral and spiritual ambiguity are where it's far more compelling and where it makes its strongest impact.

Gable, then, is one of the two reasons that San Francisco is more than an enjoyably polished studio picture; the earthquake itself is the other. It's not, maybe, the best effects work that could have been scrounged up, even in '36: the shaking sets feel an awful lot like shaking sets. But the sequence is a triumph of sound design (for which the film won its only Oscar, out of six nominations, including Best Picture) and even more of editing, which was overseen by John Hoffman for this sequence only. It's openly indebted to the Soviet montage theories of the late silent period, cutting between images with a frenzy that's impressive in the 2010s, and incomparably brutal and disorienting by the standards of the '30s. The savage chaos of the earthquake, the suddenness with which violence can strike, are both impressively communicated by this sequence; it is one of the triumphs of spectacular filmmaking in its entire generation. Even more so, given that it manages to achieve something that has evaded disaster movies since as long as they've existed (and this was by no means the first, though the genre began to take its most complete form beginning in the '30s): it depicts its disaster in an engrossing, spectacular way, while also making sure that we're not just exulting in mass death. The earthquake in San Francisco is utterly horrifying, showing how quickly and painfully human life could be snuffed out, and spending a great deal of time in the smoking, ruined aftermath, with Gable's glib Blackie turned into a shocked, dazed shell of a man as he moves through the devastation. It's closer to a horror movie than an action film, while also being as humane as any disaster picture on record. The passage of years would make onscreen devastation look more and more impressive and realistic with every new fad for the frequently-resurgent genre, but they'd tend to double-down on bland characters stuck in tired formulas (San Francisco is formulaic, but not bland), and this is one of those rare cases in which one of the earliest examples of a style is also among the very best.