Philadelphia’s 1884 tsunami

August 10, 1884 – Sunday – Philadelphia, PA to Trenton NJ and The Highlands, NJ

From the National Weather Service:

The earthquake struck about 209 pm and was a strong one for this area, registering 5.2 on the Richter Scale. It occurred during the afternoon when most people were up and about, and one of the effects on the waters occurred in Philadelphia. Shipping was affected, especially on the Schuylkill River’s confluence with the Delaware River. From The New York Times:

“The large ships loading petroleum on the Schuylkill River snapped their hawsers, and were only prevented from going ashore by the united efforts of their crews. Several large steamers were thrown strongly against the wharves in the lower section of the city, and the crews thrown out of their bunks. Huge waves backed up the rising tide, overflowed many of the wharves, and considerable property was flooded thereby. In several instances where persons were watching the river from the docks, they found themselves suddenly overtaken by waves, and were thoroughly soaked. Deeply laden steamers in the Delaware trembled without apparent injury during the existence of the shock.”

The Captain of the ferry boat “Dauntless,” on the river, was not aware of the quake until docking. The Chief Officer of the Windsor line steamer “Spartan,” experienced a “shaking of the vessel, similar to that caused by rolling a truck over the deck.” The ship rolled, as if rocked by an unseen hand, but was positive that the vessel was not in contact with the wharf. The Engineer of the docked large iron steamer “Lenora” stated that the water in the dock rose considerably. Just a little away from Port Philadelphia on the NJ side is Gloucester City.

At Gloucester City, the water in the Delaware suddenly arose, and waves 5 to 6′ high dashed over the banks immediately after the vibrations were felt. Several boats in the stream at this place were upset, the occupants having no warning; and, when they found themselves floundering in the water, they were unable to account for it. This location is on the border of Gloucester and Camden counties. A report was received further north from Burlington County. The Captain of the “Doron” noticed that the vessel reared up on her keel a little about the time the shock occurred. Also in this area, the waters of the Stop-the-Jade Creek were visibly affected; and, a number of dead fish were found in the Pensaukin (Pennsauken) Creek, which fishermen thought were killed by the shock. The last and furthest north report was from the Delaware and Raritan Canal and the Feeder, where a small tidal wave was observed. The Feeder brought water from the Delaware River north of Trenton, NJ, into the canal. The canal from Bordentown, NJ, to Trenton, had 7 locks, because of the difference in elevation of 57′ between the two cities. Perhaps this small tidal wave was independent of the river events, or possibly not. One possible scenario for all these reports is that they all occurred independently of each other. Another possible scenario connects them all.

The shape of the Delaware Bay is conducive for a tsunami to be funneled into the Delaware River. The Bay has a wide mouth gently narrowing to the river. A tsunami traveling up the bay would convert into a bore, which allows the tsunami to travel further inland than it ordinarily would be able to do. The received river reports suggest this to be a strong possibility, with this bore benefiting from a rising tide. The very strong river response at Port Philadelphia was at the confluence of the Schuylkill and Delaware rivers. A bore traveling upstream would tend to become partially diverted here, moving directly toward the docks on the Schuylkill and creating the reported havoc. The ship in the deep waters of the Delaware river was basically unaffected. At Gloucester City, the river snakes sharply, with the bore flowing to the ENE then to the NNW. This would be another natural impact area for a bore.

The next report from Burlington has a vessel rearing up on her keel. This part of the Delaware river is mostly unidirectional. There probably should not be as much activity in this region, compared to bend and curve regions. The last report is the canal. The river curve here makes the canal entrance a natural impact area. If the reported small tidal wave on the canal and feeder was related to the river bore, it could not have directly entered the canal system because of the lock. However, a tsunami contains a lot of energy, even as far up a river as Bordentown is. It might be possible that the wave slammed against the lock and transferred energy into the canal system, thus creating the small tidal wave. Ocean activity also occurred with this quake.

Steamers in New York Harbor were lifted 4 times in succession by the waves set in motion by the subterranean convulsions. Two fishermen off the NJ Highlands experienced a variety of sensations. “They experienced a sensation as though the water had all gone out from under the boat and it was grating on the sand. The water boiled around them, and they felt a distinct shock, though not like that which visited the people on shore. The shocks came closely together. The 1st one was like the concussion from a heavy explosion, and the 2nd was vibratory and the most severe.” The brig “Alice,” arriving from the Turk’s island, felt quite plainly the shock, when 7 miles off the Highlands. The Captain “felt a heavy shock, accompanied by a rumbling noise, and it seemed as if the vessel had struck a submerged wreck. The shock and rumble continued long enough for the vessel to have passed over a wreck. The pumps were sounded, but the brig was not found to be leaking.” Captain Strum thought it might have been a quake; but, the shock was the most severe he had ever experienced, so he initially thought the “Alice” had struck something. The Captains of other arriving vessels reported feeling the shock.

Many ships, even in deep ocean water, relate the experience in a quake of appearing to have become suddenly grounded, until a depth reading shows them to still be in deep water. The sailors then realize that they had experienced the effects of an earthquake. Perhaps our two Highlands fishermen were close to shore and in shallow water, that they had indeed scraped bottom, should an ocean recession along the shore had occurred? The water boiled around them is similar to the description of the storm raging on the Long Island Sound in the 1871 quake. This also describes what the previously discussed Discovery Channel’s program vividly showed, a boiling ocean caused by the release of hydrate gas. On the Hudson River in the vicinity of Marlborough (Marlboro), NY, boatmen said they felt a peculiar sensation, and one of two noticed a depression in the channel.

Was this depression a “parting of the waters”, with waves being thrown up on both sides of the river’s banks? Or, did a type of river recession occur on the Hudson, in response to the activity in NY Harbor and the neighboring Atlantic? Using this quake in trying to determine the reaction of Mid Atlantic rivers flowing into the ocean, perhaps the Hudson depression was a type of river recession, a version of the trough of a tsunami arriving first; and, the Delaware River havoc was a bore, the crest of a tsunami arriving first. Because of this Delaware River event, the 1840 Great Swell on the Delaware River, and, possibly, information-when-found on events on the river during the 1817 quake, deep consideration must be given not only to future tsunami damage along the ocean shores, but also along the inland banks of vulnerable rivers, with particular attention given to their sudden bend and curve regions.